Chicken, fake and real, looks to be a target of several consumer and nutrition groups.

The Center for Science in the Public Interest is acting as co-counsel on a lawsuit filed Thursday by an Arizona woman accusing Quorn Foods Inc. of not disclosing on labels that some people have serious allergic reactions to the main ingredient in its Quorn line of meat substitutes.

The lawsuit, which seeks class-action status, was filed in Superior Court in the Judicial District of Stamford-Norwalk, the state in which the U.S. offices of the British company are located. The U.S. headquarters are in Westport.

Quorn is derived from a protein-rich fungus, which the company grows in large vats. The fungus, Fusarium venenatum, was discovered growing in a field in Buckinghamshire, England, in the late 1960s and developed as a food product.

"In the 1960s, people were concerned that we would run out of protein and started a search for new protein sources that could feed the world and discovered this fungus that grows naturally in soil. It makes a delicious and nutritious meat alternative. It has as much protein as eggs and as much fiber as broccoli on an ounce per ounce basis," said David Wilson, managing director of Quorn, which is a division Marlow Foods, a British company.

He said the lawsuit was frivolous and unwarranted.

"Quorn has been in the U.S. market since 2002 and has been enjoyed by millions of Americans. We have developed our labeling

with the Food and Drug Administration and it is accurate and fair," Wilson said.

But the center, a Washington-based nonprofit food safety and nutrition watchdog group, disagrees. It said that more than 1,000 people have reported suffering from nausea, vomiting and diarrhea after eating Quorn's products, which include Chik'n Nuggets, Patties, Garlic & Herb Cutlets, Naked Cutlets, Recipe Tenders and Gruyere Cutlets.

According to the lawsuit, Kathy Cardinale, a 43-year-old advertising executive, ate Quorn's Chik'n Patties on three separate occasions in 2008 and "became violently ill" each time.

Meanwhile, the vegan-oriented Physicians Committee for Responsible Medicine says it is readying a lawsuit against the giant KFC fast-food chain under California law for failing to warn consumers that the chain's new grilled chicken product contains a dangerous carcinogen.

The anti-meat advocacy group said that it commissioned independent laboratory tests that show that KFC's grilled chicken contains PhIP, a chemical that it said can increase a person's risk of developing cancer even if consumed in small amounts.

Not disclosing the presence of the chemical violates California's public health law, known as Proposition 65, the group contends. It plans to file the lawsuit next week in Superior Court.

Earlier this year, the group sued hot dog makers, claiming that their products increase cancer risk and should carry a warning label similar to what comes on tobacco products.