Do multivitamin supplements reduce the risk for congenital heart defects? Evidence and gaps

Progress in the primary prevention of heart defects has been slow. Some findings suggest that multivitamin supplementation might reduce the risk for some heart defects. This review of the literature shows that two studies, one of which is a randomized clinical trial, provide data supporting a possible protective effect of multivitamins for all heart defects combined (a 25 to 50% reduction). Three of five studies support a protective effect for outflow tract defects, whereas two studies do not. More studies are clearly needed to elucidate the relation between multivitamin use and occurrence of heart defects. Such studies must take into account intake from multiple sources (diet and supplements), as well as genetic background and potential confounders. From a practical perspective, all health-care providers, including pediatric cardiologists, should ensure that women of childbearing age, regardless of whether they had a previous child with a heart defect, take a multivitamin containing 400 micrograms of folic acid, to reduce their risk of having a baby with a neural tube defect. Should such supplements eventually be proven to reduce the risk also for heart defects, this would be an important additional benefit of such supplement use.