Thursday June 19, 2014 (foodconsumer.org) -- A new review in Critical Reviews in Food Science and Nutrition suggests taking multivitamins or multivitamin/mineral supplements may help reduce risk of chronic disease.

The systemic review of randomized controlled trials (RCTs) and observational studies reveals multivitamin/mineral supplementation moderately yet significantly reduces total and epithelial cancer in male physicians.

The finding is based primarily on data from the largest and longest randomized controlled trial of multivitamin/mineral supplements - the Physicians' Health Study II (PHS II) and was consistent with another trial - the Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) trial. 

The PHS II also shows a modest yet significant reduction in incidence of nuclear cataract and this finding was consistent with several other randomized controlled trials and observational prospective cohort studies even though it remains unclear whether supplementation with multivitamin/mineral supplements reduces risk of other subtypes of cataract and age-related macular degeneration.

However, the review finds the majority of scientific studies fail to find evidence that multivitamin/mineral supplements reduce risk of chronic diseases including cancer, cardiovascular disease and age-related eye diseases.

The reviewers point out that the fact that multivitamin/mineral supplements have not been associated with reduced risk of chronic diseases may not be the fault of the vitamin supplements, but the limitations of the clinical trials and prospective cohort studies.

"The placebo-controlled trial design of RCTs may be inadequate for nutrient interventions, and residual confounding, measurement error, and the possibility of reverse causality are inherent to any observational study," the reviewers write.

The review also mentions that micronutrient inadequacies are common in the US as shown in national surveys, and dietary supplements, multivitamin/mineral supplements - the most common one, should help fulfill micronutrient requirements both in adults and children.

The review was conducted by Dr. G. Angelo at Linus Pauling Institute; Department of Biochemistry and Biophysics, Oregon State University and colleagues. (David Liu, PHD)

Angelo G, Drake VJ, Frei B.  Efficacy of multivitamin/mineral supplementation to reduce chronic disease risk: a critical review of the evidence from observational studies and randomized controlled trials.  Crit Rev Food Sci Nutr. 2014 Jun 18:0.