A Chinese herb that damaged the kidneys of dozens of Belgian dieters in the 1990s has been found to pack a vicious second punch--cancer or precancerous lesions, according to a report in the 8 June issue of The New England Journal of Medicine. These findings draw one of the strongest links yet between use of an herbal product and cancer and, critics argue, should serve as a grim warning that dietary supplements need more regulation.
In 1992, symptoms of kidney failure began showing up among Belgians who had taken a mixture of Chinese herbs and Western drugs prescribed for weight loss. On closer examination, researchers discovered an herbal mix-up: Instead of containing the plant Stephania tetrandra, as labeled, the herbal pills contained derivatives of Aristolochia fangchi, an herb known to be laden with potent kidney toxins and carcinogens. Of the estimated 10,000 people who took the pills, at least 70 experienced complete kidney failure, and some 50 others suffered kidney damage severe enough to require treatment.
The first kidney cancers were found among these patients in 1994. To deter onset of the disease in more patients, doctors at Erasme Hospital in Brussels counseled those whose kidneys and ureters had stopped functioning to consider surgical removal of the organs. Thirty-nine people opted for the operation over the past several years. When a team of researchers coordinated by kidney specialist Joélle Nortier inspected the excised tissues, they were startled to discover that cancer had already developed in 18 patients, and precancerous lesions (dysplasia) were present in 19 others. Prescription records confirmed that patients who had taken the most diet pills were most likely to have had cancer. As further proof that Aristolochia was to blame, the team found that DNA in the kidneys of these patients carried malformations typical of damage caused by the plant's toxins.
Belgium stopped importing Aristolochia and herbal mixes that might contain it in 1992. But there's little to prevent a similar disaster in the United States and other countries, asserts David Kessler, dean of Yale University School of Medicine and former commissioner of the Food and Drug Administration (FDA). Under the 1994 Dietary Supplement Act, manufacturers don't have to show a herbal remedy's safety or effectiveness before marketing it, and the FDA's hands are tied "until the horse is out of the barn," he says.
Even so, counters Varro Tyler, retired dean of the School of Pharmacy at Purdue University in Indiana, FDA could still be more vigilant, specifically by testing products that are on the market and banning them if they're harmful. "They have to take the initiative, which they've not done," says Tyler. But he agrees that until laws are beefed up, consumers can't know for sure that what they're getting at the health store is safe.