The Relationship Between Diet, Cognition, Stress, and the Gut Microbiota

Inclusion Criteria: * Be able to give written informed consent. * Be between 18 and 50 years of age. * Have a body mass index (BMI) between 18.5-29.9 Kg/m2. * Be in generally good health as determined by the investigator. Exclusion Criteria: * Are less than 18 and greater than 50 years of age. * Have a BMI below 18.5 or above 29.9 Kg/m2. * Have a significant acute or chronic coexisting illness \[cardiovascular, gastrointestinal (GI) \[to include functional GI disorders, inflammatory bowel disease, coeliac disease, lactose intolerance, food allergies\], immunological, psychiatric \[to include formal or as determined by MINI Psychiatric interview, diagnosis of current major depression, anxiety disorder, bipolar spectrum disorder, schizophrenia, other DSM-IV Axis I disorder\], neurodevelopmental disorders, immunological, metabolic disorders \[to include type I or II diabetes\], or any condition which contraindicates, in the investigators judgement, entry to the study. * Have a condition or taking a medication that the investigator believes would interfere with the objectives of the study, pose a safety risk, or confound the interpretation of the study results; all psychoactive medications \[to include anxiolytics, antipsychotics, antidepressants, anticonvulsants, centrally acting corticosteroids, and opioid pain relievers), laxatives, enemas, antibiotics, anti-coagulants, over-the counter non-steroidal anti-inflammatories (NSAIDS). Subjects should have a wash-out period of 4 weeks. * Current prebiotic or probiotic supplement use (a wash-out period of 4 weeks after cessation will allow entry to the study). * Females who are peri-menopausal, menopausal or post-menopausal. * Females who are pregnant or planning a pregnancy, or lactating. * Participants who are not fluent in English. * Are colour blind. * Have dyslexia or dyscalculia. * Are a current habitual daily smoker. * Individuals who, in the opinion of the investigator, are considered to be poor attendees or unlikely for any reason to be able to comply with the trial. * Subjects receiving treatment involving experimental drugs. If the subject has been in a recent experimental trial, these must have been completed not less than 30 days prior to this study. * Have a malignant disease or any concomitant end-stage organ disease. * Have completed a study in our laboratory in the past 4 years.