[thrusong]

I live in Winnipeg, Manitoba where it is quite cold for a big majority of the year. I have dabbled with supplements because I get a couple of major colds every year.

I've heard things like you only need 15 minutes of sunshine per day to get your recommended dose of Vitamin D, but I've also heard it can be quite bad for you if you have too much in your system (and it's hard for your body to flush excess amounts).

If there a safe level of Vitamin D supplements where you won't run this risk? I don't drink milk either because I'm lactose intolerant.

[jerf]

"Winnipeg, Manitoba" ... "only need 15 minutes of sunshine per day to get your recommended dose of Vitamin D"

That doesn't apply to you most of the time, unfortunately. Vitamin D is the result of UVB exposure. For significant portions of the year, you don't get very much [1], compare with, say, [2] Orlando Florida in the US. 10-15 minutes is for a UV index of 7 [3], so that's only 4-6 months out of the year for you. And just based on my couple minutes with Google here, that number may also include the assumption that you're not just "out in the sun" for 15 minutes, but basically sunbathing. Lesser exposure may take longer: [4] Winter times can be effectively impossible because you can't sunbathe at 10 below (regardless of which scale I'm talking about) and you're not going to spend the requisite hours in the sun for what little skin is exposed. Or they can be outright impossible if your skin is dark enough.

[1]: https://winnipeg.weatherstats.ca/charts/forecast_uv-monthly....

[2]: https://nomadseason.com/uv-index/united-states/florida/orlan...

[3]: https://overcomingms.org/program/sunlight-vitamin-d/uv-index...

[4]: https://vitamindwiki.com/dl2105?display

[soperj]

I grew up on the Canadian praries. -10C is basically shorts weather.

edit: seriously though, anything warmer than -10C you'll definitely see kids in shorts. I go skiing in shorts every year.

[mwigdahl]

I take 5000 IU per day year round and have not had any issues. Research suggests you can dose 10x that without major problems, although personally I wouldn't go higher than I am already.

https://pubmed.ncbi.nlm.nih.gov/30611908/

[ErikCorry]

That sounds like a lot:

To help prevent vitamin D toxicity, don't take more than 4,000 international units (IU) a day of vitamin D unless your healthcare professional tells you to. Most adults need only 600 IU of vitamin D a day https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...

[toomuchtodo]

Vitamin D toxicity is a legitimate concern, so those dosing should be mindful of it, depending on dosage and existing serum levels. Don't action on medical advice from strangers on the internet alone, talk to you doctor or other credentialed medical practitioner you work with if needed.

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

[lisbbb]

It's bad for your kidneys

[efsavage]

You probably have to really try to take too much Vitamin D with any over the counter supplement (<=5,000 IU), especially if you live that far north. For reference, a prescription dose for someone who is low is usually 50,000 daily.

It should be part of your standard blood tests so you should know if you're running high or low and your doctor can recommend or prescribe a good dose.

[gilfoy]

I’ve had a prescription twice and it was 50,000IU of D2 once weekly. Usually the OTC one people buy is D3.

[colechristensen]

With 5,000 IU sometimes taking several at a time I had blood levels of Vitamin D at the top of the range which wasn't dangerous it was just informative, "hey you're having enough, tone it down".

[BeetleB]

It's 50,000 weekly.

[milesvp]

First know that the body will stop making vitamin D before you reach overdose quantities. This means you should take vitamin D in the morning.m rather than the evening. Second know that vitamin D is fat soluble. So if you are losing weight, you can more easily overdose if you have high levels stored in your fat. Also know the body won’t absorb as much vitamin D if you don’t take it with fat.

This can make dosing tricky. You can be taking an amount that is safe right now, but then is too much later.

You can max out your body’s vitamin D production even on a cloudy day, though the sun’s angle of incidence effects production.

The body typically maxes production at something like 20k iu (pleae verify this number it has been a while since I learned it), so staying below this number should mostly safe.

The USDA has set its recommended daily allowance mostly to avoid rickets. It is largely considered too low a number for general well being.

I live in north western Washington, and previously used to combat seasonal affective disorder, with some pretty dark thoughts come february. Since I started taking 1k D3 some 20 years ago much of the seasonal mental health has gone away. I take 2k D3 consistently currently, and if I run out for more than a week my mood starts to deteriorate quickly. I still haven’t proved causation since there are likely reasons I’ve let myself run out of the supplement that long, but it is so consistent that I treat it as causal at this point. YMMV

Please do research above just asking a forum for dosing advice though. This is a well educated place, and I would very much trust it as a starting point, but there is a lot of good published content on the topic. Though, I admit google is so bad today, I might fail to find any of the content I referenced years ago… if you use chatgpt make sure to require references, and check them. I find that using multiple instances to review research references separately prevents some context based poisoning as well. And pointing out inconsistencies can be a good way to find nuance in a topic. Though sometimes LLM will just waffle, and the context may be done

[bluGill]

I've heard the 15 minutes is all you need. I've also heard that in winter the sun is so weak that no amount of sunshine gives you any. (even if you were naked outside in winter - risking frostbite).

I'm not a medical doctor. I cannot evaluate any of the above claims. I wish I could find a source I could trust.

[thewebguyd]

Depends on where you are. Latitudes above roughly 35 degrees N, the sun is too low in the sky roughly between October and March to allow for UV-B rays to penetrate, which is what your skin needs to synthesize vitamin D.

So yes, if you live in the northern regions, you don't produce any at all from sun exposure, even on a bright sunny day, during most of the year.

Up here in the PNW, even in the summer, you only have a window of roughly 4 to 5 hours where the sun is high enough, in July.

[snozolli]

I've heard things like you only need 15 minutes of sunshine per day to get your recommended dose of Vitamin D

The figure I read years ago was that it takes 15 minutes in short sleeves to get the necessary light exposure at the 45th parallel in winter. I'm right at the 45th parallel and I don't go out in short sleeves in the winter, so I imagine it's significantly worse for you!

[dooglius]

You can get blood tests pretty cheaply. The safe level is the level that, after you take it consistently, has you in the desired range on the test.

[Etheryte]

You don't need to guess, go to your GP and get yourself tested. It's not expensive, depending on where you're from it might even be free, and usually you get the results back already the next day.

[slow_typist]

EU considers 600 I.U. per day as safe. Probably not enough if the level is low. Blood sampling is cheap, why don’t you have it checked.

[humanfromearth9]

25000 IU weekly during winter is OK, for an adult

[a3w]

An adult with 60 kg or 160 kg of mass?

[BurningFrog]

It's possible to overdose on Vitamin D, but you have to eat absurd amounts.

Unless you eat the pills like candy, you're safe.

[LocalPCGuy]

Generally agree, but unlike water-soluable vitamins, vitamin D can store excess in fatty tissue and the liver, and so if a person takes a large dose (generally 10,000 IU daily or more), they could develop toxicity over time due to the build-up. That's why it's important to test and adjust dosages according to the data.

[hollerith]

Untrue. Source: painful personal experience.