CALM Study: Can A Prebiotic Fibre bLend Improve Stress, Mood, and Anxiety?

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

This clinical trial will investigate whether a powdered prebiotic fibre blend 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.

In this study, we're investigating how a powdered prebiotic fibre supplement can improve stress levels. You may have heard people refer to this as the 'gut-brain axis'. We'll also be looking at the link between the prebiotic fibre supplement intake and changes in 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 range required for mild-severe stress levels (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
• Diagnosis of Type 1 or 2 diabetes or cardiovascular disease or psychiatric or neurological conditions (e.g. schizophrenia, dementia) including eating disorders
• Current or previous diagnosis of depression in past 6 months
• 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)
• Currently consuming daily prebiotic or probiotic supplements
• Prior use (< 6 months) of any blood glucose or cholesterol lowering medication
• Any significant GI condition affecting GI absorption including (but not limited to) inflammatory bowel disease, weight loss surgery, irritable bowel disease.
• End stage renal disease
• Active cancer, or treatment for any cancer, in last 3 years
• Consuming more than 20g of fibre a day as assessed by the 18-item FiberScreen