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Sept. 19, 2000 -- From women trying to reduce their risk of osteoporosis to children who are lactose intolerant, millions of people take calcium supplements every day, and most assume they're safe and healthy.

That's why the findings of a new study may come as a surprise to many people. The study, of calcium supplements available from national chain pharmacies and discount stores, indicates that some contain enough lead to be dangerous if the supplements are taken in high doses, researchers say.

That doesn't necessarily mean you should stop taking your supplement. For most people, the amounts of lead found in the supplements are not harmful, and one expert notes that lead is found naturally in many foods. Still, if you're taking high doses of calcium, you might want to ask a doctor or pharmacist about your supplement's safety.

Researchers have known for decades that most calcium supplements contain some lead, says Edward A. Ross, MD, author of the study published in the Journal of the American Medical Association. Some, but not all, of these supplements are made from oyster shells, which contain lead that is generally removed in the manufacturing process. Ross is director of the end-stage renal disease program at the University of Florida in Gainesville.

In his study of 21 over-the-counter calcium supplements and two prescription formulations, Ross found that approximately one-third contained measurable lead. Makers of supplements are not required to list lead content on their labels, but some are marketed as being "essentially lead-free." In the study, two supplements that made that claim had no measurable lead content.

Of the better-known brands, both Tums Ultra and Tums EX calcium-containing antacids had levels of lead that were too low to measure by the study's standards, but Caltrate and one Eckerd brand of calcium supplements contained levels of lead that Ross estimates could exceed safe limits if taken at doses commonly prescribed for the prevention of osteoporosis.

"The labels don't help you at all," Ross says. "You might get lucky and find one that is essentially lead-free, but there is no uniform regulation for the labeling." Because of that, he says, consumers can't assume that name brands are better than lesser-known names or, for that matter, that all chain pharmacy brands are alike. Although one of three Eckerd brand supplements tested high, for instance, two Walgreens brand supplements had lead levels that were too low to measure.

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