Yogurt - a potential strategy for overcoming lactose intolerance: the significance of the dose

Introduction: Adult-type hypolactasia (ATH) is the most common enzyme deficiency in humans. Incomplete digestion of lactose may result in lactose malabsorption (LM) causing symptoms of lactose intolerance (LI). Aim: Determination the dose of lactose, administered as a single serving in the form of yogurt, that is tolerated by LI healthy young adults. Material and methods: All (10 young adults) subjects were homozygotes C/C at locus 13910 upstream of the LCT gene. The hydrogen-methane breath test (BT) was performed after a load of 400, 200 and 100 ml of yogurt (5 h). Clinical symptoms were assessed for 12 h. Results: Ingestion of 400 ml of yogurt brought about abnormal BT results in all examined individuals; consumption of 200 ml did so in two of ten subjects, while a load of 100 ml caused borderline hydrogen excretion in one individual. However, residual fermentation of lactose was observed for several hours in all subjects. All participants reported symptoms after the ingestion of 400 ml of yogurt and their severity was significantly higher than that observed after a load of 200 ml. After consuming 100 ml of yogurt, none of the examined individuals reported gastrointestinal symptoms. Conclusions: Subjective observation of clinical symptoms suggests that young adult LI may tolerate up to 200 ml of yogurt served in one meal. However, when considering the objective assessment of LM by BT, it seems that the dose served per meal definitely should not exceed 100 ml.