Sun up

The good news just keeps on coming for vitamin D. A new study of men finds that getting plenty of vitamin D seems to lessen the risk of having a heart attack.

Researchers tracked the effect of vitamin D levels in blood by testing blood samples collected from 1993 to 1995 from more than 18,000 men who were part of a long-term study of physicians. Researchers then monitored these men for 10 years. By analyzing the initial blood vitamin D readings with the men’s subsequent health history, researchers were able to assess whether vitamin D status affected heart attack risk.

The researchers found that 454 men had heart attacks during the 10-year period that followed. Men with the least vitamin D were twice as likely to have a heart attack as men with the most, says Edward Giovannucci of the Harvard School of Public Health in Boston. He and his colleagues report the data in the June 9 Archives of Internal Medicine.

The finding stood up even after the researchers accounted for differences between the groups in age, race, family history of heart attacks, weight, alcohol consumption, physical activity, history of diabetes, high blood pressure, ethnicity, fish consumption, cholesterol, triglyceride levels and the region in which they lived.

Although many factors contribute to heart attack risk, some people still have the big one without fitting the profile. Others who do have such factors don’t have heart attacks.

Some earlier studies hinted that people living at high latitudes, typically in the far north, have an added risk that is further elevated during winter months. It’s no coincidence that these are the months of low sunshine and hence low vitamin D production by the body, says Giovannucci, a physician and epidemiologist.

The finding underscores that too little vitamin D “is a straightforward risk factor” for heart attack, says study coauthor Bruce Hollis, a molecular biologist at the Medical University of South Carolina in Charleston. “It’s right up there with high blood pressure and smoking,” he says.

Hollis and Giovannucci also suspect that vitamin D fends off infections, which may indirectly account for some of this heart attack protection, since research has tied infections and the low-grade inflammation they spawn to heart disease. Giovannucci says the winter flu season and the onset of many other respiratory infections in winter might be in part attributable to a lack of vitamin D.

Giovannucci also cites animal studies and some work in people that shows that a lack of vitamin D seems to disrupt proper calcium regulation in the body, leaving less needed calcium in bone and adding more to arteries, where it contributes to hardening and a risk of heart attack.

These and other findings suggest that dermatologists’ campaign to keep people out of the sun to reduce the risk of skin cancer has left many at risk of heart attack, as well as osteoporosis, autoimmune diseases, infections and other conditions that vitamin D seems to fend off, Hollis says.