Ingredient in herbal medicines linked to urothelial cancer

If you've ever considered taking an herbal medicines under the theory that it can't hurt and it might help, read this: A study published online Monday by the Proceedings of the National Academy of Sciences reports that people who thought they were taking a harmless weightloss supplement wound up with a type of bladder cancer as a result. and Taiwan, point the finger at an herbal ingredient called aristolochic acid, or AA. It comes from plants, including wild ginger (Asarum canadense), that have been used in Chinese medicine to treat "stomach ailments, to restore a woman's energy after the birth of a child, to treat cough, allergy and breathing problems, and in some weightloss formulas," according to this 2009 story from the Los Angeles Times Health section. Scientists have been suspicious of AA for more than a decade. Food and Drug Administration warned healthcare professionals that aristolochic acid could cause cancer and kidney damage. It issued a followup letter the next year and also warned manufacturers of herbal supplements to avoid using AA in their products, which aren't regulated by the government. Times story. As Melissa Healy reported:

"The herbal medicines of aristolochic acid came to light when more than 100 women participating in a weightloss program in Belgium developed kidney damage and urinary tract cancers. All had been prescribed an herbal weightloss remedy that contained it. Though banned throughout Europe and in Japan, Aristolochia extracts continue to be used widely in China. Any product bearing the species name 'Aristolochia,' 'Bragantia' or 'Asarum' should be avoided." The country with the highest incidence of upper urinary tract urothelial carcinomas is Taiwan, according to the new PNAS study. Taiwan is also a place where herbs containing AA have been popular for a long time. So researchers looked for a link between the two.

They compared 151 patients with the urothelial cancers to a "control" group of 25 patients with a type of kidney cancer called renal cell carcinoma. They found that aristolochic acid prompted a specific type of mutation on a tumor suppressor gene known as TP53 a mutation that leads to urothelial cancer. They concluded that the widespread use of AAcontaining plants in Chinese herbal medicine is a significant factor in the growth of urothelial cancers in Taiwan over the past quarter century. The researchers noted that onethird of people in Taiwan have received a prescription for an herbal medicine containing AA, and a lot more people probably have been exposed to it through overthecounter products. Epidemiological evidence suggests that the more AA people consume over a lifetime, the more likely they are to develop urothelial cancers, they wrote. What's more, the ingredient is also common in China and elsewhere in Asia and once exposure to AA causes the dangerous genetic change, people's risk of developing urothelial cancer remains "significant" for the rest of their lives.