Emerging evidence from preclinical research suggests that prebiotic fibres may play a beneficial role in supporting mental health through modulation of the gut-brain axis-a complex communication network linking the gastrointestinal tract and the central nervous system. Chicory root-derived prebiotic fibre, already well-established for its positive effects on glycaemic control and bowel regularity, has recently shown promise in this context. The present study aims to investigate the mental health benefits of chicory root fibre in a larger and more diverse population, thereby contributing to the growing body of evidence supporting nutritional strategies for mental well-being.

Inclusion Criteria:

1. Volunteer is healthy at the time of screening.
2. TICS Screening Scale of Chronic Stress (SSCS) score ≥ 6.
3. GAD total score ≥ 5 and ≤ 14 indicating mild to moderate anxiety.
4. Male or female aged ≥18 and ≤ 70 years at the time of screening.
5. Body-Mass-Index (BMI) ≥ 18.5 and ≤ 29.9 kg/m2.
6. Volunteer is able and willing to comply with the study instructions.
7. Volunteer is suitable for participation in the study according to the investigator/study personnel.
8. Voluntary, written informed consent to participate in the study.

Exclusion Criteria:

1. No command of local language.
2. Previously or currently diagnosed neurological or psychiatric disorders.
3. Previous history of renal, hepatic, cardiovascular disease or clinically significant diabetes.
4. Gastrointestinal disorders including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) or other conditions that might affect the gut environment.
5. Contraindication or allergy to any substance in the verum or placebo product incl. lactose or fructose intolerance.
6. Use of drugs (e.g., antibiotics, aspirin, proton pump inhibitors) influencing gastrointestinal function in the previous 8 weeks before the beginning of intervention.
7. Use of laxatives and labelled pre-and probiotics in the previous 4 weeks before the beginning of intervention.
8. Participation in another study with any investigational product within 30 days of screening or during the study.
9. History of drug (recreational) or alcohol abuse.
10. Use of anti-depressants medication including selective serotonin receptor inhibitors or amitriptyline for 3 months prior to screening.
11. Bowel preparation for investigative procedures in the 4 weeks prior to screening.
12. Surgical resection of any part of the bowel.
13. Pregnant or lactating.
14. Regular smoking.
15. Previous Trier Social Stress Test (TSST) participation.

To reduce potential bias, the study will blind all key parties involved: participants, investigators, and those evaluating the outcomes.