The Federal Trade Commission is suing the marketers of AcaiPure and colon supplement colopure for consumer fraud.
The products advertised on radio, television and the Internet for as little as 99 cents shipping feature fake endorsements by U.S. television talk show diva Oprah Winfrey and celebrity lifestyle host Rachel Ray.
"Too many 'free' offers come with strings attached," David Vladeck, director of the FTC's Bureau of Consumer Protection, said in a release. "In this case, the defendants promised buyers a 'risk free' trial and then illegally billed their credit cards again and again -- and again. We estimate about a million people have fallen victim to this scam."
Vladeck said he would not use the supplement because the pills do not always contain acai, a purple berry smaller than a grape harvested from the acai palm tree.
The acai berry, native to South and Central America, is touted for its antioxidant properties but there is no scientific evidence it can contribute to rapid weight loss. The ads claimed weight loss of 25 to 30 pounds in the first month.
Since 2007, more than 2,800 complaints have been filed against Phoenix-based Central Coast Nutraceuticals Inc. with law enforcement agencies and the Better Business Bureau, the FTC said.