Dosage Key to Zinc's Immune Health Benefits

WHITE PLAINS, NYZinc supplements touted for immune and other benefits are most effective when their dosages reflect the clinical studies showing beneficial results, and Consumerlab.com  has found  not all zinc supplements on the market are accomplishing such dosing. As part of its relatively small survey, the company purchased popular zinc supplements from retail stores and tested their contents, comparing results with dosages shown to work in clinical trials on immune benefits. While all of the zinc products contained their the amount of zinc listed on their respective labels, and none contained an unacceptable level of lead, only one of the four lozenge products selected specifically for immune marketing had a dosage comparable to the studies.

All the products tested appear to have met quality standards, but Consumerlab noted highlighted what it called notable differences between the products, including cost and dosage (relative to the subcategory, such as immune health). The company said it found a large variation in price for products offering doses of 50 mg zinc, ranging from as little as 3 cents to as much as 18 cents, or even more for products with additional ingredients.

 In addition to the immune research dosage comparison, the company reported the most common dosage among zinc supplements (liquids and pills) was about 50 mg/d, which is above the Upper Tolerable Intake Level of 40 mg/d. However, they noted this dose correlated to research showing positive results on addressing zinc deficiency as well as reflecting the high-dose approach used in research on various diseases such as acne, depression and anorexia nervosa.

Dosing comparisons were made not only to immune research, but also studies on vision, specifically the Age-Related Eye Disease Study (AREDS) which contains zinc (80 mg), vitamin A (400 IU as beta carotene) and other antioxidants. Consumerlab noted two of the tested products targeted eye health met the AREDS dosage levels, but one product cost 30-percent less than the other.

Tod Cooperman, M.D., president of ConsumerLab.com, said not all supplements provide a dosage that has been proven effective. Our report on zinc supplements can help guide consumers to products that are properly made and deliver the correct dosage for specific uses," he said, adding people should avoid taking too much zinc over long periods of time, as it can have adverse effects, including reduced copper absorption and immune suppression.

For more information on the testing and results, visit Consumerlab.com. The full details, including the names of products tested, requires registration, which includes a fee.