High levels of vitamin D are linked with a lower risk of colon cancer, according to a comparison of more than half a million Europeans, published online Friday by the British Medical Journal (BMJ).
Patients with the highest levels of vitamin D in their blood had a nearly 40 percent lower risk of colorectal cancer compared to those with the lowest levels.
Vitamin D, derived mainly from sunlight but also found in foods, plays a key role in bone strength by increasing levels of calcium in the blood.
Whether it affects incidence of cancer has been hotly debated and the evidence is sketchy.
The paper draws on a very large study, the European Prospective Investigation into Cancer (EPIC) project, carried out in 10 Western European countries.
The authors sound a note of caution, saying it is unclear whether vitamin D supplements are any more effective than a balanced diet or getting regular exposure to sunlight.
Further work is needed, they add, to show whether the statistical link in this investigation is born out - and whether there could be any side effects from taking supplements or eating food fortified with vitamin D.
Smoking, obesity, a sedentary lifestyle, alcohol and eating red and processed meats have previously been established as factors in cancer of the colon and rectum.