Narrator:       This is Science Today. There's been a lot of research lately on the role of vitamin D in fighting cancer. Cedric Garland, a cancer prevention specialist at the University of California, San Diego's Moores Cancer Center, led a recent study that estimated that 600 thousand cases a year of breast and colorectal cancer could be prevented by adequate intake of vitamin D. This can be accomplished by diet, supplementation and getting enough sunlight. But how can one know if they have enough vitamin D in their bloodstream?

Garland:         It's actually quite wise for physicians to order that test for their patients once a year. Preferably in March when the vitamin D is typically lowest of all times of year and if it isn't up to 60 nanograms per mil, that is an indication of the need for supplementation and it's at that level in less than five percent of the population now.

Narrator:       Garland adds that patients who are genetically predisposed to breast or colorectal cancer may not be able to metabolize vitamin D in a way that allows it to be effective. So, they may be good candidates for taking vitamin D under physician supervision. For Science Today, I'm Larissa Branin.