Vitamin D, part 3 – The Evidence • Hacker News Board

Re: Vitamin D, part 3 – The Evidence

#111

Post by zwaps » Tue, Sep 08, 2020, 5:25 PM UTC

baccheion wrote: post #84

RL_Quine wrote: post #14

For other reasons I get tested for vitamin D every few months and managed to get my levels just above the normally recommended amount as per doctors advice. When people are saying they’re taking 25-100k UI a day I’m just stumped why they’d be doing that without medical advice, the amount to change my levels was nothing in comparison.

RDA is 400 IU. It's actually the food RDA, with 20% expected from food. Overall RDA (sun + food) is 2000 IU. Therapeutic vitamin doses are 10x the RDA. 6x is elevated while doing "nothing" and 20x is full saturation ("but why"). 2x and 4x for minerals. For vitamin D, that would then be 20,000 IU or roughly 300 IU/kg/day. No need to take that much or be outside the 40-60 ng/mL range for no reason. On the other hand, m…

This is a thread about an article citing many studies of RCTs showing no such benefit. For that reason, where is your recommendation coming from?

Re: Vitamin D, part 3 – The Evidence

#112

Post by waterhouse » Tue, Sep 08, 2020, 5:25 PM UTC

bad_user wrote: post #103

staticassertion wrote: post #71

It seems interesting that Vitamin D may be so much more prone to false correlations due to the fact that it's tied to going out in the sun, and going out in the sun is what healthy people do. Since so many illnesses and conditions, from psychological to physical, can keep you indoors, one could conclude that vitamin D is really a miracle pill. I take 1k iu a day, since I barely go outside anymore, but I'd probably cu…

RCTs are high quality, because they are done in a controlled setting, testing against a control group, testing the null hypothesis. RCTs are able to show causality. The problem with RCTs is that they are very expensive, since it involves keeping people in a clinic, so usually RCTs are short term and can only afford to look at surrogate markers. However most often than not, surrogate markers are enough. Also RCTs tend…

> The problem with RCTs is that they are very expensive, since it involves keeping people in a clinic

This may be a noob question, but why? For something like a vitamin supplement, can't you just give the study participants a box of their 50 possibly-placebo pills and require them to take one per day? If you're worried about compliance, can't you require them to write down the time each day when they take the pill—or even have the pills in a one-pill-per-box calendar arrangement and require them to take a photo with their phone each day? (Doesn't stop malicious noncompliance, but it should cover laziness/forgetting.)

Re: Vitamin D, part 3 – The Evidence

#113

Post by zwaps » Tue, Sep 08, 2020, 5:26 PM UTC

0-_-0 wrote: post #62

So what's the purpose of vitamin D then? It must be important if it was worth evolving white skin over, so why are studies failing to find that important reason?

It is important, it's just that most people do not seem to have dangerously low levels and derive no benefit from supplementation.

The article states several times that very low levels of vitamin D are not good.

Re: Vitamin D, part 3 – The Evidence

#114

Post by JPLeRouzic » Tue, Sep 08, 2020, 5:27 PM UTC

bad_user wrote: post #103

staticassertion wrote: post #71

It seems interesting that Vitamin D may be so much more prone to false correlations due to the fact that it's tied to going out in the sun, and going out in the sun is what healthy people do. Since so many illnesses and conditions, from psychological to physical, can keep you indoors, one could conclude that vitamin D is really a miracle pill. I take 1k iu a day, since I barely go outside anymore, but I'd probably cu…

RCTs are high quality, because they are done in a controlled setting, testing against a control group, testing the null hypothesis. RCTs are able to show causality. The problem with RCTs is that they are very expensive, since it involves keeping people in a clinic, so usually RCTs are short term and can only afford to look at surrogate markers. However most often than not, surrogate markers are enough. Also RCTs tend…

> RCTs are high quality, because they are done in a controlled setting

I have a personal interest in Amyotrophic Lateral Sclerosis, so I am reading patients' Internet forums since two years.

Several patients report participating in trials but they also tell that they take other drugs without telling doctors (they do not want to be expelled from the trial). Those drugs could be whatever they fancy, and they change often: A week seems too long for them, if there is no improvement.

I expect the situation being the same in every life challenging condition, so I doubt that RCTs are of high quality.

Moreover even the pharmaceutical industry seems to be not sure: Sometimes they are repetitively testing the same drug (for example Memantine in ALS):

https://clinicaltrials.gov/ct2/results?term=Memantine&cond=A...

Re: Vitamin D, part 3 – The Evidence

#115

Post by eloff » Tue, Sep 08, 2020, 5:28 PM UTC

ComputerGuru wrote: post #67

chownie wrote: post #5

Earlier quoted context omitted.

It might just be that the production of vitamin D via sunlight has other effects on the body, perhaps vitamin D has been a proxy for those effects but for obvious reasons taking it as a supplement doesn't trigger the same outcome. It's unfortunate that exposure to UV is so harmful, I'm left wondering if trials using UV lightboxes to stimulate vitamin D production would change the kinds of outcomes (cancer, heart dise…

> It's unfortunate that exposure to UV is so harmful, This is an extremely popular simplification. The scientific jury is still out on this one, as it seems that paradoxically people with constant exposure to sunlight are less likely to get skin cancer as compared to those that get sporadic exposure.

There was an interesting study (sorry I don't like to lookup citations on my mobile) showing that the prognosis for skin cancer patients is better in the summer than the winter, presumably because they get more sunlight. Not causative, but interesting nonetheless.

Also MS is extremely prevalent at high latitudes compared to the tropics. Why? We know vitamin D has a role in protecting the insulation of the nerves, so maybe that's the mechanism. Anecdotal, but the one person I know with MS is white as the snow and avoids the sun like it's the devil.

Re: Vitamin D, part 3 – The Evidence

#116

Post by grok22 » Tue, Sep 08, 2020, 5:30 PM UTC

LinuxBender wrote: post #89

Perhaps I missed it, but I did not see the study including K2 MK-7 and magnesium with D3. The 3 work together and can not support all of the metabolic functions on their own in a silo. There are also enzymes and co-enzymes that are part of the picture and I did not see any mention of them. Is there a more detailed version of the study? Again, could be me, I may have overlooked a link.

The doc said "don't think of vit-d as something magical" and you are saying "what if it was with k2 and magnesium; that might be more potent and magical" -- I think the doctor's general conclusion still holds that it is not proven that vitamin-d helps with certain diseases. And the fact that doing RCTs is time-consuming and expensive still holds. And without these RCTs, at present, we can't conclusively tell if the combination you suggest will help for those diseases that she mentioned.

Re: Vitamin D, part 3 – The Evidence

#117

Post by weezer » Tue, Sep 08, 2020, 5:32 PM UTC

m12k wrote: post #2

So Vitamin D deficiency is linked to cancer, heart disease, respiratory infection, stroke, diabetes, and death. But taking it as a supplement helps with none of the above. What is a reasonable hypothesis then? That having an active lifestyle that brings you outside in the sun both causes your Vitamin D to go up, and is correlated with better physical health in general?

Sun exposure (and even tanning beds) produces vitamin D, but it also causes other changes in the human body. It appears sun exposure OR tanning bed use (!!!) reduces all cause mortality.

"Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden cohort" https://pubmed.ncbi.nlm.nih.gov/24697969/

I think there's some confounding factors in 'outdoorsy' people having other healthy lifestyle habits, but it also seems likely that there is some other mechanism, beneficial to human health, triggered by uv exposure.

Re: Vitamin D, part 3 – The Evidence

#118

Post by zwaps » Tue, Sep 08, 2020, 5:32 PM UTC

goda90 wrote: post #81

Nursie wrote: post #53

Earlier quoted context omitted.

But we can see how supplementation affects outcomes, and it turns out that so far the results on that are pretty 'meh', unless you're supplementing specifically for severe vit D deficiency.

I guess my point is, if outcomes are affected by a couple dozen variables, unless we can control for all those variables, then we might not see any affect from this one variable. And there is a limit to how many variables we can reasonably control for.

Controling for variables is important to establish causality in observational studies. Many fields in social sciences are developing increasingly sophisticated methods to tease out causal relationships (see Pearl, Angrist&Pischke etc.).

However, many of these methods try to obtain the conditions similar to the gold standard: Randomized Control Trials.

In an RCT, if you assign treatment randomly to balanced subgroups of a population you care about (or one that is even representative), then you do not require to controls.

To see that, imagine the treatment being independent of the confounding factors and the distributions across group being the same. It then follows that you can estimate the average treatment effect without bias.

Re: Vitamin D, part 3 – The Evidence

#119

Post by staticassertion » Tue, Sep 08, 2020, 5:33 PM UTC

nradov wrote: post #99

staticassertion wrote: post #71

It seems interesting that Vitamin D may be so much more prone to false correlations due to the fact that it's tied to going out in the sun, and going out in the sun is what healthy people do. Since so many illnesses and conditions, from psychological to physical, can keep you indoors, one could conclude that vitamin D is really a miracle pill. I take 1k iu a day, since I barely go outside anymore, but I'd probably cu…

Why do you barely go outside?

I live in SF. Between the fires and the quarantine, I'm not out much the last few weeks.

Re: Vitamin D, part 3 – The Evidence

#120

Post by zwaps » Tue, Sep 08, 2020, 5:35 PM UTC

scott_s wrote: post #52

dcolkitt wrote: post #44

Earlier quoted context omitted.

> What is a reasonable hypothesis then? The logical conclusion is that vitamin D, as we measure it, is proxying for another factor that we haven't yet detected. This X-factor is heavily influenced by sun exposure, but at most weakly influenced by vitamin D supplementation in its current form. Analogously imagine that we had no concept of the health benefits of exercise. We detected that people with gym memberships we…

You're still assuming that Vitamin D is involved in some interaction that itself is the cause of people being sick. Your reasoning is not allowing for the simpler possibility: sick people have less Vitamin D because sick people are too sick to go outside.

Or, their sickness depletes their Vitamin D.