[Food allergy. Objective diagnosis and test of therapeutic efficacy by measuring intestinal permeability].

Gastrointestinal permeability was evaluated in 90 healthy subjects and in 12 patients with food allergy by oral administration of 5 g of mannitol, a marker of small molecule absorption, and 5 g of lactulose, a marker of large molecule abnormal absorption, and measurement of mannitol and lactulose urinary excretion. In the healthy subjects the mean 5-hour urinary excretion was 14.11% for mannitol and 0.26% for lactulose. The 12 patients with food allergy showed a normal urinary recovery of mannitol (14.35%) and a slightly greater urinary recovery of lactulose (0.49%). Intestinal permeability was also studied immediately after ingestion of an offending food allergen. This challenge test resulted in decrease in mannitol recovery (12.36%) and an increase in lactulose recovery (1.80%). Oral sodium cromoglycate administered before the test protected all patients against symptoms and abnormal intestinal permeability. Measuring intestinal permeability is an objective means of diagnosing food allergy and evaluating therapeutic effectiveness.