Male physicians who took a multivitamin each day for more than 11 years did not have a decrease in cardiovascular disease events compared with a placebo group, according to a randomized, controlled trial.

The results were similar regardless of the participants’ food intake, dietary patterns or baseline nutritional status.

Lead researcher Susanne Rautiainen, PhD, of Brigham and Women’s Hospital in Boston, and colleagues published their findings online in JAMA Cardiology on April 5.

Although more than 50 percent of adults in the U.S. take a multivitamin supplement, the researchers mentioned that the U.S. Preventive Services Task Force has concluded there is insufficient evidence to recommend for or against the use of multivitamins to prevent cardiovascular disease.

For this analysis, they examined the Physicians’ Health Study II, a randomized, double-blind, placebo-controlled trial that began in 1997 and followed participants through June 1, 2011. More than 13,000 physicians enrolled in the study and completed a 116-item food frequency questionnaire at baseline. All of the participants were males and at least 50 years old.

The study evaluated the effects of a multivitamin, vitamin E, vitamin C and beta-carotene on preventing cancer, cardiovascular disease, eye disease and cognitive decline.

Researchers previously found that physicians randomized to take multivitamins had no difference in the primary endpoint of major cardiovascular events and the secondary endpoints of total MI and total stroke compared with the placebo group. Multivitamin use was also not statistically significantly associated with total mortality or cardiovascular disease mortality.

The adherence rates to the multivitamins were 76.8 percent at four years, 72.3 percent at eight years and 67.1 percent at the end of the follow-up period. The adherence rates for the placebo group were 77.1 percent, 70.7 percent and 67.1 percent, respectively, which were not significantly different than the adherence rates for the multivitamins.

After a mean follow-up period of 11.4 years, the researchers found there was no effect modification on the use of multivitamins on cardiovascular disease endpoints when assessing various foods, nutrients, dietary patterns or baseline supplement use. They evaluated numerous dietary factors such as the intake of fruits and vegetables, whole grains, nuts, dairy products and red and processed meats as well as nutrients such as vitamin B6, vitamin B12 and vitamin D.

“Intuitively, many had thought that men with ‘poor’ nutritional status at baseline may benefit more from long-term multivitamin use on cardiovascular outcomes; however, we did not see any evidence for this in our recent analysis,” study author Howard Sesso, ScD, MPH, of Brigham and Women’s Hospital, said in a news release. “Given the continued high prevalence of multivitamin use in the US, it remains critical for us to understand its role on nutritional status and other long-term health outcomes through clinical trials such as PHS II and other new research initiatives.”

The researchers noted that physicians who had a healthier diet compared with the general population, so the results might not be generalizable to other groups that have different dietary patterns. They also mentioned that participants self-reported their dietary intake, which could lead to measurement errors. In addition, participants were allowed to take concomitant medications to treat cardiovascular disease risk factors such as hypercholesterolemia, hypertension and type 2 diabetes, which could have influenced the results. Further, they performed multiple tests across numerous dietary factors, so it was possible some of the statistically significant effects were false-positive results.

“Future studies should seek to include a larger proportion of individuals with a wider range of dietary intake and should use nutritional biomarkers as more objective assessments of baseline nutritional status that account for differences in absorption and metabolism to understand how they influence the long-term effects of multivitamin use on [cardiovascular disease] risk,” the researchers wrote. “The recently initiated Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) trial, which is testing a multivitamin supplement with 4 years of treatment and follow-up, will provide further context of its role in [cardiovascular disease] prevention among older women and older men, including potential effect modification by baseline nutritional status.”