The Effect of a Prebiotic Supplement on Cognition and Muscle Strength in Older Adults

Written by Harold Oster, MD. Results suggest that daily consumption of a prebiotic supplement is associated with improved cognition in older adults.

The prevalence of dementia is increasing with the aging of the population¹. Sarcopenia is an age-related condition of low muscle mass and poor muscle strength that is associated with increased fractures and mortality. In some studies, the combination of resistance training and a protein supplement has been shown to improve muscle mass and strength². Alterations in the gut microbiome may negatively affect cognition and physical function in older adults³. Prebiotics are non-digestible food ingredients that benefit the host’s microbiome⁴.

Mary Ni Lochlainn et al. studied the effect of a prebiotic supplement on muscle strength and cognition in older adults. The authors recruited thirty-six pairs of adult twins to participate in the twelve-week study. All participants consumed a daily protein supplement and performed strength exercises at least twice per week for the length of the study. One twin in each pair consumed a prebiotic supplement containing 7.5 mg of inulin daily for twelve weeks, while the other twin consumed a placebo containing maltodextrin. The participants measured their weight and body mass index at baseline and at the end of the study. Stool samples obtained at baseline and the end of the study were tested for bacteria consistent with a healthy microbiome⁵. Cognitive testing with the Cambridge Neuropsychological Test Automated Battery (CANTAB) was performed at the beginning and end of the study⁶. Muscle strength was assessed with the Short Physical Performance Battery⁷, which includes the five-time chair-rise test⁸, and by hand grip strength⁹.

The authors noted the following:

• The average age of the participants was 73 years.
• Based on exclusion criteria, 32 participants in the prebiotic group and 34 in the placebo group completed the study.
• Changes consistent with improvement in the gut microbiome were seen in the prebiotic group but not in the placebo group.
• There were no significant differences in weight or body mass index at the end of the study in either group.
• Cognition improved in the prebiotic group in two CANTAB assessments, one of which was the paired associated learning test, which has been shown to have diagnostic significance in Alzheimer’s Disease¹⁰.
• No changes in muscle strength were noted in either group at the end of the study.
• More adverse reactions were noted in the prebiotic group than in the placebo group. (8 vs 2) Reactions were mild and mostly gastrointestinal.

Results suggest that daily consumption of a prebiotic supplement containing inulin is associated with improved cognition in older adults. No change in muscle strength was noted. The study’s limitations include its short duration and the use of maltodextrin as a placebo; maltodextrin may affect the gut microbiome¹¹.

Source: Ni Lochlainn, Mary, Ruth CE Bowyer, Janne Marie Moll, María Paz García, Samuel Wadge, Andrei-Florin Baleanu, Ayrun Nessa et al. “Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial.” Nature Communications 15, no. 1 (2024): 1859.

© The Author(s) 2024

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Posted April 16, 2024.

Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.

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