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Its not possible to get any vitamin D from the sun in the winter in these high latitudes even if you outside in the sun all day with short sleeves. The angle of

Its not possible to get any vitamin D from the sun in the winter in these high latitudes even if you outside in the sun all day with short sleeves. The angle of the sun is too low. We are just beginning march now, so the sun should soon be beginning to be high enough to give some benefit.

bproven 7y ago
Yep - I learned that a few years ago.
kaztal 7y ago
Sweden here. My partner is a doctor, she claims with assurance that you can't make a carpet decision like this. People who come from norther latitudes are used to the lack of sun, and their bodies don't need more vitamin D than is provided. Depending on your heritage, ymvm.
- leto_ii 7y ago
  It may still be worth taking a blood test, especially if you have some symptoms that match vitamin D deficiency.
- v77 7y ago
  Most people in North America are not from northern latitudes genetically unless we are talking about the UK and Germany and even then..
  - orasis 7y ago
    Huh? Europe is generally populated further north than North America is.
- BurningFrog 7y ago
  Swedes need as much vitamin D as anyone, but usually get it from their diet. Herring is a vitamin D gold mine, for example :)
- abainbridge 7y ago
  That seems implausible. Obviously there was evolutionary pressure on northern Europeans to tolerate lower levels of sunlight and no doubt adaption happened. However, I expect even Swedes evolved in an environment that included more time outdoors than a modern Swedish office worker gets. So, in the absence of any actual evidence, I'd still expect a problem. On top of that, there is some evidence. Basically all the papers found by this search show some evidence of vitamin D deficiency in Swedish people: https://scholar.google.com/scholar?start=10&q=sweden+vitamin+d&hl=en&as_sdt=0,5 https://scholar.google.com/scholar?start=10&q=sweden+vitamin...
  - SketchySeaBeast 7y ago
    The first two articles I get from that search looks at vitamin d and the older population, and the third[1] suggests that even in sub-arctic elevations "Adequate levels were found in 79.2%, more often in women (82.7%) than in men (75.6%). Only 0.7% of the population were vitamin D3–deficient but 23.1% of men and 17.1% of women had insufficient levels." That doesn't seem too damning. At the end of the day I don't know enough, so I'm not making the claim about Vitamin D quantities, but isn't the evidence that there was at least some form of adaptation evident based upon skin tone alone? https://www.tandfonline.com/doi/full/10.3402/ijch.v74.27963 https://www.tandfonline.com/doi/full/10.3402/ijch.v74.27963
    - nitrogen 7y ago
      I wonder, have any northern populations developed an instinctive winter hibernation adaptation?
    - abainbridge 7y ago
      I already agreed there was adaption. I just can't see how there can have been adaption for an _indoor_ life at northern latitudes. That's doubly hard, compared to a traditional life in northern latitudes, right? Although, to argue against myself, I guess if you go far enough north, people won't be getting any sunlight in the winter even if they are outdoors all the time. People there must have adapted to that. I guess by eating things with lots of vitamin D.
- therealcamino 7y ago
  I love the phrase "carpet decision". Although we don't have it in English, I'm guessing it's roughly equivalent to "blanket statement", something that applies in all cases without exception?
  - preben 7y ago
    Very much what I meant. Happy the meaning went through.
MatthiasP 7y ago
Do you have a source for that? Even at a lower angle you still get some UV B and energy from the sun.
dreamcompiler 7y ago
It doesn't work in the binary fashion you described. Low sun angles have two results: Cosine effect and greater atmospheric absorption. The cosine effect decreases the watts per square meter you receive, if your skin is not normal (90 degrees) to the incident sunlight. Greater atmospheric absorption means more UVB is absorbed by the atmosphere before it gets to you, but some still gets through, as anyone who has ever been sunburned in the winter can attest. Higher altitudes and snow on the ground both increase the amount of UVB you receive, even when the sun is low.

bproven 7y ago

Yep - I learned that a few years ago.

kaztal 7y ago

Sweden here. My partner is a doctor, she claims with assurance that you can't make a carpet decision like this. People who come from norther latitudes are used to the lack of sun, and their bodies don't need more vitamin D than is provided. Depending on your heritage, ymvm.

leto_ii 7y ago
It may still be worth taking a blood test, especially if you have some symptoms that match vitamin D deficiency.
v77 7y ago
Most people in North America are not from northern latitudes genetically unless we are talking about the UK and Germany and even then..
- orasis 7y ago
  Huh? Europe is generally populated further north than North America is.
BurningFrog 7y ago
Swedes need as much vitamin D as anyone, but usually get it from their diet. Herring is a vitamin D gold mine, for example :)
abainbridge 7y ago
That seems implausible. Obviously there was evolutionary pressure on northern Europeans to tolerate lower levels of sunlight and no doubt adaption happened. However, I expect even Swedes evolved in an environment that included more time outdoors than a modern Swedish office worker gets. So, in the absence of any actual evidence, I'd still expect a problem. On top of that, there is some evidence. Basically all the papers found by this search show some evidence of vitamin D deficiency in Swedish people: https://scholar.google.com/scholar?start=10&q=sweden+vitamin+d&hl=en&as_sdt=0,5 https://scholar.google.com/scholar?start=10&q=sweden+vitamin...
- SketchySeaBeast 7y ago
  The first two articles I get from that search looks at vitamin d and the older population, and the third[1] suggests that even in sub-arctic elevations "Adequate levels were found in 79.2%, more often in women (82.7%) than in men (75.6%). Only 0.7% of the population were vitamin D3–deficient but 23.1% of men and 17.1% of women had insufficient levels." That doesn't seem too damning. At the end of the day I don't know enough, so I'm not making the claim about Vitamin D quantities, but isn't the evidence that there was at least some form of adaptation evident based upon skin tone alone? https://www.tandfonline.com/doi/full/10.3402/ijch.v74.27963 https://www.tandfonline.com/doi/full/10.3402/ijch.v74.27963
  - nitrogen 7y ago
    I wonder, have any northern populations developed an instinctive winter hibernation adaptation?
  - abainbridge 7y ago
    I already agreed there was adaption. I just can't see how there can have been adaption for an _indoor_ life at northern latitudes. That's doubly hard, compared to a traditional life in northern latitudes, right? Although, to argue against myself, I guess if you go far enough north, people won't be getting any sunlight in the winter even if they are outdoors all the time. People there must have adapted to that. I guess by eating things with lots of vitamin D.
therealcamino 7y ago
I love the phrase "carpet decision". Although we don't have it in English, I'm guessing it's roughly equivalent to "blanket statement", something that applies in all cases without exception?
- preben 7y ago
  Very much what I meant. Happy the meaning went through.

MatthiasP 7y ago

Do you have a source for that? Even at a lower angle you still get some UV B and energy from the sun.

dreamcompiler 7y ago

It doesn't work in the binary fashion you described. Low sun angles have two results: Cosine effect and greater atmospheric absorption. The cosine effect decreases the watts per square meter you receive, if your skin is not normal (90 degrees) to the incident sunlight. Greater atmospheric absorption means more UVB is absorbed by the atmosphere before it gets to you, but some still gets through, as anyone who has ever been sunburned in the winter can attest. Higher altitudes and snow on the ground both increase the amount of UVB you receive, even when the sun is low.