Last week the FDA announced that a number of dietary supplements promoted for weight loss and sold on various web sites and in retail stores contain an unlabeled ingredient: the weight loss drug sibutramine (Meridia), which was removed from the market in the US and Canada in 2010 because of toxicity concerns. The adulterated products include Bella VI Insane Amp’d, Bella Vi Amp’d Up, Be Inspired, Dr. Mao Slimming Capsules, Burn 7, and Perfect Body Solutions. The FDA advises consumers not to purchase or use them and, if they have already bought or used them, to stop using them and throw them away.
Sibutramine was removed from the market here because of a prospective, randomized postmarketing study that found a significantly higher incidence of non-fatal myocardial infarction, nonfatal stroke, cardiovascular death, or resuscitation after cardiac arrest in subjects taking sibutramine than in those taking a placebo. It was also withdrawn in Europe and Australia but remains on the market in some other countries. When it was first marketed in the US in 1998, The Medical Letter evaluated sibutramine as only modestly and transiently effective in promoting weight loss, observed that it caused dose-related increases in blood pressure and heart rate, and advised against using it.
Unlabeled ingredients found in dietary supplements promoted for weight loss can be much scarier than sibutramine. In the early 1990’s about 100 women in Brussels who had taken Chinese herbs for weight loss developed fibrosing interstitial nephritis caused by aristolochic acid, a known nephrotoxin that was not listed among the ingredients on their labels. At least 70 of these women required dialysis or transplantation, and at least 18 developed urothelial cancer.
And these are the dangers we know about, in the one instance because the FDA insisted on a postmarketing trial and in the other because the toxicity developed so rapidly with such catastrophic results that someone could make the connection. It has always fascinated me that the danger of taking diethylstilbestrol (DES) to prevent miscarriage was recognized because it caused vaginal cancer in the female offspring, and vaginal cancer was virtually unheard of, so someone looked back to see what these women had in common. If it had caused an increase of any magnitude in one or more common cancers such as breast, uterus or cervix, I doubt that anyone would have made the connection.
We have written in The Medical Letter over and over again that the main problems with dietary supplements are that their potency may vary and their purity is suspect. We have advised health care providers over and over again to tell their patients not to take them because we really don’t know what is in them. Hooray for the FDA for finding sibutramine in these products promoted for weight loss. But much more remains to be done.