Daily consumption of a synbiotic yogurt decreases energy intake but does not improve gastrointestinal transit time: a double-blind, randomized, crossover study in healthy adults

Abstract

Objective: Probiotic and synbiotic products are widely marketed to healthy individuals, although potential benefits for these individuals are rarely studied. This study investigated the effect of daily consumption of a synbiotic yogurt on gastrointestinal (GI) function in a sample of healthy adults.

Subjects/methods: In a randomized crossover double-blind study, 65 healthy adults consumed 200 g/day of yogurt with (synbiotic) or without (control) added probiotics (Bifidobacterium lactis Bb12, Lactobacillus acidophilus La5, Lactobacillus casei CRL431) and 4 g inulin for two 15-day treatment periods, each preceded by a 6-week washout period. GI transit time (GTT), duration of colour (DOC), GI symptoms and dietary intake were assessed and analyzed using repeated measures ANOVA, including PRE-treatment GTT as a covariate. Participants were grouped as short GTT (STT, n = 50, ≤32.7 h) or long GTT (LTT, n = 15, >32.7 h) based on their PRE-treatment GTT assessment.

Results: POST-treatment GTT and DOC were not different between synbiotic and control, and did not change from PRE-treatment, within the STT or LTT groups. There were no changes in GI symptom ratings, indicating that both yogurts were well tolerated. In STT, energy, fat and protein intakes were decreased from baseline with synbiotic (p = 0.055, p = 0.059 and p = 0.005, respectively) and dietary fibre intake was higher POST-treatment with synbiotic versus control (p = 0.0002). In LTT, decreases in energy and fat intakes with synbiotic were not significant (p = 0.14 and p = 0.18, respectively) and there were no differences in dietary fibre intake.

Conclusion: Consuming 200 g/day of synbiotic yogurt did not significantly alter GTT in healthy adults, but was well tolerated and helped to reduce overall energy intake.

Figure 1

Histogram depicting the distribution of PRE-treatment GTT ¹. Abbreviations: GTT, gastrointestinal transit time. ¹ Distribution of PRE-treatment GTT values, measured in duplicate in two separate GTT assessments, for each participant (n = 65).

Figure 2

STT (a) and LTT (b) GSRS scores for PRE, POST 7 and POST 15 days of treatment ^1,2,3,. Abbreviations: GSRS, gastrointestinal symptom rating scale; STT, short gastrointestinal transit time; LTT, long gastrointestinal transit time; PRE, pre-treatment; POST, post-treatment. ¹ Average GSRS scores. ² Mean ± SD. ³ Questions 1–5 scored as 0 for ‘no symptoms’ to 3 for ‘extreme symptoms’ and questions 6 & 7 scored as 0 to 4, where 0 and 4 indicated opposite extremes and 2 indicated normal bowel movement consistency or frequency.