Vitamin D may protect against certain types of cancer, such as liver cancer, according to a new study by Japanese researchers published in the February issue of the British Medical Journal.

“We believe that vitamin D has a beneficial effect, perhaps small, in many types of cancer,” says co-author Taiki Yamaji of the National Cancer Center in Tokyo.

The researchers examined medical records of a group of 34,000 volunteers, men and women between the ages of 40 and 69, and concluded that higher levels of vitamin D were associated with a relatively lower risk (30 to 50%) of liver cancer. The volunteers were followed for an average of 16 years. During this time, 3,301 of them developed cancer.

Vitamin D helps maintain calcium levels in the body, which contributes to good bone, tooth and muscle health, but it can also have other beneficial effects.

The human body produces vitamin D after exposure to sunlight. Vitamin D can also be taken from fatty or oily fish, red meat, liver and egg yolk.

Previous studies have shown that low levels of vitamin D are a risk factor for various types of cancer and high levels of vitamin D may help protect against the disease.

Blood samples were taken from the participants and the level of 25-hydroxyvitamin D, which is the circulating form of vitamin D, was analyzed.

During the 16-year period of the study, 3,301 new cases of cancer were identified among the study participants. It was observed that they had the lowest levels of vitamin D, compared to other participants.

After statistically eliminating other oncological risk factors, such as age, weight, smoking, etc., the researchers realized that a higher level of vitamin D is associated with a 20% lower relative risk of cancer, in both women and men. They also warned that there may be a ceiling effect, meaning that above a certain level of vitamin D in the body, additional beneficial effects will no longer be recorded.