What's in Your Beer? Fish Bladder and Antifreeze Ingredient? Food activist wants two major beer makers to disclose all their ingredients.

June 11, 2014  -- Food blogger Vani Hari's husband's favorite drink is beer and, just in time for his birthday this week, she is launching an online petition to ask the two biggest producers of American beer to list all their ingredients and brewing methods.

Hari claims some beers contain additives like high-fructose corn syrup, stabilizers and artificial flavoring, which have been linked to obesity, allergies, hyperactivity and gastrointestinal problems. She also alleges that big brewers use unappetizing things like propylene glycol – a foaming ingredient found in airplane deicing liquid – and even use fish swim bladders during brewing for clarity.

"That was alarming to me," Hari, 35, of North Carolina, told ABC News. "I thought beer was just hops, water, yeast, malt and barley."

The fact is no one but the manufacturer – not even Hari – knows for sure what's in beer or what’s used to make it, because the federal government does not require companies to disclose their ingredients or brewing processes. Hari is on a mission to get more transparency in the beer industry.

Her point is that consumers just don't know how their food and drink is made or what they put into their bodies.

"I just want full disclosure," she said, "not to change labels and go through government labels -- just to disclose it online so everyone can see."

Now, she has targeted Anheuser-Busch and MillerCoors, which are the two largest beer brewers in the United States, according to Millward Brown Optimor, a leading global research agency.

Both MillerCoors and Anheuser-Busch told ABC News that they were in full compliance with all federal and state labeling requirements.

An Anheuser-Busch spokesman told ABC News that it uses none of the ingredients cited by Hari in its "flagship brands," Budweiser and Bud Light.

Peter Marino, a spokesman for MillerCoors, told ABC News that its ingredients are "proprietary information."

"That being said, we are happy to provide allergen information, which, in our case, involves wheat," Marino said. "We do not use nuts or dairy in the brewing process. And we don't use fish bladders either."

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But Hari argues that proprietary recipes shouldn’t trump transparency.

"Coca Cola has kept their secret formula under lock and key for years," she said. "However, Coca Cola also releases the full set of ingredients on their labels -- something beer manufacturers have kept hidden for years and our government has neglected to mandate."

The average American drinks about 21 gallons of beer annually, making it the third-most-popular drink in the United States, after soda and bottled water, according to a 2010 article in Advertising Age. Beer is still the most popular alcoholic beverage, a favorite among 36 percent of Americans, according to a 2013 Gallup Poll.

"In this new decade of information about food and what we are consuming, we don't know what is in the world's most popular drink," said Hari.

Hari, an activist known as the Food Babe, takes credit for two other consumer victories: getting Kraft to remove yellow dyes from its children's Mac & Cheese products; and urging Subway to get an ingredient used in yoga mats out of its bread.

"My husband loves beer and it's one of the things that he brings into the house, and I didn't know what was in it," Hari told ABC News. ""I am very meticulous about ingredients that I put in my family's bodies. So I started to investigate."

Hari claims that MillerCoors has admitted to using high-fructose corn syrup in several of their brands, and said some of their products may contain genetically modified corn because of its prevalence in the U.S., but the companies would not comment on these claims to ABC News.

She also noted that some other brewers darken their beers with caramel color, a compound that is under review by the FDA for potential health hazards.

The FDA is currently reviewing if there should be limits on these colorings in soft drinks.

Neither MillerCoors nor Anheuser-Busch would comment to ABC News on whether their products contain caramel coloring.

As for fish bladders, some beer and wine manufacturers extract and dry them to use as filters, to help rid the beverage of particles.

The powder, known as isinglass, has historically had wound-healing properties, according to an April article in Newsweek. But, as the article noted, it renders those beverages "drinkable but also unsuitable for vegetarians."

"Just like dairy manufacturers pump cows with antibiotics and growth hormones, the beer companies should be up front about their processing and disclose that they are using fish bladders," said Hari.

She also alleged that some beer makers use "chemically altered hop extract," known as tetrahops, to add a bitter flavor and give it a longer shelf life.

Hari said she contacted the customer service departments of "every beer company under sun" for one year. Some released information on ingredients and others were not as responsive.

"They tell you the basic ingredients," she said, "but not the additives."

Beer is regulated by the Alcohol and Tobacco Tax and Trade Bureau, or TTB, which is part of the Treasury Department, but labeling is not required.

"However, an industry member who makes caloric or carbohydrate claims on a label must also include either a statement of average analysis, which provides the number of calories, as well as the number of grams of carbohydrates, protein and fat per serving size, or a serving facts statement, which adds the serving size and number of servings per container and may also include alcohol content," wrote TTB spokesman Thomas Hogue in an email to ABC News.

Allergen labeling is currently on a voluntary basis, although the TTB does require that additives like sulfite, which can cause life-threatening allergies, and yellow dye 5, which has been linked to hyperactivity in children, be on alcohol labels.

But alcohol makers must adhere to the "good manufacturing practices" enforced by the Food and Drug Administration and all its safety standards.

According to the FDA spokeswoman, Jennifer Dooren, substances directly added to food or that become part of food through contact must be safe, including ingredients used in "producing, manufacturing, packing, processing, preparing, treating, packaging, transporting or holding food."

Ingredients like high fructose corn syrup can be used "so long as their use is consistent" with the Code of Federal Regulations, or are generally recognized as safe, she said. The FDA maintains an inventory of "generally recognized as safe" or GRAS ingredients notifications on line.

Marino of MillerCoors wrote ABC News in an email, "If those regulations change, we certainly would be compliant."

"When we introduce a beer containing a non-traditional ingredient or utilizing a non-traditional brewing process, we must submit a formula to the TTB before receiving a Certificate of Label Approval (COLA)," wrote Marino. "That formula must contain a listing of all ingredients and the process that we will use in brewing our beers. Additionally, TTB may request a sample of our product and will periodically sample products in the marketplace to ensure the products comply with the approved formula and COLA. There is no TTB requirement to list the ingredients for beers on our labels since we are completely in compliance with all federal regulations controlling the brewing and labeling of our beers."

Marino added that MillerCoors was the first American alcohol company to participate in the TTB's new voluntary labeling guidelines as "step toward more transparency" with its brand Miller64.

"We are starting with Miller64 because, with its appeal to legal-drinking-age consumers who live an active, balanced lifestyle, we think the additional nutritional details will be especially relevant for Miller64 drinkers," he said. "This gives us an opportunity to get started down this path and learn more about consumer reaction."

An Anheuser-Busch spokesman told ABC News in an email that it "takes great pride in making our beers to the highest standards of quality and consistency, using pure, fresh, natural ingredients. For example, our flagship Budweiser and Bud Light brands are made with the best barley malt, rice, hops, yeast, and pure water."

The company said both those brands use American-grown rice, which by USDA standards does not contain genetically modified varieties. Anheuser-Busch cited its global consumer-information website for facts about ingredients and nutritional information.

"We, like all brewers large and small, brew all our beers to adhere to federal and state brewing and labeling standards," he said. "Our beer ingredients all meet TTB and FDA standards for food safety. ... Our beers must meet the high expectations of our consumers, which is why our high-quality ingredients and brewing standards are our top priority."

Hari said her initial research into beer ingredients stemmed from the 1982 book, "Chemicals Additives in Beer," by the Center for Science in the Public Interest. Now decades old, the book lists a number of ingredients that may or not be in beer today. But Michael Jacobson, the center's current director, said that what’s in beer is still “a big secret" and consumers deserve to know.

"Just because it sounds scary, doesn't mean the product is dangerous," he said. "It's my feeling that health problems or no health problems, consumers have a right to know the ingredients.”

Propylene glycol, which Hari pointed out is also in antifreeze, is a "harmless food additive," according to Jacobson. Even the permitted food dyes -- blue 1, red 40 and yellow 5 (which requires labeling) -- are rarely used in beer except to mix yellow and blue for green on St. Patrick's Day, he said.

"I presume there aren't many kids drinking artificially colored beer,” he said.

But caramel colorings that have been treated with ammonia in dark beers can be "a problem," he said, "though the caramel coloring industry has been cleaning up its act."

"[Hari] is generally in the right direction," he said. "She exaggerates, but who cares compared to the fact that these million-dollar companies refuse to disclose their ingredients and the government fails to require it.