The promises and pitfalls of vitamin D deserve more research, according to the American Cancer Society (ACS) and 7 other health groups. The US and Canadian groups issued a statement of findings this week from the first North American conference on vitamin D, a nutrient most people get though exposure to sunlight.

The conference, held in March, brought together experts in nutrition, sun exposure, skin cancer, and other diseases to discuss what is and isn't known about vitamin D and its effect on human health.

The consensus: There is still much to learn about how much vitamin D people need for good health, how much might be too much, and -- perhaps most importantly -- the best way to get enough.

"There is no dispute among medical professionals that vitamin D is beneficial for our health, and there is no dispute that sun exposure is the major source of vitamin D for most of us," said ACS deputy chief medical officer Len Lichtenfeld, MD, who participated in the conference.

"But there is also no dispute that exposure to ultraviolet (UV) rays from the sun and other sources can be harmful."