Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Vitamin D, part 3 – The Evidence

devaboone.com

Post reply on HN
Print view View original

211–218 of 218 posts

Re: Vitamin D, part 3 – The Evidence

#211

Post by auganov »

dcolkitt wrote: post #168
scott_s wrote: post #52

Earlier quoted context omitted.

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.

That's certainly a possibility, but we have two reasons to believe it's not true. One, even careful attempts to control confounders, still shows a substantial health benefit associated with higher sun exposure.[1] In other words, even among people with no discernible health conditions, the most sun exposed are healthier. Two, randomized control trials show improvements in biomarkers like blood pressure[2] and lipid p…

The first study you linked looked at 29518 people and that's how they controlled for comorbid illnesses:

> As a measure of comorbid illness at the start of the study, we created a dummy variable ‘comorbidity’ identifying women who have been treated with antidiabetic [Anatomical Therapeutic Chemical Classification System (ATC) A:10] or anticoagulant (ATC B:01) drugs or medications for cardiovascular disease (ATC C:01–C:10) for more than 1 month.

This is extremely simple, hardly careful controlling. If anything it's a good example of bad science. Grabbed whatever was easily available in the database and claims they've adequately controlled for comorbidity while doing no such thing.

If you look at the difference in exercise, income, education and BMI there's a LOT going on between the two groups. You'd wish scientists would include the raw data and source code to easily calculate the adjustments yourself.

Re: Vitamin D, part 3 – The Evidence

#212

Post by leftyted »

tchaffee wrote: post #208
leftyted wrote: post #200

Earlier quoted context omitted.

You could have responded to my post but instead you did this. Why? There are more than two skin tone phenotypes. It's a gradient that gets lighter as you move away from areas of higher UV radiation to areas of lower UV radiation.

> You could have responded to my post but instead you did this. Why? I responded to the part of your post that was the most important to me: that discussions like this head towards more scientific rigor the longer they go on. > There are more than two skin tone phenotypes. It's a gradient that gets lighter as you move away from areas of higher UV radiation to areas of lower UV radiation. Sure. And I'm not much intere…

If you want to look for scientific papers about the obvious correlation between melanin content and UV radiation then use google.

You should read Hume. He didn't think that casuation had anything to do with reason, but rather was a habit of the mind. You're not going to find any causal smoking gun here and you're really just blithely dismissing ideas that don't fit whatever vague, unacknowledged biases you have.

Re: Vitamin D, part 3 – The Evidence

#213

Post by treeman79 »

scott_s wrote: post #15
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?

I would frame it in the opposite direction: having a serious illness is correlated with low levels of Vitamin D. People with a serious illness may stay inside more, and go outside less. It's possible that "low levels" of Vitamin D are still within the healthy range, and they merely are an indication of how much time the person has spent outside during the day. In other words, it's possible that Vitamin D is pure symp…

Sun exposure causes me massive inflammation. So yea, I avoid the sun like the plague. Autoimmune condition. Vit D is critically low.

I can sort of tolerate a UV index of 1, usually.

So I walk a lot in evenings and early mornings.

During summer I’m basically trapped in house or gym. This past summer it was just the house.

Re: Vitamin D, part 3 – The Evidence

#214

Post by 0-_-0 »

tchaffee wrote: post #209
0-_-0 wrote: post #196

Earlier quoted context omitted.

Correlation is not causation, but you didn't ask for proof, you asked for evidence, and correlation is evidence. For example, do you know whether smoking causes cancer? Because all the evidence we have that it does is based on correlation. Or you're happy saying "I don't know" and asking more questions? How would you show a causal link between vitamin D deficiency causing the evolution of light skin colour without be…

> you didn't ask for proof, you asked for evidence I didn't ask for evidence from you. I asked more specifically "Are there any studies giving strong evidence as to the causation for evolving white skin? > do you know whether smoking causes cancer? Because all the evidence we have that it does is based on correlation. That's wrong. We understand why smoking causes cancer. Just for example one of chemicals produced by…

> I didn't ask for evidence from you. I asked more specifically "Are there any studies giving strong evidence as to the causation for evolving white skin?

Correlation is evidence of causation, and the correlation between skin colour and latitude comes from studies. Therefore I provided that evidence.

> We've gone from "It must be important if it was worth evolving white skin over" to "we can't prove that's why we have white skin".

We did evolve white skin to produce vitamin D, the evidence is overwhelming. Just like evidence was overwhelming about smoking causing cancer, even before the 2018 article you linked came out. You seem to be misunderstanding the Wikipedia article. It's not contradicting itself. The correct interpretation is that the need for dark skin at the equators doesn't explain white skin nearer the poles, therefore there must be a different reason for it (vitamin D). That article wikipedia links to can be found on SciHub.

Overall, your approach reminds me of creationists that claim that evolution is "just a theory" because noone has ever proven it in a lab, and correlation is not causation. And tobacco companies who have denied that smoking causes cancer because correlation does not equal causation.

Re: Vitamin D, part 3 – The Evidence

#215

Post by baccheion »

zwaps wrote: post #206
baccheion wrote: post #147

Earlier quoted context omitted.

I said no need to take so much.. for no reason. With advancing age, higher amounts (+ magnesium and K2) mimic/amplify the actions of hGH/IGF-1 pushing back toward youth. More D3 is often needed with age for the same effect. The combo is also protecting bone and the higher amount of magnesium does countless things: released when the body is ready to unroll inflammation, opposes excess lipid peroxidation, opposes lipof…

You are repeating yourself, so I will as well. The article claims that these health benefits do not exist for normal people. The article has studies with high quality RCTs that would trump other, observational studies.

I said higher doses wouldn't be needed for no reason.

On the other hand, I already mentioned what happens with age.

Re: Vitamin D, part 3 – The Evidence

#216

Post by neetdeth »

tchaffee wrote: post #210
neetdeth wrote: post #194

Earlier quoted context omitted.

One aspect of sexual selection is that a disadvantageous trait needn't kill to cause differential outcomes in reproduction. If a deficiency results lower hunting success, diminished fighting prowess, loss of mental acuity etc. the individual will be disfavored in mate selection. Iterated over generations, this eventually extinguishes some genes. There's also the aesthetic aspect, where some traits seem to be favored…

> One aspect of sexual selection is that a disadvantageous trait needn't kill to cause differential outcomes in reproduction. If a deficiency results lower hunting success, diminished fighting prowess, loss of mental acuity etc. the individual will be disfavored in mate selection. That makes sense, and it also supports my claim that skin cancer would likely not be a trait selected against, right? It's something that…

For skin cancer narrowly, sure. I don't know what it's like to live with white skin near the equator with primitive or no clothing and no access to sunscreen, though. Losing melanin every winter, getting scorched every summer... It seems like you'd have an individual who is pretty useless for persistence hunting across the savannah. On the other side, a darker skinned individual may experience lethargy and malaise in winter at higher latitude. So we should broaden the considerations to include chronic, nonlethal conditions, and competitive sexual selection amplifies their effects. This was my only point.

> A common example might be the preference for lighter skin in mates that we unfortunately find in several cultures. Maybe we should start calling it eugenics instead of softening it to artificial selection.

You can do that if you want. People really like their mate preferences and this seems more likely to soften their perception of eugenics as a concept than the other way around.

Re: Vitamin D, part 3 – The Evidence

#217

Post by conorh »

mola wrote: post #203
ajhurliman wrote: post #195

Earlier quoted context omitted.

I thought the opposite: It campaigns against vitamin D as if it were a wolf in sheep's clothes. I've seen the author (and her partner) post and link about the dangers of vitamin D for a while now and it seems very unscientific to come at a subject with your mind already made up. The author has clearly made up their mind about vitamin D and now they've made it duty to lobby on behalf of that belief, but I don't think…

huh? They did the research, reached conclusions, and inform the public. That's what scientists should do. Why do you think they first decided they don't like vitamin D, and only then cherry picked research to prove it? Anyway, If you are an informed enough, you don't have to believe them, you can just read all the research they provided, and see for yourself. Otherwise, all you can do is trust them. Or not.

I think the idea of these articles was to help make people more informed consumers. As Deva says:

> Finally, no one needs to blindly believe what I say - or what anyone else says - about Vitamin D. You can and should critically evaluate the evidence for yourself. Below I have listed out some of the most important RCTs and meta-analyses of RCTs, with summaries and links. When looking at meta-analyses, Cochrane always provides top quality reviews, and I often look to them first for quality analyses and thoughtful interpretations.

Re: Vitamin D, part 3 – The Evidence

#218

Post by Shorel »

ajhurliman wrote: post #195
mola wrote: post #94

This is wonderful scientific writing; approachable without being condescending or over simplifying, without a trace of sensationalism. Really beautiful.

I thought the opposite: It campaigns against vitamin D as if it were a wolf in sheep's clothes. I've seen the author (and her partner) post and link about the dangers of vitamin D for a while now and it seems very unscientific to come at a subject with your mind already made up. The author has clearly made up their mind about vitamin D and now they've made it duty to lobby on behalf of that belief, but I don't think…

I think something important we are missing is that vitamin D effects seem to be quite different when the vitamin is produced by the body and when it is taken orally.

It is a lot less effective when taken orally. This study doesn't mention this important distinction.

Post reply on HN