Objective: The aim of the study was to investigate the effects of fibre-rich rye bread and yoghurt containing Lactobacillus GG (LGG) on intestinal transit time and bowel function, and to test whether they have an interaction in cases of self-reported constipation.
Design: The study was carried out as a two-by-two factorial design.
Setting: Free-living subjects.
Subjects: A total of 59 healthy women with self-reported constipation, recruited by advertisement.
Interventions: After a baseline period, the subjects were randomized into four diet groups: (1) rye bread+LGG yoghurt, (2) rye bread, (3) LGG yoghurt, and (4) control. The 3-week dietary intervention was followed by a 3-week follow-up period. During each period, total intestinal transit time was measured and the subjects recorded faecal frequency and consistency, difficulty in defecation and gastrointestinal symptoms.
Results: The rye bread shortened total intestinal transit time (mean difference, -0.7; CI(95), -1.1 to -0.2; P=0.007), increased faecal frequency (0.3; CI(95), 0.1 to 0.5; P=0.001), softened faeces (-0.3; CI(95), -0.4 to -0.2; P<0.001) and made defecation easier (-0.4; CI(95), -0.5 to -0.2; P<0.001), but also increased gastrointestinal symptoms (1.6; CI(95), 0.7 to 2.4; P<0.001) compared to the low-fibre toast consumed in the LGG and control groups. There were fewer symptoms in the rye bread+LGG group compared to the rye bread group (-1.3; CI(95), -2.4 to -0.2; P=0.027).
Conclusions: Fibre-rich rye bread can be recommended in the treatment of constipation, and the simultaneous consumption of LGG yoghurt relieves the adverse gastrointestinal effects associated with increased intake of fibre.
Sponsorship: Valio Ltd, R&D, and Fazer Bakeries Ltd.