I understand that calcium supplements contain lead. Is there a source of calcium that is lead-free? — Michael J. Hirsch, MD, New Orleans

Calcium supplements are usually manufactured from oyster shells and other organic sources. These sources may contain quantities of lead reflecting concentrations found in their natural environments. I checked with two manufacturers of calcium supplements (from different natural sources), both of which readily reported lead concentrations in their products and assured me that the values were well below federal guidelines. I was not able to locate a source of calcium that was confirmed to be lead-free. My conclusion from this research is that lead in calcium products does not pose a significant health risk and that the health benefits of calcium supplementation, when indicated, far exceed the resultant extra exposure to trivial amounts of lead. — Walter N. Kernan, MD (145-7)