Effects of a prebiotic fibre-enriched bread in older adults: a randomised, placebo-controlled, parallel-groups...

To examine the feasibility and effects of consuming an additional 10 g/day of prebiotic fibre blend in a bread roll on cognitive, mood, gastrointestinal outcomes, and peripheral biomarkers in older adults without dementia and with low habitual dietary fibre intake.

A single-centre, randomised, double-blind, placebo-controlled parallel groups design (Registration at clinicaltrials.gov; NCT06796712).

Fifty-three community-dwelling adults aged 60-80 years without dementia and with low habitual dietary fibre intake.

Participants were assigned to either a treatment (fibre-enriched white bread roll) group (n = 28) or a placebo (matched white bread roll) group (n = 25) and consumed their assigned products for 12 weeks.

Cognitive, mood, gastrointestinal outcomes, as well as C-reactive protein, lipids, and glucose levels were assessed at the baseline and after 12-weeks.

Placebo consumption for 12 weeks was associated with improvements in memory compared with treatment. However, the treatment group showed a decrease in hostility after 12 weeks, whereas the placebo group showed an increase. The placebo group also demonstrated an increase in HDL cholesterol, while the treatment group showed a decrease. No significant differences were observed for the other outcomes.

Fibre-enriched bread may have selective effects on aspects of mood (e.g., hostility) in ageing populations, although most mood, cognitive, and biological outcomes were unchanged. The observed improvement on mood occurred independently of inflammatory or cardiovascular changes, suggesting potential involvement of the gut-brain axis and the need for additional mechanistic endpoints to clarify the underlying mechanistic pathways. Cognitive and inflammatory changes may require longer interventions, different dosing or populations, highlighting the need for further investigation in larger and more diverse samples.