Some Manganese Supplements May Exceed Safe Intake Levels

January 31, 2001

New York (MedscapeWire) Jan 31 — issued an alert on Monday that that some glucosamine and chondroitin products, used for osteoarthritis, exceed newly established upper intake levels for manganese. According to the Institute of Medicine's newly-released guidelines, the tolerable upper intake level (UL) for manganese in adults is 11 milligrams per day. Neurologic adverse effects, similar to symptoms caused by Parkinson's disease, have been observed in individuals who have consumed high amounts of manganese, and iron absorption by the gut may be inhibited.

Two products evaluated in's Glucosamine and Chondroitin Product Review last year claim to contain, respectively, 25 mg and 30 mg of manganese per suggested daily serving. These amounts far exceed the recommended UL of 11 mg per day, which includes all dietary and supplement intake. One of these products had already failed's initial testing for not having its claimed amount of chondroitin. The other product initially passed the review, but has now been removed from's list of Quality Approved Products in light of the new recommendations.

Physicans should evaluate the manganese in their patients' diets as well as supplements to determine if the combined level may be in excess of the new UL. Vegetarian patients might already have significant manganese intake (10 to 20 mg per day) from their diets.

The UL is the highest level of daily intake that is likely to pose no risk of adverse health effects for almost all individuals in the general population. As intake increases above the UL, the risk of adverse effects may increase. Individuals with liver disease may experience adverse effects at lower intake levels of manganese than the general population.

Manganese is an essential nutrient involved in bone formation and in protein, fat, and carbohydrate metabolism. Nuts, legumes, tea, and whole grains are rich sources of manganese. The recommended adequate intake of manganese for adults is approximately 2 milligrams per day, which is similar to the intake levels from typical American diets.


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