A new study has revealed that people with high levels of vitamin D in their bloodstream have a lower overall risk of developing colorectal cancer.

The research by Dana-Farber Cancer Institute investigators, which represents the first time that a link between vitamin D and the immune response to cancer has been shown in a large human population, that vitamin D, known as the "sunshine vitamin" because it is produced by the body in response to sunlight exposure, plays a key role in cancer prevention.

Senior author Shuji Ogino said that laboratory research suggests that vitamin D boosts immune system function by activating T cells that recognize and attack cancer cells.

Researchers theorized that if the two phenomena were connected, then people with high levels of vitamin D would be less likely to develop colorectal tumors that are permeated with large numbers of immune system cells and colorectal tumors that do develop in these individuals would, by the same logic, be more resistant to the immune response.

Ogino added that this is the first study to show evidence of the effect of vitamin D on anti-cancer immune function in actual patients, and vindicates basic laboratory discoveries that vitamin D can interact with the immune system to raise the body's defenses against cancer.

Ogino concluded that in the future, they may be able to predict how increasing an individual's vitamin D intake and immune function can reduce his or her risk of colorectal cancer.

The study is published by the journal Gut.