Is this about Vitamin D or Vitamin D supplements? We already know taking supplements does not equate to the body actually being able to make use of the vitamin. I'd be interested if this study also discounts Vitamin D produced by the body, or if some extra ingredient is needed to allow the body to benefit from the vitamin.
Vitamin D, part 3 – The Evidence
201–210 of 218 posts
Re: Vitamin D, part 3 – The Evidence
#202So 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…
I've always refused the idea that any sun == bad.
Being in the sun (not excessively) feels incredible, at a very deep level. The same way eating a really healthy diet and exercising every day feels.
I frequently wonder: if I'm correct, what other things are like this? Fats are good for you, not carbs as they've said. That's one example that comes trivially to mind. But I'm convinced there is a ton of stuff we do because it's "good" when in really, the positives far outweigh the negatives.
Re: Vitamin D, part 3 – The Evidence
#203This 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…
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.
Re: Vitamin D, part 3 – The Evidence
#204The July Radiolab episode it good on vitamin D and sunshine and its effect on covid and also on the 1918 flu. In both cases getting out in the sun seemed to have a dramatic reduction in deaths. https://pca.st/dwgcmlx1
I guess it must have quite an effect on things to evolutionarily justify the difference in appearance between fair skinned and dark skinned people - the fair skin is mostly to allow sun in to produce vit D in northern climes.
Re: Vitamin D, part 3 – The Evidence
#205Earlier quoted context omitted.
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.
Isn't a large fraction of the US an UK populations deficient in vitamin D? Doesn't deficiency mean that there's a benefit to supplementation? I thought that at least the correction of deficiency should have showed up in some study.
Usually there are severity levels of deficiency.
Apparently, current levels of deficiency are not enough to lead to large problems.
Re: Vitamin D, part 3 – The Evidence
#206Earlier quoted context omitted.
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?
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.
Re: Vitamin D, part 3 – The Evidence
#207Unfortunately, Vitamin D submissions are now in the same systematic group on HN as posts from NY Times, Zettelcasteln, Rust, Haskell,'Greenland is melting', 'Tesla is bound to fail', etc.
I understand that dang cannot stem the tide with the resources at his disposal, and the coming November looms over everything else. Still, one can hope for higher SNR here.
Re: Vitamin D, part 3 – The Evidence
#208Earlier quoted context omitted.
> It seems unlikely That's fairly far from any scientific method I would have confidence in.
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 interested in what "seems likely" in terms of what caused that. Lots of things that seem likely turn out to be wrong when it comes to causation.
Re: Vitamin D, part 3 – The Evidence
#209Earlier quoted context omitted.
> Correlation of latitude with skin colour is evidence of causation. Correlation is not causation. I'm sorry but I don't think you have any evidence at all that lighter skin was caused by a need for more vitamin D. It's just an educated guess on your part. Lighter skin could have just as easily been an adaptation related to less visibility to predators and prey in snow. Like the article I cited said "researchers are…
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 tobacco smoke is benzoapyrene which is a DNA disruptor, producing mutations that can lead to cancer. [1]
> It's fundamentally impossible to prove, all we have is evidence.
That's progress. 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".
The Wikipedia sentence claims an "abundance" of evidence and then only gives one source, which is behind a paywall. So I'm going to recommend an edit to that article to either give more sources or change the "abundance" claim. Furthermore just a few sentences later it contradicts itself with this:
"This accounts for the development of dark skin pigmentation of people living near the equator but does not account for the increasingly lighter-skinned people living outside the tropics."
Yet more doubt as to why we have white skin. From your source.
Finally, the article that started this discussion provides strong evidence that our need for vitamin D is less important than we previously thought. For sure very low levels of vitamin D are dangerous. But the link between vitamin D and health could be reverse causation: sick people stay inside and therefor have less vitamin D. It could also be that exposure to sun provides something more important to health than vitamin D that we are not aware of yet. So the claim that we evolved white skin just for vitamin D is increasingly on less stable ground.
I'll stop here because I'm happy that you've gone from what seemed like a factual claim to you claiming that it's something we cannot prove. Who knows, maybe someone clever can prove it. But it sure does seem like the evidence itself (about both vitamin D and skin color) is fairly rapidly changing.
[1] https://www.mskcc.org/news/how-do-cigarettes-cause-cancer
Re: Vitamin D, part 3 – The Evidence
#210Earlier quoted context omitted.
> A change like the loss of melanin requires selective pressure It does? What about genetic drift, random mutations, and artificial selection, where humans select based on qualities not necessarily conducive to survival? There is also some evidence that this change in skin color was only widespread as recently as 8,000 years ago [1]. > which in this case was likely furnished by less vitamin D How likely? > The pressu…
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 usually happens later in life and that would not be involved during mate selection.
> so I wouldn't call it artificial selection - artificial selection applied to humans is also known as eugenics.
Thanks for that distinction. If this attraction is happening naturally and unspoken, it's fair to include it as a part of natural selection. However, I do think some of it is cultural, is spoken, and goes beyond natural attraction. 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.