CALM Study
Research type
Research Study
Full title
Can A prebiotic fibre bLend improve stress, Mood, and anxiety? Assessing the impact of a daily prebiotic fibre blend on affect, inflammation, and the gut microbiome: a 12-week double-blind placebo-controlled RCT
IRAS ID
360717
Contact name
Caitlin Hall
Contact email
Sponsor organisation
Myota Limited
Duration of Study in the UK
1 years, 6 months, 0 days
Research summary
There is growing interest in how the human gut microbiota interacts with the brain to influence psychological outcomes, particularly stress, mood, and anxiety. A key mechanism linking the gut to stress regulation involves the fermentation of dietary fibre into short-chain fatty acids (SCFAs), particularly acetate, propionate and butyrate.
Prebiotic fibres, specific fermentable fibres that selectively promote the growth and activity of beneficial gut bacteria, have emerged as a promising nutritional intervention to enhance SCFA production. Several human and animal studies suggest that prebiotic intake can reduce perceived stress, modulate cortisol dynamics, reduce inflammatory biomarkers, and support more balanced gut-brain signalling.
In this study, we propose to investigate whether daily supplementation with a SCFA-optimised prebiotic fibre blend can reduce self-reported stress in otherwise healthy adults with elevated perceived stress levels. This 12-week randomised controlled trial will assess validated psychological stress measures alongside exploratory biomarkers related to gut microbiota composition, inflammation, and SCFA metabolism.
The study will enrol 156 participants aged 18–65 with moderate to high perceived stress, randomised to receive either the prebiotic fibre blend or a placebo (maltodextrin). Assessments will take place at baseline, 8 weeks (online), and 12 weeks.
REC name
West of Scotland REC 4
REC reference
25/WS/0115
Date of REC Opinion
25 Aug 2025
REC opinion
Further Information Favourable Opinion