Inclusion Criteria:  Be able to give written informed consent. Be between 30 and 60 years of age. Be in generally good health as determined by the investigator.  Exclusion Criteria:  Are less than 30 and greater than 60 years of age. Have a significant acute or chronic coexisting illness [cardiovascular, gastrointestinal (GI) [to include functional GI disorders, inflammatory bowel disease, celiac 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). Participants 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 or English is not first language. Are color 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. Participants 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 the laboratory in the past 4 years.