Chinese Herb Remains Health Threat Despite Widespread Bans

Steven Fox

March 18, 2013

A widely banned type of Chinese herb that has been linked to an aggressive form of kidney disease remains readily available via the Internet and poses enormous potential risk worldwide, according to a review article in the March 19 issue of Annals of Internal Medicine.

The authors of the review say herbs containing aristolochic acid (AA) are associated with high long-term risk for AA nephropathy (AAN) and have been linked to increased risk for urothelial cancer.

The threat is not new. In the early 1990s an epidemic of rapidly progressive renal disease was identified in a group of young female patients in Belgium. The cause was traced to a weight-loss clinic that had administered herbs containing AA, along with other medicines, to the women.

Investigators subsequently identified AA as the causative agent. AA is found in the Aristolochia genus of plants, examples of which are commonly known as birthwort or Dutchman's pipe.

These herbs have been banned in many countries, note M. Refik Gökmen, PhD, MA, MBBS, Department of Experimental Immunobiology, Kings College, London, United Kingdom and coauthors. "However," they write, "there is evidence that large-scale exposure to AA continues in Asia, with potentially devastating public health implications."

To find out more about the effect of AA, the investigators reviewed papers published since 1960, using search engines of the World Health Organization, US Food and Drug Administration, and European Union, as well as Web sites of regulatory bodies in countries where cases of AAN have been reported.

They found that most patients with AAN present with renal insufficiency, anemia, a urine sediment containing only a few erythrocytes and leukocytes, and mild proteinuria (typically < 1.5 g/24 hours).

"Aristolochic acid nephropathy is notable for its rapid progression to end-stage kidney disease despite cessation of AA-containing products," the authors write.

Histologic examination remains the best way to diagnose AAN, the authors say. "The most striking finding is extensive interstitial fibrosis associated with tubular atrophy and low numbers of chronic inflammatory cells decreasing from the outer to the inner cortical labyrinth," they write.

However, researchers have not conducted randomized clinical trials to sort out how best to manage the condition. Therefore, the best information regarding the problem comes from case series, expert opinion, and inferences from animal data.

On the basis of those data, the authors say that priorities in the management of AAN should approximate the priorities used in managing kidney disease triggered by other causes. These include close attention to control of blood pressure, reduction of cardiovascular risks, management of metabolic complications, and timely preparation for renal transplantation.

However, they emphasize that prevention is key. "Perhaps most important, improved regulation of herbal medicines could help eradicate this entirely preventable illness," they conclude.

The preparation of this review was supported in part by a project grant from the Association for International Cancer Research. The authors have disclosed no relevant financial relationships.

Ann Intern Med. 2013;158:469-477. Abstract