A Lactobacillus delbrueckii subsp. bulgaricus fermented skimmed milk powder has limited effects on gastrointestinal health in healthy individuals with mild-to-moderate gastrointestinal symptoms: results from a randomised controlled trial.

Fermented dairy foods offer potential to improve gastrointestinal symptoms due to their functional characteristics (e.g., presence of potentially health-promoting microorganisms, and/or bioactives), which may improve quality of life (QoL). This study examined the effect of a Lactobacillus delbrueckii subsp. bulgaricus fermented skimmed milk powder (FSMP) on gastrointestinal health in healthy individuals with mild-to-moderate gastrointestinal symptoms. Subjects received 20 g/day of either the FSMP, skimmed milk powder (SMP), or maltodextrin for 8 weeks. QoL, faecal calprotectin, gut transit time, gas evacuations, stool consistency, dietary intake, and anthropometry were all assessed. Eighty-four participants (62% female, 34.9 ± 5.9 years) completed the trial. SMP improved anxiety (P = 0.015), discomfort (P = 0.002), and global (P = 0.010) domain scores vs. maltodextrin. Similarly, SMP improved discomfort (P = 0.007) and global (P = 0.023) domain score relative to FSMP. No other differences between groups post-intervention were observed (P > 0.05). Sub-analyses indicated those with more severe symptoms at baseline had more normal stool consistency (P = 0.016) and fewer gas evacuations (P = 0.008) in response to FSMP relative to maltodextrin. Overall, this exploratory analysis found an L. delbrueckii subsp. bulgaricus FSMP had limited effects on gastrointestinal health in this cohort.