Harvard Women's Health Watch

In the news: Large trial will test vitamin D and omega-3s

While there's no "magic bullet" for health and nutrition, few contenders have looked as promising as vitamin D. Likewise, omega-3 fatty acids have attracted attention. (They're promoted mainly for heart health, but some research hints at anti-cancer and other benefits as well.) However, the preventive value of these nutrients is untested.

Vitamin D is best known as calcium's partner in maintaining bone health. But a growing body of evidence suggests that it may help reduce our risk for many ills, including heart disease, cancer, diabetes, multiple sclerosis, and depression. The data are sufficiently compelling that some experts advise taking at least 800 to 1,000 international units (IU) of vitamin D per day (more than twice the officially recommended intake) as a hedge against chronic disease. Yet no one knows whether a higher intake will actually help prevent disease.

The same is true for omega-3 fatty acids. Omega-3s taken in fish oil supplements are known to prevent sudden death from heart attack in people who already have heart disease, but we don't know whether they can stave off heart disease (or any other condition, for that matter) in healthy people.

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