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The Physicians’ Health Study was a randomized, double-blind, placebo-controlled trial of the role of aspirin and beta-carotene in decreasing the risks of cardiovascular disease and cancer. This study has been conducted entirely by mail among 22,071 U.S. male physicians who were between the ages of 40 and 84 years when the trial began in 1982. The aspirin component of the trial was halted prematurely, in 1988, primarily because of a statistically extreme 44% reduction in risk of a first myocardial infarction among the group of men assigned to take low-dose aspirin. The beta-carotene component of the trial, which ended on schedule in 1995, found no evidence of either benefit or harm from beta-carotene supplements on risks of cancer or cardiovascular disease after more than 12 years of treatment and follow-up.

The Physicians’ Health Study II started in 1997 as a randomized, double-blind, placebo-controlled trial to test the balance of benefits and risks of three widely used but unproven supplements for the primary prevention of cardiovascular disease, cancer, age-related eye disease, and cognitive decline—vitamin E, vitamin C, and a multivitamin. The participants are 15,000 U.S. male physicians, some of whom also took part in the Physicians’ Health Study I. The vitamin C and vitamin E components, which ended in 2007, found that these vitamin supplements do not prevent major cardiovascular events, cancer, or age-related eye disease. The multivitamin component, which ended in 2011, found that daily multivitamin use modestly but significantly reduced the risk of total cancer and did not prevent major cardiovascular events. Daily multivitamin use also modestly and significantly decreased the risk of cataract but had no significant effect on visually significant age-related macular degeneration. It also did not provide cognitive benefits. Although the trial is over, the physicians who took part in it continue to help advance our knowledge about the prevention of cardiovascular disease, cancer, and other chronic diseases by completing annual questionnaires.

To read more about the main results of the Physicians’ Health Study II, please click on the following links:

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