On November 5, a study published in the Journal of the American Medical Association (JAMA) concluded that daily consumption of a multivitamin did not reduce the risk of heart failure for male physicians over the age of 50. The results were assembled by the multivitamin and cardiovascular health arm of the Physicians Health Study (PHS) II, a randomized, placebo-controlled trial that followed a population of nearly 15,000 men over more than a decade and examined a variety of health outcomes.
Previously published results from the PHS showed a statistically significant reduction in incidence of cancer among multivitamin users versus placebo—further legitimizing the supplement industry’s most popular product category.
The results of the cardiovascular analysis follow a similarly damning study recently published in JAMA—a September 2012 meta-analysis which concluded that taking omega-3s doesn’t lead to lower risk of adverse cardiovascular events.
Perhaps better news awaits multivitamins in the near future, though. The cancer and cardiovascular results were primary endpoints researched for the PHS, while results from secondary endpoint analysis—including cognitive function and eye disease—are awaiting publication.
According to the Council for Responsible Nutrition (CRN), the study’s population was not representative of most people, and it was therefore unsurprising that multivitamins showed no impact on cardiovascular events.
“This particular population was extremely healthy, with the physicians doing everything right to prevent heart disease,” said Duffy MacKay, ND, CRN’s vice president of scientific and regulatory affairs, in a statement. “Their diets were healthy, their BMIs were low, they exercised, very few smoked, and the majority was on a daily aspirin regimen. The floor in this population may have been too close to the ceiling for a simple multivitamin to have demonstrated additional benefit for preventing strokes and heart attacks.”
The study's authors themselves said that the target population "may have limited generalizability."
This is a complicated point to make, however, and will likely be lost on mainstream press. I would expect another round of negative headlines, but no significant, material impact.
Do you think the study participants were "too healthy" to show any significant heart-health benefits? Respond in the comments below.