Effects of 28-day <i>Bifidobacterium animalis</i> subsp. <i>lactis</i> HN019 supplementation on colonic transit time and gastrointestinal symptoms in adults with functional constipation: A double-blind, randomized, placebo-controlled, and dose-ranging trial

Bifidobacterium animalis subsp. lactis HN019 (HN019) ameliorates chronic idiopathic constipation. Our aim was to determine the efficacy and safety of 28-day supplementation with 1 × 10⁹ or 1 × 10¹⁰ CFU of HN019/day for constipation. A total of 228 adults who were diagnosed with functional constipation according to the Rome III criteria were randomized in a double-blind and placebo-controlled trial. Colonic transit time (CTT), the primary outcome, and secondary outcomes that were measured using inventories-patient assessment of constipation symptoms (PAC-SYM) and quality of life (PAC-QoL), bowel function index (BFI), bowel movement frequency (BMF), stool consistency, degree of straining, bowel emptying, bloating, and pain severity-were assessed. Ancillary parameters and harms were also evaluated. There were no statistically significant differences in the primary or secondary outcomes between interventions. A post hoc analysis of 65 participants with fewer than 3 bowel movements per week (BMF ≤ 3/week) showed a physiologically relevant increase in weekly BMF in the high- (+2.0) and low-dose (+1.7) HN019 groups-by RMANOVA, the HN019 groups with BMF ≤ 3/week, pooled together, had a higher BMF versus placebo (P value = 0.01). Thus, improving low stool frequency could be a target of future interventions with HN019. High-dose HN019 also decreased the degree of straining at Day 28 versus placebo in those with BMF ≤ 3/week (P value = 0.02). Three unlikely related AEs-2 with low-dose HN019 and 1 with placebo-were followed until full recovery. In conclusion, although there were no differences in the primary analysis, HN019 is well tolerated and improves BMF in adults with low stool frequency.