Symptoms of ‘lactose intolerance’

Factors affecting or confounding the symptoms of lactose intolerance were examined by us in randomised, placebo-controlled and double-blind studies on healthy adult subjects. Evaluation of the diagnostic methods of lactose intolerance showed that cut-off values, according to the blood glucose values, varied widely. This result was based on a postal questionnaire, sent to all Finnish health centres. Symptoms were seldom recorded for a sufficiently long period. In carefully diagnosed lactose intolerant subjects, there was no difference in the severity of reported symptoms between ingestion of 0, 0.5, 1.5 and 7 g of lactose. Lactose maldigesters reported more severe symptoms after ingestion of lactose, but also sucrose, lactulose and fructo-oligosaccharides than controls. There was a strong relation among the reported symptoms in lactose intolerance, irritable bowel syndrome, the experience of abdominal pain in childhood, and female sex. Key words: Lactose intolerance, lactose maldigestion, symptoms