Prebiotic fiber for cognitive function, mood, and sleep Original paper

In this randomized controlled trial, cognitive function, sleep, and mood outcomes were mostly similar between groups who took partially hydrolyzed guar gum (prebiotic fiber) or a placebo.

The effect of partially hydrolyzed guar gum (a prebiotic fiber) on cognition, sleep, and mood among older adults.

61 Japanese adults (average age of 68; 31 men and 30 women), who did not have cognitive impairment or apparent chronic health conditions.

During this 12-week randomized controlled trial, the participants consumed 5 grams of prebiotic fiber (guar gum) or a placebo (maltodextrin) mixed with water each morning.

Cognitive function was assessed using the Cognitrax test, which includes 16 outcomes such as verbal, visual, and composite memory, as well as social acuity, motor speed, executive function, and reaction time.

Sleep was assessed using the Oguri-Shirakawa-Azumi Sleep Inventory, which includes ratings of sleep duration, refreshment from sleep, and the initiation and maintenance of sleep, as well as morning sleepiness and the frequency of dreaming.

The Profile of Mood States was used to assess overall mood disturbance and the intensity of feelings such as anger, depression, and fatigue.

All the Cognitrax scores were similar between the groups at 12 weeks, with the exception of visual memory, which was higher (better) in the prebiotic group. However, the prebiotic group’s visual memory scores did not improve from baseline, which reduces the strength of this finding.

The prebiotic group reported less morning sleepiness compared to the control group at 8 weeks, but the difference between groups was not statistically significant at 12 weeks. No differences in other sleep outcomes (such as duration or refreshment) were observed between groups.

The results from this study should be interpreted with caution, as there was no adjustment for multiple comparisons (increasing the risk of false positives).

The manufacturer of the prebiotic supplement (Taiyo Kagaku Co., Ltd.) contributed to the study design and employed most of the study authors during the trial period.