Bruce Horovitz

USA TODAY

The nation's two biggest beer makers are getting cold water thrown on their long-held policies of not disclosing all of the ingredients in their brews.

An online petition to change that — asking Anheuser-Busch and Miller Coors to post their beer product ingredients online — is being spearheaded by influential food blogger and nutritional activist Vani Hari, creator of FoodBabe.com.

At issue: It's the Treasury Department — not the Food and Drug Administration — that regulates beer. So the beer giants are not required to post ingredients on their labels or on their websites. Hari says even though the law doesn't require it, consumers have a right to know what's in the beer they drink. And she wants the beer giants to post it on their websites.

"We know more about what's in a bottle of Windex and Coca-Cola than we about one of the world's most popular drinks, beer," says Hari.

Among the ingredients Hari has discovered in some beers sold by the big beer makers: Prolyene Glycol, which is commonly used in airplane de-icing liquids, but used by some beermakers to control the head on their beers. Also, something called Isinglass, which comes from fish swim bladders, is used to make beer more clear. Some use high-fructose corn syrup, artificial colors and stabilizers that are linked to intestinal inflammation, she says.

Hari says she's not asking beer makers to change their formulas — or their labels. "I'm not asking for government involvement," she says. "I'm asking for voluntary disclosure on their websites."

Miller, in a statement sent to USA TODAY, says it's getting there. "MillerCoors led all alcohol beverage companies with a voluntary nutritional labeling panel earlier this year starting with our Miller64 brand. We value transparency and we will strongly consider the request for putting more ingredient information online," said the statement from spokesman Pete Marino.

But Hari rejects that. "Nutritional labeling is distinctly different than ingredient disclosure, and it is not enough transparency for consumers to avoid additives like the corn syrup they use in many of their beers," she says.

A-B, in a statement, says that its beers are made "to the highest standards of quality and consistency, (and) use pure, fresh, natural ingredients." It says its beer ingredients meet all standards for food safety set by the Alcohol and Tobacco Tax and Trade Bureau and the U.S. Food & Drug Administration. And it lists information about nutrition and ingredients at its global consumer information website, www.tapintoyourbeer.com.

The action comes at a time when consumers are increasingly demanding more information about what's in their products. Just last week, Panera announced plans to remove all artificial additives from its food menu by the end of 2016. Petitions by Hari are no small matter for food and beverage makers. One of her previous petitions coaxed an embarrassed Subway to agree to remove a chemical from its sandwich breads that's commonly used in yoga mats and shoe rubber.

Hari's previous petitions targeting not only Subway, but also Kraft and Chipotle, have garnered more than 500,000 signatures, she says. Because consumers — particularly tech-savvy Millennials — are so concerned about food ingredients, the big food and beverage makers are increasingly worried about consumer backlash from such petitions going viral.

Signatures on Hari's petition will be sent via e-mail to the CEOs of Anheuser-Busch and Miller Coors.

"It's shocking that these companies don't disclose their ingredients," says Hari. "But it's even more shocking that millions of us drink these beers without knowing what's actually in them."