Vitamins play important roles in keeping our bodies healthy. As Rose Hoban reports, in the past few years, researchers have been learning more about some vitamins, discovering that they have more complex roles in human health than previously understood.
Scientists know that Vitamin D is essential to the development and maintenance of healthy bones. But Dr. Thomas Wang from Harvard University says there's a lot more to the Vitamin D story.
"There is a growing body of experimental and biological literature suggesting that vitamin D might actually have an important role in the cardiovascular system," he says.
He explains that scientists have discovered receptor cells for vitamin D in the heart, and in the major blood vessels. And experimental studies in animals have suggested that deficiency of vitamin D can be associated with the development of abnormalities in both heart and vascular function.
Wang was able to use data from the Framingham Heart Study, a large trial that's followed thousands of people for close to six decades to look at the health of their heart and circulatory system.
He says about 1700 people in the study were assessed for their levels of Vitamin D in the mid-1990s. Then researchers followed these people to see what happened to their cardiovascular systems.
"Individuals in our sample, who had lower levels of vitamin D appeared to have a higher risk of developing a cardiovascular event including heart attack or stroke," Wang reports. "The magnitude of this risk was about 60 percent, so that individuals with lower vitamin D levels had about a 60 percent excess risk of having a cardiovascular event compared with individuals who have higher vitamin D levels."
Wang says the effect was even more profound for people who also had high blood pressure. They were twice as likely of having a heart attack or stroke if they were deficient in Vitamin D.
People can get Vitamin D in two ways. One is by eating Vitamin D rich foods, such as milk and oily fish. The other is by exposure to sunlight.
But Wang says a surprisingly high number of people are deficient in the nutrient. He says many factors may contribute to that. They include exposure to sunlight, which can change with where you live. And he says people tend to make Vitamin D less efficiently as they age. For example, drinking two glasses of milk provides enough Vitamin D for an adult. But people over 50 years of age need to drink almost 4 glasses of milk for the same benefit.
Wang says skin color can be a factor in Vitamin D production too. He notes, "African-Americans have a higher prevalence of vitamin D deficiency because their skin has less efficient conversion of the inactive, to active forms of vitamin D at the level of the skin."
He explains that's why different populations, even within the same geographical location may have different rates of vitamin D deficiency.
Wang and his colleagues published their research in Circulation: Journal of the American Heart Association.