BACKGROUND: Cancer is the second-leading cause of death in the United States behind heart disease. One in four men will die from the disease as will one in five women. There are many things linked to increased cancer risk including smoking, obesity and other environmental factors. One emerging area of cancer research is the role of vitamin D, which has recently shown to be a powerful player in many aspects of health.

THE POWER OF VITAMIN D: Recent research shows up to 50 percent of children and adults in the United States are at high risk for vitamin D deficiency. Low levels of vitamin D have been linked to autoimmune diseases like type 1 diabetes, infectious diseases and heart disease. Donald L. Trump, M.D., and CEO of Roswell Park Cancer Institute in Buffalo, NY, says, "Vitamin D appears to have effects that are expressed in a number of tissues, nerves, muscles, the immune system, the clotting system. Many areas of health may be impaired if vitamin D deficiency exists."

Cancer is also affected by vitamin D levels. Dr. Trump, who has been treating prostate cancer for 32 years, says 70 percent of his patients with prostate cancer are vitamin D deficient. Likewise, people who have higher levels of vitamin D seem to be more protected against cancer. Dr. Trump says, "Those individuals in the highest quartile of estimated vitamin D levels had substantially reduced risk of developing a number of cancers [including] colorectal cancer, head and neck cancer, GI cancer [and] prostate cancer."

THE RESEARCH: Many studies have been done on the effect of vitamin D and cancer and many are still ongoing. In one recent study published in the American Journal of Clinical Nutrition in June, 2007, researchers found a daily supplement containing 1,000 international units of vitamin D led to a 60-percent reduced cancer risk among postmenopausal women. Another study reported at the American Association for Cancer Research conference in 2005 shows people with lung cancer who had high levels of vitamin D and surgery to remove their lung cancer in the summertime fared better than those with low levels of vitamin D and wintertime surgeries. (Since you can get it from sunlight, vitamin D is also called the "sunshine vitamin.") Specifically, 72 percent of the lung cancer patients in the high vitamin D level/summer surgery group had a five-year survival versus just 29 percent of patients in the low vitamin D level/winter surgery group. And yet another study shows high vitamin D levels reduces the risk of colon, breast and prostate cancer by up to 50 percent.

WHAT NEXT? Dr. Trump says vitamin D may become a useful tool to extend survival in patients already diagnosed with cancer. He also believes the current recommended daily allowance of vitamin D may be too low at 400 iu/day. He and many other researchers expect that the RDA for vitamin D will be increased in the future. He says, "There are studies that have been done that show that substantially higher doses of vitamin D are quite safe." But, he warns, there is a cutoff point where too much vitamin D becomes dangerous. More research is needed to determine the optimum level.