Acute calcium assimilation from fresh or pasteurized yoghurt depending on the lactose digestibility status.

OBJECTIVE The major aim of this trial was to evaluate the potential interaction of fresh or pasteurized yoghurt intake with lactose intolerance on calcium assimilation by means of the stable isotope 43Ca as a tracer. METHODS Forty volunteers (age: 32 +/- 7 years) participated in this parallel simple blind study (20 of them with moderate lactose intolerance). The protocol included the intake of a test meal consisting on 43Ca-labelled fresh or pasteurized yoghurt. Volunteers, in whom the calcium status was assessed, collected the 24-h urine before and after the test meal to measure the stable isotope output. The intake-related 43Ca enrichment in urine was measured by isotopic rate mass spectrometry. RESULTS In lactose tolerant and intolerant volunteers taken together, the fresh yoghurt consumption resulted in a statistically higher circulating calcium levels (p = 0.028) and urinary 43Ca output (p = 0.017) than after the pasteurized yoghurt intake. The lactose maldigestion status resulted in higher urinary 43Ca excretion (p = 0.013) after the fermented milk consumption, regardless of the nature of ingested product (p = 0.887). CONCLUSIONS This novel and non-aggressive protocol allowed the in vivo comparison of calcium utilization from two different dairy sources, revealing a higher acute calcium assimilation from fresh as compared to the pasteurized yoghurt, in both lactose digesting and maldigesting subjects.