Snack Foods and Their Impact on Mental Health and the Gut-brain Axis

Inclusion Criteria:

• Adults aged 18-45 years old.

• Body mass index (BMI) between 18.50-29.99kg/m2

• Score 10-29 on the patient health questionnaire anxiety and depression scale (PHQ-ADS) for mild to moderate symptoms of depression and anxiety.

• Individuals who regularly consume snacks (Classified as ≥2 per day excluding fruit,vegetable, nut and seed snacks).

• Willing to complete the 12-week intervention by adhering to snacks, complete mentalhealth questionnaires, provide stool and blood samples, record weight and otheranthropometric values and record food intake at various timepoints throughout theintervention.

• Willing to adhere to the protocol and provide informed consent.

• Fibre intake of <30g/d

• Willing to discontinue use of pre and probiotics during the trial.

Exclusion Criteria:

• Dislike of intervention products.

• Allergy or intolerance to the intervention products

• Self-report occurrence of substance dependency or severe mental health conditions (e.g., psychosis, schizophrenia, eating disorder). Those with depressive disordersor anxiety disorders will be included in the trial providing they meet all otherinclusion criteria.

• Regular consumption of experimental product as snacks and unwilling to complete awashout (no consumption for 4 weeks before baseline or during the study period).

• Changes to medication for depression or anxiety within the last 3 months (e.g.,dosage, frequency, type)

• Initiation of any new medications for mental health or any form of talk therapywithin the last 3 months.

• Intention to start or alter medication or therapy for mental health during thestudy.

• Current or previous antibiotic treatment within 4 weeks prior to the start of thestudy.

• Consumption of probiotics or prebiotic products within the 2 weeks prior to thestart of the study

• Women who are pregnant, lactating or planning pregnancy

• Unexplained or unintentional weight loss in the past six months

• Medical history of any of the following: diabetes, major active or historicpsychiatric conditions (e.g. schizophrenia), current eating disorder, alcohol abuse,active treatment for cancer in the last year, severe neurological, endocrine, renal,cardiac or pulmonary disease (or any other chronic medical condition), severeoesophagitis, gastritis or duodenitis, active diverticulitis or intestinal/colonicstrictures, Coeliac disease, Crohn's disease or Ulcerative colitis, stem cell ororgan transplant, gut resection surgery (excluding appendicectomy andcholecystectomy), bleeding disorder, anaphylaxis or any other major or chroniccondition known to impact study outcome measures.