05.29.18
A systematic review published in the Journal of the American College of Cardiology suggested that common dietary supplements—multivitamins, vitamin D, calcium, and vitamin C—showed no advantage in the prevention of cardiovascular disease, heart attack, stroke, or premature death, and may pose a risk in certain cases.
Researchers at St. Michael's Hospital and the University of Toronto identified individual randomized controlled trials from previous meta-analyses and additional searches, and then performed meta-analyses on cardiovascular disease outcomes and all-cause mortality.
The authors assessed publications from 2012, both before and including the U.S. Preventive Service Task Force (USPSTF) review. Their systematic reviews and meta-analyses showed generally moderate- or low-quality evidence for preventive benefits (folic acid for total cardiovascular disease, folic acid and B-vitamins for stroke); no effect (multivitamins, vitamins C, D, β-carotene, calcium, and selenium); or increased risk (antioxidant mixtures and niacin [with a statin] for all-cause mortality). Conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated, therefore, any benefits seen must be balanced against possible risks, they concluded.
“In general, the data on the popular supplements (multivitamins, vitamin D, calcium, and vitamin C) show no consistent benefit for the prevention of CVD, MI, or stroke, nor was there a benefit for all-cause mortality to support their continued use,” researchers wrote. “At the same time, folic acid alone and B-vitamins with folic acid, B6, and B12 reduced stroke, whereas niacin and antioxidants were associated with an increased risk of all-cause mortality. Overall, the effects were small; the convincing lack of benefit of vitamin D on all-cause mortality is probably the reason for the lack of further studies published since 2013. However, a number of trials with high doses (2,000 IU/day) are underway (e.g., VITAL [Vitamin D and Omega-3 Trial]; NCT01169259). The effects of folic acid in reducing stroke is also convincing, with a 20% reduction.”
Since the 2013 to 2014 assessment and report of the USPSTF, the most notable finding was the effect of folic acid in reducing stroke and CVD, researchers said. They also claimed vitamin B3 (niacin) might increase all-cause mortality, which may have been related to its adverse effects on glycemic response. Antioxidant mixtures also did not appear to benefit CVD but might increase all-cause mortality, they added.
“Although sufficient studies on vitamin D exist, to be confident that there is no all-cause mortality effect, further studies on multivitamins, the most commonly used supplement, may still be useful, because of the marginal benefit seen in our analysis. In the absence of further studies, the current data on supplement use reinforce advice to focus on healthy dietary patterns, with an increased proportion of plant foods in which many of these required vitamins and minerals can be found.”
Researchers at St. Michael's Hospital and the University of Toronto identified individual randomized controlled trials from previous meta-analyses and additional searches, and then performed meta-analyses on cardiovascular disease outcomes and all-cause mortality.
The authors assessed publications from 2012, both before and including the U.S. Preventive Service Task Force (USPSTF) review. Their systematic reviews and meta-analyses showed generally moderate- or low-quality evidence for preventive benefits (folic acid for total cardiovascular disease, folic acid and B-vitamins for stroke); no effect (multivitamins, vitamins C, D, β-carotene, calcium, and selenium); or increased risk (antioxidant mixtures and niacin [with a statin] for all-cause mortality). Conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated, therefore, any benefits seen must be balanced against possible risks, they concluded.
“In general, the data on the popular supplements (multivitamins, vitamin D, calcium, and vitamin C) show no consistent benefit for the prevention of CVD, MI, or stroke, nor was there a benefit for all-cause mortality to support their continued use,” researchers wrote. “At the same time, folic acid alone and B-vitamins with folic acid, B6, and B12 reduced stroke, whereas niacin and antioxidants were associated with an increased risk of all-cause mortality. Overall, the effects were small; the convincing lack of benefit of vitamin D on all-cause mortality is probably the reason for the lack of further studies published since 2013. However, a number of trials with high doses (2,000 IU/day) are underway (e.g., VITAL [Vitamin D and Omega-3 Trial]; NCT01169259). The effects of folic acid in reducing stroke is also convincing, with a 20% reduction.”
Since the 2013 to 2014 assessment and report of the USPSTF, the most notable finding was the effect of folic acid in reducing stroke and CVD, researchers said. They also claimed vitamin B3 (niacin) might increase all-cause mortality, which may have been related to its adverse effects on glycemic response. Antioxidant mixtures also did not appear to benefit CVD but might increase all-cause mortality, they added.
“Although sufficient studies on vitamin D exist, to be confident that there is no all-cause mortality effect, further studies on multivitamins, the most commonly used supplement, may still be useful, because of the marginal benefit seen in our analysis. In the absence of further studies, the current data on supplement use reinforce advice to focus on healthy dietary patterns, with an increased proportion of plant foods in which many of these required vitamins and minerals can be found.”
