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Comment by jessaustin | Hacker News Reader

People in the Northern hemisphere could have solved their vitamin D problems by going outside for twenty minutes a few times a week over the last several months. Unfortunately sunscreen marketing has clouded our judgment.

https://www.outsideonline.com/2380751/sunscreen-sun-exposure...

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I (Scottish-level white) spend an hour or longer outside every day, all year, in London. Yet my vitamin D levels were almost zero. Unless I take around 50,000 IU per week, they drop to insufficient.

Not everyone seems to generate enough vitamin D from sun exposure.

Sounds unusual. I thought the paler you were the easier you generated it tbh. Also 50k IU sounds a lot too. I’m pale as fuck an 400iu a day and a quick walk put me in the healthy range.

> a quick walk put me in the healthy range.

Could this be due to where you live?

The winter in the UK can be very low light for quite long periods. The weeks-long ‘rain’ or whatever you call that semi drizzle is very dreary.

There is about 3x the rainfall per year where I live now but it’s short and sharp in comparison.

You're probably right. London is over 51° N latitude. Most people in the hemisphere are well south of that. Most people in Canada live south of that.

Europe in general is fairly far north. According to Citymetric, half of Canada's population lives further south than Milan, and the most populated latitude in Europe is 52° N.

The Gulf Stream distorts a lot of perceptions as does the fact that a lot of the Canadian population lives pretty close to the US border. A lot of people in the US are pretty surprised that London, Amsterdam, and even Paris are at the same latitude as northern Newfoundland and Quebec way north of Montreal.

It is essentially overcast from October until March. It barely rains, but it nearly always looks like it's about to rain!

That being said, even in the summer, when I regularly go outside enough to get a pinkish hue to my skin, I still don't generate enough Vitamin D. In an ideal world maybe I'd have an explanation for it, but I just take a supplement and don't worry about it any more. Some research suggests that there is a high degree of variability in how much Vitamin D individuals generate from sunlight.

It's pretty standard amount tho. My doctor suggested that, but I opted for a steadier amount when my D levels were low and have been using it ever since. 2 months after he suggested I had been taking 2000IU per day and my levels were back in what he called excellent range. No idea what level that is :) . I am an indoor dweller and in general don't like the sunlight and enjoy night time activities much better.

UVB is what causes vitamin D production, and UVB doesn’t penetrate the atmosphere when the sun angle is below about 50deg, so if you are not out when the sun is high enough, it doesn’t help with vitamin D

It looks like in London, the sun doesn't go above 50deg except between late April and late Aug, and on the solstice it's only above 50deg between 10:30 and 15:30. Which means for the most part, it that condition only occurs while people are inside the office, and only for half of the year.

Exactly that. Hence a permanent recommendation by PHE and NICE, that for public health reason, most of UK residents need a supplement. Alas - it is all but forgotten. Mostly acted on for newborns, where the GP surgery, probably reminds the parents or even distribute small bottles of Vitamin D drops. (administered orally) For everyone else, the widespread Vitamin D deficiency, goes virtually unnoticed. It is the default, with no-one pushing for a change. It is a low hanging fruit, wrt Covid-19 and also seasonal flus.

From early March until mid-June, we were told by government to “stay home”. There were even few events where police tackled to the ground and arrested people who were taking a walk outside, away from any crowd, in a group of two. Now people do go outside, and even though we have more detected cases of Covid-19 as compared to spring, the cases are milder and mortality rates are lower. Country: Croatia

Seems like these articles never clarify if they're talking about clothed or partially unclothed exposure. Hard to imagine much vit d being generated in the little bit of face and hand skin area exposed to sunlight by a normal clothed configuration.

If you check, you'll often find they assume shorts and t-shirt.

And they often skip over skin colour as a significant factor.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372923/#:~:tex....

From the link given above:

These seem like benefits everyone should be able to take advantage of. But not all people process sunlight the same way. And the current U.S. sun-exposure guidelines were written for the whitest people on earth.

Every year, Richard Weller spends time working in a skin hospital in Addis Ababa, Ethiopia. Not only is Addis Ababa near the equator, it also sits above 7,500 feet, so it receives massive UV radiation. Despite that, says Weller, “I have not seen a skin cancer. And yet Africans in Britain and America are told to avoid the sun.”

...

People of color rarely get melanoma. The rate is 26 per 100,000 in Caucasians, 5 per 100,000 in Hispanics, and 1 per 100,000 in African Americans.

...

How did we get through the Neolithic Era without sunscreen? Actually, perfectly well. What’s counterintuitive is that dermatologists run around saying, ‘Don’t go outside, you might die.’

At the same time, African Americans suffer high rates of diabetes, heart disease, stroke, internal cancers, and other diseases that seem to improve in the presence of sunlight, of which they may well not be getting enough. Because of their genetically higher levels of melanin, they require more sun exposure to produce compounds like vitamin D, and they are less able to store that vitamin for darker days. They have much to gain from the sun and little to fear.

A bunch of us have that kind of white skin that in adult years doesn't tan.. it burns in clearly unhealthy ways.

My son says he doesn't tan - he pinks.

Try https://fastrt.nilu.no/VitD-ez_quartMEDandMED_v2.html and err on the low side if you're worried. Regular self-examination is always a good idea for everybody and essential for very pale skins.

Vitamin D productive begins immediately when the skin is exposed.

In the northern states, you burn long before you get enough vitamin D around the winter solstice. Assuming the sky is even clear.

With vitamin d it’s about building up reserves while you can, and supplementing with food or vitamins.

I'm in Sweden, which is about the same latitude as Alaska.

My sister and mom tan, I burn. Weird thing though, when I was a kid I spent so much time outdoors. Like, all of the time.

That was before I got hold of a decent computer at like age 12 in 1989, and I started spending so much time indoors.

After 30 years or so of mostly staying indoors, I burn when UV rays hit my skin.

I'm willing to concede that my behavior is at least a part of the issue.

Swedes tend to get a good amount of vitamin D from the herring and salmon in their diet.

Well, I was eating the sorta usual amount of herring and salmon for a Swede, and was still diagnosed with a severe lack of Vitamin D, a few years ago. I got a recipe for 3200 IU/day based on my test.

In some Northern hemisphere countries we are not allowed outside.

Where is this? I feel like I should have seen something about this on the news... If this is Covid-related, you should know that time spent outside in the sun away from crowds is better for your health than time spent in any situation inside.

Example of country where you are not allowed to go outside at all (except during temporary quarantine of a couple of weeks)?

I now that even during France's confinement (which is over now), people were still allowed to leave their house for solitary outdoor exercise and walks.

I don’t know if you heard but over here on the west coast, shit’s on fire, yo.

Really?? I just met a friend who spent last week there taking surfing classes with a company - didn't seem like there were anything like that going on there. Haven't seen anything in the news, either.

The air is currently clear as a bell in the Bay Area.

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