Which nutritional supplements have demonstrated benefit on cardiovascular disease–related and overall mortality?
Supplementation with n-3 fatty acids, such as those found in fish oil and olive oil, slightly decreases the risk of cardiovascular outcomes. Coenzyme Q10 (CoQ10, ubiquinol) is associated with an overall decrease in mortality in patients with heart failure. Other common vitamins and minerals do not seem to affect any outcomes. Beta-carotene, once hailed for its antioxidant effect, is associated with increased overall mortality and cardiovascular outcomes. The evidence maps in the paper are works of art and are great for getting a quick summary of the myriad analyses. 1a
Meta-analysis (randomized controlled trials)
These researchers searched 3 databases, including Cochrane Central, to identify randomized controlled trials or previous systematic reviews published in any language. Studies were independently selected by 2 reviewers and confirmed by a third reviewer. The authors evaluated both the risk of bias and the quality of the evidence. It was a big project; after sorting through almost 4000 articles, they selected 884 randomized controlled trials that evaluated the effects of 27 types of micronutrient supplements on cardiovascular disease outcomes. They analyzed the results in every possible way, looking for effects on cardiovascular disease risk factors in specific populations and the overall effect on mortality, cardiovascular disease, and diabetes. First, the bad news: The antioxidant beta-carotene was associated with a roughly 10% increased risk of all-cause mortality, cardiovascular disease mortality, and stroke. The investigators found no effect on cardiovascular disease or type 2 diabetes risk with supplementation with vitamin C, vitamin D, vitamin E, and selenium. N-3 fatty acids (like those in fish oil) might have a small effect on cardiovascular outcomes, but not on overall mortality (low heterogeneity among the studies). Coenzyme Q10 supplementation decreases all-cause mortality rates in patients with heart failure (moderate evidence). Don’t look for any benefit from micronutrient supplements on blood pressure, lipids, or blood glucose values.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine