Table 1. The prebiotic effects of lactulose.

		n	Po	1 g	W1	2 g	W2	3 g
Defaecation frequency	(times/week)	26	3.4 ± 1.3	4.2 ± 1.8 *	3.5 ± 1.5	4.2 ± 1.5 *	3.9 ± 1.3	4.9 ± 1.9 **
Number of bifidobacteria	(log cfu/g-faeces)	26	9.93 ± 0.57	10.10 ± 0.40*	9.95 ± 0.63	10.23 ± 0.53**	10.09 ± 0.51	10.38 ± 0.28**
Defaecation days	(days/week)	26	3.1 ± 1.1	3.8 ± 1.5*	3.1 ± 1.2	3.8 ± 1.2**	3.5 ± 1.1	4.3 ± 1.4**
Bristol Stool Scale score	(per defaecation)	26	3.7 ± 1.0	3.8 ± 0.8	3.6 ± 0.6	3.9 ± 0.7	3.8 ± 0.6	3.9 ± 0.7

*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.