In a presentation at the annual meeting of the American Association for the Advancement of Science (AAAS), Dr. Michael Holick of Boston University Medical School reported on the mechanism by which natural sunlight may trigger the body's production of vitamin D.

Studies have shown that vitamin D not only helps keep bones strong, but it also activates certain genes that regulate cell growth, thus helping to prevent the uncontrolled cell division that is a hallmark of cancer.

For example, research by Gary Posner, Ph.D. and colleagues at Johns Hopkins University in Baltimore found that a chemically modified version of vitamin D showed promise as a skin cancer preventive and could someday become part of the arsenal in the fight against many types of cancer.

Posner's team created a modified version of vitamin D that they called QW1624F2-2. In tests with laboratory mice of the modified vitamin, they noticed a 28 percent reduction the incidents of new skin cancer tumors and a 63 percent lower number of overall tumors. It appeared that the modified vitamin D acted to delay tumor formation and minimize tumor multiplication without compromising the health of the animals.

In his presentation at the AAAS convention, Holick noted that sunlight is a more effective way for a person to get vitamin D than taking supplements. Furthermore, he added, vitamin D from sunlight lasts longer in the body. Also, vitamin D is fat soluble; if a person stores enough of it from sunlight during the warmer months, the body can use its stores of the nutrient during winter.

While he cautioned that too much sun exposure increases the risk of skin cancer, Holick said that 5 to 10 minutes of sunlight exposure 2 to 3 times a week is all that a Caucasian needs to build a sufficient store of vitamin D. African Americans and people with darker skin may require 10 to 20 times this amount of exposure because their skin allows less UV-B radiation to penetrate, he said.

Holick told the attendees that vitamin D deficiency is a major unrecognized epidemic, with up to half the adult population over age 50 consuming insufficient amounts of the vitamin. He also suggested that some people who appear to have fibromyalgia, a condition marked by chronic muscle and joint pain, may in fact have vitamin D deficiency.

SOURCE:
Annual meeting of the American Association for the Advancement of Science, February 15, 2002, Boston, Massachusetts