People who have higher levels of vitamin D in their blood are at less risk of contracting colorectal cancer. This has become evident from a large European study, the results of which will be published this month (January, 2010) in the British Medical Journal. Epidemiologist Dr. Bas Bueno-de-Mesquita, who is affiliated to the University Medical Center (UMC) Utrecht and the National Institute for Public Health and the Environment (RIVM), is one of the leading researchers of this study.
The study participants were included in a large European study into cancer and nutrition known as the EPIC study. Between 1992 and 1998, blood samples were taken from the participants entering the study who were then followed for a period of between four and eleven years. During that time, 1 248 people contracted some kind of colorectal cancer. The researchers measured the concentration of vitamin D in the blood of these patients and in that of 1 248 control subjects. Based on the results of the blood samples, the participants were then placed in five groups. People with the highest levels of vitamin D in their blood appeared to be forty percent less likely to develop colorectal cancer at a later stage than those people with the lowest concentrations.
“Based on these results we cannot, however, conclude that extra vitamin D that is added to a person’s diet or taken as a supplement can prevent colorectal cancer”, says Bueno-de-Mesquita. “This could only be determined by conducting a clinical trial. Therefore, advice regarding the prevention of colorectal cancer remains the same: stop smoking, exercise more, reduce your waist size, and limit your intake of alcohol and red meat.
Indications that vitamin D protects people against colorectal cancer have existed for some time but originate mainly from the United States. This study is the first time that the effect has been confirmed in Europe, in population groups that differ from each other and from those in America regarding both diet and lifestyle. It is not clear exactly how vitamin D reduces the risk of colorectal cancer although it is thought to be connected to calcium metabolism. A higher intake of calcium may also reduce the risk of colorectal cancer. Vitamin D is mainly acquired by the body through its production in the skin upon exposure to sunlight, but the vitamin is also contained in certain foodstuffs such as fatty fish.
In the EPIC study, which stands for: European Prospective Investigation into Cancer and Nutrition, researchers have been following more than half a million West Europeans. The EPIC results contain data from Denmark, France, Greece, Germany, Italy, the Netherlands, Norway, Spain, Sweden and Great Britain. Taking part on behalf of the Netherlands are UMC Utrecht and the RIVM.
Epidemiologist Dr. Bas Bueno-de-Mesquita is the second author of the article published in the BMJ. He is leading the RIVM’s contribution to the EPIC study and is also affiliated to the Department of Gastroenterology and Hepatology at UMC Utrecht. There he is conducting epidemiolgical research into the prevention of cancer in the gastrointestinal canal, together with gastroenterologist Professor Peter Siersema.