ConsumerLab.com Passes 90 Percent of Tested Magnesium Supplements

WHITE PLAINS, N.Y.--In the latest product review conducted by ConsumerLab.com, 90 percent of tested magnesium supplements passed. Two out of 19 failed because they contained lead levels that exceeded California's Proposition 65 recommendations, and one contained 50 percent more magnesium that what was listed on the product. Both failed products were magnesium-only supplements.

The recommended daily allowance of magnesium is 300 to 350 mg/d. The product that exceeded label claims delivered nearly 1,200 mg/d--three times the Upper Tolerable Intake Limit (UL) established by the National Academies of Science. An overdose of magnesium can cause vomiting, muscle weakness, difficulty breathing, dangerously low blood pressure and an irregular heartbeat.

"While there are times when it is appropriate to exceed the tolerable limit to prevent or treat deficiency, it seems irresponsible for a manufacturer to recommend a dose far in excess of the limit and, on top of that, put in one-and-a-half times the labeled amount," said Tod Cooperman, M.D., president of ConsumerLab.com. "All of the other products were well within range of their claims, indicating that accurate formulation is certainly possible." He added that the failed products were not grossly contaminated with lead, but they still had levels significantly above Prop 65's maximum recommendation of 0.5 mcg/d for magnesium-only products. Magnesium products containing calcium are allowed up to 1.5 mcg/d under Prop 65.

According to Max Motyka, M.S.R., Ph.D., director of Albion Laboratories' human products division, it is conceivable that the magnesium-only companies did not worry about lead levels since this is more of a calcium issue. (This concern has been occasionally raised since lead is naturally occurring in calcium; however, the lead levels are very minute and calcium acts to block lead absorption.) "Quite honestly, I am surprised anyone failed Consumerlab.com's test on magnesium quantity, since many of these companies--regardless of label claims--are using magnesium oxide, which is extremely inexpensive and comes at a high elemental magnesium value," Motyka said.

ConsumerLab.com also reported that all tablets disintegrated properly during testing, although capsules and enteric-coated products did not undergo disintegration testing.

More about these results can be found at www.consumerlab.com/results/magnesium.asp.