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Most dietary supplements, interventions may not improve risk for CVD or death
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Although reduced salt intake and certain supplements may decrease the risk for some cardiovascular outcomes, most nutritional supplements and dietary interventions do not improve risk for cardiovascular disease or death, according to an evidence review published in the Annals of Internal Medicine.
In addition, the combined use of calcium and vitamin D may increase risk for stroke, according to researchers.
“Current U.S. dietary guidelines recommend several healthy eating patterns, including U.S., Mediterranean and vegetarian diets,” Safi U. Khan, MD, of West Virginia University, and colleagues wrote. “Although the guidelines recognize the occasional need for nutritional supplementation or food fortification for specific nutrients that may be consumed in inadequate amounts, they do not recommend routine use of any dietary supplement to reduce risk for cardiovascular disease (CVD) or other chronic diseases. Despite these recommendations, most U.S. adults use supplements to enhance their diets, with uncertain health benefits.”
Researchers conducted a search of multiple databases from inception to March 2019 to identify randomized controlled trials and meta-analyses of randomized controlled trials about dietary interventions and nutritional supplements that included estimates for all-cause mortality or CV outcomes. Two independent investigators abstracted data, evaluated the evidence and determined the certainty of evidence.
After exclusions, nine systematic reviews and four randomized control trials involving 277 trials, 24 interventions and 992,129 participants were included in the review. A total of 16 of supplements and eight dietary interventions were evaluated.
Researchers found moderate-certainty evidence that suggested reduced salt intake decreased the risk for all-cause mortality in normotensive patients (RR = 0.9; 95% CI, 0.85-0.95) and CV mortality in patients with hypertension (RR = 0.67; 95% CI, 0.46-0.99).
Omega-3 long-chain polyunsaturated fatty acid use was associated with reduced risks for both myocardial infarction (RR = 0.92; 95% CI, 0.85-0.99) and coronary heart disease (RR = 0.93; 95% CI, 0.89-0.98) through low-certainty evidence.
The risk for stroke decreased in those who used folic acid supplements (RR = 0.8; 95% CI, 0.67-0.96, low certainty), but increased in those who combined calcium and vitamin D supplements (RR = 1.17; 95% CI, 1.05-1.3, moderate certainty).
There was no significant effect on mortality or CVD outcomes with the use of other supplements, including multivitamins, selenium, vitamin A, vitamin B6, vitamin C, vitamin E and iron. Most dietary interventions, including the Mediterranean diet, reduced saturated fat or modified fat intake, and increased omega-3 ALA or omega-6 PUFA intake had no effect on all-cause mortality or CVD outcomes.
In an editorial accompanying the study, Amitabh C. Pandey, MD, and Eric J. Topol, MD, of Scripps Research Translational Institute, Scripps Research, and Scripps Clinic, noted that the findings were limited by the quality of evidence. As a result, they stated that “it would be reasonable to hold off on any supplement or diet modication in all guidelines and recommendations,” until further evidence is found. – by Erin Michael
Disclosures: Khan, Pandey and Topol report no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.