People who take dietary supplements often get more nutrients from food than non-supplement users, and may be getting too much of certain minerals, according to research published in the American Journal of Clinical Nutrition. In this analysis, researchers examined mineral intakes from the diet by supplement-use categories and how these supplements contributed to meeting or exceeding Dietary Reference Intakes (DRIs) for selected minerals.

Data from adults (≥19 y of age; n = 8860) who participated in NHANES 2003–2006, a nationally representative, cross-sectional survey, were examined. Supplement use was defined as the participant’s self-reported use of a supplement that contained one or more of selected minerals.

Individuals who used mineral-containing dietary supplements had higher mineral intakes from food sources in the diet than did non-users. For all minerals examined, and particularly for calcium and magnesium in men and women and iron in women, supplement use decreased the prevalence of intake inadequacy for each respective mineral; however, supplements contributed to risk of potentially excessive intakes for calcium, iron, zinc and magnesium.