Effect of exogenous β-galactosidase in patients with lactose malabsorption and intolerance: a crossover double-blind placebo-controlled study

Objective: To evaluate the efficacy of the addition to milk, 5 min and 10 h before its consumption, of a lactase obtained from Kluyveromyces lactis in lactose malabsorbers with intolerance. Design: Double-blind, placebo-controlled, crossover study. Setting: University Hospital. Subjects: In total, 11 male and 19 female (aged from 18 to 65 y, mean age 43.3 y) lactose malabsorbers with intolerance participated. Interventions: Each patient underwent three H2 breath tests, in a random order. We used 400 ml of cow's semiskimmed milk as substrate and a beta-galactosidase obtained from K. lactis. The test A was carried out adding to the milk the enzyme (3000 UI), 10 h before its consumption; the test B was performed adding the beta-galactosidase (6000 UI) 5 min before milk ingestion and the test C was made using placebo. We evaluated the maximum breath H2 concentration, the cumulative H2 excretion and a clinical score based on intolerance symptoms (bloating, abdominal pain, flatulence and diarrhoea). Results: Our study showed a significant reduction of the mean maximum H2 concentration after both test A (12.07+/-7.8 p.p.m.) and test B (13.97+/-7.99 p.p.m.) compared with test C (51.46+/-16.12 p.p.m.) (ANOVA F=54.33, P<0.001). Similarly, there was a significant reduction of the mean cumulative H2 excretion after both test A (1428+/-1156 p.p.m.) and test B (1 761+/-966 p.p.m.) compared with test C (5795+/-2707 p.p.m.) (ANOVA F=31.46, P<0.001). We also observed a significant reduction of the mean clinical score after both test A (0.36+/-0.55) and test B (0.96+/-0.85) compared with test C (3.7+/-0.79) (ANOVA F=106.81, P<0.001). Moreover, with regard to the mean clinical score, there was a significant reduction after test A with respect to test B (Bonferroni's P=0.03). Conclusions: Our study shows that in lactose malabsorbers with intolerance, the lactase obtained from K. lactis can represent a valid therapeutic strategy, with objective and subjective efficacy and without side effects.