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Regular use of Vitamin D supplement is associated with fewer melanoma cases

pubmed.ncbi.nlm.nih.gov

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Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#81

Post by itake »

beowulfey wrote: post #22
docflabby wrote: post #3

People who avoid the sun more likely to take vitamin D supplements?

Here is the description how they measured the impact of sun exposure to the results: > The exposure of skin to UV radiation was clarified with different questions. The self-estimated lifetime exposure was studied with the following question ‘How often have you exposed yourself to sunlight during your lifetime?’ The answer options were (1) ‘seldom’, (2) ‘occasionally’, (3) ‘often’, or (4) ‘very often’. The sunburn his…

I wish they asked exact rates and timelines. Like living in Florida, getting a bad burn only once per year might be considered seldom. But if you lived in Alaska, I’m sure that would be qualify as often.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#82

Post by andreareina »

jmckib wrote: post #16
docflabby wrote: post #3

People who avoid the sun more likely to take vitamin D supplements?

I don’t have access to the full paper, but I would expect that they at least tried to control for sun exposure. In general, if you can think of an obvious confounding factor in about five seconds, then it’s a safe assumption that professional researchers thought of it too.

Accounting for confounders is hard. Otherwise randomised controlled studies wouldn't be needed, and we'd not have taken this long to walk back the consensus that red meat causes cancer.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#83

Post by oarfish »

thenerdhead wrote: post #33

I see research on essential vitamins all the time on HN. It really makes you think. There's cohorts who will debunk the studies based on methodology or glaring flaws. There's cohorts who will provide anecdotal evidence in support. There's even cohorts who will bring up a history lesson/"conspiracy" we all forgot about. It really makes you wonder about essential vitamins though. There's so many of these types of studi…

One issue with supplementation is the food matrix effect - Yes, Vitamin deficiencies are associated with all kinds of badness, but just supplementing this one nutrient doesn't address the underlying problem and often doesn't improve clinical outcomes. Rather, the deficiency is an indicator of poor health satus and to be fixed by adjusting the dietary pattern.

That's the thing with a lot of vitamin d and c associations anyway.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#84

Post by hombre_fatal »

hn_throwaway_99 wrote: post #48
alsobrsp wrote: post #17

Earlier quoted context omitted.

It did, they state that right in the summary.

But they don't necessarily say what those confounding factors are in the abstract (I'm assuming they do in the full paper but I don't have access). It's easy for me to imagine tons of confounding factors that are associated with vitamin supplementation, e.g. wealth (wealth is associated with better health outcomes nearly everywhere you look), diet in general, exercise levels, etc. I highly doubt they accounted for al…

Then the confidence levels would blow up.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#85

Post by hombre_fatal »

hn_throwaway_99 wrote: post #49
experimenting wrote: post #18

Earlier quoted context omitted.

The most plausible reason is that the scientific peer-reviewed result is correct, not the tiring "correlation does not imply causatian" commenter on HN who at most skimmed the paper. 2009: > Epidemiological data show an inverse relationship between vitamin D levels and breast cancer incidence. In addition, there is a well-documented association between vitamin D intake and the risk of breast cancer. Low vitamin D int…

> The most plausible reason is that the scientific peer-reviewed result is correct, not the tiring "correlation does not imply causatian" commenter on HN who at most skimmed the paper. Quite the odd take given the last sentence in the abstract of this paper is essentially "correlation is not causation": > In conclusion, regular use of vitamin D associates with fewer melanoma cases, when compared to non-use, but the c…

They could be just saying they don’t know why.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#86

Post by yesbut »

amenhotep wrote: post #74
yesbut wrote: post #47

Earlier quoted context omitted.

For context, this study found that 30 minutes of midday summer sun exposure in Oslo, Norway was equivalent to consuming 10,000–20,000 IU of vitamin D. https://www.ncbi.nlm.nih.gov/pubmed/19667143 Must be much higher in sunnier regions.

The neat thing about vitamin D synthesis in the skin is that it stops once there's enough of it - it is literally impossible to overdose on vitamin D through sun exposure. So, there's a ceiling that makes "must be higher in sunny regions" far from obviously true!

What happens to unused vitamin D consumed from supplementation?

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#87

Post by Auracle »

garciasn wrote: post #38
lowmagnet wrote: post #28

Earlier quoted context omitted.

Doctors recommend supplementing vitamin D if you have a measured deficiency. Most people naturally settle to 20 ng/mL or higher, and just incidental exposure, or eating certain foods can help you either absorb or synthesize it. There are also people, like me, who no matter what, we can't make as much vitamin D for whatever cluster of genetic factors causes that. Some of us are always tired unless we take 50,000 IU of…

That’s over double the dose considered “safe”. Obviously, I’m not suggesting you do otherwise; it’s just way outside the bounds of what most adults would do unless directed to by their physician.

I’m prescribed 50,000 3x a week. The RDA was possibly miscalculated, but the only real way to know what will work for you is test - dose - test, repeat.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#88

Post by oldgradstudent »

Calavar wrote: post #43
jmckib wrote: post #16

Earlier quoted context omitted.

I don’t have access to the full paper, but I would expect that they at least tried to control for sun exposure. In general, if you can think of an obvious confounding factor in about five seconds, then it’s a safe assumption that professional researchers thought of it too.

> In general, if you can think of an obvious confounding factor in about five seconds, then it’s a safe assumption that professional researchers thought of it too. I work in academic medicine. I read a lot of papers. This is not at all a given in my experience, except maybe in the tippy top journals (Nature, NEJM). When in doubt, read the paper, see if they mention the confounder you thought of.

Not even NEJM:

Recent letter to the editor in NEJM about that paper that showed 90% drop in Covid-related mortality after the first booster:

https://www.nejm.org/doi/full/10.1056/NEJMc2306683

It turns out that there was also a similar non-disclosed drop in non-Covid-related mortality. Either we discovered a magic elixir, or the entire effect is probably just confounding.

The original authors even say in their response that

> However, boosters were generally not administered to hospitalized patients who were at high risk for death from any cause.

They never even attempted to control for it.

Edit: at least NEJM accepts letters to the editor about the crap it publishes.

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#89

Post by globular-toast »

chrisco255 wrote: post #63
globular-toast wrote: post #26

Earlier quoted context omitted.

That seems like far too much, especially if you ever go outside. In the UK doctors recommend no more than 1,000 IU/day during the winter months. Any more than that is only if you are actually deficient. It seems really hard to get clear answers on it, though. People taking 10x the recommended dose of something seems strange. It makes me think it's being stored somewhere that isn't your blood. It's fat-soluble after a…

Vitamin D is a fat soluble vitamin, so of course it is being stored in fatty tissues in the body. Where else would it be stored? Your blood stream is not a storage mechanism but a transportation mechanism. Daily Recommend Values for basic nutrients aren't the same as medicinal dosages. Nobody ever gets Daily Recommended Values for all the essential nutrients anyways, and many of them are regularly exceeded by a singl…

So what if the vitamin D is being accumulated in fat and the blood can only carry so much regardless of how much is accumulated in fat? Seems dangerous to keep taking more and more at a really high dose doesn't it?

Re: Regular use of Vitamin D supplement is associated with fewer melanoma cases

#90

Post by globular-toast »

pigeonhole123 wrote: post #32
globular-toast wrote: post #26

Earlier quoted context omitted.

That seems like far too much, especially if you ever go outside. In the UK doctors recommend no more than 1,000 IU/day during the winter months. Any more than that is only if you are actually deficient. It seems really hard to get clear answers on it, though. People taking 10x the recommended dose of something seems strange. It makes me think it's being stored somewhere that isn't your blood. It's fat-soluble after a…

He is actually deficient, and 10k IU is not that unusual.

When I was deficient I took 20k IU per week for 6 weeks and was back to normal levels at the end. Taking 10k IU a day indefinitely seems insane. The numbers are just so wildly different.
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