BOSTON, MASSACHUSETTS. The intense publicity associating unprotected exposure to the sun with an increased risk of skin cancer has resulted in vitamin D deficiency becoming endemic in adults over the age of 50 years. Humans meet by far the majority of their vitamin D needs by exposure to the sun. Covering up or excessive use of sunscreens results in a deficiency. Danish doctors recently reported that Arab women and other ethnic Danish Moslems were vitamin D deficient even though their daily estimated vitamin D intake from dietary sources was about 600 IU. Native Danish women who do not cover up were not vitamin D deficient even though their dietary intake was only 300 IU/day. The doctors also observed that while none of the native Danes suffered from muscle cramps 72 per cent of Arab women did.
Other researchers have linked a vitamin D deficiency to an increased risk of
dying from breast, colon, prostate, and ovarian cancers. Dr. Michael Holick of
the Boston University School of Medicine is convinced that "The fear of vitamin
D intoxication that swept Europe in the 1950s and resulted in laws forbidding
fortification of milk and other products is antiquated". He recommends wider
use of vitamin D fortification, but emphasizes that the optimum way of getting
vitamin D is through exposure to sunlight. In the spring, summer, and autumn
(in Boston) unprotected exposure of hands, arms, and face two to three times a
week for 5 to 15 minutes is probably adequate. Sunbathing in a bathing suit can
generate 10,000 IU of vitamin D or more within a relatively short time period.
Dr. Holick points out that it is impossible to get too much vitamin D by
sunbathing. Nursing home residents and other house-bound individuals can keep
their vitamin D status up to par by monthly injections of 50,000 IU.