More than one in five weight loss, slimming and diabetes supplements failed an evaluation by the US-based ConsumerLab.Com association.
The review by ConsumerLab.com looked at evidence for and against the use of popular ingredients used for such products and included laboratory testing of 18 dietary supplements containing chromium (used to aid sugar metabolism in diabetes and weight loss), CLA (conjugated linoleic acid, a polyunsaturated fatty acid found naturally in milk and meat fats which is used to increase lean body mass), and/or pyruvate (used to increase fat metabolism).
Other ingredients covered by the review include ephedra, hydroxycitric acid (HCA) from the fruit Garcinia cambogia and L-carnitine. The products tested consisted of seven CLA products, seven chromium products, two pyruvate products, and two combination products (one with pyruvate and chromium and the other containing chromium, Garcinia cambogia, CLA, L-carnitine and other ingredients).
Four of the products tested by ConsumerLab.com failed the evaluation, for a variety of reasons.
One product contained only 5 per cent of the labelled amount of chromium, and ConsumerLab.com said that such a reduction in the level of chromium "should be of concern to anyone relying on the product for its potential effect on insulin and blood sugar levels" .
A different chromium product was found to contain a very small amount of a toxic form of chromium - chromium (VI) or hexavalent chromium, an industrial by-product and a potential carcinogen. The amount found in the product would not be expected to be harmful but is not desirable, ConsumerLab.com said. Chromium (VI) was not detected in the other chromium products passing the review.
A third product, whose name included the words "Pyruvate 1000" and claimed to contain "1000mg of pyruvate complex" was considered potentially misleading as it was found to have only 240mg of pyruvate, while the fourth product which failed the test contained only 85 per cent of its claimed amount of pyruvate.
"This review is a microcosm of the problems ConsumerLab.com has found with other supplements," said Tod Cooperman, president of ConsumerLab.com. "Two products had less than what they claimed. Another was contaminated. And a third, due to vague language, could easily lead a consumer to expect four times the amount of active ingredient actually in the product. If a consumer is going to try a supplement, they should be able to get what they expect - nothing less and nothing more."
The products which passed the test include Puritan's Pride Chromium Picolinate, Vitamin World Naturally Inspired Yeast Free Chromium Picolinate, NOW CLA Dietary Supplement, and Nutrilite Trim Advantage Weight Management Support Pack. The complete list of products that passed the review, as well as tips on buying and using these types of supplements, can be found on the ConsumerLab.com website.