High Vitamin D Levels Linked to Lower Risk of Colon Cancer
Many European studies have found a link between vitamin D and decreased risk of colon cancer, however most have been inconclusive with limited information. However, a new, larger study of over 520,000 people from 10 Western European countries has confirmed the link, finding that the risk of colon cancer was cut by as much as 40% in those with the highest vitamin D levels.
Between 1992 and 1998, participants in the European Prospective Investigation into Cancer Study (EPIC) completed detailed diet and lifestyle questionnaires and had blood samples collected. The subjects were then followed for several years. Those with vitamin D blood level concentrations of between 50-75 nmol/l had the lowest incident of colorectal cancer.
Researchers do not know if achieving higher vitamin D levels for cancer protection is best obtained from diet, regular and moderate exposure to outdoor sunlight, or nutritional supplements, although a 1996 study from Harvard University stressed the importance of supplemental vitamin D.
Colorectal cancer is the second most common form of cancer in the United States. About 150,000 are diagnosed each year. African-Americans have a higher incidence and mortality than non-blacks. Vitamin D deficiency is also more common among the black population.
Vitamin D may help the body get rid of its own toxic digestive acid. The consumption of red meat and animal fat causes the production of lithocholic acid. Colon cancer patients have been found to have high concentrations of lithocholic acid. Vitamin D can attach to a receptor and switch on a detoxifying gene.
Scientists first linked the importance of adequate blood levels of vitamin D in preventing colon cancer more than 20 years ago. In 1980, two researchers from Johns Hopkins University discovered that colon cancer was significantly less likely in those who lived in sunny areas. About 90% of the average persons’ vitamin D comes from the sun. In 2002, researchers at St. Luke’s-Roosevelt in New York found that those with higher levels of blood calcidiol, the activated form of vitamin D, had fewer precancerous cellular changes in the colon.
According to the National Institutes of Health’s Office of Dietary Supplements, adults should get 400 IU of vitamin D each day. The upper tolerable limit is 2000 IU a day, as too much vitamin D causes calcium to leach out from the bones and into the blood stream. Foods rich in vitamin D include dairy foods and oily fish.
Overall, the best recommendation to reduce the risk of colorectal cancer is to stop smoking, increase physical activity, reduce obesity, increase fiber intake, and limit intake of alcohol and high fat, red and processed meats.