The US Food and Drug Administration has proposed standard definitions for manufacturers who want to label their products as being gluten-free.

The FDA said last week that it is proposing that foods bearing the claim cannot contain "20 parts per million or more" gluten, reported just-food. The agency said the limit was based on the available methods for gluten detection, as current methods cannot reliably detect the amount of gluten in a food when the level was less than 20ppm.

The threshold is also similar to the labelling standards used by many other countries, and conforms to the standards set by the Codex Alimentarius Commission in 2008, the FDA said.

"Before finalising our gluten-free definition, we want up-to-date input from affected consumers, the food industry, and others to help assure that the label strikes the right balance," said FDA deputy commissioner for foods Michael Taylor.

"We must take into account the need to protect individuals with coeliac disease from adverse health consequences while ensuring that food manufacturers can meet the needs of consumers by producing a wide variety of gluten-free foods."