Acute Berry Intake on Metabolic Control and Cognitive Function

The proposed study will be conducted in humans according to Good Clinical Practice (GCP) guidelines. All subjects will review and sign an Informed Consent Form approved by the Illinois Institute of Technology's Institutional Review Boards (IRB) prior to screening. This multi-center clinical trial is a randomized, single-blind, 2-arm, placebo-controlled, within subject cross-over trial, featuring a repeated postprandial sampling paradigm to evaluate the effects of acute dietary red raspberry intake on cognitive function, inflammation, insulin sensitivity / glucose handling and vascular function in overweight/obese older adults after consuming a standardized challenge meal. A planned sample size of 30 will be enrolled into the study. This study will require one initial screening visit and 3 study visits. This study will take approximately 3-4 weeks per subject to complete. The initial screening visit will provide subject with their site-specific, IRB-approved informed consent document prior to the start of any study related procedures. Subject eligibility will be determined through anthropometric measurements, vital signs, fasting blood glucose test (finger prick), and completion of a survey relate to general eating, health, mood and exercise habits. Eligible subjects will follow a limited polyphenolic diet throughout the duration of their participation, although stricter guidelines will be imposed during the 3 days prior to a study visit. Shopping lists and meal plans will be provided to subjects, along with counseling by the investigator's study dietitians, to help subjects adhere to the limited polyphenolic diet. The trial will initiate with a 3-day food diary to assess background (pre-study) dietary intake followed by counseling to follow a diet relatively low in (poly)phenolic rich-beverages/foods, which will be maintained for the duration of the experiment. After an initial 7 day run-in period on the limited polyphenolic diet, subjects will be randomized to 1 of 2 treatment sequences. Treatment codes will be maintained by the principal investigator/study physician. All subjects will receive both treatments, once each on 2 different occasions and separated by at least 1 week. Red raspberries or placebo will be provided with a standardized meal providing 840 kcal. A low-polyphenol snack will be provided to subjects after their final cognitive assessment. Each visit will last \~ 9.5 hours and subjects will be required to remain at the Clinical Unit for the duration of the visit. Blood samples will be collected at 0 (fasting) and at 0.5 h, 1 h, 2 h, 4 h, 5 h, 6 h and 7.5 h via a catheter placed on the non-dominant arm by a registered nurse. Cognitive function will be measured at 0 (fasting), 2 h, and 6 h. FMD or NIRS will be conducted at the CNRC or the HNRCA, respectively at 0 (fasting), and at 1 h and 5 h.