Effects of a high-prebiotic diet versus probiotic supplements versus synbiotics on adult mental health: The “Gut Feelings” randomised controlled trial

Abstract

BackgroundPreliminary evidence supports the use of dietary interventions and gut microbiota-targeted interventions such as probiotic or prebiotic supplementation for improving mental health. We report on the first randomised controlled trial (RCT) to examine the effects of a high-prebiotic dietary intervention and probiotic supplements on mental health.Methods“Gut Feelings” was an 8-week, 2 × 2 factorial RCT of 119 adults with moderate psychological distress and low prebiotic food intake. Treatment arms: (1) probiotic supplement and diet-as-usual (probiotic group); (2) high-prebiotic diet and placebo supplement (prebiotic diet group); (3) probiotic supplement and high-prebiotic diet (synbiotic group); and (4) placebo supplement and diet-as-usual (placebo group). The primary outcome was assessment of total mood disturbance (TMD; Profile of Mood States Short Form) from baseline to 8 weeks. Secondary outcomes included anxiety, depression, stress, sleep, and wellbeing measures.ResultsA modified intention-to-treat analysis using linear mixed effects models revealed that the prebiotic diet reduced TMD relative to placebo at 8 weeks [Cohen’s d = −0.60, 95% confidence interval (CI) = −1.18, −0.03; p = 0.039]. There was no evidence of symptom improvement from the probiotic (d = −0.19, 95% CI = −0.75, 0.38; p = 0.51) or synbiotic treatments (d = −0.03, 95% CI = −0.59, 0.53; p = 0.92). Improved anxiety, stress, and sleep were noted in response to the prebiotic diet while the probiotic tentatively improved wellbeing, relative to placebo. No benefit was found in response to the synbiotic intervention. All treatments were well tolerated with few adverse events.ConclusionA high-prebiotic dietary intervention may improve mood, anxiety, stress, and sleep in adults with moderate psychological distress and low prebiotic intake. A synbiotic combination of high-prebiotic diet and probiotic supplement does not appear to have a beneficial effect on mental health outcomes, though further evidence is required. Results are limited by the relatively small sample size.Clinical trial registrationhttps://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372753, identifier ACTRN12617000795392.

Exploring the Influence of Gut–Brain Axis Modulation on Cognitive Health: A Comprehensive Review of Prebiotics, Probiotics, and Symbiotics

“…Ongoing studies aim to deepen our understanding of the interactions within the microbiome-gut-brain axis, particularly exploring mechanisms between the gastrointestinal tract and the nervous system [122,[156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171]. Future research should focus on more precise analyses and explorations of the composition of gut microbiota, identifying which strains are dominantly associated with conditions such as anxiety, depression, Parkinson's disease, and other psychiatric and cognitive disorders, including Alzheimer's disease [172][173][174][175][176][177][178][179][180][181][182][183][184]. Areas that remain less explored, such as the various negative associations of different bacterial strains, including inflammatory diseases, neuroinflammation, and metabolic disorders or postpartum depression, require further investigation for a deeper understanding.…”

An Overview of the Potential Role of Nutrition in Mental Disorders in the Light of Advances in Nutripsychiatry

“…Furthermore, no significant differences were observed in terms of other psychological outcomes and serum biomarkers ( p > 0.05). Freijy et al [ 121 ] 118 adults with moderate psychological distress and low dietary prebiotic intake (< 3 g/day) • Intervention groups: (1) probiotic supplement and usual diet (probiotic group, n = 30) (2) high prebiotic diet (at least 5g/day) and placebo supplement (prebiotic diet group, n = 28) (3) probiotic supplement and high prebiotic diet (synbiotic group, n = 32) (4) placebo supplement and usual/normal diet (placebo group, n = 28) It was concluded that the prebiotic diet significantly reduced mood disorders compared to the placebo group within 8 weeks ( p = 0.039). However, it was determined that there was no improvement in symptoms with probiotic or synbiotic treatments ( p = 0.51 and p = 0.92, respectively).…”

Personalizing Nutrition Strategies: Bridging Research and Public Health

“…These products regulate the intestinal microbiota and reduce the possibility of metabolic and inflammatory alterations [272]. Among the most prominent are the Lactobacillus casei strain Shirota, which reduces anxiety levels and improves overall mood, the formula Lactobacillus helveticus and Bifidobacterium longum, which reduces psychological anxiety, and B-GOS, which improves cognitive functioning and reduces cortisol levels [273,274].…”