HealthDay News — For older patients with a history of myocardial infarction, a high-dose oral multivitamin and multimineral mixture is safe, but does not significantly reduce cardiovascular events, study findings indicate.
Rates of composite cardiovascular events were similar among patients assigned to a high-dose multivitamin and those assigned to placebo (27% vs. 30%; hazard ratio 0.89; 95% CI: 0.75-1.07), Gervasio Lamas, MD, of Mount Sinai Medical Center in Miami Beach, Fla., and colleagues reported in Annals of Internal Medicine.
“Evidence is sufficient to advise against routine supplementation, and we should translate null and negative findings into action,” Eliseo Guallar, MD, DrPH, of the Johns Hopkins Bloomberg School of Public Health, and colleagues urged in an accompanying editorial. “The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided.”
Recent studies show that the use of multivitamins and other supplements is on the rise in the United States, increasing from 42% from 1988 to 1994 to 53% from 2003 to 2006, despite insufficient evidence regarding health benefits.
To assess the effectiveness of high-dose multivitamins on secondary prevention of atherosclerotic disease, Lamas and colleagues analyzed data from from 134 U.S. academic and medical centers, which included information from 1,708 patients aged 50 years or older, who had had an MI at least six weeks earlier and who had serum creatinine levels of 2.0 mg/dL or lower.
The researchers randomly assigned participants to to an oral 28-component high-dose multivitamin and multimineral mixture or to placebo, and followed them for a median of 55 months. Patients in the treatment group took their multivitamins for a median 31 months vs. 35 months in the placebo group.
Overall, 76% of the vitamin and placebo groups completed at least one year of oral therapy (P=0.98), while 47% and 50%, respectively, completed three years of therapy (P=0.23). Nearly half (46% in each group) discontinued the regimen (P=0.67) and 17% of participants withdrew from the study.
The primary end point of composite time to total death, recurrent MI, stroke, coronary revascularization or hospitalization for angina occurred in 27% and 30% of those in the vitamin and placebo groups, respectively (hazard ratio, 0.89; P=0.21). There was no difference for the individual components or for cardiovascular death (5% vs. 7%, HR 0.80; 95% CI: 0.54-1.18).
In no category of adverse events was there evidence of harm from vitamin therapy. Serious adverse events occurred in 15% of the multivitamin group and 12% of the placebo group.
“These conclusions must be interpreted cautiously because of a high rate of non-adherence to the study regimen,” the researchers concluded.
However, the findings were enough to prompt Guallar and colleagues to declare, “enough is enough.”
“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,” the editorialists wrote.