The U.S. Food and Drug Administration on Friday said that only food products containing less than 20 parts per million of gluten can be labeled "gluten free."
The new guideline is intended to provide uniformity in the labeling of food products and provide confidence to about 3 million Americans who suffer from celiac disease and must eat a gluten-free diet, the agency said.
The FDA's rule also requires foods with the claims "no gluten," "free of gluten" and "without gluten" to meet the definition for "gluten free."
Food manufacturers will have a year after the rule is in effect, which begins 30 days after it is published in the Federal Register, to adhere to the new requirements, the agency said.
People with celiac disease who eat foods that contain gluten trigger production of antibodies that attack the lining of the small intestine. That leads to problems such as nutritional deficiencies because they are unable to absorb nutrients.