Vitamin D is an important hormone in the prevention of osteoporosis and rickets — but beyond that, has major functions in the prevention of heart disease, cancers, diabetes and regulating the immune system. Foods naturally rich in vitamin D are all from animal sources: cod liver oil, finfish and shellfish. The only naturally occurring plant sources of vitamin D are certain mushrooms, in which it is present in only small amounts. Therefore, there has been concern that vegetarians would have lower blood levels of vitamin D than non-vegetarians.

AHS-2 looked at the vitamin D status of vegetarians, partial vegetarians and non-vegetarians. The results demonstrated that a vegetarian diet was not associated with lower levels of vitamin D. Other factors — such as vitamin D supplementation, degree of skin pigmentation and sun exposure — had a greater influence on vitamin D levels than diet.

Skin Pigmentation and Vitamin D

Of the factors mentioned above, degree of skin pigmentation caused the greatest difference in vitamin D concentrations. Regardless of dietary preferences, the percentage of subjects with deficiencies was much higher among black participants (75.4%) than whites (47.5%), even when other areas (such as vitamin D intake and sun exposure) were equal.

Our researchers cited this reason: When exposed to sufficiently strong sunshine, lighter skin can produce higher amounts of vitamin D in a shorter period of time. Despite lower vitamin D levels, black participants generally had good bone health. Whether lower vitamin D levels affect other aspects of their health is not yet clear.