High levels of vitamin D in the blood appear to be linked to lower risks of  colorectal cancer, although it’s not clear if higher intake of the vitamin actually prevents the disease, researchers say.

Still, the findings are food for thought: Scientists found that those with the highest levels of vitamin D in their blood had as much as a 40 percent lower risk for developing colorectal cancer than those with the lowest levels.

The research, published online Jan. 21 in BMJ, is based on a study of more than 520,000 people from 10 countries in Western Europe. The study participants gave blood samples and filled out diet and lifestyle questionnaires between 1992 and 1998. They were then tracked for several more years to see what happened to them.

During the follow-up period, 1,248 were diagnosed with colorectal cancer. These participants were compared with a similar group of 1,248 people who were not diagnosed with the disease.

The researchers cautioned that it’s not clear if there are risks from consuming high levels of vitamin D, which is available in supplements. It’s also not known whether supplements are necessary if people reach certain levels through a healthy diet, exercise and moderate exposure to sunlight.

The study authors noted that current recommendations for preventing colorectal cancer include exercising, not smoking, reducing obesity and abdominal fat, and limiting consumption of alcohol and red and processed meats.