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> Unless you live in a northern hemisphere and have darker skin. Why is this a problem for darker skinned people living in northern hemisphere? Their bodies do
by victor106 6y ago
> Unless you live in a northern hemisphere and have darker skin.
Why is this a problem for darker skinned people living in northern hemisphere? Their bodies dont make enough vitamin D even after exposure to the sun?
- amanaplanacanal 6y agoDarker complexion mean you need to stay out much longer to get the vitamin D you need. This is why humans lost their natural pigmentation when they migrated to Europe and Asia.
- ks6g10 6y agoYes, people with darker skin is at higher risk of vitamin D deficiency in northern territories. "Vitamin D synthesis is highly dependent on the concentration of melanin in the skin as melanin absorbs and scatters UVR-B, resulting in a less efficient conversion of 7-dehydrocholesterol to previtamin D3[3]. Therefore, dark-skinned individuals will experience slower vitamin D synthesis than light-skinned ones. " https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4067096/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4067096/
- Delk 6y agoNot really "northern hemisphere", but rather northern (and, at least in theory, southern) enough latitudes. The amount UV-B exposure needed for vitamin D synthesis depends on the season and the latitude, as well as probably cloud cover etc. Anecdotal article I found about latitude vs. UV-B exposure: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5037520/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5037520/ I live at ~60° of northern latitude, and AFAIK people around here commonly don't get enough UV-B exposure for sufficient vitamin D synthesis for half of the year or so, so you need to get it either from nutrition or supplements.