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swiing t1_iwn0aul wrote

Do people in Northern Latitudes still produce Vitamin D in the winter? Is it proportional to the amount of UV * exposed skin or is there a minimal level of UV required to generate any Vitamin D?

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Indemnity4 t1_iwnqikv wrote

Anyone living north of the 37th parallel gets effectively zero vitamin D from sunlight during the winter months (e.g. north of Los Angeles in the USA).

The UV index needs to be > 3 to generate any vitamin D. During those northern months no amount of sun exposure will cross that threshold. Basically, if you need to wear sunscreen, the UV index is high enough to make vitamin D.

The time exposure between min UV and max UV is minor. 5 minutes at the sunniest day and 15 minutes at the dimmest day. After that it falls off a cliff and no amount of sun will help.

Instead, you are rely on stores your body built during the summer months.

There are some limited dietary sources. Fatty fish such as salmon or tuna, eggs, mushrooms or fortified foods.

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swiing t1_iwo1hzq wrote

Thanks Indemnity4. Sounds like I need to head south for the winter.

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