A proposed class action has been filed in California, accusing Dannon Co Inc of false advertising in their marketing of yogurt containing probiotic bacteria, alleging that the claimed health benefits have never been proven.

(Dannon products are spelled "Danone" in Canada and are part of Groupe Danone, of France.)

The lawsuit contends Dannon's own studies failed to support its advertised claims that its Activia, Activia Lite and DanActive were "clinically" and "scientifically" "proven" to have health benefits that other yogurts did not.

The suit alleges that all U.S. purchasers of Activia, Activia Lite and DanActive should be compensated. It also demands that Dannon begin "a corrective advertising campaign."

Dannon spokesman Michael Neuwirth said the company was not aware of the lawsuit but stood by "the claims of our products and the clinical studies which support them."

The packaging of Activia, launched in the United States in 2006 and sold as well in Canada, says it contains trademarked bacteria called "Bifidus regularis" which "helps naturally regulate your digestive system."

The DanActive probiotic drink product was recently launched in Canada. The Danone Canada website says the product contains "unique bacterial culture L. casei Defensis exclusive to Danone."

"DanActiveTM helps strengthen the body's natural defenses when consumed daily. Scientific studies (37, more precisely) have proven DanActive's effectiveness," the website claims.

The U.S. lawsuit cites its own scientific reports showing that there was no conclusive evidence that "Bifidus regularis" prevented illness or was beneficial to healthy adults -- and that Dannon knew this.

The suit claims Dannon has spent "far more than $100 million" to convey deceptive messages to U.S. consumers while charging 30 per cent more for the product than other yogurts.

The ads helped Dannon sell hundreds of millions of dollars of ordinary yogurt at inflated prices, plaintiffs' attorney Timothy Blood of Coughlin Stoia Geller Rudman & Robbins said.

The lawsuit would not apply to Canadian consumers.

Dr. Gregor Reid, a microbiologist at the University of Western Ontario and the director of the Canadian Research and Development Centre for Probiotics says Danone and others have completed vast amounts of research on the probiotics involved.

"So I object when someone says that Activia and DanActive are not based on science. There is plenty of scientific data on both," he told CTV.ca.

"I'm aware of four studies on Activia's effect on regularity alone. So this is certainly not a case where they made outrageous claims about Activia with no data whatsoever. The science behind DanActive, as well, has been very well documented - certainly over 100 papers, many of which were clinical trials.

"So to say there is no data is not true at all."