Vitamin D and Heart Attack and Atherosclerosis in Men
The June 9, 2008 issue of Archives of Internal Medicine published by the American Medical Association presented the finding of Harvard researchers that men who have deficient vitamin D levels have a greater risk of myocardial infarction (heart attack) than men whose blood levels of the vitamin are sufficient.
Edward Giovannucci, MD of Harvard School of Public Health and his associates reviewed data from men aged 40 to 75 who participated in the Health Professionals Follow-up Study, a prospective cohort investigation designed to evaluate associations between the occurrence of chronic disease and diet among male health care professionals who now have been followed for many years. Blood samples collected from 1993 to 1995 were analyzed for plasma 25-hydroxyvitamin D (25-OHD), lipoprotein and triglyceride levels, and diet and lifestyle factors were determined though the use of questionnaires which were given to each of the participants on study entry. Nine hundred participants without heart disease were matched for age, smoking status, and time of blood collection with 454 men of similar age (age 40 to 75) who had fatal coronary heart disease or non-fatal heart attack which was diagnosed in the 9 to 11 year period between the time of blood sample collection through January, 2004.
Adjusted analysis of the data found a 2.42 times greater risk of heart attack among subjects with plasma vitamin D levels of 15 nanograms per milliliter or less compared with those whose levels were sufficient at 30 nanograms per milliliter or higher. Even those men whose vitamin D levels fell in an "intermediate range" had a 43 to 60 percent greater risk of heart attack compared to men with sufficient levels. Adjustment for a number of factors, such as family history of heart attack, failed to significantly reduce the association. Men with low levels of vitamin D were more likely to live in northern states (where there is less exposure to the sun, especially during winter months), and less likely to be white or to use a multivitamin supplement, among other characteristics revealed by the analysis.
In their commentary, the authors cite the known beneficial effect of Vitamin D on smooth muscle cell proliferation, inflammation, vascular calcification, and blood pressure via the renin-angiotensin system as possible protective mechanisms against myocardial infarction. Vitamin D as an anti-inflammatory agent showing benefit in cardiovascular disease is a possible mechanism of benefit, as cardiovascular disease has been linked in the past to inflammation and inflammatory markers such as C reactive protein, a protein often present when inflammation is present in the body. Other potential mechanisms include protection against type 2 diabetes, inflammation, and seasonal respiratory tract infections (especially influenza), all of which can impact cardiovascular disease mortality.
“These results further support an important role for vitamin D in myocardial infarction risk,” the authors stated. “If this association is causal, which remains to be established, the amount of vitamin D required for optimal benefit may be much higher than would be provided by current recommendations (200-600 IU per day), especially in those with minimal sun exposure. 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 levels substantially large enough for potential health benefits.”