While it is wise to avoid burning [Kennedy et al., 2003] or excess tanning from solar or indoor ultraviolet radiation (UVR), it should be realized that solar UVB radiation (290-315 nm) is the primary source of vitamin D for most Americans and Europeans. Dietary sources are inadequate and supplements have to be used carefully.

Mid-day summer sun is the best source of UVB, since minimal exposure times are required, and the UVB to UVA (315-400 nm) ratio is highest. If using sunscreen, it might be advisable to go into the sun for 10-15 minutes without sunscreen to generate a day's worth of vitamin D.

As for melanoma and other skin cancer, several points should be made. First, while UVR generates free radicals that can do some of the damage, dietary antioxidants and skin pigmentation are nature's way of fighting free radicals. A recent paper by Millen et al. [2004] reported that diets high in antioxidants and low in fats and alcohol can reduce the risk of melanoma by about 50%. Smoking is also a risk factor for non-melanoma skin cancer. Second, occupational exposure to UVR is associated with reduced risk of melanoma [Kennedy et al., 2003].

The health benefits of UVB through production of vitamin D are considerable, with more benefits being recognized at a rapid pace. My work indicates that over 20,000 Americans die prematurely annually from insufficient UVB/vitamin D [Grant, 2002]. I also estimate that half of those with multiple sclerosis in the U.S. would not have MS if they had as much UVB exposure as those living in the southern states.

For more information on the health benefits of UVB, please visit, http://www.sunarc.org.


Grant WB. An estimate of premature cancer mortality in the United States due to inadequate doses of solar ultraviolet-B radiation, Cancer. 2002;94:1867-75.

http://www3.interscience.wiley.com/cgi-bin/abstract/91016211/START (30 ISI citations) (note - this puts the paper in the top 1 percentile of clinical medicine papers published in 2002; threshold = 26 on May 1, 2004) http://www.in-cites.com/thresholds-highly-cited.html

Kennedy C, Bajdik CD, Willemze R, De Gruijl FR, Bouwes Bavinck JN; Leiden Skin Cancer Study. The influence of painful sunburns and lifetime sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic nevi, atypical nevi, and skin cancer. J Invest Dermatol. 2003 Jun;120(6):1087-93.

Millen AE, Tucker MA, Hartge P, Halpern A, Elder DE, Guerry D 4th, Holly EA, Sagebiel RW, Potischman N. Diet and melanoma in a case-control study. Cancer Epidemiol Biomarkers Prev. 2004 Jun;13(6):1042-51.

By William B. Grant Ph.D.