Aristolochic Acid by Ray Sahelian, M.D.

Aristolochic acid is present in at least 65 different kinds of plants, many of which are used as herbal folk remedies. Aristolochic acid is considered one of the most potent plant carcinogens in humans and animals. It has been associated with the development of urothelial cancers in humans, and kidney and forestomach tumors in rats. Prolonged exposure to aristolochic acid was shown to pose rapid progressive renal fibrosis in Belgian women in a slimming regime in the early 1990s. Aristolochic acid has demonstrated to be strong carcinogen in rats. The carcinogenicity of aristolochic acid is generally believed to be related to the nitro-reduction of aristolochic acid, in which the aristolactam-nitriumion ion with a delocalized positive charge is the ultimate carcinogen. Certain frequently used Chinese herbal medicines commonly used for weight control, may contain toxic Aristolochia species, which have been associated with severe nephropathy and urothelial cancer in humans and animals. The toxic entities in Aristolochia species are aristolochic acid-I (AA-I) and aristolochic acid-II (AA-II).

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Xi Xin

Aristolochic acid found in a Chinese herbal formulation called Xi Xin has been found to cause nephropathy.

Longdan Xierganwan

Longdan Xierganwan appears to have played a role in the development of bladder cancer and kidney disease in a 30-year-old Chinese man. In July 2003, the man presented to Whittington Hospital in London after referral from his family physician for blood in the urine. Further questioning revealed that the man had been taking Longdan Xierganwan for at least 5 years to "enhance" his liver. His tests confirmed bladder cancer. Although the patient stopped using Longdan Xierganwan, which, at the time, contained aristolochic acid, a chemical linked to kidney trouble and bladder cancer, he developed recurrent tumors. In April 2004, the patient had a kidney biopsy and was found to have interstitial fibrosis consistent with Chinese herbal nephropathy (kidney disease). Since then, he has progressed to end-stage renal failure and is now preparing for dialysis. Longdan Xierganwan no longer contains aristolochic acid. China Tong Ren Tang, the manufacturer of the product, changed the formula in 2002 after the US Food and Drug Administration issued a warning about the toxic effects on the kidneys.