Scientists in Britain have pulled together previous studies about an ingredient in some herbal medicines that can cause severe kidney disease and cancer.
The research is a wake-up call to users of some traditional remedies and to governments that could regulate use of the herbs.
In the early 1990s, an epidemic of kidney disease broke out in Belgium among young women who had been treated with Chinese herbal medicines at a weight-loss clinic. The herbs come from a family called Aristolochia. They are used to treat skin conditions, joint pain and other symptoms.
Graham Lord of Kings College London says the ailment was traced to aristolochic acid, an ingredient in some of the herbs.
“It binds to DNA and causes kidney disease," Lord says. "It causes cancer in areas where it’s most concentrated, which probably explains why the cancers are mostly focused around the urinary tract and the kidney.”
Lord is the lead author of a new paper describing the kidney disease, now known as aristolochic acid neuropathy (AAN), and suggesting standardized diagnosis and treatment protocols.
Herbs containing aristolochic acid are banned from Europe and the United States, and the resulting form of kidney disease is now mostly found elsewhere.
“Import bans, working with the herbal practitioners that in the past have used this drug, can be extraordinarily effective,” Lord says.
In places where use of these herbs is common, cases of AAN persist.
“In Chinese Taiwan, there’s epidemiological surveys suggesting that tens if not hundreds of thousands of people have been exposed to this particular herb,” says Lord, who acknowledges it’s hard to know how many people are actually getting kidney disease from these herbs. A definitive diagnosis requires advanced testing to differentiate from other kinds of kidney disease.
In his review of two decades of published medical literature, Lord found reports of the disease in Europe, North America and Asia. But nothing in other areas of the world where herbal medicines are widely used.
“That’s probably because we’ve not looked in a systematic manner," he says. "It would surprise me if there wasn’t an incidence of this disease in Africa and in South America as well.”
Treatment of AAN usually requires dialysis or even kidney transplant. Lord says it’s important to identify kidney disease caused by aristolochic acid, so doctors can monitor the patient for cancer, which is more likely than with other causes of kidney failure.