(CBS) Could popping a daily vitamin D pill help prevent cancer?
It's too early to say for sure, but a new study adds to the growing body of evidence linking a deficiency of the "sunshine vitamin" to colorectal cancer as well as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis.
That's big news, as up to a billion people around the world are believed to have a vitamin D deficiency - including up half of adults and children in the U.S.
The study, conducted by a team of English and Canadian scientists, revealed a detailed "map" of the molecular interactions between vitamin D and certain genes. The map showed extensive connections between the vitamin and certain genes associated with cancer and autoimmune diseases.
"Genes involved in autoimmune disease and cancer were regulated by vitamin D," study author Dr. Sreeram Ramagopalan of Oxford University told WebMD.
The skin makes vitamin D upon exposure to sunlight. In addition, the vitamin is found in many foods, including oily fish like salmon and milk and other foods that have been fortified with the nutrient.
Current guidelines call for 200 international units (IU) for people up to age 50, 400 IU for people 51 to 70, and 600 IU for people over 70, according to WebMD. But many experts say those doses are too low.
Ramagopalan says 2,000 IU may be more like it, though some experts warn against jumping the gun.
"We will soon have a better understanding of the optimal doses of vitamin D and the optimal blood levels associated with the best balance of benefits and risks," Dr. JoAnn Manson, chairman of the preventive medicine department at Harvard University, told WebMD. "But right now there are too many unanswered questions."