TUESDAY June 10, 2008 (foodconsumer.org) -- Taking vitamin D supplements or getting enough exposure to sunlight may help reduce risk of myocardial infarction (heart attack), according to a new study in the June 9 issue of Archives of Internal Medicine.

Studies have showed the rate of cardiovascular disease-related death is higher in regions located at higher latitudes and during the winter time and lower at high altitudes, according to the background information in the study report.

Exposure to sunlight triggers biosynthesis of vitamin D in the body.   This means that vitamin D in the body may probably affect the risk of cardiovascular disease.

“This pattern is consistent with an adverse effect of hypovitaminosis D, which is more prevalent at higher latitudes, during the winter and at lower altitudes,” the authors write.   Hypovitaminosis D is also known as vitamin deficiency.

The association between the risk of death from cardiovascular disease and exposure to sunlight is not a causal relationship though. Still, the possibility can’t be excluded that vitamin D may play a role in cardiovascular health.

In the study, Edward Giovannucci, M.D., Sc.D., of Harvard School of Public Health and Brigham and Women’s Hospital, Boston, and colleagues compared 454 men age 40 to 75 who had non-fatal heart attack or fatal heart disease during the follow-up period with 900 men who did not have a history cardiovascular disease.

Blood samples were collected for measurement of 25-Hydroxyvitamin D between January 1993 and December 1995 and even since subjects were followed until January 2004.   The men's diet and lifestyle factors were also surveyed through self-administered questionnaires.

After adjusting the matched variables, the risk for heart attack among men deficient of vitamin D or having 15 nanograms per milliliter of blood or less was found 2.42 times higher than those with a sufficient amount (having 30 nanograms per milliliter of blood or more of vitamin D).

“After additional adjustment for family history of myocardial infarction, body mass index, alcohol consumption, physical activity, history of diabetes mellitus and hypertension, ethnicity, region, marine omega 3 intake, low- and high-density lipoprotein cholesterol levels and triglyceride levels, this relationship remained significant,” the authors write.

Specifically, after additional adjustment, the relative risk for men with a vitamin D deficiency was 1.6 times higher than that for those with a sufficient amount.

Giovannucci said, cited by Reuters, vitamin D may protect against heart attack by affecting e risk factors for cardiovascular disease such as lowering blood pressure, regulating inflammation, reducing calcification of coronary arteries, affecting the heart muscle or reduce respiratory infections in winter.

Vitamin D, commonly known for its role in bone health, has recently been found to have a strong protective effect against a number of cancers such as breast cancer.   Deficiency of this vitamin has been linked to higher risk of autoimmune disease and hypertension.

“Vitamin D deficiency has been related to an increasing number of conditions and to total mortality. These results further support an important role for vitamin D in myocardial infarction (heart attack) risk,” the authors conclude.

“Thus, the present findings add further support that the current dietary requirements of vitamin D need to be increased to have an effect on circulating 25(OH)D [vitamin D] levels substantially large enough for potential health benefits.”

The current recommended daily allowance for vitamin D is 200 IU per day for people age under 50.   Research has found that healthy people can tolerate intake of up to 10,000 IU per day. Vitamin D experts have already suggested that the current RDA is too low to have a protective effect and recommended that the RDA should be increased to 1,000 IU.

 Sunshine is the major source of the vitamin, but a few foods including oily fish such as salmon, sardines, and mackerel , egg yolk and some fortified foods and supplements can also provide the vitamin.

Source:

25-Hydroxyvitamin D and Risk of Myocardial Infarction in Men - A Prospective Study

Edward Giovannucci, MD, ScD; Yan Liu, MS; Bruce W. Hollis, MD, PhD; Eric B. Rimm, ScD

Arch Intern Med. 2008;168(11):1174-1180.