OBJECTIVE

To compare the digestibility and tolerance of lactose from three semi-solid fermented dairy products with the same amount of lactose but different lactase contents and bacterial cultures in lactase deficient adults.

DESIGN

Measurement of breath hydrogen (H2) concentration and of clinical symptoms after consumption of the test meals.

SETTING

Metabolic ward for healthy volunteers, INSERM U290, Hôpital St. Lazare, Paris.

SUBJECTS

Fifteen lactase-deficient healthy adult volunteers (20-45 y) started the study. One subject became a non-H2-producer during the study; therefore the results of 14 subjects are presented.

INTERVENTION

Each subject consumed, on four different days and in random order, after a 12 h fast, three semisolid test meals containing 18 g of lactose, and a 10 g dose of lactulose which allowed calculation of lactose malabsorption. The three meals were: traditional yoghurt, fermented milk (Ofilus) that contained Lactobacillus acidophilus and Bifidobacterium sp., and a similar product 'Bulgofilus' enriched with Lactobacillus bulgaricus to increase the lactase content.

RESULTS

Compared with lactulose, the sum of symptoms was significantly lower for Bulgofilus (P = 0.05), and bloating was less severe for Ofilus (P = 0.06). Between the fermented milks, there were no differences. The area under the breath H2 curve was significantly lower for each fermented milk when compared to lactulose (P < 0.0001). The degree of maldigestion of lactose did not differ significantly between the products; it was 21 +/- 3% (range 6-52) for Ofilus, 21 +/- 3% (range 6-44) for Bulgofilus, and 18 +/- 3% (range 3-43) for yoghurt.

CONCLUSION

Despite the differences in the lactase and bacterial content, lactose was as well digested and tolerated from the three different semi-sold fermented dairy products. This could be due to a slow gastric emptying of the semi-solid milk.