Thousands of Americans each year suffer liver injury from common drugs they take, but a growing percentage also experience liver damage from largely unregulated dietary supplements such as green tea extract used for weight loss. The American College of Gastroenterology released a new guideline last week warning physicians about the risks of supplements and how to advise about their use.
“We encourage patients to talk to their doctor about all medications, and herbal and dietary supplements should be no exception,” said Dr. Herbert Bonkovsky, a gastroenterologist with the Carolinas HealthCare System in Charlotte.
Damage from dietary supplements accounts for nearly 20 percent of drug-related liver injuries requiring hospital care, up from 7 percent a decade ago, the Drug-Induced Liver Injury Network says. The guideline lists the drugs that pose the biggest risk: the antibiotics amoxicillin and isoniazid and non-steroidal anti-inflammatory painkillers. For supplements, green tea extract, anabolic steroids, and pyrrolizidine alkaloids — in comfrey tea and some Chinese herbal medicines — topped the list. Bonkovsky said a cup of green tea has 50 to 150 milligrams of catechins — antioxidants that are the major active ingredients. In some green tea extract pills used for weight loss,
catechin levels can be over 700 mg. per pill, which can be toxic to the liver when taken multiple times a day.