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Is vitamin D really a cure-all, and how should we get our fix? (theguardian.com)
328 points by pmoriarty 10 months ago | hide | past | web | favorite | 131 comments

Related: a 9-year, n=25871 study looking at long-term health outcomes of blind Vitamin D/Omega 3/placebo supplementation just ended and will have results out this summer.


That is awesome that you were able to get funding for a large study of vitamin supplements. I wish there were more studies like this to identify whether supplements are beneficial beyond placebo (or potentially harmful).

One question: blind or double blind? Does the distributor also not know which product is being given to the patient?

I look forward to the results!

The link said triple blind, technically -- ”Masking: Triple (Participant, Investigator, Outcomes Assessor)”

Thank you. The tables were screwy on my phone.

Incredible news. I cannot wait for this study. I expect positive results for both the supplements. What's your prediction?

I think you're missing the point.

I'm neither a participant nor scientist in the study, so I don't see what point I'm missing. Actually even for both those groups, making predictions is fine, really, so long as the study is properly blinded.

From anecdotes, the correlation studies, and my personal experience, I believe the results will be positive. If the results show otherwise, I'll accept it and try to understand why I was wrong.

Late reply: I'm curious to see the results, but scientifically speaking Vitamin D is a tricky substance. Determining if you have 'the right levels' is tricky, considering that the same sample can lead to 20-33% false positive rate of being misclassified as Vitamin D deficient[1], despite being measured using the same method, in two independent laboratories, compared with a different, gold standard: mass spectrometry.

Moreover, even in cases with low Vitamin D, where medical professionals are unsure if treatment with Vitamin D would be beneficial at all (in this case: for osteoporosis prevention)[2].

Finally, recent randomised, double-blind clinical trial (n=5108) assessed if monthly administration of a high dosage (100.000 IU) of Vitamin D for more than a year would in any way prevent cardiovascular disease, and found no benefit in patients receiving treatment or placebo after a 3.3 year follow-up period[3]. Another study (n=2303, 4-year long, 2000 IU/d), testing the efficacy of Vitamin D to prevent cancer, actually suggests that low dose of Vitamin D is may increase cancer.[4]

Taken together, I hope that this helps illustrate how 'making a prediction' or 'expecting a certain result' is neither scientifically ethical, nor possible, given the controversial results in the literature so far.

[1] https://www.ncbi.nlm.nih.gov/pubmed/21395958

[2] http://www.nejm.org/doi/pdf/10.1056/NEJMcp1009570

[3] https://jamanetwork.com/journals/jamacardiology/article-abst...

[4] https://www.ncbi.nlm.nih.gov/pubmed/28350929

Nah it's more real if you guess first. Perception starts with engagement.

He has a hypothesis based on his limited observations. He's just doing the scientific method

Vitamin D deficiency and autism - Somali immigrants (very dark skinned, and thus northern Sun is too weak for them to cause generation of enough vitamin D plus they have more skin surface covered by clothing in Sweden compare to what it was back in Somali) in Minnesota and Sweden have very low, sometimes undetectable, vitamin D levels and high (compare to Somalis in Somali as well as to other populations around them in Sweden or Minnesota) autism rates of children born in immigration there.

Another Swedish study, non immigrant related, found a pattern of higher autism rates among children whose 3rd trimester was during winter. For illustration - brain formation during 3rd trimester - http://www.brainfacts.org/-/media/Brainfacts2/Archives/Artic...

Looks like difference of vitamin D levels were not significant in the 2010 study between mothers of Somali origin with or without a child with autism. http://onlinelibrary.wiley.com/doi/10.1111/j.1651-2227.2010....

Do you have another source for the statement in the first paragraph?

>between mothers of Somali origin with or without a child with autism

"increasing chances" and "necessarily leading to" are 2 different things. Consider for example smoking and cancer - among people who smoke the same amount of tobacco some will get cancer, some will not. That doesn't falsify the fact that smoking increases the chances of the cancer.

You link is actually enough here. From your link :

"Results:  Between 12 and 17 mothers from the different groups accepted to participate, both groups of mothers of Somali origin had significantly lower values of 25-hydroxyvitamin D compared with Swedish mothers. "

So, i'm not sure what of the 2 well established facts you are arguing against :

1. Somalis in Sweden have very low D

2. Somali children born in Sweden have much higher autism rate.

Of course correlation isn't necessarily causation, yet the correlation (both - between populations as well as inside the Somali mothers population) is clearly stated in your link (have you read it yourself?) :

"Conclusion:  Our findings of low vitamin D levels in Somali women entail considerable consequences in a public health perspective. The observed tendency, i.e. the lowest values in mothers of Somali origin with a child with autism was in the predicted direction, supporting the need for further research of vitamin D levels in larger samples of Somali mothers of children with and without autism."

I wasn't trying to argue against. Just trying to understand better.

1. Yes, Somalis in Sweden have very low D. That is quite obvious [from Table 1] after winter.

2. Yes, Somali children born in Sweden have higher rate (according to this study: 17 in 2437 [0.7%] for Somali background, 484 in 250565 [0.19%] for non-Somali): http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8749.2008....

However we should also consider the effect of other compounding factors about parents coming from Somali.

Here: https://link.springer.com/article/10.1007/s10803-017-3232-z

"Results lend support to previous studies that found higher rates of ASD intellectual disability in children of immigrants from low human resource index countries compared to other groups."

coming from Somali also means coming from a low human resource index country. all kinds of air/water pollutants and chemicals/pesticides might be at play -together with- vitamin D deficiency.

Vitamin D effect itself is hard to isolate from just this. Further studies need additional data about these other factors (air pollution, exposed chemicals etc)

>"Results lend support to previous studies that found higher rates of ASD intellectual disability in children of immigrants from low human resource index countries compared to other groups."

>coming from Somali also means coming from a low human resource index country. all kinds of air/water pollutants and chemicals/pesticides might be at play -together with- vitamin D deficiency.

>Vitamin D effect itself is hard to isolate from just this.

If anything, your link confirms vitamin D theory even more :) What is the most common trait for all these low human resource index countries? They are closer to equator, i.e darker skin of the population.


It is very well established epidemiological fact that darker skin immigrants have noticeably lower vitamin D in higher altitudes (i.e where the higher developed countries are that they immigrate into).

If by "theory" you mean "darker skin in higher altitudes -> low vitamin D", I don't have anything against that.

If by "theory" you mean "low vitamin D -> autism", you're reading science wrong (by only using correlation when reasoning about it). You have to control for other factors in Somali population. That's how you do proper research. In its current form, as the researchers themselves point out, this says that a future study is needed.

Let me repeat: you might be entirely right but "this correlation supports the theory better" is not scientific evidence. It's just a hint to direct research.

As I said, if they find Swedish mothers with really low vitamin D and compare with Swedish mothers with high vitamin D, that would say a lot more.

I'm starting to think a study focusing on Swedish mothers with really low D (similar to Somali mothers) with Swedish mothers with high D would solve all the mystery here.

I would recommend reading this article about the connection between vitamins D, A, and K, and how they inter-play with one another: https://www.precisionnutrition.com/stop-vitamin-d

It was pretty eye-opening (and alarming) when I read it.

In short: While Vitamin D is great for everyone, your body will begin lacking in vitamins A and K because of the effects of D (too much of a good thing, essentially). It's all about finding the right balance for yourself.

Snippet from the closing:

1. Get enough vitamin D… but not too much. Doses of around 1,000 IUs per day — even as high as 2,000 IUs a day in the winter months when you’re not exposed to much sunlight — are likely safe. Especially when other key nutrients are included, such as vitamin K, vitamin A, and magnesium. You can ensure you are getting enough of these by taking a quality multi-vitamin.

2. Support vitamin D’s work Remember that other nutrients act together with vitamin D. Consume a wide variety of minimally processed foods to help get vitamin D’s nutritional colleagues such as magnesium, vitamin A, and vitamin K.

Eat your greens and fermented foods. Dark leafy greens — such as kale, spinach, or Swiss chard — are good sources of vitamin K1. They’re also high in dietary magnesium. Fermented veggies such as sauerkraut along with eggs, meats (especially organ meats such as liver) and fermented/aged cheeses are good sources of vitamin K2.

Eat the rainbow. The carotenoid form of vitamin A is found in colorful fruits and veggies. Eggs, butter, full-fat dairy (such as cheese) and organ meats are also great sources of the active retinol form of vitamin A.

Keep your intestinal flora happy and healthy. Vitamin K conversion happens in the GI tract. So eat plenty of fermented foods and prebiotic fiber, consider a probiotic supplement, and avoid antibiotics unless absolutely necessary (research has found that broad-spectrum antibiotics can reduce K production by up to 75%).

Review all medications and supplements with your doctor and/or pharmacist. Many medications, such as corticosteroids like Prednisone, weight loss drugs like Orlistat, cholesterol-blocking drugs like statins, and/or high blood pressure drugs like thiazide diuretics can disrupt the delicate balance of vitamin and mineral regulation in the body. Make sure you know all the side effects and interactions of any medications (or “healthy” supplements) you are taking.

> taking a quality multi-vitamin

I try to be cautious with vitamins. It appears that taking them in pill form might not be safe. I switched to a high-nutrient diet that focuses on getting nutrients from food wherever possible.

Some examples of cases where vitamins that are beneficial in food form might be dangerous in extracted form:

Vitamin E and the Risk of Prostate Cancer: https://jamanetwork.com/journals/jama/fullarticle/1104493

Dietary Supplements and Mortality Rate in Older Women: https://jamanetwork.com/journals/jamainternalmedicine/fullar...

Death Stalks Smokers in Beta-Carotene Study: https://www.webmd.com/smoking-cessation/news/20041130/death-...

I haven't checked the others, but in the first one they seem to have given people 400 IU Vitamin E, which is equivalent to 180mg synthetic Vitamin E or 12x the RDA for Vitamin E. And they did that for 7-12 years straight. Also, the increase in cancer risk doesn't seem that significant if I'm reading the results right.

I'm not a fan of multivitamins that go crazy over the RDA unless I know the RDA number is way too low to begin with (like in Vitamin D's case). It's also an especially bad idea to go crazy over RDA with fat-soluble vitamins, because those are the ones that are stored in your body for longer periods of time. At least the water-soluble ones come out when you pee, but I think there's some new evidence that even some of those is stored or at least it may not be a good idea to "mega-dose" on them.

Some vitamin E supplements have 1000 IUs. See my other comment in this thread.

I recall Rhonda Patrick explaining on a podcast that they used an extremely high amount of vitamin E, all in the form of alpha-tocopherol which leads to depletion of gamma-tocopherol.

But I agree about trying to get your vitamins from your diet in general.

I wouldn't call the dose extremely high. Some over the counter supplement pills have 1000 IUs and it looks like the study was done with only 400 IUs. (It's over the current recommended daily intake though.)

Here is some more reading:

* Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements http://annals.org/aim/fullarticle/1789253/enough-enough-stop...

* Vitamin B.S. https://www.theatlantic.com/health/archive/2015/02/vitamin-b...

* Experts: Don't Waste Your Money on Multivitamins https://www.webmd.com/vitamins-and-supplements/news/20131216...

* The Case Against Multivitamins Grows Stronger https://www.npr.org/sections/health-shots/2013/12/17/2519558...

* A Scientist Debunks The 'Magic' Of Vitamins And Supplements https://www.npr.org/sections/health-shots/2013/07/23/2045251...

> Get enough vitamin D… but not too much. ... even as high as 2,000 IUs a day

2,000 IU is not a high level of Vitamin D. That's a medium-to-low level of Vitamin D. 20,000 IU is high.

Most people can very safely take 5,000 IU and won't come even remotely close to seeing negative health consequences. Quite the opposite, studies have suggested you may need that level of VitD intake just to get up to a healthy blood reading, especially if you have low sunlight exposure.

The old RDA guidelines have increasingly been shown to be a scientific embarrassment over the last 20 years.

Correct me if I'm wrong, but don't the vast majority of cases of hypercalcaemia caused by excessive D consumption involve daily doses of 40-50,000 IU? I'm sure I've read this before. If 20,000 IU is high, 50,000 IU must be enormous, so I too would very much doubt 2,000 is 'high'.

For reference, i was on a 50k IU dose of D3 last year for schools of months. It's considered therapeutic for diagnosed and lab-confirmed deficiency.

Since then I've periodically stayed on s 10k IU supplement three times a week. That's just over the counter.

Do you take vit K and magnesium to compensate possible side effects?

I take a daily multivitamin that supplements those.

did a doctor prescribe the 10ks? that seems high compared to what I was suggested for a lab confirmed deficiency. Someone I know with a severe deficiency was prescribed very high levels only for a month or so.

10k IU is available OTC, so its not a prescription, but I do take it on my doctor's recommendation. I don't get a lot of sun, especially in the winter, and I've had chronic deficiency of D3, so I supplement at higher levels than what I'd get in your average multivitamin. 50k IU is what I was prescribed for two months to get me above the minimum recommended blood levels, and it barely did that.

I do also get my D3 levels checked annually as well, as should anyone with a diagnosed deficiency.

I've had doctors prescribe 10k IU vitamin D. Mine was really low and i have auto-immune thyroiditis. Vitamin D works really well for auto-immune disease for me. It has gone.

It very much depends. There are genes having a strong influence on vitamin D metabolism, and there are people for whom 5k I.U. are too much. (Essentially, they are metabolizing D3 into calcitriol and the other form I keep forgetting too fast)

50,000 IU is typically taken on a 1-4 week interval. Being in renal failure, I myself take it once a month and increase to twice per month in the winter.

My doc had me on 25,000 IU once a week for a few months to get me through a sluggish period where I felt low T even though I was excercising. It’s funny how people claim certain doses are low or high. This is probably based upon what their doctor told them to take or what they heard from someone just as uninformed as themselves. Surely there’s a body mass chart for dosing that would clear this up for everyone?

Did your doc give you vitamin K as well, and did they check your calcium level?

Yes. She gave me K. I don’t recall if the blood test showed calcium.

Did the treatment seem to work? Did your T-levels rebound?

Oh yes. It was paired with other treatments too though so I can’t be sure of causality.

I was getting acupuncture, began excercising more, eating more veggies, and dealt with the factors that were bringing about my depression.

> So eat plenty of fermented foods and prebiotic fiber, consider a probiotic supplement

There is very little conclusive evidence that suggests probiotics are actually useful. In the EU and USA companies are not able to claim health benefits from them legally.

Some good studies cited on the Wikipedia article: https://en.wikipedia.org/wiki/Probiotic#Scientific_reviews_a...

Yeah, many diseases are related to the microbiome (although there is the question of where does the cause/effect arrow point?), but current probiotics are for the most part not sticking around in the gut. The usual suspects just have an indirect effect on the bacteria you already have, and get excreted within days/weeks. Spore forming bacteria survive longer, but might become a problem of their own if overpopulated. Also.. if your goal is a more diverse microbiome, then supplementing the most abundant L-bacillus strains might not be a particularly effective option?

And the microbiome is so vast that it’s hard to influence on the long term. With a very strong probiotic you get 5 * 10^10 bacteria (of which most die in the stomach and small intestine), but at the same time you have 3.8 * 10^13 native bacteria settled and accustomed to your body, feeding on the sugar you have just eaten. You need a lot of those tablets to have a meaningful impact.

Just like a great body, a great microbiome gets made in the kitchen. AFAIK dietary changes work way faster than popping probiotics. With the exception that you are missing certain strains (eliminated by antibiotics?), which should be replaced.

They may be useful in some situations https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424311/

I was prescribed some a year or so ago when I was on some heavy antibiotics. Reading that article still makes it look like efficacy is pretty minor. Since it doesn’t really hurt to take it why not?

Every time I've had to take antibiotics here (which admittedly has only been a couple of times) the doctor made sure to tell me to take probiotics as well until the course of antibiotics was over.

If you are deficient then the amount you take is dependent on how your levels change given a trial amount. No one is the same here.

Testing is really the only way to know how much you should be taking

I went to an eye doctor due to blurry vision and dry eyes last year; he suggested both Vitamin D and Demodex (which kills mites which live in eyelash follicle roots).

I took the blood test for Vitamin D (25-hydroxy) and I was something around 7, where the desired number is more like 20-50. Started taking 10k-20k IU of Vitamin D per day (plus K and also a range of other daily vitamins added at the same time), as well as a 4 or 8 dose course of demodex over 2-3 weeks, and both problems were resolved within a month. Apparently low D causes the cornea to sag so the lens itself is out of shape and thus astigmatic.

This is interesting, my wife experienced something exactly the opposite. She started taking Vitamin D couple of years ago since she was quite deficient just like you. After a year or so of 5k IU daily, she started experiencing severe eye issues, including daily crust buildup, irritation, redness, and blepharitis.

We tried all sorts of drops and cleaning regimes to no avail. She went for another blood test and learned her Vitamin D levels were through the roof (somewhere around 90+). She immediately stopped the Vitamin D supplements and after a few weeks, all her eye issues were gone!

Goes to show we definitely need some good studies examining long-term Vitamin D intake.

5,000 IU per day is an excessively high dose.

4,000 IU is the upper limit. 2K is high.


I read that people get 10,000 - 20,000 IU from 30 minutes in sun. With that, wouldn't that make the upper limit dangerously low?

4,000 IU per day is the recommended supplement limit.

You can synthesize 1000 IU from 10 minutes in the sun if... you're young, have light skin (of which most is visible), don't wear sunscreen, it's the middle of the day & summer, and you're lying down to get roasted.

4,000 IU is equivalent to getting burnt to a crisp.

This is off by a factor of 10. You get between 10,000 and 25,000 IU in just a little under the time your skin takes to burn. https://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get...

You are very unlikely to develop excess vitamin D unless you supplement more than 10,000 per day for months, and typically not even then unless you exceed 40,000 per day via supplements. https://www.vitamindcouncil.org/about-vitamin-d/am-i-getting...

Additionally, if you supplement or take K2 with vitamin D, the risks are substantially mitigated (Vitamin D adds calcium ions to things, K2 takes them out).

There are already good studies and it is well known that Vitamin D is toxic if too much quantity is taken over time. 5K IU is 5x more than the recommended daily limit. She should have dropped to 1K IU after 4 months of taking 5K IU, that is, if she continued not to get regular sun exposure or eat food rich in Vitamin D. The problem lies in the prescribed amount and the duration and not because of lack of studies. Did a doctors advise 5K IU without a time limit?

Yeah, that's the weird thing about Vitamin D, every single individual metabolizes it differently.

Some people get adequate amounts just from "regular food", others (like me) need extra large doses to keep up, especially during the winter months.

And then there's people like your wife who go through the roof if they see a supplement at the store :D

> Goes to show we definitely need some good studies examining long-term Vitamin D intake.

Goes to show that the recommended level of it are about right.

No, one person needing support at 2.5-5× the recommended upper limit and another person experiencing problems at half the low end of that range doesn't shown that the recommended level is about right.

Apparently my memory is bad - it was treated with oral ivermectin, to kill dermodex (which are the mites).

The eye doctor, who has a journal article somewhere about this, is Dr. James McMillan, of Medina Eye (in Bellevue, WA). Expensive ($400 for a visit), but great care.

Hey! I'm having the exact same issues right now. Why did you add demodex? How could you tell you had mites?

Killing the demodex both helps with dry eyes apparently, and is supposed to reduce infection on eyelid margin (which I'd had a few times).

(And we had the "yeah, but by changing two variables at once (vit D and ivermectin) it means we'll never know which helped, but since the ivermectin is one-time and the vit D has other benefits, who cares?" discussion in the office, for about 30 seconds.)

All adult humans have eyelash mites. "Demodex" is the name of the mite, not the mite-killer.

Having never heard of this before I am now terrified. [1] :-)

[1] https://en.wikipedia.org/wiki/Demodex

There was good discussion around a study that showed recommended amounts of Vitamin D were much too low. Many people have reported benefits of taking supplements: https://news.ycombinator.com/item?id=15867918

Wasn't the mostly unanimous agreement in this thread that this paper was of low quality and its conclusions are questionable at best?

I'm not going to wait for a study to show evidence. The evidence is only as good as the study, and this is very hard thing to setup a study for, given the many years they'd need to study subjects and as someone else pointed out on here, its systemic nature makes it hard to pinpoint.

The explanatory arguments are more than sufficient: skin colour corresponds to the availability of sunlight - with the exception of dark-skinned Inuits who maintain a fish based diet - which indicates the importance of vitamin D to survival.

Only in the modern era do we now spend more time inside than outside, which could be an explanation for increasing incidence of diseases.

As for this ridiculous quote:

> And as Adrian Martineau, clinical professor of respiratory infection and immunity at Queen Mary University of London, points out, even in the summer, “sunshine isn’t going to be the answer, especially because there is an associated risk of skin cancer.”

No, sunshine is the answer. The risk of skin cancer is elevated if you get sunburnt, if you expose your pale skin suddenly to the sun in the height of summer. Nobody is suggesting you do that. Build up a tan gradually throughout the year, follow common sense.

>The risk of skin cancer is elevated if you get sunburnt, if you expose your pale skin suddenly to the sun in the height of summer

This is very common skin cancer myth that can be debunked by few minutes of googling.

Any change in your natural skin color is a sign of skin damage and that damage is cumulative. Getting a tan is a sign of damage. Total UV dose you build up over time, rather than getting sunburnt, matters most (Sunburn is used as a proxy for skin cancer risk because it is related to individual sun sensitivity and UV exposure).

UV radiation is complete carcinogen. It's both a mutagen and a non-specific damaging agent. It's both tumor initiator and a tumor promoter. Three most common types of skin cancer are basal cell carcinoma (BCC) , squamous cell carcinoma (SCC) and malignant melanoma. Chronic cumulative exposure is associated with BCC and SCC and melanoma with sunburns and childhood exposure but melanoma may develop through multiple pathways.

Intuitively, based on what you're saying people around the Mediterranean (to take one region with a lot of Sun) should be dropping like flies due to these dangers you outline. Why don't they have a mortality rate affected by skin or other cancers? The Anglo world has been studying their diets due to the opposite perception.

Mediterranean sun is relatively benign. I am pale and used to have red hair. A full day in summer Mediterranean sun and I get a mild burn. If I go 20 minutes in New Zealand I’m toast, and mid summer it’s less than that. Even cloudy days can burn you easily here, and I’ve been burn in rainy days too. Ozone makes a hell of a lot of difference.

Don't forget behavior. You grow up in a sunny place, you learn the joys of sun-hats, parasols, and assorted other strategies as succinctly documented in Noel Coward's 1931 song "Mad Dogs & Englishmen"[1].

1: http://www.traditionalmusic.co.uk/folk-song-lyrics/Mad_Dogs_...

> Why don't they have a mortality rate affected by skin or other cancers?

What makes you assume that they don't?

Burden of cancer in the Eastern Mediterranean Region, 2005–2015: findings from the Global Burden of Disease 2015. https://link.springer.com/article/10.1007/s00038-017-0999-9

It doesn't say how much of that is associated with skin cancer, which is the cancer you're talking about.

>Why don't they have a mortality rate affected by skin or other cancers?

Do you have a source for that? A source that compares people from further North living in the Mediterranean region compared to further North for skin cancer?

So I just typed "skin cancer mortality rate by region" into DuckDuckGo and here are a few results from the first page:

the CDC on US Skin Cancer Rates By State: https://www.cdc.gov/cancer/skin/statistics/state.htm - if you squint there sure is a general north-south gradient, with LESS skin cancer in the South. Also note that "Melanoma is much more common among non-Hispanic whites than people of other races and ethnicities. More than 9 out of 10 cases of melanoma are diagnosed in non-Hispanic whites."

Forbes on "skin cancer hotspots of the world": https://www.forbes.com/2008/07/28/skin-cancer-hotspots-forbe...

relevant excerpt: "Studies have shown that while there is generally an increase in the incidence of melanoma as latitude decreases (closer to the equator), mortality from melanoma is four to six times higher in Nordic countries than in Mediterranean countries, according to the WHO." It then goes on to talk about cultural differences that essentially boil down to "people raised in sunny places get taught strategies for dealing with lots of sun".

You could probably find better studies, this is just five minutes of searching.

I’ve reduced what I’ve read about cancer and skin cancer down to the following:

Cancer is essentially triggered by damage to cellular DNA which results in a “pathological” strand. That strand then multiplies throughout our bodies through cell regrowth with the pathological DNA.

Sun light “flips the dice” with our skin cell DNA, among just generally harming our skin. Some people go their whole lives without any pathological DNA damage, and others not so much.

The skin cells of Caucasians have little to no natural defense to the sun’s rays.

Add as an anecdote: I saw a documentary with a girl born without any pigment (I think?). I forget the exact specifics. But she has to walk around in a 100% UV blocking hood and completely covering draped clothing when the sun is out. If any UV touches her skin she will get cancer then and there. She had a hole in the fabric of one of her hoods as a toddler and they had to do things to counteract that (I think they cut away that skin).

Presumably because evolution has selected genetic mutations which have provided protection against the amount of UV radiation people get in those geographic areas.

"This is very common skin cancer myth that can be debunked by few minutes of googling."

Please don't do this. Almost nothing is trivially googleable. For instance, the pages I'm reading say a tan is equivalent to about 2-3 SPF, which isn't a huge amount of protection (it corresponds to a 50-66% reduction in UV exposure). However, I'm not sure how to compare that 2-3 SPF to sunscreen measurements. SPF measurements for sunscreen are based on using something 4 teaspoons, or 1/3rd of a bottle per usage. No one I know does that.

On top of that, as a very pale person, I find that I don't get sunburnt because I put on SPF 15 and it's not strong enough--I get sunburnt when I don't reapply the SPF 50 after sweating for a few hours.

Or even better, trivially googling Basal Cell Carcinoma gets me to wikipedia which says that it's unclear if sunscreen even affects your risk of BCC. I probably shouldn't trust wikipedia, but that's what you're telling me to do when you say "it's easy to google for".

Short story: I'm still willing to believe that you're right. You clearly know more than I do about the subject. But "just google it" is not typically helpful.

I realize that "just google" is dangerous and I should rephrase my advice.

What I meant is to google basic public health information provided by national health authorities and international health organizations. They usually give a balanced view. For example, it's not beneficial to avoid going outside or not doing outdoor activities because they have other health benefits that outweigh skin cancer risk. Tanned skin is damaged skin but maybe you should accept the risk not avoid getting some tan.

For example:


I'm not sure saying "tanned skin is damaged skin" directly answers the original question, or at least the way I'd ask it. Suppose, I go outside for a little bit at a time with my kids during the spring, and get something of a tan, then I go to the beach and am a lot of direct sun.[0] Although the articles say the tan is not much protection (2-3 SPF max), it is some. On the other hand, I had lots of exposure during the spring. Both effects are real, but which is bigger? For that matter, how big are the effects of those exposures? Can you just add up the entire time spent outside during peak hours?

[0] I do use sunscreen, but between getting in the water, uneven application or whatever else, I end up with part of my body burning a fraction on the time.

It's not clear that all UV is a complete carcinogen. Narrowband UVB is used for the treatment of psoriasis. It certainly causes a change in your natural skin colour but studies have not found that it elevates the risk of skin cancer e.g.:


You make it sound like it is a linerar relationship though, e.g. 5x 1h sun exposure over a week is the same as 1x 5h exposure. However, it is very much an exponential relationship, e.g. 50x 1h exposure is the same as 1x 5h.

> Only in the modern era do we now spend more time inside than outside, which could be an explanation for increasing incidence of diseases.

Do we have increasing incidence of diseases? [citation needed]

I see little reason for evolution to favor long lives. Setting offspring early and living long enough to support your offspring sure. But beyond that returns are quickly diminishing.

The idea that it's natural to live a long healthy life is very romantic, but hardly realistic.

I was just going to ask about evidence of increasing disease. The OP's claim smacks of rosy retrospective bias.

Even if the numbers did increase, most of the time this is due to improved detection, or shifting age distributions, ie. an older population will necessarily have more health issues.

> Even if the numbers did increase, most of the time this is due to improved detection, or shifting age distributions, ie. an older population will necessarily have more health issues.

Other than what you say about older people, it is pure conjecture to say that "most of the time" these are the causes.

Yeah, not really. If what you said were true, mortality would be increasing dramatically. This clearly isn't the case, therefore any apparent increase in disease rates must be due to improved detection. Or disease rates aren't really increasing at all.

> rosy retrospective bias

Is exactly the term I was looking for :)

I feel like some of the love people have for: natural medicine, organic food, natural coloring, flavors and preservatives are somewhat similar... Granted there are environmental benefits to some of it for sure.

Are you saying there is no increasing incidence of diseases? Of any disease? That would be a difficult argument to make (you might want to find a citation). Note: I did not say all diseases.

I asked for citations.

It's quite possible that diseases suspect of being due to vitamin D deficiency are up, but evidence to that effect needs to be cited.

I'm not convinced that we have higher incidence of diseases today, than we did 50 years ago. At least not when you correct for age, and population size, etc. Maybe diabetes is up, but... still evidence is good.

The rationale is quite simple. The body needs sunlight to produce the vitamin. Without adequate sunlight there will be a deficiency and need of a substitute. The supplements aren’t magic, its the removal of systemic health effects caused by deficiency. I rather find that the studies deal with how severe these effects are and the systemic nature makes it hard to pin point. However, I don’t even understand why this has been contested for such a long time.

Maybe because it's politically unhealthy (excuse the pun) to point out that the country you live in is too far away from the equatorial regions and its geographical location itself is a source of chronic health issues?

As a Finn, I have found that the natives really don't want to hear that most of the country is on the same latitudes as Alaska.

More a case of it's a bit pointless to make an issue of it? It's not like everyone is just going to pickup and move elsewhere is it?

Most people don’t realize that the sunlight levels here aren’t sufficient to trigger vitamin D (precursor) synthesis except during noon and early afternoon hours in the middle of the summer. And of course only if it’s not cloudy. It is likely that most people at these latitudes don’t synthesize enough vitamin D even during the summer months.

Well, being aware of a health problem is the first step of being able to address it. If the environment is making you sick, shouldn't you at least know about it?

As for your question, well... <snark value="11">I did.</snark> Wonderful ice breaker in pubs, btw. "I moved to London for the weather."

According to the study in the other HN link here, they made an error in calculating how much Vitamin D you need.

The medical community also seems to think that 20 ng/ml is when the deficiency starts, when in reality it's more like 40. Some studies have shown that you can see benefits upwards of 60 ng/ml. Other research has shown that Vitamin D helps with sleep in the 60-80 ng/ml range.

I've seen many people on Reddit say that their blood tests level came out at 5-10. That's crazy. Get your 25(OH)D level checked.

Some of the studies that have shown "no improvement" from Vitamin D saw that result mainly because they were still prescribing far too little Vitamin D (yet still higher than the RDA).

10,000 IU may be necessary just to maintain your level. However, you also have to keep in mind that you won't be getting D only from the supplement, so throughout the year you should actually increase your Vitamin D level as you get more sun exposure. Meanwhile the 10,000 IU (which by the way is "only" 250 micrograms) will maintain those high levels. Then, in the second year, you may further increase your Vitamin D level as you once again get more exposure in the sunny days. So you should check your Vitamin D at least after a year, to ensure your levels aren't too high. After you're stabilized you should need around 5,000-7000 IU, but it's really dependent on each person's needs, so you'll have to figure out on your own through trial and error.

However, you also need to keep in mind that not everyone uses Vitamin D as efficiently. You may have undiscovered gallbladder issues for instance, or your gut bacteria is not well balanced, or your stomach doesn't have enough acid, or you're not taking Vitamin D with enough fat, and all of these factors which could impact how easily you're absorbing Vitamin D.

This is part of the reason why the FDA can't just recommend "everyone should take 10,000 IU". Plus, people of color need much more Vitamin D, so if the FDA recommends everyone 2,000 IU as a higher minimum, that may still not be enough for them.






How did societies in northern regions historically get enough vitamin D? Yes they would have spend more time outdoors than we do now, but they’d also be mostly covered to keep themselves warm, so even on a rare day when it’s sunny they wouldn’t get much exposure.

They ate a lot of fish, at least in northern Europe

Even before, likely everyone was deficient in Vitamin D during winter. You "charge up" in the summer, but then you start dropping below the beneficial levels long before the sunny spring starts again. It's part of the reason people get sicker in the winter, feel more "blue", and so on.

The way I understand it, if you're pale enough, there's more than enough sunshine in a dreary UK winter to get enough exposure. The problem is much more related to how we don't take advantage of it as a culture. Odds are, that the day on which you should be outside soaking in some rays is going to be a day that you cannot leave your office for more than a lunch.

Is it?

I don't think so.

'The body needs sunlight to produce the vitamin' okay. But now i say: '15 Minutes of sunlight a day is enough for your body'.

What now?

Where is your study saying how much sunlight is relevant? And if it makes sense to supplement? And what are the dangners of too much?

You can carry out your own study. Stand outside in the sun for a while. Did you get sunburnt? Ok, that's too long, and the danger of that is skin cancer.

Apparently skin cancer risk from sunburn only appreciably increases when a child. As an adult, your risk is far less affected by exposure. A light tan is good, heavy sun for years will leave you looking like a florida leatherback. In all things, moderation.

Sunburns and risk of cutaneous melanoma, does age matter: a comprehensive meta-analysis


After reviewing over 1300 article titles and evaluating 270 articles in detail, we pooled ORs from 51 independent study populations for “ever” sunburned and risk of cutaneous melanoma. Among these, 26 studies reported results from dose-response analyses. Dose-response analyses were examined using both fixed-effects models and Bayesian random-effects models.


An increased risk of melanoma was seen with increasing number of sunburns for all time-periods (childhood, adolescence, adulthood and lifetime). In an attempt to understand how risk between life-periods compares, we also report these same linear models on a scale of 5 sunburns per decade for each life-period. The magnitude of risk for 5 sunburns per decade is highest for adult and lifetime sunburns.


Overall, these results show an increased risk of melanoma with increasing number of sunburns during all life-periods, not just childhood. Prevention efforts should focus on reducing sunburns during all life-periods.

This is probably one of the most authoritative source on whether Vit D is good for you [1]. I was never much of a believer, but this article prompted me to reinvestigate it, and I'm surprised to see that there is an effect if you're looking at elderly adult population.

Also, as others have mentioned, there is such a thing as too much - taking too much can affect the balance of your other vitamin levels. There was a nice trial on beta-carotene which showed it increasing mortality which was very unexpected, but made sense once people understood the biochemical pathways better.[2]

[1] http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD007470...

[2] https://www.ncbi.nlm.nih.gov/pubmed/20155614

FWIW, here's an anecdote from someone with an auto-immune disorder. I've had MS (multiple sclerosis) for 20 years. In that time, I've lived in 7 different climates for a year or longer each. I didn't get my first symptoms until I moved to northern Europe during the winter. The times that I've had no disease progression, I was closer to the equator. For example, I had no issues at all in the 5 years I lived in central Texas. The times I've had disease progression, I've been further north (above the 37th parallel). Since I'm currently living in the 47th parallel, I take 10,000 I.U. of Vitamin D a day. The one time I've had a serious increase in disease activity while living here, I tried taking a year off the Vitamin D supplements because I thought my medication was sufficient.

googling myelin and vitamin D does bring a bunch of info in that direction, for example :


"In the central nervous system (CNS) the main proteins of myelin are proteolipid protein (PLP), myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and CNPase.


The mice were treated by cuprizone for five weeks in order to induce demyelination.


a significant increase in the MOG and CNPase expression was seen in vitamin D injected group as compared to SHAM and control groups. It is concluded that vitamin D plays a role in the process of remyelination by increasing MOG and CNPase expression in the cortex."

Recommendations for vitamin D seem to be a bit of a trend recently, but the evidence for their efficacy does not necessarily seem to be there.

Meta-analysis suggests that supplementation in vitamin-D deficient populations does not reduce cancer, fractures, cardiovascular problems or all cause mortality (http://www.sciencedirect.com/science/article/pii/S2213858713..., https://academic.oup.com/jcem/article/96/7/1931/2833735).

One limitation of this research is that most studies are done with fairly low doses (700-800 IU is common). However, those few studies that look at higher doses (5000-1000IUs) you don't necessarily see any better signs. On the contrary, there is some evidence that high doses seem to be associated with e.g. higher risk of falls and fractures in elderly patient populations (https://jamanetwork.com/journals/jama/fullarticle/185854, https://jamanetwork.com/journals/jamainternalmedicine/fullar...).

Fwiw, there is mounting opinion and evidence that vitamin D recommendations need to increase by an order of magnitude, essentially casting those levels as experiments in vitamin D deficiency.

>A statistical error in the estimation of the recommended dietary allowance (RDA) for vitamin D was recently discovered; in a correct analysis of the data used by the Institute of Medicine, it was found that 8895 IU/d was needed for 97.5% of individuals to achieve values ≥50 nmol/L. Another study confirmed that 6201 IU/d was needed to achieve 75 nmol/L and 9122 IU/d was needed to reach 100 nmol/L.

>The largest meta-analysis ever conducted of studies published between 1966 and 2013 showed that 25-hydroxyvitamin D levels <75 nmol/L may be too low for safety and associated with higher all-cause mortality, demolishing the previously presumed U-shape curve of mortality associated with vitamin D levels....

>This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter. Actions are urgently needed to protect the global population from vitamin D deficiency.


Just like with other fat soluble vitamins, there is evidence that there is optimal level and U-shaped correlation with risks.

There is a U-shaped association between vitamin D concentrations and total mortality[1], inflammatory markers[2], etc. but more studies are needed[3] to be sure.


[1]: Plasma vitamin D and mortality in older men: a community-based prospective cohort study. https://www.ncbi.nlm.nih.gov/pubmed/20720256

[2]: Association between serum vitamin D concentrations and inflammatory markers in the general adult population. https://www.ncbi.nlm.nih.gov/pubmed/24928661

[3]: Do studies reporting ‘U’-shaped serum 25-hydroxyvitamin D–health outcome relationships reflect adverse effects? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4951179/

The NHS website has just published an informative and easily readable review of recent research on vitamin D and cancer.

Vitamin D may reduce the risk of some cancers: https://www.nhs.uk/news/cancer/vitamin-d-may-reduce-risk-som...

If you live in US and your insurance Blue Cross don't expect them to cover your vitamin D level test: https://www.horizonblue.com/providers/news/news-legal-notice...

This is for patients without symptoms. They'll cover it if you come in feeling ill and your doctor orders a diagnostic test. They will also likely cover the follow-up testing for vitamin D. Testing for testing's sake is what is not covered.

As with most supplements, ask your doctor. Do a blood test every year. Maybe see a nutritionist.

Vitamin D is ambivalent: as said in the article, it helps calcium absorption so if you're too low on vitamin D you might be too low on calcium and thus have frequent cramps and what not. But if you're a little too high on vitamin D and consume your fair share of calcium, then calcium absorption could be too high and you'll end up with premature atherosclerosis and other vascular issues.

See https://academic.oup.com/ndt/article/27/5/1704/1844110

I've had success taking a combination of vitamins D3 and K2 in liquid dropper form. I noticed the benefits more than when I was just taking capsules of D3.

Interestingly, I've managed to avoid getting a seasonal cold this year unlike most of my coworkers and friends, and my guess is that the D3/K2 has helped with that because I haven't changed much else.

There are billions of things that have changed this year compared to last year and you're attributing your lack of getting a cold to Vitamin D?

Anedote. I became a vegetarian and started 10,000 unit daily vitamin D supplementation this winter. I've also experienced cold after cold. My nose is a river. Body aches, fevers. So has my family, and our friends' families.

So by the logic of the other children of the parent I should quit my vitamin D supplementation, and probably avoid friends that take Vitamin D. ;-)

Purely anecdotal, but same story here. D3 only, vegetarian. I can't think of a single point in my life where I didn't get sick (cold/flu), if I was surrounded by sick people. This year, 8 sick people in my house and extended exposure with my wife sick for two weeks. I'm still fine.

> Purely anecdotal, but...

It’s not just anecdotal, it’s bad reasoning. You can’t prove that your supplement prevented you from getting sick. Maybe you were immune to whatever was going around. Maybe you didn’t touch your face at the right times. Maybe you washed your hands really well. There are thousands of possible explanations, and it’s misleading and wrong to attribute it to some random supplement.

Please stop doing that. It’s the same reasoning people use when they say that they prayed and God answered. Just because B happens after A doesn’t mean that A caused B; it just means B happened after A.

> Just because B happens after A doesn’t mean that A caused B; it just means B happened after A.

This is where you committed a fallacy for a change. Next time be more careful! With this kind of thinking you'd rule out any causality.

When I was a kid my father told me to get sunshine as much as I can do I wouldn’t be sick easily during cold weather. So I understand him now.

Does anyone know how problematic a "bad" SNP in the VDR Taq gene is? (VDR=vitamin D receptor)

I am VDR Taq positive and from what I gathered as long as you check your vitamin D levels from time to time and supplement accordingly it shouldn't be an issue. Also there are co-factors for sulfation of vitamin D like zinc, B6, DAO, lysine so you need to check those too. It becomes more complex when, like me, you also have mutations that makes B6 and zinc less abundant.

Sunlight ftw.

Very true but depending on what latitude you live at, it may be impossible to get enough on sunlight alone. There's dermatologist that claims a link between latitude and mortality:


Recommended watching - there is more to sunlight than Vitamin-d.

That isn't so easy. I live in Norway. Where I am, winter days are only 4-5 hours long and the sun isn't all that strong. One can easily work through the sunlight.

In addition, you should be out with some skin exposed - more than just your face - for at least 15 minutes a day during daylight hours. In some areas, this makes it somewhat prohibitive during winter and you still might need supplements.

Rant time:

Go outside more. Take 15 min with your shirt off in the sun. In some areas of the world this can be a true challenge, but cold exposure has its own benefits. It will boost mood, improve eyesight, and process vit D. Skin cancer is real, but unless you are getting burnt to the point of peeling or blisters, there is virtually zero risk as an adult. A good tan won't make you look like a lifelong smoker. Just beware akward tanlines, and curious neighbors when trying to eliminate said tanlines.

I had a cancerous mole removed in 2013 (melanoma stage 1a) and my dermatologist basically told me tanning is NOT ok and was never ok.

"There is no such thing as a healthy suntan. Any change in your natural skin color is a sign of skin damage. Evidence suggests tanning greatly increases your risk of developing skin cancer. The increase in skin pigment called melanin, which causes your skin to tan, is a sign of damage. Once skin is exposed to UV radiation, it increases the production of melanin in an attempt to protect the skin from further damage. The increase in melanin may cause your skin tone to darken over the next 48 hours."


You shouldn't tan, but you also shouldn't avoid the sun all together. 15 minutes in the sun with your shirt off every other day doesn't even give me a tan or burn, and I'm the palest person I know.

And soreness after every workout is a sign of muscle damage. It's desirable and makes the muscle grow back stronger. I'm not saying tanning is definitely good or bad, but I can confidently say that it is at least possible that occasional, low-grade skin damage is good for you.

What's your 'natural skin colour'? The colour of your skin if you never go outside? Or the colour if you spend a 'healthy' amount of time in the sun?

I'm female. In many places, I literally cannot follow your advice without getting arrested.

Additionally, I'm too far north for this to do enough. December days are only 4-5 hours long. If I work a normal first shift, I'd have to do this during my half hour lunch or I'd miss daylight completely... plus the fact that the sun isn't strong enough to give me enough benefits.

Now, the good news: It isn't all bad advice. I had low vitamin D this winter, and felt pretty sick. The doctor's advice once I'm done with my 3-months of prescription vitamins: From September through April, I need to take a supplement. 20IU a day. The rest of the year, I need to be out in the daylight for 15 minutes a day, with at least arms exposed (not just my face). It isn't that one needs their shirt off, just skin exposure. This is quite doable.

There are many places and times of year where you just never cannot get enough sunlight through this method. Right now in the UK is midday, and it is completely cloud covered, and this will be the case most days for a large proportion of the year.

For the UK, the main criteria is latitude. It's only next month in April that, even when it's sunny, people in the UK can start to get vitamin D from the Sun.

(The UK is at the same latitude as Vancouver)

Indeed. Look for the "UV index" in your local weather reports. If it's below 3 [on a sunny day, during wintertime] it means that the low angle of the sun, even at noon, reduces UV intensity to such an extent that your skin cannot produce vitamin D.

Most of it is further north AFAICT - the south coast of the mainline is roughly inline with Vancouver, but then it extends a substantial distance north.

As far as I know, even in sunlight, you won't get enough UV to trigger vitamin D synthesis in UK in winter.

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