Herbal remedies, an 'overlooked' global health hazard

Herbal remedies may seem safe because they have been used for many years, but a recent study has suggested something else.

Researchers from Baylor College of Medicine and Stony Brook University are raising awareness that long-term use of herbal remedies is no guarantee of their safety.

Dr. Donald M. Marcus and Dr. Arthur P. Grollman discussed the scientific evidence showing that the plant Aristolochia can cause aristolochic acid nephropathy (AAN). People with this condition experience interstitial nephritis, renal failure and cancers of the urinary track.

The authors remark that in Taiwan, according to the national prescription database, between 1997 and 2003, 8 million people were exposed to herbals containing Aristolochia. Studies of patients with renal failure and cancer in Taiwan and China show that tens of millions of people in those countries are at risk of AAN.

In genetically susceptible people, consuming Aristolochia can lead to the formation of complexes between aristolactam, a compound in Aristolachia, and DNA in renal tissues. These complexes lead to mutations in the TP53 tumor suppressor gene, which in turn initiate the process toward kidney cancer. Additional studies have shown that this process may also lead to the development of cancer in the liver and the bladder.

Marcus and Grollman indicate that other herbals and traditional medicines are responsible for severe adverse events in Africa and Asia, but in these cases epidemiological data are lacking.

Although Aristolochia has been used as a herbal remedy for more than 2000 years, "the intrinsic toxicities were not recognized, owing, in large part, to the latency period between exposure and the onset of symptomatic disease, and, in part, to genetic determinants that confer susceptibility to only approximately 5 percent of those exposed to this herb," said the authors. The long-term scientific study of AAN revealed the association of the disease with Aristolochia.

The authors emphasize that their primary concern is "the prevention of toxicities associated with herbal medicine and not a categorical rejection of traditional healing practices. Herbal remedies pose a global hazard. We encourage the global health community to take actions that will evaluate both long- and short-term safety, as well as the efficacy of botanical products in widespread use."

The study appears in EMBO reports.