I’VE HEARD SO MUCH ABOUT THE BENEFITS OF VITAMIN D, AND THAT THE BEST SOURCE FOR IT IS THE SUN. DOES THIS MEAN I SHOULD EXPOSE MYSELF TO THE SUN MORE?
SKIN SHORT: Don’t start basking yet. Skin cancer is the bigger threat and you can get adequate vitamin D from supplements.
MORE SKINFO: There has been lots of new research proving the benefits of vitamin D, from increasing bone density to protection against some cancers, diabetes, hypertension, myocardial infarction and even depression.
But this has to be balanced against the well-proven risks of sun exposure.
In addition, studies are showing that if vitamin D can do all that it seems it can, we need more of it than we can get from daily sun exposure and our regular diets.
The vitamin D debate is still raging strong but two things seem to have the majority agreeing:
1) sun exposure is not advisable (it won’t give you enough vitamin D; the risks far outweigh the benefits), and
2) taking a supplement while evidence is still being amassed is a good idea.
While it differs for each person, current recommendations hover in the 1,000 and 2,000 IU range (make sure to ask your doctor before increasing or taking new supplements).
Additional Details:
There is a need to balance the claims for vitamin D—for not just increasing bone density, but also for protection against some cancers (breast, colon), diabetes, hypertension, myocardial infarction, and even depression—versus the well-proven dangers of cancers and melanoma from sun exposure.
A review of current nutrition data strongly indicates that vitamin D sufficiency is needed not just for calcemic but also non-calcemic health at all stages of life. This review cites optimum serum levels of 25-hydroxy Vitamin D: 25(OH)D to be – approximately at – or higher than 30-50 ng/ml (75-125 nmol.L). These serum levels can be maintained by 500-1000 IU of vitamin D/ day (0.06 ng/ml/IU/day).
For darker skin, the MED in the summer noonday sun in the southern United States is about 60-80 minutes (75). From this it has been computed, and we can further extrapolate, that sun exposure to sub-erythemal doses (25% -50 % MED) of about 20%-40 % of the body surface would produce about 1000 IU Vitamin D.
However, compared to apparently normal Caucasian women of the same age on similar diets, in Boston, African-American women 20-40 years old were found to have half as much 25 (OH) D. In the summer/fall, this was a low 16.5±6.6, down to 12.1±7.9 ng/ml in winter/spring. It was therefore suggested that sunlight stimulates the skin to make vitamin D, but pigmented skin makes less. The same observation was made of Norwegians living at 600N, compared to Africans who despite living 100N had a high rate of vitamin D deficiency. Veiled women have also been found to be vitamin D deficient.
Therefore, children and adults with darker skin, even if living in the tropics, may need 1000 IU vitamin D daily supplementation to achieve the 30-50ng/ml blood levels. Consult your doctor for guidance.
REFERENCE: Verallo-Rowell VM. Chapter X: Photoprotection in Pearl Grimes, et al. Eds., Aesthetics and Cosmetic Surgery in Darker Racial Ethnic Groups, USA, Lippincott Williams & Wilkins, 2007
