A new study finds men who get more of vitamin D from food and supplements have a lower risk of cardiovascular disease.
Researchers at the Harvard School of Public Health looked at 75,000 women and 45,000 men in two large, long-term studies. The findings: Over more than 20 years of follow-up, men who got at least 600 IU a day were 16 percent less likely to develop heart disease than those who got 100 IU a day or less. Each D dose of 143 IU per day decreased men’s cardiovascular disease risk by 2.6 percent. (The recommended daily dose is 600 IU, according to the Institute of Medicine, although many experts recommend more.) Women, however, didn’t see any apparent heart benefit from vitamin D.
Sun or Supplement?
Why did they want to study diet and supplements only? Especially during winter months, not everyone can get enough vitamin D from sunshine, notes study author Qi Sun, M.D., Sc.D. “For people who avoid sunlight exposure, live in high-latitude areas, or have dark skin, dietary or supplemental vitamin D becomes essential for maintaining optimal vitamin D levels,” Dr. Sun says. “Keep in mind, too, that excessive sun exposure or sunburn will increase the risk of skin cancer.” (Related: The Men’s Health Skin Cancer Center.)Note: These numbers came from questionnaires filled out by the men and women themselves—a method that can be unreliable. But Dr. Sun points out that when they compared these reports to blood vitamin D levels collected from a subset of study participants, the numbers were closely aligned.
The Heart-Health Connection
Vitamin D may reduce inflammation, an overreaction of the immune system that’s been implicated in the development of heart disease. It also seems to help control blood pressureand prevent artery damage.As for why there would be a gender difference: “To be honest, we don’t know yet,” Dr. Sun says. “We suspect that perhaps women may need higher vitamin D intake levels to reach an optimal internal dose of vitamin D than men do. But we need to have more evidence in this regard.”
What to Do about D
No single large trial has yet examined the role of vitamin D alone in heart disease. There’s one under way—the Vital study, to test the effects of high-dose supplements on cardiovascular outcomes—but the five-year trial is still recruiting participants, so results won’t be available for years. And because there’s so much interest in vitamin D for conditions ranging from heart disease to colds to weak sperm, it’s hard to put a finger on the best dose to cover all your bases.