Fig. 1.

Study design and the prebiotic effects of the various doses of lactulose.

(A) Study design. Defaecation, stool forms, and health conditions were recorded in a diary by each subject during the study periods. Faecal sample collection is indicated with an arrow. (B) Defaecation frequency, n=26. (C) Number of bifidobacteria, n=26. (D) Defaecation days, n=26. ^*p<0.05 vs. prior to the ingestion period (paired t-test). ^**p<0.01 vs. prior to the ingestion period (paired t-test). Data are presented as the mean ± standard deviation. Po, pre-observation period; 1 g, 1 g/day ingestion period; W1, washout period 1; 2 g, 2 g/day ingestion period; W2, washout period 2; 3 g, 3 g/day ingestion period.