Analysis of Dietary Supplements for Nutritional, Toxic, and Other Elements

Abstract Thirty-six elements were determined in 42 dietary supplements by using square wave anodic stripping voltammetry, inductively coupled plasma-atomic emission spectroscopy, instrumental neutron and prompt gamma-ray activation analysis, and flame and graphite furnace atomic absorption spectroscopy. This multielement capability enabled determination of concentrations of nutritional and toxic elements. For most products, Al levels can be explained by the presence of a soil component. Soil and excipient content (as much as 10.9 and 27.6% by weight, respectively) and the fraction of elements in soil and biological portions of the matrices were estimated. Potential element intakes from these supplements based on label dosages and average dietary intakes from food were calculated. Some products were found to provide amounts of Pb, Zn, Mn, Mo, Cu, and Fe in excess of levels generally accepted as safe by national and international organizations. Intakes of Mg, Cr, and Ca from some supplement products may augment average dietary intakes from food to meet established nutritional requirements.