Despite their common use, high doses of vitamins and minerals may not protect against cardiovascular events after a heart attack, a study published online Dec. 17 in Annals of Internal Medicine found. However, the study investigators noted that participant withdrawals and nonadherence may have skewed the data.

Researchers led by Gervasio A. Lamas, MD, of Mount Sinai Medical Center in Miami Beach, Fla. randomized 1,708 patients 50 years of age and older who suffered a heart attack at least six weeks earlier to receive either a placebo along with a saline intravenous placebo or an oral high-dose multivitamin and mineral combination along with EDTA-based intravenous chelation therapy. The primary outcome was the composite of the time to all-cause mortality, reinfarction, stroke, coronary revascularization or an angina hospitalization. The secondary outcome was the composite of time to death from cardiovascular causes, reinfarction or stroke. The research took place between 2003 and 2010 at 134 centers in the U.S.

The primary endpoint occurred in 27 percent of the vitamin group participants and 30 percent of the placebo group. Fifteen percent of the vitamin group and 12 percent of the placebo group experienced serious adverse effects.

“[A] 28-component, high-dose oral multivitamin and multimineral regimen used as secondary prevention in patients who have had MI did not statistically significantly reduce cardiovascular events,” the authors wrote.

However, they also noted that 46 percent of participants discontinued their vitamin or placebo regimen. Most simply opted to no longer take the supplements, but others were advised to discontinue by their physicians or stopped because of adverse effects.

In an accompanying editorial, Eliseo Guellar, MD, DrPH, of the Johns Hopkins Bloomberg School of Public Health in Baltimore, Md. and colleagues argued that the findings of Lamas et al and other research suggest that the billions of dollars spend on supplements may be going to waste.

“Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed—supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful.”