Gibert A et al. (2006) Consumption of gluten-free products: should the threshold value for trace amounts of gluten be at 10, 100 or 200 ppm? Eur J Gastroenterol Hepatol 18: 1187–1195

Celiac disease is treated effectively by a strict, gluten-free diet. 'Gluten-free' products made from naturally gluten-free cereals can, however, contain traces of gluten if contamination has occurred during grain harvesting and processing or if they contain gluten-extracted ingredients. The safe daily limit for gluten intake in patients with celiac disease is estimated at <30 mg. Guidelines recommend that foods made only from naturally gluten-free ingredients should contain <20 ppm gluten, but whether the proposed 200 ppm limit for foods that contain gluten-extracted ingredients is safe is unclear.

Gibert and colleagues assessed gluten-free food consumption with a 10-day diet diary, completed by 1,359, 273, 226 and 56 patients with celiac disease in Italy, Spain, Norway and Germany, respectively. Regional consumption patterns differed; Spanish patients consumed the least gluten-free food. In all countries, bread was the most frequently consumed item, and patients in Norway and Germany consumed about twice as much as those in Italy and Spain. Pasta was rarely consumed in Norway but popular in Italy, Spain and Germany.

These patients' maximal daily exposure to gluten was 8.0–20.1 mg if the 20 ppm threshold was used, and 80–210 mg if the 200 ppm threshold was used. Gibert et al. recommend use of the 20 ppm limit for naturally gluten-free products and for frequently consumed foods. A provisional 100 ppm limit could be adopted for foods that contain or consist of gluten-extracted ingredients; this limit should, however, be revised as new data become available.