Good dietary sources of vitamin D include salmon and other oily fish, eggs, fortified milk and cereals, orange juice, and vitamin supplements. “Many multivitamins contain D2, which is poorly absorbed,” said Dr. Spencer, past cochairman of the National Council on Skin Cancer Prevention. “Look for those that contain vitamin D3.”
Dr. Holick maintains that it is “next to impossible” to get enough vitamin D from diet alone; some exposure to sunlight must play into the mix. “If you were to go outside in a bathing suit on the beach in the summertime and get a light pinkness to your skin, a minimal erythemal dose—which is 15–20 minutes for a white person—that's equivalent to ingesting 10,000–20,000 IU of vitamin D.”
While it's known how much vitamin D is needed to prevent deficiency and bone disease, Dr. Spencer said, “We do not know what level of vitamin D may be optimal for health maintenance. Therefore, we keep an open mind to future research.”
As for Dr. Holick, he points to a position statement on sun exposure issued in 2006 by groups that included the Australian College of Dermatologists and Cancer Council Australia, which support his view (www.cancer.org.au
The importance of obtaining vitamin D is not in dispute; it is how it is obtained that is, according to Dr. James M. Spencer. Courtesy Dr. James M. Spencer