In middle–aged and older men, long–term daily multivitamin use does not prevent cardiovascular disease (CVD), regardless of baseline nutritional status, according to a new analysis of the Physicians Health Study II.

Results of the PHS II reported in 2012 showed no effect of long–term multivitamin use on risk of CVD, but whether baseline nutritional status may have modified the lack of effect was not known.

In the new analysis, published online April 5 in JAMA Cardiology, researchers investigated whether baseline intake of key foods, nutrients, dietary patterns, and dietary supplements modified the long–term effect of multivitamin use on CVD.

In this new analysis of over 13,000 physicians who received a daily multivitamin or placebo and were followed for an average of about 11 years, there was “no consistent evidence” of effect modification by various foods, nutrients, dietary patterns, or baseline supplement use on the effect of multivitamin use on CVD endpoints, the authors said.

“This new report from the PHS II trial takes our findings for CVD a step further by understanding whether a multivitamin may have differential effects on CVD based on initial nutritional status,” Dr. Howard Sesso, from Brigham and Women's Hospital and Harvard Medical School in Boston, told Reuters Health by email. The result, he said, “reinforces our view that a multivitamin has no clear effect on CVD risk–regardless of baseline nutritional status.”

Dr. Sesso said his research group has initiated a new clinical trial known as COSMOS to retest a multivitamin in 18,000 older men and women, to provide additional trial evidence on multivitamins, “which remain the most commonly used supplement in the U.S.”

For now, Dr. Sesso told Reuters Health, “Any individual decision whether to take a multivitamin should be made in consultation with their health care provider or with a nutritionist. It is important to first identify whether one has an overall balanced and healthy diet, in which case a multivitamin may not provide much additional nutritional benefits. Those with insufficient nutrient intake may wish to consider a multivitamin after a discussion with their provider. Many others feel compelled to take a multivitamin for general health or to prevent specific conditions, but there remains insufficient evidence on the role of multivitamins on such outcomes.”

In an editorial in JAMA Cardiology, Dr. Linda Van Horn, registered dietician and professor of preventive medicine at the Feinberg School of Medicine, Northwestern University, Chicago, says, “Few questions are more complicated for nutritionists and health care professionals than, 'Should I take a vitamin–mineral supplement?' Despite decades of evidence contributed by numerous well–conducted, carefully controlled studies among different age, sex, and racial/ethnic groups, the most accurate answer seems to be 'Maybe or maybe not.'”

In email to Reuters Health, Dr Van Horn added, “In this era of 'Precision Medicine' the need for 'Precision Nutrition' becomes even more relevant. Decisions regarding benefits or risks of vitamin/mineral/herbal or any other supplements require careful consideration based on the patient’s nutrient needs including pharmacologic intake, multiple risk factors, age, sex and current dietary intake. By starting with the latter, e.g., nutritional assessment of current dietary intake, decisions regarding the risk/benefit of supplements are better informed.”

A related paper online April 5 in JAMA Cardiology finds that monthly high–dose vitamin D supplementation does not prevent CVD.

Dr. Sesso has received investigator–initiated grants from the Council for Responsible Nutrition Foundation and Pfizer.

—Megan Brooks