Using data from 884 studies and more than 883,000 patients, researchers at Brown University systematically reviewed all of the existing evidence on micronutrients taken as dietary supplements. After evaluating 27 different types, they identified several that reduced the risk of cardiovascular problems like heart attack or stroke, as well as others that offered no benefit or even had a negative effect. This analysis represents the first comprehensive, evidence-based map quantifying micronutrient supplements’ potential effects on heart health outcomes, said principal investigator Simin Liu, MD, MPH, professor of epidemiology and medicine at Brown University, in a press release. “Our study highlights the importance of micronutrient diversity and the balance of health benefits and risks,” he said.
Omega-3 Fatty Acids, Folic Acid, and CoQ10 Had Strongest Evidence of Heart Benefits
The randomized controlled intervention trials included in the research found the strongest evidence of heart benefits in the following supplements:
Omega-3 fatty acids (fish oil), which decreased mortality from cardiovascular diseaseFolic acid, which lowered stroke riskCoenzyme Q10, marketed as CoQ10, which decreased all-cause mortality (death)
Other supplements showing evidence of reducing cardiovascular risk were omega-6 fatty acid, L-arginine, L-citrulline, vitamin D, magnesium, zinc, alpha-lipoic acid, melatonin, catechin, curcumin, flavanol, genistein, and quercetin.
Useless and Potentially Harmful Supplements for Heart Health
The research found that some supplements weren’t associated with heart benefits. Vitamin C, vitamin E, and selenium showed no effect on long-term cardiovascular disease outcomes (or type 2 diabetes risk). One particularly concerning finding: Beta-carotene supplements were associated with an increase in all-cause mortality. The study authors called for large, high-quality interventional trials to investigate the long-term effects of certain micronutrients. “Identifying the optimal mixture of micronutrients is important, as not all are beneficial, and some may even have harmful effects,” said Liu. RELATED: Dietary Supplements Don’t Lower ‘Bad’ Cholesterol, Study Finds
Antioxidant Supplements Are Not Equivalent to Antioxidant-Rich Foods
Antioxidant supplements are thought to play a role in heart health because these nutrients work to reduce so-called “oxidative stress,” a known contributor to many types of cardiovascular disease. Programs like the Mediterranean diet and Dietary Approaches to Stop Hypertension, which feature foods that are naturally rich in antioxidants, are both compatible with the most recent American Heart Association dietary recommendations. But the nutrients in supplements aren’t exactly the same as those in foods, and the results from previous studies looking at the benefits of antioxidant supplements have been inconsistent — one reason why supplements haven’t been widely adopted in preventive cardiology, according to the authors. Previously, research on micronutrient supplementation has mainly focused on the health effects of a single vitamin or mineral or a few at a time, said Dr. Liu. “We decided to take a comprehensive and systematic approach to evaluate all the publicly available and accessible studies reporting all micronutrients, including phytochemicals and antioxidant supplements and their effects on cardiovascular risk factors as well as multiple cardiovascular diseases.”
Interested in Taking Supplements? Check with Your Doctor First
“It’s a good idea to check in with your doctor before taking supplements,” says Elizabeth Bradley, MD, medical director of Cleveland Clinic’s Center for Functional Medicine in Ohio, who was not involved in this research. If your doctor recommends an omega-3 fish oil supplement, be aware that different brands can vary in quality, says Dr. Bradley. Your provider may have suggestions about what to look for in labeling. Or you can research different brands at independent websites such as ConsumerLab.com, which reviews and rates supplements.
