Twenty-five years ago, Dr. Cedric Garland and his brother, Frank, proposed that many cases of cancer were caused by lack of vitamin D. The medical community treated these respected epidemiologists as if they were nuts. Vitamin D was discovered in 1922 as the vitamin that prevents and treats rickets, a disease that causes children and adults to have such weak bones that they bend.

The Garland brothers showed that people who live in the northern parts of the United States have more than three times as many colon cancer deaths as those who live in the South. They explained that very few Americans meet their needs for vitamin D from the food, so we have to meet our needs for vitamin D from sunlight. Sunlight is less intense in the northern latitudes, and people in the colder climates often do not go out in the winter; therefore, they often suffer from lack of vitamin D.

Forty-two percent of African American women have low blood levels of vitamin D, compared to only 4.2 percent in Caucasians. That means that African Americans are ten times more likely to suffer from vitamin D deficiency than Caucasians. Lack of vitamin D interferes with immunity and a person's ability to kill germs and cancer cells. Every day, the human body makes millions of cancer cells. Your immunity then filters out these cells and prevents them from growing. When immunity is impaired, the cancer cells can grow to form solid cancers, such as cancer of the breast, prostate or colon.

All men will develop prostate cancer if they live long enough, but the average Caucasian develops prostate cancer after age 85, while the average African American develops it many years earlier. People of color require far more ultraviolet light to make vitamin D than those who have lighter skins. Lack of vitamin D damages immunity to cause cancers, diabetes and infections.

My advice is for you to think about your vitamin D status. A person with light skin can get enough vitamin D from a few minutes spent in sunlight each day, but the darker your skin, the more sun exposure you need to meet your daily requirements. During the winter months in northern latitudes, even light-skinned people will have difficulty meeting their needs from sunlight. You can get vitamin D from vitamin supplements, fish oils, fish or fortified cereals. (Fortified milk is not a good source because calcium uses up vitamin D.) If you are not sure if you are getting enough vitamin D from food or sunlight, go to your doctor and request a blood test for vitamin D. If your blood level of vitamin D is below 15 micrograms/liter, you should take 400 international units or 5 micrograms of vitamin D each day. I am convinced that you will be protecting yourself from cancer and infections. Women will also be protecting their future babies from infections and possibly birth defects. Don't wait for the medical community to agree on this.

Gabe Mirkin, M.D.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.