Prebiotics confer benefits for affect, cognition
Prebiotic interventions lasting less than a day or for at least 28 days help improve affect and cognition, according to a study.
Researchers conducted a systematic review of studies evaluating the effect of a prebiotic intervention, with a specific focus on dietary fibres that tend to modulate the gut microbiota. Outcome variables were related to affect (eg, emotion, mood, psychological well-being, anxiety and depression) and cognition (eg, memory, attention, perception and executive functions) in humans.
The meta-analysis included 14 randomized controlled trials, including five crossover, seven double-blind, one simple-blind and one without a control group. The intervention duration ranged from 10 minutes to 13 weeks, with prebiotic doses varying between 5 mg and 10 g. There were 988 participants in total, and sample sizes ranged from 153 to 2,653.
Data were pooled according to the length of the intervention. Those classified as chronic studies lasted ≥28 days, while those classified as acute interventions lasted <1 day. Some chronic prebiotic interventions (ie, xylo-oligosaccharides [XOSs], a combination of polysaccharides, beta-glucan) improved affect and verbal episodic memory compared with placebo. On the other hand, acute prebiotic interventions were more effective at improving cognitive variables, particularly verbal episodic memory.
Researchers pointed out that while the results involved a small number of studies to draw conclusions from, it is possible that a combination of high-dose (8 g) and long-term intervention (21 days), a very long-term intervention (12 weeks), or the type of prebiotic (eg, XOS) may explain the positive effects on affect and cognition.
Additional studies of prebiotic interventions using adequate methodologies and recruiting patients with dysbiosis, inflammation or psychopathology are needed to identify the conditions required to obtain beneficial effects on affect and cognition, they added.