Dietary Fiber, Microbiota and Cognitive Function in Healthy Adults

Summary

Dietary fiber is well-known for its many health benefits, including the support of gastrointestinal, metabolic, and mental health. Although studies investigating whole dietary patterns in relation to cognition have demonstrated that diet quality and a healthy dietary pattern are associated with better cognitive performance, the role of dietary fiber in this regard is understudied. In the last decade, the role of the microbiota (trillions of microbes inhabiting the gut) in influencing various aspects of human health, including mental health and behavior, has also become established. Importantly, dietary fiber has been shown to positively affect the microbiota composition.

In this study, the role of dietary fiber in cognition through the lens of the microbiota is investigated. A two-part study including an observational (study 1) and interventional (study 2) arm has been designed. In study 1, the observational arm, 150 healthy individuals (30-60 years of age) will be recruited and grouped into high-fiber (\>25 g/day, n=75) and low-fiber (\<18 grams/day, n=75) consumers based on habitual dietary intake. Cognitive tasks (attention, episodic memory, decision making), psychological dimensions including impulsivity and emotional reactivity, biological samples (feces, blood, saliva, urine) and questionnaires about general health will be collected. In study 2, the interventional arm, a subgroup (n=60) of individuals from the low-fiber group will further be randomized into an 8-week randomized-controlled, parallel, single-blinded intervention to either receive a high fiber (n=30, aim 30 grams/day) or control (n=30) diet education. During the intervention period, individuals will provide repeated fecal samples in order to assess temporal microbial changes. At the end of the intervention period, individuals will undergo the same testing regarding cognitive and psychological variables and the same biological samples will be collected.

The investigators hypothesize that participants with higher dietary fiber intake at baseline will perform better in the cognitive tasks compared to individuals with low fiber intake, and that this difference can, in part, be mediated by the gut microbiota. Further the investigators hypothesize that through the dietary intervention the microbiota composition will positively shift to include more beneficial microbes and that cognitive performance will improve following the intervention.

Conditions

• Healthy

Interventions

OTHER

High fiber diet

30 grams of fiber per day

OTHER

Control diet

No diet education and change in diet

Sponsors & Collaborators

• University College Cork

  lead OTHER

Principal Investigators

• John F Cryan, PhD · APC Microbiome Ireland, University College Cork

• Gerard Clarke, PhD · APC Microbiome Ireland, University College Cork

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

30 Years

Max Age

60 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2021-07-31

Primary Completion

2023-07-31

Completion

2023-07-31

Countries

• Ireland

Study Locations