Updated

You'll have to pardon the puns, but...

Taco Bell might want to change it's "Think Outside the Bun" campaign to "What's Really in That Taco?" after a class-action lawsuit filed against the fast-food giant claimed its taco filler doesn't, um, "meat" federal standards.

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The suit against the YUM-brands chain also has a "beef" with the company's advertising, charging its claims of using "seasoned ground beef" or "seasoned beef" in its food products is false.

According to the suit filed by the Alabama law firm Beasley, Allen, Crow, Methvin, Portis & Miles, the YUM-brands owned chain is using a meat mixture that contains binders and extenders, and does not meet the minimum requirements set by the U.S. Department of Agriculture to be labeled as "beef.”

Attorney Dee Miles said the meat mixture contained just 35 percent beef, with the remaining 65 percent containing water, wheat oats, soy lecithin, maltodrextrin, anti-dusting agent and modified corn starch.

The suit was filed on behalf of Taco Bell customer and California resident Amanda Obney, who is not seeking monetary damages, but instead wants a court to order Taco Bell to be honest in its advertising.

"We are asking that they stop saying that they are selling beef," Miles said.

Irvine, Calif.-based Taco Bell spokesman Rob Poetsch said the company denies that its advertising is misleading and said the company would "vigorously defend the suit."

While the company does list its ingredients on its website — and indicates whether they are allergens — registered dietitian and Fox News contributor Tanya Zuckerbrot said the fillers could be a danger for some consumers.

“Wheat oats, soy lecithin and maltodrextrin are common allergens that are often added to processed foods as fillers because they are much less expensive than meat,” she said. “Aside from being misleading, this form of false advertising puts the consumer at risk as well.”

Zuckerbrot said according to the USDA, “ground beef can have seasonings, but no water, phosphates, extenders, or binders added.” The meat from Taco Bell does not meet the minimum requirements set by the USDA, she said.

“Rather than Taco Bell calling the meat ‘seasoned ground beef’ they should refer to it as ‘mixed meat’ and list the additional ingredients so consumers can know what they are putting into their mouths,” she said.

The Associated Press contributed to this article.