African-American women had lower vitamin D levels than white women, and vitamin D deficiency was associated with a greater likelihood for aggressive breast cancer, according to data presented at the Third AACR Conference on the Science of Cancer Health Disparities. "We know that darker skin pigmentation acts somewhat as a block to producing vitamin D when exposed to sunlight, which is the primary source of vitamin D in most people," said Susan Steck, Ph,x factor supplement.D., M.P.H., associate professor of epidemiology at the University of South Carolina. Steck and colleagues observed 107 women who were all diagnosed with breast cancer in the previous five years. Sixty of these women were African-American, while the remaining 47 were white. All women donated a blood sample,...