Vitamin D Part 1: Is the Deficiency Epidemic Real?

[Regina] (0:00 - 0:10)
Kristin, I think we need to rebrand vitamin D, right? Viagra for bones. That's good, right?

 

It keeps your bones hard all night long.

 

[Kristin] (0:15 - 0:38)
Welcome to Normal Curves. This is a podcast for anyone who wants to learn about scientific studies and the statistics behind them. It's like a journal club, except we pick topics that are fun, relevant, and sometimes a little spicy.

 

We evaluate the evidence, and we also give you the tools that you need to evaluate scientific studies on your own. I'm Kristin Sainani. I'm a professor at Stanford University.

 

[Regina] (0:38 - 0:43)
And I'm Regina Nuzzo. I'm a professor at Gallaudet University and part-time lecturer at Stanford.

 

[Kristin] (0:44 - 0:49)
We are not medical doctors. We are PhDs, so nothing in this podcast should be construed as medical advice.

 

[Regina] (0:49 - 0:54)
Also, this podcast is separate from our day jobs at Stanford and Gallaudet University.

 

[Kristin] (0:55 - 1:11)
Today, I want to talk about vitamin D. For years, I've been hearing this claim that there is an epidemic of vitamin D deficiency in the Western world. Regina, you've probably heard this before, that most people are too low in vitamin D and that we should all be getting more.

 

[Regina] (1:11 - 1:31)
Actually, Kristin, to prepare for this episode, I listened to another podcast. I confess, yes.

 

[Kristin]Which one?

 

Huberman Lab. And Huberman said in his vitamin D episode repeatedly said that 70% of the U.S. population is inadequate, has inadequate vitamin D.

 

[Kristin] (1:31 - 1:52)
Regina, this is exactly what I'm talking about. Actually, first of all, that's wrong, and we're going to talk about why. But this is exactly the kind of statistic that you see thrown around all the time to support this claim that low vitamin D has reached epidemic proportions.

 

It turns out, though, that the entire basis for this claim was recently reversed in 2024.

 

[Regina] (1:52 - 1:53)
Really? Reversed?

 

[Kristin] (1:53 - 2:26)
Yep. But I think most people are completely unaware of this reversal, even doctors, and also unaware of the story behind this whole idea that there is an epidemic of vitamin D deficiency. Where did that even come from?

 

It turns out to be a fascinating story, Regina. It is a wild ride with lots of twists and turns that we are going to traverse in this episode, from a study on Hawaiian surfers to dueling medical guidelines and statistical cockroaches to a story about court cases on child abuse.

 

[Regina] (2:27 - 2:36)
So many twists and turns, in fact, that we had to divide it into two episodes, vitamin D part one, this one, and vitamin D the sequel.

 

[Kristin] (2:37 - 2:53)
Right. Part one focuses on this claim that a large swath of the population is vitamin D deficient. Part two will look at the body of literature that claims to show that raising your vitamin D level confers multiple health benefits, such as preventing depression and cancer and boosting immunity.

 

[Regina] (2:54 - 2:55)
I'm looking forward to that.

 

[Kristin] (2:55 - 3:14)
Regina, let's start by talking about where we get vitamin D from. You can get it from sun exposure. Your body makes vitamin D when your skin is exposed to UV light.

 

You can also get vitamin D from food and supplements. In the U.S., our milk is fortified with vitamin D. It's also found in egg yolks, oily fish like salmon, and in cod liver oil.

 

[Regina] (3:14 - 3:29)
Yummy. You know, given the choice between cod liver oil and a beach, I'm going with the beach because I grew up in Florida in the 80s, where tanning was an art form. So I confess I do love my sun.

 

[Kristin] (3:30 - 3:41)
Yes, the beach is definitely more fun. But remember, sun exposure causes wrinkles and skin cancer. I wrote a lot about this when I was writing for Allure magazine back in the day.

 

Regina, have you ever had your vitamin D checked?

 

[Regina] (3:42 - 3:51)
I did, actually. My GP checked it just a few years ago, and she actually told me I was too high.

 

[Kristin]
Too high?

 

[Regina]
Too high.

 

[Kristin] (3:52 - 3:55)
I've never heard of anybody being told that they were too high.

 

[Regina] (3:55 - 4:08)
Right. What is the opposite of a deficiency? Right.

 

A surplus. She didn't say, you know, hey, you're going to die tomorrow of vitamin D toxicity, but she was a little like, hey, maybe you can cut back on those supplements.

 

[Kristin] (4:08 - 4:08)
Wow. Did you look up the number?

 

[Regina] (4:09 - 4:18)
I did just for this episode, and it was 92. So that is 92 nanograms per milliliter.

 

[Kristin] (4:19 - 4:28)
Wow, 92. I'm kind of blown away by that. I had mine done a few years ago.

 

My GP just threw it in for good measure. It was 46 nanograms per milliliter.

 

[Regina] (4:29 - 4:31)
So half mine. Mine was double yours.

 

[Kristin] (4:31 - 4:33)
You are exactly double. Yes, yes.

 

[Regina] (4:33 - 4:37)
What can I say? I'm an overachiever.

 

[Kristin]
You are an overachiever, Regina.

 

[Kristin] (4:37 - 4:47)
And it's not like mine was low, right? My vitamin D is good because I live in California. I run outdoors.

 

So even though I try to avoid the sun, it's really hard to do in California.

 

[Regina] (4:48 - 5:01)
Yeah, mine was not just from the sun, it was coming from supplements.

 

[Kristin]
Large amounts of supplements, perhaps?

 

[Regina]
It didn't seem like it at the time, but I have a cut back since then.

 

[Kristin]
That's probably a good thing.

 

[Kristin] (5:02 - 5:42)
But neither of us would be considered low in vitamin D, right? My lab report indicates that below 30 nanograms per milliliter is, quote, insufficient in vitamin D and below 20 is deficient in vitamin D. And we are going to stick with those units today, the nanograms per milliliter, ng per ml.

 

Just be aware that vitamin D comes in other units as well. I'll put a note in the show notes of how to convert to the other units if anyone is curious. Just in case.

 

Regina, does your lab report give the same ranges for defining low vitamin D, that 20 and 30?

 

[Regina]
Yeah, it said the exact same thing.

 

[Kristin]
Okay, keep those two numbers in mind, 20 and 30, because they are going to keep coming up in this podcast.

 

[Regina] (5:43 - 5:50)
But before we get into the numbers, I'm wondering if you can give us a little science behind what is vitamin D? Why do we care about it? Why do we need it?

 

[Kristin] (5:51 - 5:51)
Right.

 

[Regina] (5:51 - 5:51)
Okay.

 

[Kristin] (5:52 - 5:58)
You need vitamin D to be able to absorb calcium and phosphate from your diet to build bones.

 

[Regina] (5:59 - 6:00)
Yummy. Phosphate.

 

[Kristin] (6:02 - 6:10)
Well, bones are kind of fascinating though, Regina. Do you remember back in our grad school days, I did part of my PhD thesis on bones.

 

[Regina] (6:11 - 6:15)
Oh, I think I had forgotten that. But it was bones and women runners, right?

 

[Kristin] (6:15 - 6:16)
Exactly. That's right.

 

[Regina] (6:17 - 6:19)
Do you remember anything?

 

[Kristin] (6:19 - 6:45)
Not much, I must admit, didn't really stick with me. But I do remember a few things. Bones have a soft part and a hard part.

 

They're made up of this flexible protein collagen mesh. That mesh is infused with calcium and phosphate. And it's those minerals, right, calcium and phosphate, that make your bones hard.

 

If you don't have enough vitamin D, then you can't absorb those minerals and your bones end up under-mineralized and too soft.

 

[Regina] (6:45 - 7:06)
Too soft. And you do not want soft bones.

 

[Kristin]
No. You want hard bones.

 

[Regina]
You want hard boners. That's what I'm hearing. Yes, I went there.

 

It's the theme of the podcast. Kristin, I think we need to rebrand vitamin D, right? Viagra for bones.

 

That's good, right? Keep your bones hard all night long.

 

[Kristin] (7:07 - 7:10)
That is a really good way to remember what vitamin D does.

 

[Regina] (7:10 - 7:12)
Come on, it's a lot sexier that way.

 

[Kristin] (7:12 - 7:24)
It is a lot sexier, yes. But we do, we want our bones to be hard, right? Bones.

 

[Regina]
Bones, boners.

 

[Kristin]
Right, so that they don't bend or break. All right, because you've probably heard of rickets, right?

 

[Regina] (7:25 - 7:25)
Rickets. Yeah, actually.

 

[Kristin] (7:25 - 7:36)
Kids get rickets when their bones are too soft due to the lack of vitamin D. And they get those characteristic bowed legs because the bones actually bend.

 

[Regina] (7:37 - 7:44)
Oh, okay. That's where the bow legs come from. I remember hearing, but you don't hear about rickets.

 

I feel like it's something out of a Dickens novel, right?

 

[Kristin] (7:44 - 7:54)
It's not that common in the U.S. because we do fortify our milk with vitamin D. It does still happen in the U.S., but it's not common. It is really common, though, still in some other parts of the world.

 

[Regina] (7:55 - 7:57)
What about adults? Do they get rickets too?

 

[Kristin] (7:57 - 8:21)
In adults, it's called osteomalacia, and osteo means bone. Malacia means soft, so literally soft bones. I found an interesting case report in the literature about osteomalacia.

 

You want to hear it?

 

[Regina]
Absolutely. Stories are good.

 

[Kristin]
This was a 30-year-old, otherwise healthy man. He worked from home, so he didn't leave the house much, and he was also vegan. He didn't eat meat, fish, eggs, or milk.

 

[Regina] (8:22 - 8:23)
Sounds like a walking party.

 

[Kristin] (8:26 - 8:38)
All right, but he went to the doctor because he started to have symptoms, muscle weakness, pain, trouble walking, and these are all symptoms of osteomalacia. His vitamin D was four nanograms per milliliter.

 

[Regina] (8:39 - 8:46)
That puts my 92 in the perspective. You are not going to get osteomalacia. I am not at risk for osteomalacia, and I leave the house.

 

[Kristin] (8:47 - 8:49)
Which is generally a good thing.

 

[Regina] (8:49 - 8:54)
Right, but I am at risk for osteoporosis, and is it the same thing or it's different?

 

[Kristin] (8:54 - 9:35)
Those are different. Osteoporosis means porous bone. You end up with holes in your bone because you're taking calcium out of the bone.

 

Your body is taking calcium out of the bone faster than it's putting it back in, and that makes your bones brittle rather than soft. Osteoporosis is more common than osteomalacia, but sometimes the elderly can have both going on at once.

 

[Regina]
That doesn't sound good.

 

[Kristin]
Not good. One other thing to note, you can get soft bones if your vitamin D is fine, but if you are deficient in calcium. Because the vitamin D helps you absorb the calcium from your diet, but if you don't eat any calcium, then of course your bones are going to be too soft.

 

So, you need both.

 

[Regina] (9:35 - 9:36)
You need vitamin D and calcium.

 

[Kristin] (9:36 - 9:37)
You need both, and that's really critical.

 

[Regina] (9:37 - 9:46)
So, I'm hearing you say that I need to go out into the sun and eat some ice cream. Calcium plus vitamin D.

 

[Kristin] (9:46 - 9:54)
Well, I'm going to say yes to the ice cream. Little clogged arteries, no problem, but no to the sun because you don't want to get wrinkles or skin cancer.

 

[Regina] (9:55 - 9:57)
Don't take my sun away from me, please. Don't do it.

 

[Regina] (9:57 - 10:03)
Okay, so that gives us background on vitamin D and bones. What about some actual studies? What's happening with deficiency?

 

[Kristin] (10:03 - 10:12)
Let's talk about studies. All right, I'm going to start with a 2007 study from the Journal of Clinical Endocrinology and Metabolism that had a very surprising result.

 

[Regina] (10:12 - 10:17)
Okay, so that journal article, we'll put that in the show notes along with all the other.

 

[Kristin] (10:17 - 10:32)
All the citations will be there. Yes, yes. This was a study where a researcher went out and recruited participants from a surfboard shop in Hawaii.

 

I'm thinking, you know, that's a fun study. Yeah, I need to go to Hawaii. I think so.

 

To do a research study, right?

 

[Regina] (10:32 - 10:35)
We both do, and hanging out at the surfboard shop.

 

[Kristin] (10:36 - 10:51)
Right. They ended up recruiting primarily young surfers, not surprisingly, from a surfboard shop. Ninety-three people in the study.

 

They measured their vitamin D and they asked them, how much time do you spend in the sun on average? Regina, you want to guess how many hours per week they were in the sun?

 

[Regina] (10:52 - 10:57)
Okay, so they're going after work and they're getting in, you know, good hours, just seven hours a week.

 

[Kristin] (10:57 - 11:06)
Twenty-nine. Twenty-nine hours per week in the sun, 22 of which they said were without sunscreen. So a lot of times they were not wearing sunscreen.

 

[Regina] (11:07 - 11:12)
Oh, that is a lot of vitamin D. But first of all, what is their job? Are they professional surfers?

 

[Kristin] (11:12 - 11:20)
Well, I'm guessing maybe some of them were professional surfers, because you had to have a job where you could spend four plus hours a day.

 

[Regina]
Sign me up, first of all.

 

[Kristin] (11:21 - 11:31)
Do you surf?

 

[Regina]
I do not, but I'm willing to learn.

 

[Kristin]
It does sound like a great life.

 

[Regina]
It does sound like a very good life. Okay, so they had a lot of sun.

 

[Kristin] (11:32 - 11:35)
Way more than you need in order to get enough vitamin D.

 

[Regina] (11:36 - 11:36)
Yeah.

 

[Kristin] (11:36 - 11:43)
On a sunny summer day in Hawaii, most people would actually meet their daily vitamin D requirement after just a few minutes out in the sun.

 

[Regina] (11:43 - 11:46)
Oh, that kind of takes the fun away, though. You can't even say, I'm doing it for the vitamin D.

 

[Kristin] (11:46 - 11:48)
You can't really justify the longer time.

 

[Regina] (11:49 - 11:50)
Okay.

 

[Kristin] (11:51 - 11:53)
You want to hear the surprising part of this study?

 

[Regina] (11:53 - 11:53)
Yeah.

 

[Kristin] (11:53 - 12:00)
The researchers reported that half, 51% of the surfers were, quote, low in vitamin D.

 

[Regina] (12:00 - 12:06)
Low in vitamin D? Well, that doesn't make any sense. We just talked about them spending, you know, 20-plus hours a week. Lots of time without sunscreen

 

[Kristin] (12:06 - 12:07)
I told you it was surprising, right?

 

[Regina] (12:07 - 12:14)
Okay, this is weird.

 

I bet this got some good headlines and attention.

 

[Kristin] (12:14 - 12:21)
Oh, it did. Yes, it defies common sense. And people love stories that defy common sense, right?

 

They're exciting.

 

[Regina] (12:21 - 12:22)
They do.

 

[Kristin] (12:22 - 12:28)
Yeah, this paper had 50,000 page views on the journal site.

 

[Regina] (12:28 - 12:31)
50,000 page views for a scientific article?

 

[Kristin] (12:31 - 12:56)
For a scientific article, that's a lot, yes. Yeah, that's a lot. But, you know, when you see surprising results that defy common sense, I think you need to be a little skeptical, right?

 

We're going to be skeptical on this podcast in general. We are, yes. So, one interpretation of that result is what the author said, which is essentially, wow, isn't this shocking, right?

 

We must have a rampant epidemic if even surfers are part of this epidemic, right?

 

[Regina] (12:56 - 13:25)
Yeah, I'm rolling my eyes at this. It's like when journalists are writing all these clickbait headlines, right? Everything that you know about surfers and sun and vitamin D is wrong.

 

If you're doing that as a scientist, also, it's easier for you to get published, right? Oh, for sure, yes, yes. Everyone loves— And media coverage, yes.

 

The sexy, surprising results, media coverage. Okay, so if we're not going to be so credulous and sensationalistic about these surprising results, Kristin, we would do what instead?

 

[Kristin] (13:25 - 13:34)
Well, the other way to look at this would be to say, wow, this is so surprising that it's wildly implausible, right?

 

[Regina] (13:34 - 13:35)
Wrong. Maybe it's just wrong.

 

[Kristin] (13:35 - 13:42)
Right, maybe there's something wrong with the study or maybe we should question how we are defining low vitamin D.

 

[Regina] (13:42 - 13:47)
Yeah, that's what I was wondering because it all hinges on what you are saying.

 

[Kristin] (13:47 - 14:15)
Yes, that's the question of the day. And in this study, remember back to our lab reports, we talked about that on those reports, it indicated that below 30 nanograms per milliliter was vitamin D insufficiency. So, in this paper, the surfers were called low if they were below that 30 mark.

 

[Regina]
So, what do they mean by vitamin D insufficiency?

 

[Kristin]
Insufficiency is also called mild deficiency or borderline deficiency.

 

[Regina] (14:16 - 14:24)
So, it's on the border of a deficiency.

 

[Kristin]
Exactly.

 

[Regina]
Insufficiency is a stupid name.

 

Why can't we just call it borderline deficiency?

 

[Kristin] (14:24 - 14:28)
You're right, borderline deficiency is easier to remember. Let's just call it that.

 

[Regina] (14:28 - 14:37)
Okay, good. All right. So, that is the borderline.

 

But back to the deficiency, on our lab results, things are flagged as being deficient if they're less than 20, right?

 

[Kristin] (14:37 - 14:39)
That's right, less than 20.

 

[Regina] (14:39 - 14:54)
So, a little sidebar here. So, if I'm at 92, if I were to somehow, you know, immediately overnight get down to 19.

 

[Kristin]
You were to stay inside and become a vegan for a long time.

 

[Regina]
Not on my to-do list, but you never know.

 

[Kristin] (14:54 - 14:55)
Right, yeah, for whatever reason.

 

[Regina] (14:56 - 15:01)
Let's say I'm over that threshold now and I'm deficient, right?

 

[Kristin] (15:01 - 15:05)
Yeah, 19. You would get flagged in the lab report as being vitamin D deficient.

 

[Regina] (15:05 - 15:12)
Right. So, now I'm at risk for osteomalacia then, right?

 

This is the point where I get symptoms.

 

[Kristin] (15:13 - 15:28)
It's interesting because...It's not, you're really not at that high risk if you're at like 19. If you look at most people who have a vitamin D related case of osteomalacia or rickets, they are usually below 5 nanograms per milliliter. Often they have undetectable vitamin D, actually.

 

[Regina] (15:28 - 15:32)
5? But 5 is a long way from 20. That doesn't make any sense.

 

[Kristin] (15:32 - 15:36)
Yeah, it's kind of curious because 20 seems like an awful lot of buffer, exactly.

 

[Regina] (15:37 - 15:39)
Yeah, why do they have it so high?

 

[Kristin] (15:39 - 15:40)
I started to wonder that.

 

[Regina] (15:41 - 15:41)
Oh, okay.

 

[Kristin] (15:43 - 15:56)
And really wondered. So, where did this 20 and 30 that we keep talking about, where did they come from? They're on our laboratory reports that must be based on something.

 

So, I got curious and I decided to do a deep dive into the scientific literature to figure out the history.

 

[Regina] (15:57 - 16:02)
I love deep dives with you, Kristin. They are always fascinating. So, okay, what did you find?

 

[Kristin] (16:02 - 16:18)
All right, before the year 2000, vitamin D deficiency was typically defined as less than 10 nanograms per milliliter. And that borderline category was defined usually anywhere between less than 12 to less than 16 nanograms per milliliter.

 

[Regina] (16:19 - 16:22)
That's a big difference from 20 and 30. What happened?

 

[Kristin] (16:23 - 17:00)
Well, what happened was that those thresholds used to define low vitamin D, they started to gradually creep up in the literature between about 1998 and 2007. And this was driven by a few key papers. I'm going to put details about those papers in the show notes, but I want you to remember that they all share a common author, Michael Holick.

 

He's going to come up again, so remember that name.

 

[Regina]
Michael Holick, got it.

 

[Kristin]
In 2007, Holick wrote a highly influential paper in the New England Journal of Medicine.

 

It's actually his most cited paper. It's had over 20,000 citations in Google Scholar citations.

 

[Regina] (17:01 - 17:02)
Whoa, 20,000? That's huge.

 

[Kristin] (17:02 - 17:41)
It's huge. Most scientists don't have 20,000 citations for their entire body of work, let alone a single paper.

 

[Regina]
So this was influential.

 

[Kristin]
Very influential. Here, Holick declared that the threshold for borderline deficiency was 30 nanograms per milliliter and for deficiency was 20.

 

And I should note that Holick did have some scientific reasons for picking those numbers. They are not completely out of thin air, but it's controversial. And we'll get back to that controversy later when we talk about the dueling medical guidelines.

 

But Holick's New England Journal of Medicine paper, that is really where those numbers, the 20 and 30, got locked in.

 

[Regina] (17:42 - 17:44)
That's where it got locked in back, that was 2007.

 

[Kristin] (17:44 - 17:45)
2007, yes.

 

[Regina] (17:46 - 18:06)
So we went then from borderline being something like 12 or 16, all the way up to 30, right? And deficiency used to be 10 and now it's up at 20, right? That is a big jump.

 

[Kristin]
It's a big jump, yeah.

 

[Regina]
That is fascinating. So I see what you're getting here.

 

This is how you create an epidemic. This is a recipe for an epidemic.

 

[Kristin] (18:07 - 18:07)
Yeah, absolutely, yeah.

 

[Regina] (18:07 - 18:08)
You just move the goalposts.

 

[Kristin] (18:08 - 18:29)
Exactly, yeah. So let's go back to that surfer study. Actually, it's a really good illustration.

 

I looked carefully at the data in that paper. And you know how many surfers would have been counted as, quote, low in vitamin D if the authors had used that traditional definition of less than 10 nanograms per milliliter?

 

[Regina]
I don't know, maybe 15, 15 percent?

 

[Kristin]
No, none. Zero percent.

 

[Regina] (18:29 - 18:39)
So just using what used to be the threshold, none would be labeled low. Well, that's not a headline, is it?

 

[Kristin] (18:39 - 19:21)
Well, now the headline would be, surfers are not deficient in vitamin D. You probably would not have gotten 50,000 page views. No, no.

 

But here's the key. If you shift the threshold for low vitamin D from less than 10 nanograms per milliliter to less than 30, that's when suddenly 51 percent of surfers appear low.

 

[Regina]
And we've just created an epidemic.

 

[Kristin]
We've just created an epidemic. And it's even worse if we look at people who are not surfers.

 

[Regina]
Normal people with boring jobs.

 

[Kristin]
Normal people, right. If we use recent data on the general population of the U.S., if you define low vitamin D as less than 10 nanograms per milliliter, only 2.5 percent of people are low.

 

[Regina] (19:22 - 19:29)
Wow. So again, using that historical threshold, not many people are low in vitamin D. No epidemic, right?

 

[Kristin] (19:29 - 20:13)
Right. I mean, it's a few more than the surfers, but it's not huge numbers. But if we move the goalpost and define low vitamin D as less than 30 nanograms per milliliter, then 60 percent of the population is now low in vitamin D.

 

It's curious, though, Regina, remembering that you said in the Huberman podcast, they said that 70 percent of the population was low in vitamin D. I'm wondering where they got that statistic from. I'm pretty sure they use that same threshold, that lower than 30 nanograms per milliliter is widely used.

 

But if you actually look at the general population of the U.S., it's 60 percent below that threshold, not 70 percent. So where did that even come from?

 

[Regina]
Creative math.

 

[Kristin]
Heavy rounding? Maybe a selective paper that only looked at certain people and not the general U.S. population, right?

 

[Regina] (20:13 - 20:14)
Cherry-picking numbers.

 

[Kristin] (20:14 - 20:20)
Maybe. In any case, it is more than half of the U.S. population that is below that 30 threshold.

 

[Regina] (20:20 - 20:25)
But this is not because vitamin D levels as a whole have been dropping than in the U.S.

 

[Kristin] (20:25 - 20:31)
No, actually the levels have increased, at least since we've been, you know, measuring vitamin D routinely.

 

[Kristin] (20:31 - 20:39)
So like in the last 40 years, they've actually gone up, and especially at the very high end have gone up, probably because of all the people taking supplements.

 

[Regina] (20:39 - 20:39)
Guilty.

 

[Kristin] (20:39 - 20:41)
Not naming any names here, yes.

 

[Regina] (20:41 - 21:10)
Guilty, uh-huh. Okay, so if I understand what you're saying, essentially what used to be normal vitamin D level for the population is now considered a condition, right? And we've created a problem, and now what, 60% of the population needs an intervention.

 

They need something to fix that problem that we've just created.

 

[Kristin]
Exactly, exactly.

 

[Regina]
Ooh, this is a great way to publish papers.

 

It really is, and get publicity and have a good career. Props for them, I guess, you know?

 

[Kristin] (21:10 - 21:15)
Yes, researchers can now publish all these sexy and exciting papers.

 

[Regina] (21:15 - 21:18)
Oh yeah, and this is what researchers need to do. They need to publish.

 

[Kristin] (21:19 - 21:28)
I love it. Yes, yes. Regina, I think we need to move the goalpost on something and come up with our own epidemic so that we can get published.

 

[Regina] (21:29 - 21:38)
Fame and fortune shall be ours. Can I also, can we do this on something that is going to benefit us?

 

[Kristin] (21:38 - 21:39)
Well, of course.

 

[Regina] (21:40 - 21:50)
Personally, I would love to move the goalpost on what is considered sexy and sexually attractive for middle-aged women. Middle-aged women who love stats, let's say.

 

[Kristin] (21:50 - 22:02)
Nerdy, nerdy middle-aged women. Ooh, I like it. All right, right.

 

So, you're saying that we can make that definition more lenient and then more middle-aged women can be diagnosed with sexiness.

 

[Regina] (22:03 - 22:25)
Please diagnose me with sexiness. I would love to have this condition. Yes, I want to be an overachiever, actually, here.

 

Okay, this is great. I love what they're doing with this, but I'm guessing that the researchers, unlike us, were not so transparent about the fact that they are moving the goalpost so they can do something.

 

[Kristin] (22:25 - 22:28)
They're not saying, hey, we moved the goalpost so we can publish a whole bunch of papers.

 

[Regina] (22:30 - 22:33)
I'm guessing they had some sort of science behind it, at least to justify.

 

[Kristin] (22:33 - 22:55)
Right, they had some rationale, and I do want to go into that because the science is actually controversial. And in 2011, an important scientific body in the United States, the Institute of Medicine, issued a report in which they directly pushed back on these shifting goalposts. And that set off a feud between different factions in the medical community.

 

[Regina] (22:56 - 23:32)
I love scientific feuds. They are the best feuds ever, actually. So, this is the dueling medical guidelines that you were talking about earlier.

 

I am so excited about this. Want to hear about it. I think before we get into that, we should take a quick break.

 

[Regina]
Welcome back to Normal Curves. Before the break, we were discussing how to create an epidemic by changing how you define the disease. Now we're going to talk about some dueling medical guidelines.

 

Kristin, set the stage.

 

[Kristin] (23:32 - 23:57)
All right. By 2011, now there were tons of papers being published on vitamin D deficiency and lots of attention on vitamin D in the lay public. But in early 2011, the Institute of Medicine issued a report that brought some of this research into question. The Institute of Medicine or IOM, I should note that they have since changed their name and they're now called the National Academy of Medicine.

 

[Regina] (23:57 - 24:11)
Institute of Medicine. So, maybe we should just back up and explain what that is. Really prestigious body, right?

 

They bring together independent, objective scientists, subject matter experts in a field, and they evaluate scientific evidence about something.

 

[Kristin] (24:12 - 24:37)
That's right. In 2011, they put out their own recommendations on the optimal blood levels for vitamin D. And I'm just going to read one line from the conclusion of their paper that I think sums up their feelings well.

 

The committee finds that the prevalence of vitamin D inadequacy in the North American population has been overestimated by some groups due to the use of inappropriate cut points.

 

[Regina] (24:38 - 24:57)
This is actually a bit of a burn here, isn't it? Like an academic burn. I said, overestimated by some groups.

 

They're pointing fingers without pointing fingers. So, inappropriate cut points. Are they talking about like the surfer study, what they use there?

 

[Kristin] (24:57 - 25:11)
They are directly repudiating that 20 nanograms per milliliter and 30 nanograms per milliliter. And that means they are directly repudiating a lot of the literature on vitamin D, right? Because a lot of papers were using those thresholds.

 

[Regina] (25:12 - 25:14)
Wow. The 20 and 30 that we still get on our lab reports, right?

 

[Kristin] (25:14 - 25:15)
That we still get on our lab reports, yeah.

 

[Regina] (25:15 - 25:22)
Okay. So, this was 2011. You said, I don't remember this.

 

Did it get a lot of coverage?

 

[Kristin] (25:22 - 25:25)
It did not get very much news coverage, surprisingly.

 

[Regina] (25:26 - 25:27)
That's weird.

 

[Kristin] (25:27 - 25:39)
There was some reporting on it, but the reporters kind of missed the punchline of this report that they were pushing back on this whole thing. And it did get some pushback pretty quickly from some people in the scientific community who did not like this.

 

[Regina] (25:39 - 25:43)
Oh, so this is the dueling guidelines, I guess, we'll get into.

 

[Kristin] (25:44 - 26:02)
So, there's this professional medical society called the Endocrine Society, and they were not happy with the IOM report. So, they issued a conflicting report the same year in the same journal, and they fought back and they said, no, these cut points, these thresholds we've been using, 20 for deficient and 30 for borderline deficient, no, those are correct.

 

[Regina] (26:03 - 26:06)
This is high drama. High drama in academia.

 

[Kristin] (26:06 - 26:11)
Tabloid level celebrity couple drama, I'm translating for those who are not in academia.

 

[Regina] (26:12 - 26:21)
Right, right. Taylor Swift and Travis, right there. And Maddie and Joe.

 

[Kristin]
Okay, I know Taylor Swift.

 

[Regina]
Okay, good.

 

[Kristin] (26:21 - 26:37)
Who I've heard of because, you know, one of my colleagues was emailing me and saying that she was giving a talk at a Taylor Swift conference. I actually thought she was pulling my leg.

 

[Regina]
Taylor Swift conference, not concert.

 

[Kristin]
Not concert, yes. So, they actually have academic conferences on Taylor Swift.

 

[Regina] (26:38 - 26:40)
I am guessing not a lot of statisticians.

 

[Kristin] (26:40 - 26:43)
I don't know, maybe more humanities, I'm guessing.

 

[Regina] (26:44 - 27:06)
Okay, okay. But we can still, statisticians, we can co-opt that for our analogy. So, I'm going to say this is high drama.

 

Taylor Swift and Travis. Okay, all right. So, bringing it back to the 20 and 30.

 

IOM said these thresholds you're talking about, these 20 and 30, they are inappropriate. Right, yes. So, did they have a recommendation for what you should be using?

 

[Kristin] (27:06 - 27:17)
This is a little tricky, Regina, because the IOM actually takes a more nuanced approach. And to understand their approach, I'm going to have to take a little statistical detour now.

 

[Regina] (27:17 - 27:24)
Oh, I love statistical detours, stopovers, layovers.

 

[Kristin]
Statistical layovers, I like that.

 

[Regina]
All right, go ahead.

 

[Kristin] (27:24 - 27:47)
The IOM does not assume that there is one universal, magical cut point threshold that once you hit it, you fall off a cliff. They recognize that nutrient needs in the population vary from person to person.

 

Like, Regina, you might need more vitamin D than me, maybe because of your genetics or your build or your calcium intake.

 

[Regina] (27:47 - 27:51)
Right, right, right. So, one size did not fit all.

 

[Kristin]
Exactly.

 

[Regina]
They are saying there's a distribution.

 

[Kristin] (27:53 - 28:08)
Distribution, that is music to a statistician's ears. Yes, we love distributions. Yeah, it makes us happy, right.

 

Right, the IOM assumes that nutrient needs in the population follow a normal distribution, a bell curve. Okay, not surprising.

 

[Regina] (28:09 - 28:10)
Right, we love our bell curves, yes.

 

[Kristin] (28:10 - 28:14)
We love that. Let's take a little statistical detour and talk about bell curves.

 

[Regina] (28:15 - 28:15)
Okay.

 

[Kristin] (28:15 - 28:17)
How do you teach bell curves or normal distributions in your class?

 

[Regina] (28:18 - 28:24)
I actually have an example that I use often that fits in with the theme of the podcast. Are you ready? It's a little PG-13.

 

[Kristin] (28:24 - 28:26)
Ooh, okay. Are you ready?

 

[Regina] (28:26 - 28:29)
Go for it, yep. Penises, penis lengths. Ooh.

 

[Kristin] (28:29 - 28:33)
Yes. Wow, well, I use height usually, so I'm a little more boring.

 

[Regina] (28:33 - 28:35)
It makes them pay attention.

 

[Kristin] (28:35 - 28:38)
I'm sure you wake up a few students when you bring that one out.

 

[Regina] (28:39 - 28:43)
Right, the mature students. So, where did I get it? I bet you are wondering.

 

[Kristin] (28:44 - 28:45)
Yeah, where is that example from?

 

[Regina] (28:45 - 29:16)
It is my own data. It is not my own data. I actually wrote a journalism article, believe it or not, for Nature.

 

[Kristin]
For Nature?

 

[Regina]
For Nature, it was covering a study that looked at the most attractive penis length. What did women find to be the most attractive length?

 

And part of that, they referenced another study that I read. This was talking about the distribution of penis lengths in the population, and they said it was roughly normally distributed.

 

[Kristin] (29:16 - 29:18)
Oh, okay. I admit, I'm a little curious. What does that distribution look like?

 

[Regina] (29:18 - 29:39)
Admit that you are a lot curious. Just admit it, okay?

 

First, I should mention what the population was. First, it was specifically young Italian men. Italian stallions here.

 

And even more important, the other disclaimer, is that they were flaccid penises.

 

[Kristin] (29:39 - 29:43)
Oh, that is an important detail. Yes, yeah, that matters.

 

[Regina] (29:44 - 30:11)
Floppy, floppy penises.

 

Right, okay. Normal distribution, often called a bell curve, as you said, because it visually resembles...

 

[Kristin]
It looks like a bell.

 

[Regina]
A bell, right, right. So that shape is actually important, as you know, because it's telling us that most people are clustered around the middle, around the average, and that there's that big bell, that big hump, right? And there are only a few people that are out in the tail that are much higher than average or much lower than average.

 

[Kristin] (30:11 - 30:28)
Right, and this distribution pops up a lot in nature because a lot of traits follow a normal distribution because most people are close to average because it's average. And there are, you know, fewer people that are very far from average. All right, Regina, so what was the average penis length in Italian men?

 

[Regina] (30:28 - 30:31)
I thought you would never ask. So I use this a lot.

 

[Kristin] (30:31 - 30:31)
Okay.

 

[Regina] (30:31 - 30:39)
So I actually have it in my head. The average length for these Italian stallions, 9 centimeters flaccid.

 

[Kristin] (30:39 - 30:46)
Okay, so that means that the typical man is 9 centimeters, and I'm going to have to try to convert that into inches.

 

[Regina] (30:46 - 30:57)
So it's 2.54 centimeters per inch.

 

[Kristin]
So what is that? About three and a half.

 

[Regina]
Three and a half inches. Again, flaccid, guys, everyone out there.

 

[Kristin] (30:58 - 31:06)
All right, so that's the mean, the average, but it varies. And the other super important concept that we love in statistics, what was the standard deviation?

 

[Regina] (31:07 - 31:28)
Exactly, standard deviation. This is why statisticians really focus on this sort of thing because it's telling us how much variability there is in penis length in the population. As we know from personal experience, it does vary man to man.

 

We might know that. They're not all the same. Okay, standard deviation was 2 centimeters.

 

[Kristin] (31:29 - 31:43)
Okay, so on a normal distribution, 95% of people are going to fall within two standard deviations of the average. So let me do a quick calculation here. So the average was 9, plus or minus, two standard deviations would be plus or minus 4.

 

[Regina] (31:44 - 31:44)
Plus or minus 4.

 

[Kristin] (31:44 - 31:52)
So 95% of those Italian men are going to fall between 5 to 13 centimeters long.

 

[Regina] (31:52 - 32:01)
Yeah, yeah, yeah. I love that you say that with a straight face. Like, okay, we're just talking statistics here.

 

It has nothing to do with actual genitalia.

 

[Kristin] (32:01 - 32:02)
I'm not blushing at all.

 

[Regina] (32:04 - 32:11)
So 95% of these Italian men were in between 5 centimeters and 13 centimeters, right? That's typical.

 

[Kristin] (32:11 - 32:35)
So going along the same here, if you encounter one that's below 5 or above 13 centimeters, those would be considered kind of atypical because only 2.5% of men are below 5 centimeters. Only 2.5% of men are longer than 13 centimeters.

 

[Regina] (32:35 - 32:45)
Right, right. I wonder how many people are getting out their notebooks right now. Making notes, yes.

 

Making notes for this very important real life example.

 

[Kristin] (32:45 - 33:07)
Okay. Anyway, all right. Back to nutrients. The IOM estimated that the distribution of vitamin D requirements in the population, they estimated that it follows a normal distribution with an average of 16 nanograms per milliliter, that being the average need that people have in the population, and a standard deviation of 2 nanograms per milliliter.

 

[Regina] (33:07 - 33:16)
Okay, so they are saying that the typical person needs 16, on average, right? Oh, well, that puts my 92 into perspective.

 

[Kristin] (33:17 - 33:18)
You are way higher.

 

[Regina] (33:19 - 33:32)
And the standard deviation was 2. I'm like 30 standard deviations.

 

[Kristin]
Yeah, that is way out in the tail.

 

[Regina]
Okay, yeah, I'm a little embarrassed about this now.

 

[Kristin]
Yeah, you're an overachiever.

 

[Regina]
Okay, so what did they do with this?

 

[Kristin] (33:32 - 33:44)
So the IOM then takes this normal distribution and they set different target values for the nutrients for the population. I'm just going to talk about one of those target values, which you've probably heard of, which is the RDA or Recommended Daily Allowance.

 

[Regina] (33:44 - 33:49)
Oh, you know, I see RDA all the time, but I didn't realize that it was related to normal distribution.

 

[Kristin] (33:49 - 34:09)
I didn't either, yes. So I learned that the RDA, what that is, is it's the average need in the population plus two standard deviations. And they choose that value because if you do the average plus two standard deviations, you're going to meet or exceed the needs of 97.5% of the population. You're only going to be missing that 2.5% out in the tail.

 

[Regina] (34:11 - 34:19)
So 16, right, that is the average plus two standard deviations. That gets us 16 plus 2 times 2, so 20.

 

[Kristin] (34:19 - 34:31)
That gets us to that 20, yes. And that means, though, that almost everyone's needs are met at 20 nanograms per milliliter, and many people actually need less than this. Not everybody needs to be up at that 20.

 

[Regina] (34:31 - 34:41)
Interesting. I love the way that you're putting this. So 20 meets most everyone's needs, but our lab reports say we would, we get flagged if we're below 20.

 

[Kristin] (34:41 - 34:56)
Yes. Anybody who is below 20 gets flagged as deficient on those lab reports. But like, let's say you were 18.

 

That's actually still above the average need in the population. So most people actually are just fine at 18. So it's weird that you get flagged at 20.

 

[Regina] (34:56 - 35:04)
Wow. Okay, so IOM is saying just if we aim to get the population at 20, then the vast majority of people will be fine.

 

[Kristin] (35:05 - 35:16)
And that's different than saying that we're aiming to get everyone at 20, right? We just want to aim for 20 so that we get, we meet everybody's needs. But that does not mean that we're trying to get everybody at 20 or above.

 

This is a subtle point.

 

[Regina] (35:17 - 35:41)
Subtle, yes. But it's like, so we have a safety buffer.

 

[Kristin]
Yeah, exactly.

 

[Regina]
So I'm thinking of an analogy, let me try this. So also something I use when I teach stats, it's commuting time. So let's say my commute to work on average takes me 16 minutes.

 

Okay, right to fit with the IOM thing. But it's not going to be the same every day.

 

[Kristin] (35:41 - 35:44)
You might hit red lights more. There's some traffic, accident.

 

[Regina] (35:44 - 35:49)
Yep. And let's say that because I'm a nerd, I know the standard deviation.

 

[Kristin] (35:49 - 35:50)
You've clocked it. You've collected data.

 

[Regina] (35:51 - 35:55)
Let's just say, all right, and let's say the standard deviation is two minutes.

 

[Kristin] (35:55 - 35:57)
So again, to match those numbers, right?

 

[Regina] (35:57 - 36:13)
Like the IOM. So if I set my recommended daily commute time, like the IOM, and if I set that to 20 minutes, that would mean that 97.5% of the days I'm going to be on time. I'm going to be fine.

 

[Kristin] (36:13 - 36:19)
And actually, you're going to be early most days if you leave yourself 20 minutes for commute every day.

 

[Regina] (36:19 - 36:22)
Right. But that's just to be safe. To be cautious.

 

[Kristin] (36:22 - 36:36)
I have to say, I am an underachiever on commute time. I don't usually leave myself the recommended daily commute time. I'm aiming for more like the average, right?

 

If I'm, you know, on average on time, if I'm a few minutes late, it's okay. It's academia.

 

[Regina] (36:37 - 36:40)
I think this might be the only thing that you're an underachiever on.

 

[Kristin] (36:40 - 36:43)
Well, they don't have clocks in academia, right?

 

[Regina] (36:44 - 36:52)
Yes. Okay, so back to the dueling guidelines. So that was IOM. And now we understand how the normal distribution.

 

[Kristin] (36:52 - 36:53)
That's where all that comes from.

 

[Regina] (36:54 - 36:58)
Right, that safety. But what about that other group, the rebels, the Endocrine Society?

 

[Kristin] (36:58 - 37:30)
The Endocrine Society, their report defined vitamin D deficiency as less than 20 nanograms per milliliter and insufficiency or borderline as less than 30 nanograms per milliliter. Interestingly, they actually cite the IOM to help justify that 20 mark, but that is a total misrepresentation of what an RDA is. And the IOM actually came back and pointed out that, no, that doesn't mean just because we happen to have that number 20, that 20 is not a threshold for deficiency.

 

It's just the RDA, which is something totally different.

 

[Regina] (37:31 - 37:35)
So they misunderstood the whole normal distribution idea.

 

[Kristin] (37:35 - 37:35)
Exactly, yes.

 

[Regina] (37:36 - 37:47)
They didn't have enough statisticians.

 

[Kristin]
They didn't listen to our podcast.

 

[Regina]
They didn't listen to our podcast. We put it all into context.

 

Okay, so those were the inappropriate cut points.

 

[Kristin] (37:47 - 37:48)
That's why they called them inappropriate cut points. Yes, exactly.

 

[Regina] (37:48 - 38:01)
Okay, so we have these two groups. We have IOM, Endocrine Society, but they're both full of really smart scientists, right?

 

So how do they justify coming to such different conclusions?

 

[Kristin] (38:02 - 38:23)
Okay, so I'm actually going to start with a commonality between both groups. They both based their recommendations solely on the effect of vitamin D on bones. They focused on outcomes like calcium absorption, bone softness, and fracture risk.

 

They both agreed that there was too much uncertainty about those potential non-skeletal effects of vitamin D to base any recommendations on those data.

 

[Regina] (38:23 - 38:27)
Things like immunity, depression, cancer, aging.

 

[Kristin] (38:27 - 38:34)
Exactly. Of course, much of the hype and interest in vitamin D is around those potential non-skeletal effects.

 

[Regina] (38:34 - 38:41)
That's why we are going to focus our second episode on vitamin D, vitamin D part two, on all of those potential effects.

 

[Kristin] (38:43 - 39:33)
But here, both groups focused only on the body of research related to bones. Regina, I do kind of wonder if maybe the Endocrine Society, maybe some of the committee members had those potential non-skeletal effects in the back of their minds when making their recommendations, but it wasn't part of their formal reasoning.

 

[Regina]
Okay, that's similarities, but what about differences?

 

[Kristin]
Okay, they took very different approaches. The IOM was very comprehensive. They reviewed tons and tons of studies, over a thousand studies.

 

I feel like the Endocrine Society cited a much smaller body of evidence. Often those papers published by the authors themselves, so I would characterize it as a more selective body of research. I would call the IOM approach kind of glass half empty, and the Endocrine Society was more of a glass half full approach.

 

[Regina] (39:34 - 39:35)
All right, interesting. Tell me more.

 

[Kristin] (39:35 - 40:03)
Well, the IOM was just much more stringent. They took the attitude, if there isn't strong evidence to support the need for that higher level of vitamin D, they were not going to endorse that higher level. Glass half empty, right?

 

But the Endocrine Society was much more lenient. It seems to me that their attitude was, if there was any data, any hint or suggestion supporting that need for those higher levels of vitamin D, they were going to err on the side of recommending more, glass half full.

 

[Regina] (40:03 - 40:22)
Interesting. So, I have an analogy that doesn't have to do with glasses half full. Do you mind if I try it here?

 

All right, expensive face cream, right? Okay, La Mer, for example. Very, very expensive, very fancy face cream.

 

Are you using it, by the way?

 

[Kristin] (40:22 - 40:25)
I have never heard of La Mer, so clearly not.

 

[Regina] (40:25 - 40:45)
Smells really good.

 

Okay, I am not actually sure that there's hard scientific evidence, right? A high bar of evidence saying that this is going to turn back the clock and reduce my aging and all of a sudden, you know, make me look super good and beautiful. But on the off chance that it might work, I go ahead and spend the money.

 

[Kristin] (40:45 - 40:47)
That is a great analogy.

 

[Regina] (40:47 - 40:48)
Okay, thank you.

 

[Kristin] (40:48 - 40:50)
You are the Endocrine Society for face cream.

 

[Regina] (40:51 - 40:51)
I'm very hopeful.

 

[Kristin] (40:51 - 41:08)
So basically, if there's any chance it might work, then you think, why not? Why not splurge just in case it works? Right, right.

 

I think I'm the IOM here.

 

[Regina]
Are you?

 

[Kristin]
I have to admit that I get my face cream mostly at Trader Joe's.

 

The real knockoff version. I can't justify spending that higher amount without the hard evidence.

 

[Regina] (41:09 - 41:10)
Well, your face looks great.

 

[Kristin] (41:10 - 41:11)
Thank you. You too, Regina.

 

[Regina] (41:11 - 41:21)
So it must be working. Okay, so I am the glass half full kind of person when it comes to anti-aging, aka a little desperate.

 

I am desperate. I see what you're saying.

 

[Kristin] (41:21 - 41:45)
Regina, though, I can totally see the appeal of your expensive face cream approach and the Endocrine Society's approach, right? I mean, it's kind of like, what's the harm of erring on the side of caution on the side of overdoing it, right? It might help.

 

Why wouldn't you? It might work.

 

[Regina]
Right.

 

[Kristin]
The issue, of course, is that there's always a trade-off. There are always costs and you always have to think about what those costs are.

 

Nothing, there's no free lunch.

 

[Regina] (41:46 - 41:55)
Right, right. Every policy, everything has a cost and a benefit for my expensive face cream. It's expensive and maybe I could be using that money somewhere else.

 

[Kristin] (41:56 - 42:10)
Something, right, yes. And same with vitamin D, right, supplements. I mean, they're expensive and people are, if you don't really need that, the mega doses, people are wasting a lot of money on vitamin D.

 

Vitamin D testing is also really expensive.

 

[Regina] (42:10 - 42:14)
Oh, this is a good point. Yeah. So, you and I may not be paying for it out of pocket, but our insurance.

 

[Kristin] (42:15 - 42:17)
Our insurance pays and that's not free, it's society.

 

[Regina] (42:17 - 42:20)
Right, society somehow is paying.

 

[Kristin] (42:20 - 42:27)
Yeah, it all comes back to our premiums and things, yeah. It's also possible to get too much vitamin D. You're not going to want to hear this, Regina.

 

[Regina] (42:27 - 42:29)
I don't, I don't.

 

[Kristin] (42:29 - 42:35)
Your body stores vitamin D, so it is possible to build up toxic levels if you take too much.

 

[Regina] (42:35 - 42:40)
Don't tell me it's like 92.5.

 

[Kristin] (42:40 - 42:44)
You're going to be okay, don't worry. It's actually pretty uncommon to get up to toxic levels.

 

[Regina] (42:44 - 42:44)
Okay.

 

[Kristin] (42:45 - 43:00)
But it does happen. I found a case report on a 12-year-old boy. He came into the emergency room with stomach pain, vomiting and kidney failure.

 

He had a vitamin D level, though, of 535 nanograms per milliliter.

 

[Regina] (43:00 - 43:03)
92 now doesn't sound so bad, right?

 

[Kristin] (43:03 - 43:04)
Not so bad in comparison, right.

 

[Regina] (43:04 - 43:07)
Okay, so what happened? How did he get that high?

 

[Kristin] (43:07 - 43:21)
His mom had been giving him cod liver oil supplements and she was giving him too many pills, more than was recommended on the bottle and the bottle was also mislabeled and the dose they put on the bottle was much lower than what was actually in the pills.

 

[Regina] (43:21 - 43:39)
This is good to remember, especially we're talking about supplements because they're not regulated in the same way. Okay, so now we have, bringing it back to these dueling medical guidelines, we've got IOM, we've got the rebels, the Endocrine Society, they're battling it out. How did it shake out?

 

What happened?

 

[Kristin] (43:39 - 43:56)
All right, so I'm not going to give away the entire story yet. I'm going to keep the suspense going to see, you know, how this shakes out in the end. There actually is a resolution eventually, but I'm going to postpone that until the end of the episode to keep people listening.

 

[Regina] (43:56 - 43:57)
I do like suspense.

 

[Kristin] (43:57 - 44:27)
Yeah, I'm going to put a little suspense in here. But immediately after this controversy came up, it was kind of like the Endocrine Society won out. They got way more attention than the IOM.

 

The IOM report has had over 40,000 page views. Okay.

 

That's a lot. It is. But think about it.

 

That's even lower than that surfer study got. And they were in the same journal. So it's kind of a good comparison.

 

The Endocrine Society report has had over 400,000 page views.

 

[Regina] (44:28 - 44:31)
400,000 versus 40,000. So like 10 times more.

 

[Kristin] (44:31 - 44:56)
Exactly. A lot more. The Endocrine Society got a lot more traction in other ways, too. For example, a lot of medical societies adopted their recommendations.

 

And the laboratories adopted their recommendations. Both of our reports cite that 20 and 30. And they actually cite the endocrine, at least my report cited the Endocrine Society report as why they're using those thresholds.

 

[Regina] (44:56 - 45:08)
Interesting. So Kristin, I think this gets back to what we were talking about before that surprising things, dramatic things get attention. They get traction.

 

And sometimes it's also better for business.

 

[Kristin] (45:08 - 45:20)
There's a business angle here. The labs are going to sell a lot more vitamin D tests if 60% of the population is low compared with if just a few percent of the population is low.

 

[Regina] (45:21 - 45:25)
Oh, yeah. That doesn't feel great.

 

When money is involved.

 

[Kristin] (45:25 - 45:42)
Right. Regina, I want to point out one other thing. The Endocrine Society, the committee that they assembled to make these guidelines, the chair of that committee was Michael Holick. And I've mentioned him before.

 

And now I actually want to spend some time talking about Michael Holick in more detail.

 

[Regina] (45:42 - 46:18)
All right. More about Michael Holick and some statistical sleuthing, I think. But first, a short break.

 

Welcome back to Normal Curves. Before the break, we were discussing dueling medical guidelines. Now we're going to talk about Michael Holick, who is the chair of the Endocrine Society committee that came up with these recommendations.

 

And we are also going to hear some of Kristin's world famous statistical sleuthing. I can't wait. Kristin, first tell us about this researcher, Michael Holick.

 

Who is he?

 

[Kristin] (46:18 - 47:04)
He is a biochemist by training, also a physician. And he did pioneering work in the 70s and 80s on the basic biochemistry of vitamin D. For example, he identified the active form of vitamin D in the body and he helped to synthesize it.

 

[Regina]
Not a slacker.

 

[Kristin]
Not a slacker. But he is controversial.

 

Over the years, he's drifted more from bench work over to public health and epidemiology. And he became what I might characterize as a proselytizer for vitamin D. He's had a big influence in the scientific community.

 

We talked about some of that already. He's also written two popular books about vitamin D. So he's also had a big influence in the lay public in bringing vitamin D into kind of star status.

 

[Regina] (47:05 - 47:07)
You mentioned controversy. What's the controversy here?

 

[Kristin] (47:08 - 47:25)
Holick is a controversial figure. In 2004, he was actually asked to resign from the dermatology department at Boston University where he had an appointment. He still holds appointments in other departments at BU.

 

He's still at BU. But he is no longer welcome in the dermatology department.

 

[Regina] (47:26 - 47:26)
What happened?

 

[Kristin] (47:27 - 47:43)
He wrote a popular book in 2003 called The UV Advantage. And the chair of the dermatology department at the time did not like his book because it was advocating deliberate sun exposure and indoor tanning, both of which, of course, are bad for skin.

 

[Regina] (47:43 - 47:48)
Right. It was advocating for more UV light, which dermatologists don't like.

 

[Kristin] (47:48 - 48:06)
And there was actually some reporting on this by the journalist David Armstrong, who's been reporting on his career. Apparently, according to Armstrong, the chair of the dermatology department called Holick's book schlock science. And she called Holick a poster boy for the tanning industry.

 

[Regina] (48:06 - 48:22)
Well, OK, this is just this is serious burn no matter what. This is a big clapback. Schlock science and poster boy.

 

Was he a literal poster boy? I'm picturing like tanning industry calendar and Michael Holick shirtless under a tanning lamp.

 

[Kristin] (48:22 - 48:27)
No, no. That would be more interesting. But no, he was receiving research funding from the tanning industry.

 

[Regina] (48:27 - 48:28)
All right. I guess that makes more sense.

 

[Kristin] (48:30 - 48:38)
Now, he said, you know, hey, that was just a small percentage of my total research funding. It didn't influence me. But of course, it did raise eyebrows.

 

[Regina] (48:38 - 48:40)
Yeah, yeah. OK, is that it or is there more?

 

[Kristin] (48:40 - 49:04)
He's actually had many financial conflicts of interest over the years. There was a big story that came out in the New York Times in 2018, revealed that Holick has been consulting for years for companies that make vitamin D tests and vitamin D supplements like Quest Diagnostic. This is one of the biggest makers of vitamin D tests.

 

He's been consulting for them since 1979.

 

[Regina] (49:05 - 49:21)
Yikes. So by creating an epidemic, we're also creating a market.

 

[Kristin]
Yeah, we are.

 

[Regina]
Oh, so he's not necessarily a disinterested scientist, right? He stands to make money from this.

 

[Kristin] (49:21 - 50:03)
Yeah, the market value for vitamin D testing in the United States, it's about $360 million. Wow. And it's a huge growth industry.

 

Yeah. People are making money off of testing. And his book, I found it interesting, OK, in his book, he makes this big point, it's almost like a big conspiracy theory.

 

He's like, nobody wants you to know that the sun is good for you because the sun is free and therefore no one can make money off of it. So he's kind of saying like, hey, nobody's told you this because they can't make money off of it. But of course, people can make money off of indoor tanning, vitamin D tests, supplements, as we've talked about.

 

And I mean, people make money off of water, so why not the sun?

 

[Regina] (50:03 - 50:06)
So he's making it seem like it's this big counterculture thing. We're sticking it to big business.

 

[Kristin] (50:06 - 50:11)
Yes, exactly. Although he is, yeah, kind of in the pocket of big business.

 

[Regina] (50:12 - 50:21)
So we can't know his motivations, of course, but from the outside looking in, this is not a good look.

 

[Kristin] (50:21 - 50:50)
Yeah, it's not a good look. And we've talked about this before, Regina. I'm not of the mind that just because you have industry funding that you are necessarily tainted.

 

Sometimes industry does better research than academics. I also think it's super important to remember that it's not just money that can be a conflict of interest.

 

[Regina]
Good point.

 

[Kristin]
There are a lot of motivators that can bias scientists. Like, we want to get promoted. We need to publish papers.

 

We want fame. We want to get recognized. It's not just money.

 

[Regina] (50:50 - 51:14)
Not just money, especially for academics, I think. Sometimes identity these days. Being a public intellectual is a big motivation.

 

It's kind of recent, but the TED Talk bias, right? Like, I feel like a lot of us, we feel an obligation to have our own TED Talk. Right.

 

And it needs to be snappy and surprising and, right, have a clear story. TED Talk bias, let's call it that.

 

[Kristin] (51:14 - 51:25)
Yeah, I like that. TED Talk bias.

 

All right, since we're making up bias names here.

 

[Regina]
Yeah. You got a good one?

 

[Kristin]
I got another one, yeah. How about true believer bias?

 

[Regina] (51:26 - 51:26)
Oh, absolutely. I like that.

 

[Kristin] (51:26 - 51:36)
Yes, this is the idea that if you've worked on the same topic, you know, for 60 years or however long, you might really start to see the world through that lens.

 

[Regina] (51:36 - 51:36)
Yeah.

 

[Kristin] (51:36 - 51:47)
All these topics people work on, they tend to be very narrow. Yeah. And if you've been working on vitamin D forever.

 

Right. You might start seeing the world through vitamin D tinted glasses, right?

 

[Regina] (51:48 - 51:51)
I feel like this is a very human approach, right?

 

[Kristin] (51:51 - 51:56)
I've read now a lot of Holick's work, and it strikes me that he really might be a true believer.

 

[Regina] (51:57 - 52:00)
So what makes you think that he's actually a true believer?

 

[Kristin] (52:00 - 52:10)
Right, so he seems to think like vitamin D is the key to everything in the world. He's actually been quoted as having said that vitamin D might be responsible for the extinction of the dinosaurs.

 

[Regina] (52:12 - 52:16)
Your kidding. No. Extinction of the dinosaurs?

 

Why? What? They couldn't get enough supplements?

 

[Kristin] (52:17 - 52:28)
Well, okay, remember that people think that the dinosaurs went extinct because a big asteroid hit the earth. Yeah. Kicked up a bunch of soot and dust into the atmosphere and partly blocked the sun.

 

You can see where I'm going with this.

 

[Regina] (52:28 - 52:29)
Yeah, yeah, yeah.

 

[Kristin] (52:29 - 52:36)
Holick has speculated that the lack of sun might have caused the dinosaurs to die of rickets and osteomalacia.

 

[Regina] (52:36 - 52:40)
I'm picturing dinosaurs running around with rickets now.

 

[Kristin] (52:41 - 52:41)
T-Rex and bowlegs.

 

[Regina] (52:42 - 52:49)
Their poor little bowlegs. And they're looking for a tanning booth. And some vitamin D pills.

 

[Kristin] (52:49 - 52:59)
I mean, there's some logic here. But of course, the more obvious explanation would be if the sun goes out, the plants die and you die of starvation, not of rickets.

 

[Regina] (52:59 - 53:03)
No, no, no, no, no. They're running around with rickets and bowlegs. And they're very sad.

 

[Kristin] (53:03 - 53:04)
But you can see the true believer bias.

 

[Regina] (53:04 - 53:14)
Yeah, the true believer bias. Okay, true believer bias.

 

I like this. Sometimes I've heard people call it motivated cognition.

 

[Kristin]
That's the boring term.

 

[Regina] (53:14 - 53:26)
It is. It's not as much fun.

 

[Kristin]
My daughter calls it cotton candy bias because researchers spin the evidence like spinning cotton candy to prove what they want to prove.

 

[Regina] (53:26 - 53:32)
Officially, Kristin, your daughter is adorable. Right. And brilliant.

 

And I'm stealing this.

 

[Kristin]
Yeah, you can steal it.

 

[Kristin] (53:32 - 53:54)
Totally fine. All right, Regina, to prepare for this podcast, I read parts of Holick's popular books, starting with The UV Advantage. And that was a book that promoted what he called sensible sun exposure.

 

You're going to love this. And this is the idea that we should all go out in the sun without sun protection and get that deliberate sun exposure because UV rays are good for you.

 

[Regina] (53:54 - 53:55)
Right. I'm a true believer.

 

[Kristin] (53:56 - 54:03)
All right. I want to read now the first paragraph of the first chapter of the book because it sent me down a rabbit hole.

 

[Regina] (54:03 - 54:04)
I love your rabbit holes.

 

[Kristin] (54:05 - 54:48)
Okay, here we go. Here it was, the summer of 1997. And for months, my staff and I had been studying the vitamin D status of a random group of people in Boston.

 

I had designed and was leading the study. I was sitting in my office when the results came in, although I had a strong suspicion by that time of what the study would reveal. The actual numbers were staggering.

 

Fully 42% of the people we studied were vitamin D deficient. My study, which was accepted for publication in The Lancet, only one in 100 papers submitted to this renowned journal are published, confirmed what most scientists in the field believe, that there is an epidemic of vitamin D deficiency in the United States and much of the Western world.

 

[Regina] (54:48 - 54:55)
I'm giving you an Academy Award for that dramatic re-enactment.

 

Very nice. Does he brag much?

 

[Kristin] (54:55 - 54:55)
Right.

 

[Regina] (54:56 - 54:58)
Yes, The Lancet. The Lancet, one in a hundred. Okay.

 

Yep.

 

[Kristin] (54:59 - 55:04)
All right. But Regina, when he's talking about this study, what does it make you picture? What are you thinking the study was about?

 

[Regina] (55:04 - 55:07)
So he's sitting in his office, right? Very dramatic, light streaming in through the windows.

 

[Kristin] (55:07 - 55:09)
He's not the one collecting the data, clearly. Right, right.

 

[Regina] (55:10 - 55:12)
But he got the data, and what you said, 42%?

 

[Kristin] (55:12 - 55:14)
42%, that's the key number, yes.

 

[Regina] (55:14 - 55:26)
Of the random sample of people in Boston? Yes. Was it Boston?

 

Okay, so I'm picturing he went out and recruited people, a random sample, like putting posters up in the tube, is there a tube or Boston Common?

 

[Kristin] (55:26 - 55:28)
It’s the T, yes.

 

[Regina] (55:28 - 55:31)
By the T, there you go. And they brought them and in 42% of this random sample.

 

[Kristin] (55:31 - 55:39)
I'm picturing this mobile vitamin D testing lab driving up to a Dunkin' Donuts and everybody gets a free donut if they get a vitamin D test, right?

 

[Regina] (55:39 - 55:47)
Why Dunkin' Donuts?

 

[Kristin]
Well, I grew up in New England, so I'm a fan of Dunkin' Donuts.

 

[Regina]
That is, okay, I like yours better.

 

So, is that what they did?

 

[Kristin] (55:47 - 56:19)
No, so I actually went and tried to find the study in the Lancet because I was curious, where did this 42% come from? How many people? I didn't tell us the sample size, how many people did he study?

 

How did he define vitamin D deficient? Right. And I thought it would be easy to find this study because I knew the journal and I knew the approximate date, right?

 

The book was published in 2003, so a few years before that. I went through all his papers in the Lancet, and he does have several papers in the Lancet, but I couldn't find it. There weren't any studies in the Lancet.

 

About a random sample of people in Boston.

 

[Regina] (56:20 - 56:22)
Oh, that's weird. Did he get it wrong?

 

[Kristin] (56:22 - 56:49)
Well, this sent me down a rabbit hole because then I thought, okay, maybe he mixed up the journal, right? He publishes a lot of studies and maybe he thought it was a paper in the Lancet, but it was actually in some other journal. And I spent an entire three-day weekend reading all of his papers from like 1995 to 2005 to try to find this study, and I couldn't find it.

 

There were no studies that matched any of those details.

 

[Regina] (56:49 - 56:53)
That is so weird. Was it like all a fever dream, a hallucination?

 

[Kristin] (56:54 - 57:31)
Well, okay. I finally, after three days, circled back to the Lancet, and I looked more carefully at a 1998 paper of his in the Lancet. It's actually that the study that they're describing in that paper is just a study of 35 people in their bone clinic, and they gave them all vitamin D supplements.

 

So when I first saw it, I didn't think it had anything to do with the prevalence of vitamin D deficiency. But I actually went back and read every line finally in that paper, and I found one sentence at the end of that paper that I think is describing the quote-unquote study where that 42% statistic came from.

 

[Regina] (57:31 - 57:40)
You need a medal for this, Inspector. Can I promote you to Inspector General?

 

What'd you find after you went through all the sentences?

 

[Kristin] (57:40 - 58:05)
Right, okay. So here it is. Here's the sentence.

 

After reviewing 169 patients seen in our bone health clinic, 86% women, average age 62, 41% were found at risk for vitamin D deficiency with vitamin D concentrations less than 20 nanograms per milliliter. All right, I know that it says 41%, not 42%. I'm chalking that one up to some kind of rounding difference.

 

[Regina] (58:05 - 58:11)
Okay, I'll give you that. But more important is who are these people? You said there was a bone clinic?

 

[Kristin] (58:12 - 58:15)
It's a bone health clinic. This is not a random sample of people at Dunkin' Donuts.

 

[Regina] (58:16 - 58:20)
That's right, this is, yeah. You said it was mostly women? Mostly women, older women.

 

[Kristin] (58:20 - 58:36)
Older women, come on. Average age 62. Probably most of them have osteoporosis because they're at a bone clinic.

 

A bone clinic? Yeah, and this is a group we would expect to have a lower vitamin D than the general population. So this 42% is totally misleading.

 

This is not a random sample of people in Boston.

 

[Regina] (58:36 - 58:53)
This is not a random sample. I am so disappointed in this. This seems exaggerated.

 

And I'm especially disappointed because this was published in a book. And you have these expectations about things published in books should be accurate. It would have been fact-checked, right?

 

[Kristin] (58:53 - 59:03)
I mean, especially the first paragraph of the first chapter. Like maybe they got lazy later, but at least fact-check the beginning of the book. Now, to be fair, Holick had a co-author.

 

[Regina] (59:04 - 59:04)
On the book?

 

[Kristin] (59:04 - 59:14)
Yes, because typically it's often, it's common for scientists to pair up with a science writer when they're writing a popular book to help them translate it for the lay public. And I can imagine that something might have got lost in translation.

 

[Regina] (59:15 - 59:18)
So, yeah, everyone makes mistakes, right? Right. Yeah, I guess.

 

[Kristin] (59:18 - 59:30)
We might make a few on this podcast. Hopefully not too many.

 

But it's one thing to make a mistake. And it's a different thing to have a pattern of mistakes.

 

And, Regina, we are going to break news here.

 

[Regina] (59:31 - 59:37)
Muck-raking investigative journalism happening here, Kristin. You heard it here first. Oh, yeah.

 

[Kristin] (59:37 - 59:58)
I talked about some other investigative journalists who have looked into Michael Holick. They have found some worrying things like the conflicts of interest. But one thing I haven't seen, at least at any major news outlets, I haven't seen anybody actually fact-check his work.

 

[Regina]
Oh, and you did.

 

[Kristin]
I fact-checked his work, and I found a worrying pattern of errors.

 

[Regina] (59:58 - 1:00:04)
Oh, that does not sound good. And this is in his book and his published papers?

 

[Kristin] (1:00:04 - 1:00:49)
Both his popular books and the scientific literature, yes.

 

And we don't have time to go into all the examples I found. I'll put some additional ones in the show notes.

 

[Regina]
Oh, good.

 

[Kristin]
But I want to talk about a few. I went and pulled his second popular book. This is called The Vitamin D Solution from 2010.

 

This book is now adding to the first book by saying, not only should you get that sensible sun exposure, but you should take supplements and get more vitamin D from your diet. So focusing on the vitamin D rather than the UV rays. And he's touting all sorts of potential benefits of vitamin D for things like fertility and anti-aging.

 

I'm going to read you one line from the book, Regina, just because I think you might like this. He says, Vitamin D may be the most underappreciated and misunderstood anti-aging secret. You're on board now, aren't you?

 

[Regina] (1:00:50 - 1:01:01)
All right, I'm convinced then. I understand. I have my biases.

 

All right, that's at the stage where he's coming from, right? Vitamin D is everything. But what about the fact-checking?

 

[Kristin] (1:01:01 - 1:01:11)
So that's just what the book is about. But as I was reading along in his book, I again came to a point where he cited one of his own studies. And I feel like if you're citing your own study, you should be able to get that right.

 

[Regina] (1:01:11 - 1:01:12)
You should. Right?

 

[Kristin] (1:01:12 - 1:01:22)
Okay. I'm going to read a passage in a minute here. But Regina, I want you to pay close attention to the numbers because when I'm done reading, I am going to give you a math test.

 

[Regina] (1:01:22 - 1:01:27)
Uh-oh. Do I need to run and get a calculator?

 

[Kristin] (1:01:27 - 1:01:29)
No calculator necessary. You can do this in your head.

 

[Regina] (1:01:29 - 1:01:35)
Okay, all right. I'm scared. I'm nervous, I gotta say.

 

But so I need to be listening for what?

 

[Kristin] (1:01:35 - 1:02:01)
For a math inconsistency.

 

[Regina]
Okay. All right, go ahead.

 

[Kristin]
This is the quote. In one of my studies, we looked at 40 newborn babies whose mothers were seemingly doing everything right before giving birth. 70% of them took prenatal vitamins, 90% drank fortified milk, and all ate fish.

 

Upon giving birth, 76% of the moms and a full 81% of the newborns were vitamin D deficient.

 

[Regina] (1:02:01 - 1:02:07)
All right. Mathematical inconsistency here. So 40 moms and babies.

 

[Kristin] (1:02:07 - 1:02:11)
Right. There was one baby per mom. So 40 moms and 40 babies, no twins.

 

[Regina] (1:02:11 - 1:02:44)
All right. So 40 pairs. Yep.

 

Right? Mom, baby pairs. And you said that 70% of them took vitamins, 90% of them drank milk, fortified milk.

 

And 76% of the moms were deficient. And 81% of the babies were vitamin D deficient. Okay.

 

So it's those last two numbers that kind of get my math spidey sense going. And that's because 40, whatever, pairs. And then we talked about 70%, 90%.

 

Those are nice round.

 

[Kristin] (1:02:44 - 1:02:45)
Right? Yeah.

 

[Regina] (1:02:45 - 1:03:11)
There are multiples of 10 in there. But I don't know if you can get 76%. All right.

 

I really want to get a calculator now. But you're mean. And I'm old.

 

We learned fractions growing up. So let me see if I can do this fraction. Half, 50% of 40 would be 20.

 

Yep. So 75% would be half again of that, 30 babies. But so you can't have 76%.

 

[Kristin] (1:03:11 - 1:03:14)
You can't have 76%. That would be a piece of a mom. We can't have pieces of moms and babies.

 

[Regina] (1:03:14 - 1:03:18)
And 81%. Same thing.

 

[Kristin] (1:03:18 - 1:03:39)
Good job. Yes, you passed my test. The percentages here have to be in increments of 2.5%. Because 1 in 40, that's 2.5%. 2 in 40, that's 5%. 3 in 40, that's 7.5%. And so on. You can't have 76% or 81% because they are not increments of that 2.5%.

 

[Regina] (1:03:39 - 1:03:41)
That's a neat way of looking at it. I like how your brain works a little different than mine.

 

[Kristin] (1:03:41 - 1:03:55)
A little differently, yeah. You want a funny story?

 

[Regina]
Of course.

 

[Kristin]
All right. Right after I fell down that rabbit hole, I happened to be interviewing candidates for my department's PhD program. And I'm a tough interviewer.

 

[Regina] (1:03:55 - 1:03:57)
Yeah. Why am I not surprised?

 

[Kristin] (1:03:57 - 1:04:17)
I do not care how many canned cookbook statistics courses you have aced or how many papers you've published. Because, you know, a lot of papers are garbage. They are.

 

[Regina]
Amen. Yep. Amen.

 

[Kristin]
So when I give an interview, what I do is I talk through some math and statistics problems with the candidate. It's essentially a test. I don't call it a test.

 

[Regina] (1:04:17 - 1:04:20)
Ooh, like an oral exam on the spot. On the spot.

 

[Kristin] (1:04:20 - 1:04:25)
Yes. And this year, I gave them that problem that I just gave you.

 

[Regina] (1:04:25 - 1:04:30)
That you had me do right live on the episode. So I got admitted to your PhD program.

 

[Kristin] (1:04:30 - 1:04:32)
You can be in my PhD program. Yes, yes.

 

[Regina] (1:04:33 - 1:04:33)
You're scary.

 

[Kristin] (1:04:34 - 1:04:38)
I'm not trying to be mean or scary, but I really do get the best PhD students.

 

[Regina] (1:04:39 - 1:04:41)
I believe it. I believe it.

 

[Kristin] (1:04:41 - 1:05:03)
Yeah. I should note that my department does offer other educational programs where the admissions does not require a scary math test on the spot like this, Regina. We have a wonderful remote certificate program in epidemiology and clinical research. You can take it from anywhere in the world.

 

And you take the same Stanford classes as on-campus students, including some of my statistics courses. And you get Stanford credit and a Stanford transcript. So this is highly recommended.

 

[Regina] (1:05:04 - 1:05:07)
And no scary test interview for admission.

 

[Kristin] (1:05:08 - 1:05:23)
Exactly. That's right. But Regina, getting back to the math error, someone might look at an error like this and say, you know, come on, Kristin, you are being overly picky.

 

Stop it. I mean, some of my interviewees may have thought that.

 

Maybe it's a typo or they rounded wrong. Like, who cares?

 

[Regina] (1:05:24 - 1:05:34)
Right, right, right. No, no, no, no. I'm actually with you on this, right.

 

Because where there's one, there's many, right? It's like cockroaches.

 

[Kristin] (1:05:35 - 1:05:47)
Yes, cockroaches, yes, yes. So of course, isolated mistakes happen. But you and I know that so often when you find one of these little math errors and then you start to dig further, the whole thing unravels like a big ball of yarn.

 

[Regina] (1:05:48 - 1:05:52)
So what happened when you started to unravel? Did you find a ball of cockroaches?

 

[Kristin] (1:05:52 - 1:06:07)
I found cockroaches, yes. All right. This time I was able to find the paper, no problem.

 

It was a 2007 clinical pediatrics paper. But right away, I noticed a bunch of funny things. We only have time for one.

 

I'll put the rest in the show notes.

 

[Regina] (1:06:08 - 1:06:08)
Okay.

 

[Kristin] (1:06:08 - 1:06:24)
So if you go to the table, it shows details about the moms, like how many of them were eating fish and how many had taken prenatal vitamins. And I'm going to give you an easier math test here, Regina. So it gives a value for the number of moms who ate fish of 44.

 

[Regina] (1:06:25 - 1:06:28)
But 44 is bigger than 40.

 

[Kristin] (1:06:28 - 1:06:45)
And you said there were 40. I should have put that on the test. I thought it was quite a bit easier.

 

Yes, there's only 40 moms. And of course, at first I thought, oh, that's just a typo, right? Somebody meant to type a zero, but they typed a four.

 

Okay. But I actually think now that it's more nefarious than that.

 

[Regina] (1:06:46 - 1:06:46)
Nefarious? Tell me.

 

[Kristin] (1:06:47 - 1:07:12)
Yes. He actually cites this same mother-baby study in another article of his back in 2003 in Mayo Clinic Proceedings. He cites it as unpublished data because back in 2003, it hasn't yet been published. But when he describes the study, that 76% pops up, but he says it was 76% in 50 mother-infant pairs, not 40.

 

[Regina] (1:07:13 - 1:07:21)
So that's where that 76% comes from, because you can get 76% of 50.

 

[Kristin]
Increments of 2%.

 

[Regina]
All right. That explains the first error.

 

[Kristin] (1:07:21 - 1:07:36)
It also explains the second error, because I'm guessing there might have been an earlier draft of the paper where they had all 50 mother-infant baby pairs. Yeah, yeah. And then they updated it, removing 10 of them, but they forgot to change that one number because it could have been 44 originally, right?

 

[Regina] (1:07:37 - 1:07:45)
Okay, yes. But the more important question is where did those 10 mother-baby pairs, where did they disappear?

 

[Kristin] (1:07:45 - 1:07:58)
I went through the entire paper in clinical pediatrics, and there was absolutely no mention of those extra 10 pairs that were clearly in the data set before. And of course, sometimes we do have to exclude data. That's not wrong.

 

[Regina] (1:07:58 - 1:08:07)
Right, but if you have a good reason to do so, and you disclose it. You have to disclose it. You can't just silently delete 10 out of 50 data points.

 

[Kristin] (1:08:07 - 1:08:21)
That's 20% of their data. And the fact that it just disappeared makes me suspicious that maybe they disappeared those data points because they didn't fit some story or some narrative that they were trying to tell, and you can't do that.

 

[Regina] (1:08:21 - 1:08:24)
Oh, that is possible. Maybe they were cherry picking.

 

[Kristin] (1:08:24 - 1:08:28)
Cherry picking, yeah, we don't know, but it just doesn't look good.

 

[Regina] (1:08:28 - 1:08:28)
Yeah, no.

 

[Kristin] (1:08:29 - 1:08:32)
And this makes me question his objectivity and his credibility.

 

[Regina] (1:08:33 - 1:08:33)
Yeah, I'm with you on that.

 

[Kristin] (1:08:34 - 1:08:36)
Do we have time for one more fun one?

 

[Regina] (1:08:36 - 1:08:37)
Of course, absolutely.

 

[Kristin] (1:08:38 - 1:08:51)
Here is an example where he cites somebody else's papers, not one of his own. He says that 28% to 100% of healthy adults in Europe are vitamin D deficient.

 

[Regina] (1:08:51 - 1:09:00)
So, potentially, every single person in Europe is vitamin D deficient. Come on. No, that's just ridiculous.

 

[Kristin] (1:09:00 - 1:09:05)
Yeah, we should say up to 100% of nerdy middle-aged women are sexy, right?

 

[Regina] (1:09:06 - 1:09:11)
Oh, I like that one. I like that one better. We're going to move the goalpost like that.

 

Okay, this doesn't even make any sense.

 

[Kristin] (1:09:11 - 1:09:24)
Where did that number 100% come from? So, I pulled the studies that he cited for that range of values. Regina, you want to guess what population the 100% came from?

 

[Regina] (1:09:24 - 1:09:29)
You know, I can't even because after the dinosaurs, I feel like I'm just tapped out.

 

[Kristin] (1:09:30 - 1:09:32)
It was a study in Italians.

 

[Regina] (1:09:32 - 1:09:34)
Yeah. Oh, the Italian stallions.

 

[Kristin] (1:09:34 - 1:09:58)
No, not the Italian stallions. Are you ready? This was a study in Italian centenarians.

 

[Regina]
Centenarians? They were... How old?

 

[Kristin]
98 to 105 years old.

 

[Regina]
That is not representative of anything.

 

[Kristin]
Very select group. And I think he got the quote healthy because they were not allowed to be in the study if they had an acute illness.

 

[Regina] (1:09:58 - 1:09:59)
Or dead.

 

[Kristin] (1:10:00 - 1:10:12)
They pretty much got in for being alive. They had to be breathing and 100 years old. You know, didn't have an acute illness, but a whole bunch of them were in nursing homes and half of them could not walk.

 

[Regina] (1:10:12 - 1:10:16)
Oh, no, come on. This is misleading.

 

[Kristin] (1:10:16 - 1:10:16)
Of course.

 

[Regina] (1:10:17 - 1:10:18)
This doesn't...They are 100.

 

[Kristin] (1:10:18 - 1:10:18)
Right.

 

[Regina] (1:10:18 - 1:10:22)
That's not representative of anything. You cannot say, okay, this generalizes.

 

[Kristin] (1:10:22 - 1:10:24)
Of course, they're all low in vitamin D, yes.

 

[Regina] (1:10:24 - 1:10:35)
Okay. So this goes, again, to credibility because...

 

[Kristin]
Credibility, yes.

 

[Regina]
That is exaggerated. We can also say maybe 0% of people, right? You can't go in that direction.

 

[Kristin] (1:10:35 - 1:10:54)
Yeah, that range is ridiculous. All right. I want to mention one last thing about Holick.

 

There was an article out by both the New Yorker and ProPublica in 2018. This was also by David Armstrong. He's this journalist I mentioned who's been covering Holick for a while.

 

The article is called the Child Abuse Contrarian.

 

[Regina] (1:10:54 - 1:10:58)
Oh, child abuse. Okay, we're getting to that thread that you foreshadowed before.

 

[Kristin] (1:10:58 - 1:11:05)
Yes. It turns out that Holick has been working as an expert witness defending accused child abusers.

 

[Regina] (1:11:06 - 1:11:08)
Oh, this is... This sounds serious.

 

[Kristin] (1:11:08 - 1:11:09)
Yeah.

 

[Regina] (1:11:09 - 1:11:11)
What is the vitamin D connection?

 

[Kristin] (1:11:12 - 1:11:49)
So kids who are abused tend to show up in the emergency room with often multiple broken bones. Yeah, yeah. And Holick has been diagnosing these kids with conditions that might give them fragile bones.

 

Specifically, he's diagnosed most with a rare genetic disorder called Ehlers-Danlos syndrome or EDS. This affects the connective tissue, that mesh in the bones we've talked about. He's also diagnosed a lot of them with vitamin D deficiency.

 

So his argument is that the kids are fracturing because of bone fragility rather than because of abuse.

 

[Regina] (1:11:49 - 1:11:57)
Oh, this is super heavy. How is he diagnosing these people with this genetic condition?

 

[Kristin] (1:11:57 - 1:12:40)
There isn't a genetic test for this. It's diagnosed clinically because people with EDS have hypermobile joints. And according to that reporting by Armstrong, he is actually diagnosing a lot of these kids over the phone.

 

So not even seeing them in the clinic.

 

[Regina]
Over the phone?

 

[Kristin]
Yeah, according to that article.

 

[Regina]
Can you even do that?

 

[Kristin]
And at the time that David Armstrong wrote that article, apparently Holick had defended more than 300 cases. And in all of those cases, he had diagnosed the kids with EDS and or vitamin D deficiency.

 

And of course, I don't know anything about the individual cases. He could be right, right? But it probabilistically, it seems like a stretch to believe that these are all cases.

 

[Regina] (1:12:40 - 1:12:41)
All of them.

 

[Kristin] (1:12:41 - 1:12:43)
Undiagnosed bone fragility.

 

[Regina] (1:12:43 - 1:12:51)
So what about the financial part of this? Expert witnesses get paid?

 

[Kristin] (1:12:51 - 1:13:04)
Expert witnesses get paid a lot.

 

According to Armstrong's article though, Holick says he's not taking any money personally. But he does take money for his research because he has now started a research program on Ehlers-Danlos Syndrome.

 

[Regina] (1:13:04 - 1:13:06)
That probably raised eyebrows though.

 

[Kristin] (1:13:06 - 1:13:21)
This whole thing has been very controversial. In fact, the Boston Medical Center where he works has restricted his physician privileges. So he is only allowed to see pediatric patients as part of his research study, but not in clinical practice.

 

[Regina] (1:13:21 - 1:13:31)
Not clinically.

 

[Kristin]
Yeah. And Regina, we were talking about true believer bias before.

 

[Regina]
Yeah, yeah. Like hammer and nail, right? If you have a hammer, everything looks like a nail.

 

[Kristin] (1:13:31 - 1:13:35)
If all you have is vitamin D, everything looks like a vitamin D receptor.

 

[Regina] (1:13:36 - 1:13:37)
Yeah, yeah.

 

[Kristin] (1:13:37 - 1:14:01)
He, I think, might really believe that he is protecting parents who have been falsely accused. I've listened to him speak on like YouTube. I've seen some of his quotes in these articles.

 

Yeah. And it does seem like he might really believe this.

 

[Regina]
Yeah, and maybe he is.

 

[Kristin]
We don't know. But again, like that true believer bias, it goes to credibility. He's really, yeah.

 

[Regina] (1:14:01 - 1:14:03)
It fits in with the pattern that we're talking about, right?

 

[Kristin] (1:14:04 - 1:14:04)
Yeah, exactly.

 

[Regina] (1:14:04 - 1:14:08)
Everything is in favor. It doesn't seem objective anymore.

 

[Kristin] (1:14:08 - 1:14:17)
No. One more thing before we wrap up here, Regina. I now want to get back to the dueling medical guidelines and give you the resolution of what happened.

 

[Regina] (1:14:18 - 1:14:20)
Finally, because I have been on the edge of my seat.

 

[Kristin] (1:14:20 - 1:14:59)
Oh, I'm sure. I have an update.

 

[Regina]
Yeah.

 

[Kristin]
Because the Endocrine Society recently revamped their entire guideline writing process.

 

[Regina]
The process. Oh, interesting. What happened?

 

[Kristin]
They came under fire. Okay, so the Endocrine Society has these committees that write clinical practice guidelines for lots of things, not just vitamin D.

 

They came under fire because people pointed out that their guidelines were not always as rigorous as they should be. Remember we talked about that glass half full? They also pointed out that a lot of members of these committees, about four in ten, had financial conflicts of interest directly related to the guidelines they were writing, just like Holick.

 

[Regina] (1:14:59 - 1:15:09)
Oh, so four out of ten stood somehow to gain from this. Financial gain. Oh, not good.

 

So they changed their approach.

 

[Kristin] (1:15:09 - 1:15:36)
They revamped their whole process to be more rigorous and to minimize conflicts of interest. And are you ready for this?

 

[Regina]
Oh, yeah.

 

[Kristin]
In June of 2024, recently, the Endocrine Society released new updated vitamin D guidelines where they used this more rigorous process and they had a new committee. That new committee only included one researcher who was on the old committee in 2011, and it was not Michael Holick.

 

[Regina] (1:15:36 - 1:15:37)
Not Holick.

 

[Kristin] (1:15:37 - 1:15:38)
Nope, he got the boot.

 

[Regina] (1:15:38 - 1:15:45)
So they pretty much replaced everyone. They started over. Oh, new guidelines.

 

OK, what'd they say?

 

[Kristin] (1:15:46 - 1:16:03)
All right, you ready, Regina? They completely capitulated. The IOM won out.

 

[Regina]
You're kidding.

 

[Kristin]
I am not kidding.

 

[Regina]
They reversed it?

 

[Kristin]
They reversed themselves completely. It's a little subtle, though, OK? It's almost like they were trying to hide or bury the fact that it's a complete reversal.

 

[Regina] (1:16:04 - 1:16:06)
Not surprising when you think about it.

 

[Kristin] (1:16:06 - 1:16:07)
Right, they didn't want to admit error.

 

[Regina] (1:16:07 - 1:16:09)
Human nature. Uh-huh.

 

[Kristin] (1:16:09 - 1:16:20)
And the report did get some media coverage, but the media completely missed the context in the punchline. It seems like the reporters might have been unaware of the whole 2011 controversy.

 

[Regina] (1:16:20 - 1:16:36)
Wow. Well, this is why people need to listen to our podcast, right? We put it all in the context and perspective.

 

[Kristin]
We put it into context, and we're old enough to know the context.

 

[Regina]
Benefit to being old. All right, new guidelines for vitamin D.

 

And?

 

[Kristin] (1:16:36 - 1:17:02)
OK, so first of all, here's what I think is the most interesting part. This is a direct quote from the paper. The Endocrine Society no longer endorses the target vitamin D level of 30 nanograms per milliliter suggested in the previous guideline.

 

Similarly, the Endocrine Society no longer endorses specific vitamin D levels to define vitamin D sufficiency, insufficiency, and deficiency.

 

[Regina] (1:17:03 - 1:17:11)
Wow. Wait a minute. So that 20 and 30 that we've been talking about, just gone?

 

It's just gone.

 

[Kristin] (1:17:11 - 1:17:23)
Yes, gone. They're saying we no longer endorse that. I mean, everything hinged on those numbers, right?

 

Everything hinged on it. And they're getting rid of them. Essentially, they are completely agreeing with the IOM.

 

[Regina] (1:17:23 - 1:17:38)
Oh, my God, that's amazing. That means those numbers in our lab reports no longer valid? Exactly.

 

[Kristin]
The labs shouldn't be using those numbers anymore.

 

[Regina]
Wait a minute, though. If we don't have thresholds anymore, what do we need to be testing for?

 

[Kristin] (1:17:38 - 1:17:45)
Well, that's the other thing that these new guidelines say. They say that we should not be doing routine vitamin D testing.

 

[Regina]
Really?

 

[Kristin]
Yeah, not at all.

 

[Regina] (1:17:45 - 1:17:46)
No testing?

 

[Kristin] (1:17:46 - 1:18:00)
No testing unless you have a specific indication, like maybe you have symptoms of osteomalacia or rickets. Then you should go for vitamin D testing. But you have to have something specific that appears to be related directly to vitamin D.

 

[Regina] (1:18:00 - 1:18:01)
Like a reason.

 

[Kristin] (1:18:01 - 1:18:04)
Otherwise, we shouldn't be routinely testing people.

 

[Regina] (1:18:04 - 1:18:16)
I wonder if the labs are just going to pretend like they never saw this. They never heard this. Because this is huge.

 

This is going to affect them financially. What about supplements? Would they stay there?

 

[Kristin] (1:18:16 - 1:18:19)
Well, they also changed their recommendations on vitamin D supplements.

 

[Regina] (1:18:21 - 1:18:25)
OK, so not only did they hit the labs, now they're hitting the supplement companies.

 

[Kristin] (1:18:26 - 1:18:53)
They revised their recommendations for how much vitamin D people should be getting every day from their diet or supplements. They revised it downward to match what the IOM had said back in 2011. They also recommend against routine vitamin D supplementation.

 

They said just a few groups, like children and pregnant mothers because of the risk of rickets, those groups should consider supplements. But they said most people, including us, Regina, don't need supplements.

 

[Regina] (1:18:55 - 1:19:02)
So, according to them, I don't need to be spending money on all this vitamin D pills. OK, this is a huge reversal.

 

[Kristin] (1:19:03 - 1:19:16)
It's a complete reversal. The IOM won out. And again, this kind of went under the radar.

 

Maybe after our podcast, people will get the message. I hope so. But I've got to believe that there are some IOM committee members out there having a victory dance.

 

[Regina] (1:19:16 - 1:19:20)
Dancing around, high-fiving each other. They did not miss this. No, because this is big.

 

[Kristin] (1:19:20 - 1:19:22)
It's big, yes. It changes a lot of things.

 

[Regina] (1:19:22 - 1:20:06)
And I can see why that Endocrine Society kind of swept this under the rug. All right, I think now we are ready to wrap things up and rate the strength of evidence for this claim today. And that is that there is an epidemic of vitamin D deficiency in the Western world.

 

And we do this, Kristin, of course, with our highly scientific, trademarked smooch rating scale. One to five smooches, kind of like Amazon stars, except better. And one smooch means there's little to no evidence for this claim.

 

Five is that there's a lot of strong evidence. So, Kristin, kiss it or diss it. What do you say?

 

[Kristin] (1:20:06 - 1:20:13)
Well, Regina, you can probably guess what I'm going with on this one. I feel like, why don't we have a zero? I need like a negative smooch.

 

[Regina] (1:20:13 - 1:20:16)
Or negative.

 

[Kristin]
Yes, I need a negative.

 

[Regina]
What's the opposite of a smooch, though?

 

[Kristin] (1:20:17 - 1:20:19)
This is like a martini in the face.

 

[Regina] (1:20:20 - 1:20:23)
How many martinis in the face are you giving this one?

 

[Kristin] (1:20:23 - 1:20:25)
This is three martinis in the face for me.

 

[Regina] (1:20:25 - 1:20:25)
Three martinis.

 

[Kristin] (1:20:25 - 1:20:58)
Yeah, that's how much I think that this is a completely manufactured epidemic. The narrative here that there's this epidemic, it was largely created by Michael Holick, and I actually just don't think he's credible. And the Endocrine Society, who were the other people pushing this whole narrative, they've completely reversed themselves.

 

They flipped.

 

[Regina]
They flipped. Who's left arguing this?

 

[Kristin]
There's nobody left arguing this. The fact that they reversed themselves has not yet permeated into the general conversation here. Not yet.

 

They need to listen to our podcast.

 

[Regina] (1:20:58 - 1:21:06)
Yes, they do. So, I am not going to go so far as to throw an alcoholic drink in anyone's face, but I will give it one smooch at the very bottom of our scale.

 

[Kristin] (1:21:06 - 1:21:08)
All right, I've convinced you, yes.

 

[Regina] (1:21:08 - 1:21:21)
I am looking forward to part two, however, because this is where we're talking not about the epidemic, the evidence for an epidemic, but we're talking about evidence for the effect in our bodies.

 

[Kristin] (1:21:21 - 1:21:27)
Should we all be really boosting our levels to really high levels to get these health benefits? Yes, yes. To the 92 nanograms per million.

 

[Regina] (1:21:29 - 1:21:47)
You're not going to let me ever forget that. Okay, let's talk about our methodological morals. So, like Aesop's Fables, you know, you get a nice little moral at the end of the story.

 

We do the same thing, except they are methodological morals, so a little nerdier, a little geekier. What is yours?

 

[Kristin] (1:21:47 - 1:21:56)
Regina, how about: Arbitrary thresholds make for arbitrary diseases. Do you like that?

 

[Regina]
Oh, I love it.

 

That's what they've done. Yes, exactly.

 

[Regina] (1:21:56 - 1:22:01)
Just like we were going to create an arbitrary disease of, what, extreme sexiness?

 

[Kristin] (1:22:01 - 1:22:05)
Yeah, you can make anything. A hundred percent of people have it.

 

[Regina] (1:22:05 - 1:22:10)
Up to a hundred percent of people are extremely nerdy.

 

[Kristin] (1:22:10 - 1:22:17)
Up to a hundred percent of middle-aged women who like statistics are extremely sexy. Yes, very good. How about you?

 

[Regina] (1:22:17 - 1:22:25)
I am going to go with: Statistical errors are like cockroaches: where there's one, there's many.

 

[Kristin] (1:22:25 - 1:22:35)
I love it. Yes, it is so true, and we saw that today. So, if you are afraid of cockroaches, you might not want to dig further in those numbers once you see a mistake.

 

[Regina] (1:22:35 - 1:22:38)
They are not living alone. There's a whole nest of them.

 

[Kristin] (1:22:38 - 1:22:38)
A little scary.

 

[Regina] (1:22:38 - 1:22:47)
Yeah, yep, yep, yep. Kristin, this has been a fascinating episode, and I think your statistical sleuthing here deserves a prize.

 

[Kristin] (1:22:48 - 1:22:48)
Oh, thank you, Regina.

 

[Regina] (1:22:48 - 1:22:59)
I don't know what to give you, but you deserve a prize. I think you've changed a lot of opinions here, and this has been exciting. I'm looking forward to the next one.

 

[Kristin]
Yeah, looking forward to part two. Thanks, Regina.

 

[Regina]
See you.