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Like all studies into Vitamin D supplementation that aren’t randomized controlled trials, it’s very hard to tell apart cause and effect. Vitamin D naturally occ

Like all studies into Vitamin D supplementation that aren’t randomized controlled trials, it’s very hard to tell apart cause and effect. Vitamin D naturally occurs when people go outside and get exposed to the sun, and going outside is correlated with all sorts of healthy traits. Also, publicity of the association of vitamin D with good health has led people who care about their health or who have access to good medical care to supplement vitamin D. Studies that look at the health of people who choose to supplement vitamin D are examining the overall health of those people and can’t specifically measure the effects of the vitamin D supplementation. That’s one of the problems randomized controlled trials are designed to solve. The study mentions these limitations: > Considering that sun exposure is the most important natural source of vitamin D, the lack of information on participant-level exposure to sunlight can be considered another limitation of the present study. > While we included education in our models, the NACC dataset has a dearth of information related to SES and therefore, SES differences could not be accounted for in our study. Future studies using cohorts with more comprehensive data on SES and other social factors would certainly provide valuable information on the associations of SES with exposure to supplementation and risk of dementia. For what it’s worth, controlling for a variable like education can only partially remove related bias from a result (you don’t have a perfect measure of how a person decided to take vitamin D).

moremetadata 4y ago
>Vitamin D naturally occurs when people go outside and get exposed to the sun, and going outside is correlated with all sorts of healthy traits. And also increases the risk of skin cancer and Parkinson's!
- hobo_mark 4y ago
  You what? Sun gives you Parkinson's now?
  - moremetadata 4y ago
    If you have limited melanin where does it go, your sun tan or substantia nigra?
    - bigbillheck 4y ago
      I make melanin in my melanocytes.
      - Supermancho 4y ago
        > I make melanin in my melanocytes. It's a finite rate, which means there's a useful limit of production.
        bigbillheck 4y ago
        I don't think the ones in my meninges are making it for my skin.
rogers18445 4y ago
When evolution molds a genepool it does so with inbuilt assumptions, one the assumptions is exposure to some level of sunlight. Deviating from these assumptions would result in undefined behavior (in the CS sense) for individuals. If an individual cannot or will not expose themselves to sunlight, taking D3 is probably the best option they have.
- fshbbdssbbgdd 4y ago
  In my opinion, these are the best options if you want to be healthy like people who get sun exposure (in order from most to least likely to work): 1. Act like a person who is exposed to sunlight. Walk, run, don’t spend every day at a bed, couch, or desk. 2. Expose yourself to sunlight. 3. Supplement vitamin D.
- copperx 4y ago
  The last time I took a casual glance at studied, it seemed that vitamin D deficiency was correlated with multiple health conditions; however, vitamin D supplementation had not clearly prevented or reversed those conditions. That is, this isn't like scurvy. A common hypothesis was that vitamin D status was a proxy for sun exposure and not a complete explanation for those health problems.
Aldipower 4y ago
> Vitamin D naturally occurs when people go outside and get exposed to the sun, ... Not sure where you are living? If I go outside in winter (+2 months around) I need gloves, cap, scarf. Literally only a little portion of my face gets some sunlight until 5pm. Then it is dark! I live in Germany! So, this isn't an argument for a lot of people in cold countries or dark countries. Mostly both.. Exposing to the sun is very hard here around the year.
- napierzaza 4y ago
  [dead]
- tedunangst 4y ago
  It's hard to find good answers on actual timelines, but vitamin D is fat soluble and you don't become insufficient after just a week of sitting in the dark.
  - freeone3000 4y ago
    More like six months.
  - Aldipower 4y ago
    I am talking about months of actual lack of sunlight, not a week. I for myself know 2 friends which diagnosed with vitamin D insufficiency. Because we are relatively young this lead to bone problems while doing sports. Without sports it wouldn't be recognized.
    - neffo 4y ago
      Interestingly, this was a bit over-diagnosed maybe 10ish years ago. Not saying this was the case, but some doctors were ordering VitD tests, getting results that said below average or below normal and interpreting it as insufficiency.
  - crazygringo 4y ago
    You sure do by February or March though, if the last time you spent an afternoon at the park (or the beach) was late August.
twawaaay 4y ago
It is not limitations. It is just that the findings should be presented truthfully and the authors should not try to suggest more than can actually be inferred from the data. Correlation between facts is interesting in itself, but to general public it should be clearly presented that "although we can prove these things are correlated, we don't know why and how and whether one causes another or vice versa or there is something else causing dementia as well as making people more likely to supplement with vitamin D". Without putting this warning label I treat it as kind of "scientific clickbait"
cogman10 4y ago
I'd also mention this isn't the only study with this sort of problem. Any health study looking at things that push people out of the house have this problem. People that can leave their homes tend to be in better health than people that can't.
- roundandround 4y ago
  I think the influence on this study is probably inverted though as supplementation could be based on a recommendation to compensate for lack of outdoor time as opposed to a study that measured levels.
xg15 4y ago
> Vitamin D naturally occurs when people go outside and get exposed to the sun, and going outside is correlated with all sorts of healthy traits. There is a difference between studying the effects of vitamin D and the effects of vitamin D supplements though. I agree with you on the "general health" variable, because I think it's likely there is some correlation between being somewhat health-conscious and taking vitamin D supplements (unprompted). However, there is no correlation between going out in the sun and taking supplements. (There might actually be a slightly negative one as some people might start taking them in winter when they don't get a lot of sunlight). So if you see a strong correlation between taking vitamin D supplements and reduced prevalence of dementia, I don't think this could be caused by sunlight exposure.
elevaet 4y ago
It's possible that all these studies are wrong and that Vitamin D supplementation is pointless. Information is never perfect. But at this time, on the balance, vit D supplementation seems like a pretty sensible bet for anyone living in far latitudes during winter, especially people with more pigmented skin. It looks like there's very little risk of harm, and it's cheap stuff.

moremetadata 4y ago

>Vitamin D naturally occurs when people go outside and get exposed to the sun, and going outside is correlated with all sorts of healthy traits. And also increases the risk of skin cancer and Parkinson's!

hobo_mark 4y ago
You what? Sun gives you Parkinson's now?
- moremetadata 4y ago
  If you have limited melanin where does it go, your sun tan or substantia nigra?
  - bigbillheck 4y ago
    I make melanin in my melanocytes.
    - Supermancho 4y ago
      > I make melanin in my melanocytes. It's a finite rate, which means there's a useful limit of production.
      - bigbillheck 4y ago
        I don't think the ones in my meninges are making it for my skin.

rogers18445 4y ago

When evolution molds a genepool it does so with inbuilt assumptions, one the assumptions is exposure to some level of sunlight. Deviating from these assumptions would result in undefined behavior (in the CS sense) for individuals. If an individual cannot or will not expose themselves to sunlight, taking D3 is probably the best option they have.

fshbbdssbbgdd 4y ago
In my opinion, these are the best options if you want to be healthy like people who get sun exposure (in order from most to least likely to work): 1. Act like a person who is exposed to sunlight. Walk, run, don’t spend every day at a bed, couch, or desk. 2. Expose yourself to sunlight. 3. Supplement vitamin D.
copperx 4y ago
The last time I took a casual glance at studied, it seemed that vitamin D deficiency was correlated with multiple health conditions; however, vitamin D supplementation had not clearly prevented or reversed those conditions. That is, this isn't like scurvy. A common hypothesis was that vitamin D status was a proxy for sun exposure and not a complete explanation for those health problems.

Aldipower 4y ago

> Vitamin D naturally occurs when people go outside and get exposed to the sun, ... Not sure where you are living? If I go outside in winter (+2 months around) I need gloves, cap, scarf. Literally only a little portion of my face gets some sunlight until 5pm. Then it is dark! I live in Germany! So, this isn't an argument for a lot of people in cold countries or dark countries. Mostly both.. Exposing to the sun is very hard here around the year.

napierzaza 4y ago
[dead]
tedunangst 4y ago
It's hard to find good answers on actual timelines, but vitamin D is fat soluble and you don't become insufficient after just a week of sitting in the dark.
- freeone3000 4y ago
  More like six months.
- Aldipower 4y ago
  I am talking about months of actual lack of sunlight, not a week. I for myself know 2 friends which diagnosed with vitamin D insufficiency. Because we are relatively young this lead to bone problems while doing sports. Without sports it wouldn't be recognized.
  - neffo 4y ago
    Interestingly, this was a bit over-diagnosed maybe 10ish years ago. Not saying this was the case, but some doctors were ordering VitD tests, getting results that said below average or below normal and interpreting it as insufficiency.
- crazygringo 4y ago
  You sure do by February or March though, if the last time you spent an afternoon at the park (or the beach) was late August.

twawaaay 4y ago

It is not limitations. It is just that the findings should be presented truthfully and the authors should not try to suggest more than can actually be inferred from the data. Correlation between facts is interesting in itself, but to general public it should be clearly presented that "although we can prove these things are correlated, we don't know why and how and whether one causes another or vice versa or there is something else causing dementia as well as making people more likely to supplement with vitamin D". Without putting this warning label I treat it as kind of "scientific clickbait"

cogman10 4y ago

I'd also mention this isn't the only study with this sort of problem. Any health study looking at things that push people out of the house have this problem. People that can leave their homes tend to be in better health than people that can't.

roundandround 4y ago
I think the influence on this study is probably inverted though as supplementation could be based on a recommendation to compensate for lack of outdoor time as opposed to a study that measured levels.

xg15 4y ago

> Vitamin D naturally occurs when people go outside and get exposed to the sun, and going outside is correlated with all sorts of healthy traits. There is a difference between studying the effects of vitamin D and the effects of vitamin D supplements though. I agree with you on the "general health" variable, because I think it's likely there is some correlation between being somewhat health-conscious and taking vitamin D supplements (unprompted). However, there is no correlation between going out in the sun and taking supplements. (There might actually be a slightly negative one as some people might start taking them in winter when they don't get a lot of sunlight). So if you see a strong correlation between taking vitamin D supplements and reduced prevalence of dementia, I don't think this could be caused by sunlight exposure.

elevaet 4y ago

It's possible that all these studies are wrong and that Vitamin D supplementation is pointless. Information is never perfect. But at this time, on the balance, vit D supplementation seems like a pretty sensible bet for anyone living in far latitudes during winter, especially people with more pigmented skin. It looks like there's very little risk of harm, and it's cheap stuff.