New York: Vitamin D that is produced by skin exposed to sunlight can protect people from heart diseases and keep bones strong, according to a five-year study in the US though this runs contrary to the understood risk of skin cancer by over-exposure to sunlight.

A major chunk of the body's requirement of the vitamin is generated from exposure to ultraviolet rays of the sun, which stimulates its production by the skin, while the rest comes from food items such as fish, eggs and fortified milk and breakfast cereal.

"Our data raise the possibility that treating vitamin D deficiency, via supplementation or lifestyle measures, could reduce cardiovascular risk," said Thomas Wang who led the research.

The mechanism by which vitamin D reduces cardiovascular risks is only partially understood, but the vitamin has been shown to slow the rate of growth of cancer cells and may boost the function of blood vessels or the immune system, reported the online edition of the Daily Mail.

"Sunlight stimulates the body to produce vitamin D, which has been proven to offer protection from some cancers, osteoporosis, rickets and diabetes," Johan Moan, lead researcher of the study, said.

Another study by scientists at the US Department of Energy's Brookhaven National Laboratory and colleagues at Norway's Institute for Cancer Research in Oslo suggests that sunshine might also help people live longer.

"However, as diet cannot provide enough vitamin D and the need for each of us to expose our skin to sunlight for short periods of time to make it (vitamin D) runs contrary to the advice of avoiding over exposure to sunlight which is said to trigger skin cancer," a spokesman for the Health Supplements Information Service said.

People have become frightened of getting skin cancer and they are avoiding exposure to sunlight but that exposure also offers one of the best sources of vitamin D, which protects the body from a number of diseases, the study concluded. IANS