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Comment by trevorkoob | Hacker News Reader

Did my masters on Vitamin D - It is very difficult to extract CLINICALLY RELEVANT information from retrospective epidemiological studies.

However, there a a few things that are clear:

1. Calcium absorption from the intestine increases with vitamin D supplementation dose up to around 8-10,000 IU D3 daily.

2. 15 minutes of full body exposure in noon sun is equivalent to a dose of ~20,000 IU D3

3. There are few cases of vitamin D overdose in the literature - doses in the 1,000,000 IU+ range within days is generally where symptoms are noted - this excludes people with kidney disorders.

Personally, I take 10k IU D3 a day. The D3 is important because D2 has 1/2 to 1/3 the effect per dose in raising calcium absorption levels.

I would recommend this level of supplementation to anyone who doesn’t have a kidney disorder.

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Re #2: the figure gets thrown around a lot. But who is outside, naked, at noon for fifteen minutes? It's really hard to translate that to anything meaningful or actionable.

Here's a tool that can help calculate useful exposure depending on your location/time of year. Doesn't take clothing into account however..

https://fastrt.nilu.no/VitD-ez_quartMEDandMED_v2.html

The point is that being outside naked at noon every day for 15 minutes wouldn't hurt you. Therefore, a daily dose of 20,000 IU / day won't hurt you. Therefore, a 5000 IU supplement every day won't hurt you either.

One does not follow the other. Maybe taking 5000 IU orally has a vastly different effect to letting it acculumate through skin? That's purely speculation on my part though, just trying to illustrate that these two are not necessarily equivalent.

It is certainly a different mechanism. There are inactive isomers of pre-Vitamin D (tachysterol and lumisterol) that prevent over-production of Vitamin D from continued UV exposure.

I list these numbers to give a general idea of the levels of Vitamin D that people experience without oral supplementation.

My conclusion was that too many studies were being done to determine the correct or safe amount to supplement rather than testing regularly to determine a safe/optimal blood concentration.

Very excited for good prospective studies of Vitamin D.

That's a bold assumption to be making, especially regarding a fat soluble vitamin that builds up in the body.

A bag of carrots wont hurt you yet an equivalent dose of betacarotene (vit A) supplement definitely will and is strongly associated with increasing certain cancers. There's a reason you won't see those on the shelf apart from miniscule amounts in multivitamins.

Nothing in nutrition exists in a vacuum.

Why do we think that the various effects of sun exposure are caused by vitamin D, rather than vitamin D just being one of the effects?

is this just an extrapolation or does my body actually constantly produce the same amount of vitamin D if i sit in the sun even if I don't have a deficit?

Because usually phisiological processes are in some kind of equilibrium and regulated, so it's not straightforward to compare it to supplements.

7-dehydrocholesterol is photolyzed by UV to previtamin D. There is then spontaneous isomerization between this previtamin D, vitamin D and 2 inactive isomers. As vitamin D is used by the body, and the inactive isomers remain in the skin, there is an equilibrium - as vitamin D is used by the body it is drawn from the skin, leading to more conversion of inactive isomers to active vitamin D.

The article goes into some detail on this, my understanding is that Vitamin D is produced in inactive form with sunlight exposure and then this is more-slowly released as needed (over winter apparently, but nobody's quite sure apparently).

Skin shade, location, time of year, and atmospheric conditions are other huge variables.

My pale skin in the midday desert sun for fifteen minutes in July? I'd have a pretty serious burn.

Your skin may be burned but you wouldn’t likely have a vitamin D overdose.

You must be really pale. I'm super pale and it takes at least twice as long to start a light burn.

I'm not that pale but it's shocking how fast you can burn in some places. Denver, for example, has a mile less atmosphere protecting you and little UV-blocking humidity. While New Zealand famously has the ozone hole. I don't burn nearly as fast in San Francisco.

This is really dangerous advice to be peddling on internet forums. Statements 1 & 2 are both misleading.

It is certainly true that a few high dosages of vitamin D are not harmful. The issue is the negative effects of having too high of a vitamin D status.

Anyone taking more than 2k IU/day should do so after consulting their doctor or at least testing of their vitamin D levels.

And your statement is wiser because?

I've been taking vitamin d3 10K IU/day for 10 years and it has allowed my blood V-D3 levels to go from 12 ng/mL to ~50 which is within normal range. The NIH recommended dose has been going up over the last 2 decades starting at 400 IU and now 4,000 IU as we learn more and more about it's effectiveness.

The NIH states that 4000 IU is the tolerable upper intake: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessiona...

If you are rounding down your vitamin D status then it is currently at what the NIH say should be avoided. Have you consulted with a medical professional about your vitamin d status?

10k IU/day can be great when someone's level is 12, but it's not a maintenance dosage once at healthy levels.

https://pubmed.ncbi.nlm.nih.gov/28768407/

"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. Since all-disease mortality is reduced to 1.0 with serum vitamin D levels ≥100 nmol/L, we call public health authorities to consider designating as the RDA at least three-fourths of the levels proposed by the Endocrine Society Expert Committee as safe upper tolerable daily intake doses. 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."

It is pretty easy to cherry pick a paper advocating whatever you want to advocate for vitamin D. The paper you cite is entirely founded on another paper about fixing the daily estimate. That paper states about its improved estimate: "As this dose is far beyond the range of studied doses, caution is warranted when interpreting this estimate."

I have no doubt that the mainstream NIH advice is not optimal. The best thing for everyone to do though is not to recommend high dosages for everyone but instead to recommend getting vitamin D levels tested.

I noted the levels needed to maximize intestinal calcium absorption because this is the best studied aspect of Vitamin D. Rickets was the main reason Vitamin D was discovered and supplemented.

Vitamin D level blood testing is imprecise - I would not consider any one test of Vitamin D levels to be accurate.

This person's cited paper corresponds with the calcium absorption data that suggests around 8,000 IU D3 is where calcium absorption begins to plateau and more vitamin D leads to minimal additional calcium absorption.

Since I haven't been going outside, I take vitamin D 10,000 IU daily. You are correct in that one shouldn't just take the advice of random internet strangers - I should be more careful in posting. My personal experience with Vitamin D has been extremely positive and so I get excited about sharing what I know - of course I had to work and couldn't actively respond to this thread as much as I would like.

Its nice to see someone not get upset about the criticism!

Things that work well for one person can be dangerous for others. It's fine to share your positive experiences, but it's another step to be recommending the same to others.

There are a lot of other factors besides calcium absorption to consider. In fact maximizing calcium absorption with vitamin D likely has negative consequences unless there is proper vitamin K intake as well.

> It is pretty easy to cherry pick a paper advocating whatever you want to advocate for vitamin D.

Which is just what you did before.

I do quarterly blood panels to make sure all numbers are within range. All is good.

so are you saying that it is not ok to stand naked in the sun at noon for 15 minutes ? our bodies producing 20k IU is harmful? what idiot designed our bodies!

Not sure why this is being downvoted. This advice is far more useful than OPs.

Be careful of anyone claiming to be an expert on anything, especially on an anonymous forum - even if that forum has in general higher quality opinion.

And the OP does not mention Vitamin K2 at all. How does anybody who claims to have done a Masters on Vitamin D not mention K2?

I didn't mention K2 because I didn't study it. I make no claim to expertise, only familiarity.

Personally, I eat dark green leafy vegetables every day - one serving of kale contains 443% daily value of vitamin K and I probably consume 2-3 servings a day.

Most food we eat doesn't contain vitamin D. A serving of farmed salmon, for example, contains about 250 IU D3 - 32% of the daily value.

In any case, I highly agree with not trusting anonymous internet opinions.

> 2. 15 minutes of full body exposure in noon sun is equivalent to a dose of ~20,000 IU D3

For someone who claims to have done a masters on Vitamin D, I find this generalized statement disturbing. What skin tone the person has, what season it is, what latitude the person lives at, age of the person etc., are factors in how much Vitamin D is produced by the body on exposure to sunlight. I’m afraid I can’t take the other points seriously because of the brevity and lack of nuance.

Yes, this was overly brief and a tilde is not enough to qualify this statement, and I should have said noon equatorial sun.

My point here was meant to be about how this is essentially the daily maximum dose from UV radiation due to the isomerization of previtamin D into inactive isomers, and to give context to a dose of 10,000 IU D3 seeming large when it is half the amount a person might receive from sun exposure.

>this excludes people with kidney disorders.

Can increased calcium absorption lead to kidney disorders?

This is my biggest worry when taking Vitamin D3 supplements, I have Vitamin D deficiency but when I take supplements it quickly reaches to toxicity levels (> 80 ng/mL) and so I have the revert to monthly supplement of 60,000 IU of Cholecalciferol.

PSA: I'm a dwarf, possibly Achondroplasia, but during childhood (4 - 15years) I wasn't categorised as such and my bone troubles were always attributed to Vitamin D deficiency. After age 17, I didn't have much of bone problems and so I didn't follow up on my Vitamin D deficiency.

Fast forward to age 32, I was diagnosed with Spinal Stenosis among other cerebral spinal fractures risking becoming quadriplegic[1]. So, if you have bone problems due to Vitamin D deficiency, please follow it up regularly, it's likely going to be life-long but taking proper supplements is better than a fracture. Also visiting a good endocrinologist to get to the root of Vitamin D problems is recommended.

[1]https://abishekmuthian.com/i-was-told-i-would-become-quadrip...

IANAD, but the word is you should couple it with vitamin K to offset the extra calcium absorption. Which is a good idea on general principles, since K is one of the other very few supplements worth taking by the gen pop.

There are many cases of kidney disorders causing issues in vitamin D metabolism - the majority of literature examples I read involved genetic kidney disorders which would not be be caused by increased calcium absorption.

I hope you are receiving the treatment you need.

Interesting, I've always heard of the calcium absorption effect as a negative aspect of D over-supplementation — I guess the theory is that it raises your blood calcium level too high, leading to arterial calcification? Is that effect overblown in your opinion?

In acute hypervitaminosis D, there can be organ calcification that has to be treated. These cases are rarely reported - one case occurred when the patient ingested crystalline vitamin D - dosing themselves in the range of 1-2 million IU D3 per day for weeks, and although there was not an extensive follow-up to determine the long-term effect on the patient, the acute calcification was reversed with treatment.

Vitamin D is involved with calcium in the body in many different ways, specifically I was talking about a measure of the absorption of calcium into the body from food as promoted by vitamin D.

Organ calcification is extremely serious and a very understandable reason why doctors have been hesitant to recommend higher doses of vitamin D, however most medical thinking about vitamin D until recently has focused on the prevention of Rickets, which requires only a small amount of constant supplementation (500 IU D3) to avoid serious effects. In context, 10,000 IU seems like an enormous dose. However if you look at the blood serum levels of people who receive consistent UV exposure, they have much higher levels than someone who is being supplemented with 500 IU D3 and no UV. So much of this debate is around trying to find out what the "optimal" vitamin D level is rather than what level is "sufficient" to prevent Rickets.

Not an expert, but from what I read that is exactly why you should not supplement high dosage vitamin D without also supplementing vitamin K2 (mk7 all-trans). Studies that show positive health effects from D3 typically supplement 40ug K2 for every 1000IU D3.

I knew people that would go for a walk during lunch around the office building with a friend. Ate a packed sandwich, got a walk in, a conversation, and apparently got a much needed dose of D3.

Seems like such a low effort, high reward thing to do.

Depending on the latitude and skin complexion that may be all thats needed for D3.

When my vitamin D levels tested a little low, I asked my doctor about it, and he said studies don't show any benefit for supplementing vitamin D deficiencies that are asymptomatic. At the time, I looked up the study, though I can't seem to find it now.

The studies I've seen relaying the same sentiment of no appreciable benefit only looked at a single outcome, normally bone density or bone fracture occurrence. Vitamin D levels affect expression of almost 300 different genes in humans (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3604145/) so looking at a single outcome to gauge the entire efficacy of that vitamin is absurd and disappointing that so many other doctors push their narrow minded interpretations of those same limited studies.

My thesis argued that we should not be testing supplementation levels, instead we should be testing the effects of maintaining people at various serum levels of vitamin D year-round.

Hi trevor, super intereseting what you mention. Wondering where you did the master since its not common (at least in my country). Thanks man.

Ditto re 10K. I've been taking Vitamin D3 10K IU/day for 10 years and it has allowed my blood V-D3 levels to go from 12 ng/mL to ~50 which is within normal range. The NIH recommended dose has been going up over the last 2 decades starting at 400 IU and now 4,000 IU as we learn more and more about it's effectiveness.

Re lux with full body exposure. I was under the impression it's an hour per day to get 15-20 IU? Either way it means exposing legs, hands and face to the sun which most people rarely do on a daily basis.

Will your body make vitamin d from sunlight if you already have a enough from a supplement?

I’m worried about overdosing if I take 5000 UI and get a lot of sun.

I personally aim for 10,000 IU D3 daily from either sun or supplement. In normal times, living in New York, I would supplement 10,000 IU D3 from November through March, and then I would make sure to be outside 1 hour a day with at least arms and face exposed.

Shots of 250,000 IU are given clinically and the therapeutic dose was traditionally 50,000 IU D2 weekly - corresponding to a dose of about 3,500 IU D3 daily.

I highly recommend getting tested for kidney disease if you are worried and get multiple vitamin D tests - the tests are imprecise but will give you a general idea of what your levels are.

No, it won’t, but that’s only after a certain limit that’s much higher than 5000IU. Even if you spend all day in the sun, your body will stop the synthesis at a certain level (10000IU in the day is what I had read long ago, but that may be incorrect or outdated).

In other words, 5000IU is much lower than what the body would naturally produce when exposed to sunlight for long durations in a day (assuming good latitude, sunny season, lower atmospheric pollution, around noon, lighter skin tone, etc.).

Do you know what would the baseline vitamine D intake been for our ancient (read : outdoor lifestyle) ancestors?

It depends - ancient ancestors had a lot of different lifestyles. For example, Soranus of Ephesus reported deformations in the bones of children as early as the 100 CE.

However, this is I think what you are trying to get at:

One particular epidemiological study stands out as a guide for what typical 25-(OH)D levels might have been be for our earliest ancestors.

Luxwolda et al. studied populations of pastoral Masai and hunter-gatherer Hadzabe, sampling their blood for 25-(OH)D levels and taking note of their daily habits in reference to UV exposure.

The mean 25-(OH)D concentration in these populations was 115 nmol/L, with a range of 58 nmol/L to 171 nmol/L.

This study provides a general framework for the expected 25-(OH)D level of active, healthy humans working outdoors at a low (< 5 degrees) latitude. Humans have modified their living conditions greatly from this model of ancestral life, leading to reduced exposure to UV radiation.

Thank you for your answer, that is pretty interesting!

Welcome! I highly recommend the study - even though the numbers are low, the data is very interesting.

I calcium absorption increases, should you also supplement calcium?

>2. 15 minutes of full body exposure in noon sun is equivalent to a dose of ~20,000 IU D3

Define "full-body exposure", please? I'm not going to walk around naked outside in the sun.

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