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Comment by pcarolan | Hacker News Reader

What dose is recommended for adults and what is the best way to get it into your system?

From the last couple sentences of the abstract:

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.

So 8000 IU for adults

I was already taking 10.000IU a day (in winter) to battle Seasonal Affective Disorder. I live above 51N latitude though, so I practically don't see the sun in winter.

This is per day?

I have been deficient for a few years now and I take ~6000 IU per day, but it doesnt seem to make a big difference in my blood tests. I already thought 6K was a lot...

Are you taking it with food? I think it dissolves in fat, so you might want to take it with some oil for better absorption.

Yup - it's a fat soluble vitamin - this is a very good point to bring up. I made the "taking it with my low fat meal of the day" (breakfast) and made a change to correct that.

I've been told I should be taking it in the morning though, because it can affect sleep if you take it in the evening - anyone know differently?

Gwern ran a self-experiment finding that it did affect his sleep: https://www.gwern.net/zeo/Vitamin-D

eat bacon.

I didnt know that - I usually take it shortly after breakfast, but ill try this - thanks!

My doc prescribed me 25,000 IU once a week for 8 weeks then 10,000 IU daily thereafter. The kicks of 25k were what made the diff for me. YMMV

holy smokes, thats a ton. Are there any effects of too much?

Yeah, it's fat soluble so you can take too much (but you'd have to take a ridiculous amount).

The normal doctor prescription to increase levels is a 50k pill once a week for a couple months. The previous recommended level was 20ng/ml, but they increased it to 30ng/ml.

When I got tested mine was 11ng/ml (and this is in the sunny bay area). To have the recommended value from normal sun exposure you'd need face/legs/arms exposed to sunlight for ~30-45 minutes a day which most people don't get. It's very hard to increase D from food.

I'm also not sure how they determine the recommended amount and there seems to be a ton of pseudoscience around all of this stuff so it's hard to tell what's true.

Yah like doing 25k a day. That could cause problems.

Surprisingly few problems. Wife has been doing 80k a day for the past few years and have help tremendously with her auto immune decease.

If you're going to do high doses, stay away from anything with significant amount of calcium in your food (dairy, nuts etc)

80,000 IU is a terrifying number for daily intake. Did you mean 8k and not 80k?

I meant 80k. See studies from Dr Cicero Coimbra for more background if you're interested.

Interesting. I started taking it since I've started working inside for my day job. Apparently I should be upping my dosage. I take a multi and one or two D tablets and probably get a max of ~5600 from that outside of any absorbed from foods.

I also eat a lot of eggs. My girlfriend will be pleased to know that I'll be upping our egg intake!

> Apparently I should be upping my dosage.

Get your current nmol/L value and decide based on that data.

In Germany, you have to pay around €30 for that test. It's not covered by insurance for some reason. Anyhow, if they ask for significantly more than that, they are ripping you off.

I'll be booking my yearly physical soon, so I'll ask for a test then.

edit: Just having checked I misread the dosages completely. Right now it's much less.

    Multivitamin  - 400IU
    D3 Supplement - 400IU

I thought the multi was 4000 and I occasionally take 2 of the supplements, but usually 1. Maybe the double strength next time...

Better watch out with egg intake upping, check your cholesterol and trigliceride levels. Anyway good to consult with professional nutrituonist.

Ask your doctor, really. When I got diagnosed with vitamin D deficiency (inside on the computer all the time, I'm quite pale) a few years ago the prescription I got was for pills that had 50,000 IUs each and I was to take one twice a week. I recently got a new doctor and was getting bloodwork done and she saw the mention of the deficiency and she asked if I wanted that tested for... she said she usually doesn't bother because everyone in my state (West Virginia) is deficient, she just recommends people take 1000 IUs a day or so. Personally I take 10,000 IUs about every other day. At least assuming the stuff I ordered off Amazon is at all legitimate (vitamins and such things are such a super sketchy market, companies get busted selling sawdust pills all the time).

One thing that I was not expecting, when I was on that prescription at first I noticed a marked improvement in my hearing (which I had not noticed being degraded at all previously...). I thought I was imagining it but upon doing some research it turns out that hearing loss is one of the possible complications of vitamin D deficiency.

you could also investigate in vitamin D lamps (Sperti, for example), they are not cheap though

an hour of sunshine a day?

Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.

Check out the map: https://www.health.harvard.edu/staying-healthy/time-for-more...

I saw the quoted text, but missed any explanation. I would love a clarification on whether they claim the skin is not getting exposed to sun or, even when exposed, does not make any vitamin D, which is how I read the above.

This is an honest question -- if it is the first, I am not too concerned. I grew up in a colder climate and, while living far in the shaded area today, routinely wear short sleeves and walk a lot outside from early spring to late fall. If it is the second, I would love to learn the underlying causes at least as a scientific curiosity (and start thinking about vitamin D supplements).

The sun is too low in winter and the atmosphere blocks the UVB rays our skin needs to produce Vitamin D. The same thing happens around sunrise and sunset even in summer. Here's a good explanation from HN's favorite site:

https://physics.stackexchange.com/questions/268509/why-is-th...

BTW, here is the equivalent South Parallel: https://en.wikipedia.org/wiki/37th_parallel_south

Argentina and Southern Chile in it. Buenos aAires looks ok. Bu

That line was a lot lower than I imagined! Surprised that Denver is “too far north”.

It is silly to go through the trouble of including a map, only to reinforce the imprecision of the parallel approximation. Obviously People in Denver get more sunlight than e.g. people in Nashville, given the altitude and weather patterns. More detailed maps don't limit themselves to drawing a straight line.

That's me. Any idea how well supplements are absorbed? Which are better or worse?

Get a blood test first so you know your Vitamin D level (they're cheap: https://news.ycombinator.com/item?id=15869485), maybe you already get enough from your diet.

If you do need supplementation, then Vitamin D3 (specifically Cholecalciferol) is vastly better absorbed than Vitamin D2. If you want a specific recommendation, buy this: https://www.amazon.com/gp/product/B07234TTCC and take it twice per week (Sunday & Thursday for example), that'll average to about 1400 IU per day.

According to the article, it is safe and recommended to take one of those 5000 IU capsules per day.

I see 8000 IU for adults:

Supposedly this is why Northern Europeans evolved lactose tolerance. Asians got the D they needed from the sun and leafy veggies.

Seems odd, considering cow milk contains virtually no vitamin D. It is often enriched with vitamin D, but that practice likely does not predate the evolution of lactose tolerance.

When it comes to nutrition, the majority of unsourced information on web forums is made-up nonsense. Perhaps not maliciously in bad-faith (i.e. maybe OP really has heard this before)... but usually someone repeating something they heard 3rd or 4th-hand without any real fact-checking.

Milk is high in vitamin D because it's intentionally added. Like iodine in table salt, or fluoride in drinking water. Obviously these things had no role in human evolution before they started in the 20th century.

Vitamin D is only absorbed in the presence of fat in the intestine. Milk is a source of fat. Of course it isn't the only source of fat, but the hypothesized explanation is more plausible than you might think.

I have observed 'seanmcdirmid to be a thoughtful commentator. It would be uncharitable to suggest that he thinks that USDA has regulated milk drinking for millennia.

Most "1st-hand" nutritional research is also wrong. That has been the case for decades, which explains the field's relative lack of progress. The reason is that most nutritional research is funded by large commercial food interests.

Oops. You are right, I was thinking of calcium, which you can get from green veggies as well. I get confused because we had to deal with them all at once when my wife was pregnant.

I know the subthread went in another direction, but: vitamin D increases the absorption of calcium. With minimal vitamin D synthesis from sun exposure in northern Europe, it makes sense that extra dietary calcium would be an evolutionary advantage. Hence, lactose tolerance. So OP's comment made sense even while confusing vitamin d and calcium.

Hah, that's a direction I hadn't considered. That is indeed exactly why vit D is added to milk in the first place. The milk industry claims it's a good source of calcium, but fails to mention it's generally a poorly absorbed source of calcium. Hence the addition of vit D.

Hard cheeses are generally very low in lactose, by the way, but I guess lactose intolerant societies are unlikely to discover this on their own.

Lactose intolerant societies generally have cheese and other forms of curd. Also, babies are generally lactose tolerant regardless, losing this tolerance later.

Lactose tolerance evolved in several different populations independently (including African populations), so I think Vitamin D can only be part of the story. Lactose tolerance gives you access to nutrients from milk, which has a huge impact.

I don't know any of the history, but I would wager high protein content as that's also the huge benefit meat-eating brought humans.

You would need 1) the sun to actually be shining, 2) no cloud cover and 3) probably be naked. Most of us won't get enough vitamin D from being outside for an hour.

1. The key UV for vitamin D production by our skin are UVB rays, optimal between 10am and 2pm, except in the winter at 40+ latitude when the rays travel longer through the atmosphere due to the low solar angle. For instance in Washington state your skin cannot produce vitamin D from November to February.

2. UVB do pass through clouds. (But not through glass windows.)

3. Arms and face exposure are sufficient if you spend 10, 20, or 30 minutes a day depending on UV index of the day (the higher the UV index the less time you need to trigger vitamin D production) and on your skin color. There is some kind of "reservoir" effect that limits production of vitamin D to a maximum, so sun exposure time beyond the above does not have any benefit in terms of vitamin D production.

That's easier said than done for some. A couple of years ago we had an exceptionally bleak November here, with one city for example having only 12 minutes of sunshine in the whole month of November. (I'm not talking about places within the Arctic Circle, although relatively speaking they could almost seem that way for some, of course.)

The average where I live for Nov is about an hour of sunlight per day, but to catch that you'd have to spend all the light hours of day outside (and for sure, November sunshine isn't quite the same as summer sunshine).

UVB rays do pass through clouds.

It is more complicated than that. A dark cloudy day (no gaps to sky) will not have much UVB. A day with thin high clouds won't block much, and may make it worse (reflecting or scattering).

And here's a calculator:

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

They calculate to 1000 UD if I see that right, I assume it's linar over time so just multiply that.

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