Vitamin D deficiency has been linked to 26 percent greater risk of death in men and women, according to a study published Monday that appears to confirm the importance of this essential nutrient.
Researchers from the Johns Hopkins University School of Medicine, in Baltimore, Maryland, studied 13,000 initially healthy men and women from 1994 to 2000, comparing the mortality rate between those with low and normal levels of vitamin D in the blood.
They found that of the 1,800 people who died by December 31, 2000 -- 700 from cardiovascular diseases -- 400 were deficient in vitamin D, which translated to a 26 percent increased risk of death.
The number of heart disease-related deaths was insufficient to establish a cause-and-effect link to vitamin D deficiency, the researchers said in the study published in the latest issue of the Archives of Internal Medicine.
However, the study "does highlight a trend, with other studies linking shortages of vitamin D to increased rates of breast cancer and depression in the elderly," the researchers said.
Earlier research conducted by the same Johns Hopkins team found an 80 percent increased risk of peripheral artery disease from vitamin D deficits.
The researchers noted that other 2007 studies on animals and humans also found a link between low vitamin D levels and cardiovascular diseases, but that due to small sample numbers and other factors, the findings could not be generalized to the public at large.
"Our results make it much more clear that all men and women concerned about their overall health should more closely monitor their blood levels of vitamin D, and make sure they have enough," says study co-lead investigator Erin Michos.
An Austrian study of 3,258 patients published in June in the Journal of the American Medical Association also found people with low vitamin D levels had twice the mortality rate of those with higher levels.
The reason low vitamin D levels lead to higher mortality rates, however, has yet to be determined.
Chiefly produced by exposure to the sun, vitamin D plays a vital role in the immune system, and according to Archives 50 percent of adults aged 50 and older are vitamin D deficient, as well as a significant number of younger adults.
Lack of outdoor exercise and activities, pollution and aging are cited as possible reasons for vitamin D deficiency.
Doctors recommend a 10-15-minute daily exposure to the sun for adequate levels of vitamin D, which can also be obtained from fatty fishes.
The US Institute of Medicine suggests that an adequate daily intake of vitamin D is between 200 and 400 international units.