BALANCE Study: Beneficial Effects of A Diverse Prebiotic Fibre bLend on Affect, iNflammation, Cognition, and the Gut microbiomE

Beneficial Effects of A Diverse Prebiotic Fibre bLend on Affect, iNflammation, Cognition, and the Gut microbiomE: a Double-blind Placebo Controlled Randomised Controlled Trial

This clinical trial will investigate whether a powdered prebiotic fibre blend, at two doses, can improve perceived stress levels in healthy adults with mild-severe stress levels.

There is growing interest in how the gut microbiota interacts with the brain to influence psychological outcomes, particularly stress. Even in otherwise healthy individuals, persistent psychological stress is associated with measurable physiological changes-including elevated cortisol levels, heightened hypothalamic-pituitary-adrenal (HPA) axis reactivity, and systemic low-grade inflammation. These biological signatures are increasingly understood to be shaped, in part, by the composition and activity of the gut microbiota.

This study will investigate how a powdered prebiotic fibre supplement can affect stress levels. Secondary endpoints include the effects that the prebiotic fibre supplement will have on other areas of health, like depression, mood, anxiety, cognition, inflammation, and the gut microbiome.

Inclusion Criteria:

• Aged 18-50 years of age
• Capacity to give informed consent to participate in the study
• Able to comply with study requirements and visits
• Meet the criteria for mild-severe stress levels (scores between 15-33) as assessed by DASS-42 Stress Subscale
• Normal or corrected to normal vision and/or hearing

Exclusion Criteria:

• Current smoker
• Having food allergies and/or intolerances
• Current diagnosis of Type 1 or 2 diabetes, cardiometabolic disease, or psychiatric or neurological conditions (e.g. schizophrenia, dementia) including eating disorders
• Current or previous diagnosis of depression in past 6 months
• Currently receiving medications that lower cholesterol, blood pressure, blood glucose levels, or improve insulin sensitivity
• Receiving antidepressant or anti-anxiety medications or treatments
• Receiving hormonal birth control
• Perimenopause or menopause
• Pregnancy, lactation, or an intent to become pregnant during the course of the study
• Continuous antibiotic use for > 3 days within 1 month prior to enrolment
• Continuous use of weight-loss drug for > 1 month before screening
• Major change in dietary intake in past month (e.g. excluding whole food groups)
• Consuming a restricted diet, including a vegan, vegetarian, and ketogenic diet
• Currently consuming daily prebiotic or probiotic supplements
• Any significant GI condition affecting absorption including (but not limited to) inflammatory bowel disease, weight loss surgery, irritable bowel syndrome.
• Active cancer, or treatment for any cancer, in last 3 years
• Consuming more than 20g of fibre a day as assessed by the FiberScreen