The Impact of Diet on the Gut-Microbiota-Brain Axis

Healthy Clinical Trial

— NMB  

Official title:

An Interventional Study on the Association Between Diet, Cognitive Function, Stress and the Gut Microbiota in Healthy Volunteers.

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT05931562
• Other study ID #: APC 150b
• Status: Recruiting
• Phase: N/A
• Start date: July 14, 2022
• Est. completion date: July 2026

Study information

• Verified date: June 2023
• Source: University College Cork
• Contact: Elizabeth Schneider, PhD
• Phone: (+353) 021 4901721
• Email: eschneider[@]ucc.ie
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This study aims to investigate the effects of an 8-week dietary intervention on cognitive function, stress, and the gut microbiota in healthy adults with low fibre intake.

Description:

The gut microbiota communicates bidirectionally with the brain via the microbiota-gut-brain axis to influence various aspects of human physiology, including host metabolism, immune function, behaviour, and cognition. Diet is a key modulator of the microbial composition, suggesting that the microbiota could explain the association between poor nutrition and decreasing health of the population. Dietary fibre is the main energy source for the gut microbiota and fundamentally impacts its composition and function. The microbiota-gut-brain axis has been proposed to mediate some of the effects of dietary fibre on the brain, for example through microbial metabolites (e.g., short-chain fatty acids (SCFA)), regulation of the immune system, and the microbial impact on gut hormones and neurotransmitters. Similarly, intake of fermented foods is positively associated with cognitive health and has been shown to alter the microbiota composition and function and exert an anti-inflammatory effect. However, no studies to date have examined the singular and combined effects of fermented and fibrous foods on the gut microbiota, cognition, and emotion. The present study aims to determine the role of diet on the microbiota-gut-brain axis and mental health. Using a randomized-controlled, parallel, single-blinded design, participants consuming a habitually low fibre diet (N=200) will undergo an 8-week dietary intervention. Participants will receive one of four diets (n=50 in each group): high fibre (aim 24-35 grams/day), fermented foods (aim 4-6 portions/day), combined diet of fermented foods and high fibre (aim 25-30g/day of fibre and 3-4 servings/day of fermented foods) or control (dietary education according to national Irish guidelines). Cognitive, psychological, and biological measures will be compared at baseline and endpoint. During the intervention period, individuals will provide repeated faecal samples to assess temporal microbial changes.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 200
• Est. completion date: July 2026
• Est. primary completion date: July 2026
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 50 Years

Eligibility

Inclusion Criteria:

• Be able to give written informed consent.
• Be between 18 and 50 years of age.
• Have a body mass index (BMI) between 18.5-29.9 Kg/m2.
• Be in generally good health as determined by the investigator.

Exclusion Criteria:

• Are less than 18 and greater than 50 years of age.
• Have a BMI below 18.5 or above 29.9 Kg/m2.
• Have a significant acute or chronic coexisting illness [cardiovascular, gastrointestinal (GI) [to include functional GI disorders, inflammatory bowel disease, coeliac disease, lactose intolerance, food allergies], immunological, psychiatric [to include formal or as determined by MINI Psychiatric interview, diagnosis of current major depression, anxiety disorder, bipolar spectrum disorder, schizophrenia, other DSM-IV Axis I disorder], neurodevelopmental disorders, immunological, metabolic disorders [to include type I or II diabetes], or any condition which contraindicates, in the investigators judgement, entry to the study,
• Have a condition or taking a medication that the investigator believes would interfere with the objectives of the study, pose a safety risk, or confound the interpretation of the study results; all psychoactive medications [to include anxiolytics, antipsychotics, antidepressants, anticonvulsants, centrally acting corticosteroids, and opioid pain relievers), laxatives, enemas, antibiotics, anti-coagulants, over-the counter non-steroidal anti-inflammatories (NSAIDS). Subjects should have a wash-out period of 4 weeks.
• Current prebiotic or probiotic supplement use (a wash-out period of 4 weeks after cessation will allow entry to the study).
• Females who are peri-menopausal, menopausal or post-menopausal.
• Females who are pregnant or planning a pregnancy, or lactating.
• Participants who are not fluent in English.
• Are colour blind.
• Have dyslexia or dyscalculia.
• Are a current habitual daily smoker.
• Individuals who, in the opinion of the investigator, are considered to be poor attendees or unlikely for any reason to be able to comply with the trial.
• Subjects receiving treatment involving experimental drugs. If the subject has been in a recent experimental trial, these must have been completed not less than 30 days prior to this study.
• Have a malignant disease or any concomitant end-stage organ disease.
• Have completed a study in our laboratory in the past 4 years.

Related Conditions & MeSH terms

• Healthy

Intervention

Other:
• Fermented Foods
Participants will recieve dietary education to include 4 to 6 portions of fermented foods to their normal diet.
• High Fibre
Participants will recieve dietary education to increase their fibre intake to 24-35g/day in their normal diet.
• Combined Diet
Participants will recieve dietary education to increase their fibre intake to 25-30g/day and include 3 to 4 portions of fermented foods to their normal diet.
• Control
Participants will recieve dietary education based on the Irish healthy food pyramid.

Locations

Country	Name	City	State
Ireland	APC Microbiome Ireland	Cork

Sponsors (1)

Lead Sponsor	Collaborator
University College Cork

Country where clinical trial is conducted

Ireland, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Trait stress/mood: self-report	self-report questionnaires	Change from baseline at 8 weeks
Primary	Trait stress/mood: hypothalamic-pituitary-adrenal axis activity	Cortisol from saliva samples	Change from baseline at 8 weeks
Primary	Responses to acute stress: self-report	Self-report questionnaires	Change from baseline at 8 weeks
Primary	Responses to acute stress: sympathetic-adrenal-medullary pathway activity	Galvanic skin response taken from the skin on the hand	Change from baseline at 8 weeks
Primary	Responses to acute stress: hypothalamic-pituitary-adrenal axis activity	Cortisol from saliva samples	Change from baseline at 8 weeks
Secondary	Cognitive performance: working memory	Spatial Working Memory	Change from baseline at 8 weeks
Secondary	Cognitive performance: episodic memory	Modified Rey Auditory Verbal Learning Test (ModRey)	Change from baseline at 8 weeks
Secondary	Cognitive performance: decision making	Iowa Gambling Task	Change from baseline at 8 weeks
Secondary	Cognitive performance: emotional inhibition	Emotional Stroop	Change from baseline at 8 weeks
Secondary	Cognitive performance: sustained attention	Rapid Visual Information Processing	Change from baseline at 8 weeks
Secondary	Cognitive performance: visual pattern recognition memory	Pattern Recognition Memory	Change from baseline at 8 weeks
Secondary	Cognitive performance: cognitive flexibility	Intra-Extra Dimensional Set Shifting	Change from baseline at 8 weeks
Secondary	Cognitive performance: social cognition	Emotion Recognition Task	Change from baseline at 8 weeks
Secondary	Cognitive performance: affective perceptual bias	Emotional Bias Task	Change from baseline at 8 weeks
Secondary	Microbiota composition and function	Shotgun metagenomics of fecal samples	Change from baseline at 8 weeks
Secondary	Microbial and host metabolomics	Untargeted metabolomics analysis	Change from baseline at 8 weeks
Secondary	Inflammation	Inflammatory markers in lipopolysaccharide stimulated and unstimulated bloods	Change from baseline at 8 weeks