A March 14, 2007 piece describes colon-irrigation advocate Lidia Huzar-Nash but also mentions skepticism about colonics, quoting ACSH Advisor Dr. Stephen Barrett:
Supporters of colonic hydrotherapy believe it cleanses and detoxifies the system. Traditional medicine takes issue with that view, says Dr. Stephen Barrett, a retired psychiatrist in Allentown, PA, who runs a consumer Web site, Quackwatch.org. He also is vice-president of the National Council Against Health Fraud, an advisory group of the American Council on Science and Health.
That term, "cleansing the system," that's a quacky word, he said in a telephone interview. Barrett said the human body is built to clean itself.
Your liver detoxifies any foreign chemicals, which are then excreted by the kidney, he said. The idea of colon hydrotherapy was abandoned by mainstream medicine long ago, he said.
About 100 years ago or more, this idea of the large intestine as a toxic waste dump was popular, Barrett said. But it was medically abandoned in the 1920s or so. Doctors look inside the bowel everyday, and they don't see that (buildup), he said.
See also: "How Clean Should Your Colon Be?" by ACSH's Karen Schneider.