Some weight loss pills still list banned ingredients on their labels, according to a new study in the Journal of American Pharmacists Association, adding to the long list of concerns about the dangers of taking dietary supplements.  

As Consumer Reports noted in our investigation "Supplements Can Make You Sick," dietary supplements are regulated differently than prescription drugs: Supplement makers don't have to prove that their products are safe for their intended use, or that they work as advertised, or even that their packages contain what their labels say they do. As a result, the products pose a number of risks to consumers. They can be contaminated with microbes or heavy metals, dangerously mislabeled, or—as the current study shows—spiked with illegal substances. 

Researchers at Regis University in Denver visited one of every vitamin-selling retail chain within a 10-mile radius of their campus, including GNC, Vitamin World, Walgreens, Walmart, and Whole Foods. They examined the weight loss pills in each of those venues, and found a total of 51 supplements containing ingredients that were either banned or strongly discouraged by the Food and Drug Administration. (In all, 17 products contained at least one banned ingredient, and 46 contained at least one discouraged ingredient). Overall, the study authors say, stores dedicated to supplement and sports nutrition had the most supplements that included banned and discouraged ingredients.

The banned ingredients included ephedra and DMAA, both of which have made headlines in the past. Ephedra was linked to more than 800 reports of serious toxicity and caused 22 deaths (including of one professional baseball player) before the FDA succeeded in banning it. And DMAA was linked to a rash of serious problems—including heart, liver and neurological damage—and several deaths, before the FDA made it illegal to use.

Stimulants and Other Worrisome Ingredients

The researchers say they found other causes for concern as well. “Many supplements contained a variety of ingredients that were used for the same purpose, especially stimulants” the authors wrote. For example, a product labeled Commander, made by a company called 1st Phorm, lists caffeine, cocoa extract, BMPEA, evodiamine, synephrime, green coffee bean extract, and guarana seed extract among its ingredients, all seven of which are stimulants.

Some stimulant-laden weight loss pills contained additional chemicals that can help the stimulants stay in the body longer, thereby enhancing their effect. For example, Thermogenic Pharma Athlete contained ephedra, DMAA, and a chemical called 6,7-dihydroxybegamottin, which is known to interfere with metabolism.

Other weight loss pills boasted an absence of one chemical, like caffeine, but still contained other chemicals with similar (or even near-identical) effects. For example, Phenolox (shown above), a weight loss supplement made by Metabolic Nutrition, is advertised as being “caffeine and yohimbine free,” but contains several other ingredients that cause similar effects.

While such maneuvers are often legal, they can present unique dangers for consumers, especially those who need to avoid caffeine due to medical conditions like diabetes, epilepsy, and heart arrhythmias.

Another trick the researchers found is to camouflage dangerous or undesirable ingredients with different, but still technically correct names. For example, caffeine is often listed by its scientific name 1,3,7-trimethylxanthine. “It’s deceiving,” says Pieter Cohen, M.D., a Harvard University researcher who was not involved in the current study. “And it’s potentially dangerous for consumer.”