GNC has agreed to institute new testing procedures on its herbal products, after the New York State Attorney General’s office accused the company and other major retailers of selling adulterated and/or mislabeled dietary supplements.

The company is the nation’s largest specialty retailer of dietary supplements, according to The New York Times. The new testing procedures will greatly exceed quality controls required by federal law.

New York State Attorney General Eric Schneiderman last month accused GNC, Target, Walgreens and Walmart of selling fraudulent or contaminated herbal supplements.

In a news release, GNC said its herbal products have passed several rigorous quality control tests. Over the next 18 months, the company will add additional quality control measures. The new tests will use advanced DNA methods to authenticate the plants used in its store-brand herbal supplements. The company will extensively test for common allergens such as soy, tree nuts and wheat.

In February, New York State authorities said they had conducted tests on products including echinacea, ginseng and St. John’s wort. They found many products did not contain any of the herbs listed on the label. In many cases, pills labeled medicinal herbs mostly consisted of powdered rice, houseplants and asparagus.

Some pills contained substances that could be dangerous for people with allergies. For example, one product sold at Walmart as ginko bilboa contained wheat, even though the label said the product contained no wheat or gluten. Some GNC products had pills that contained powdered legumes, the class of plants that includes peanuts and soybeans.

Dietary supplements are exempt from the strict regulatory oversight required for prescription medications. The move by Schneiderman was the first time a law enforcement agency had threatened large retail and drugstore chains with legal action for selling what he called deliberately misleading herbal products.