2.3. Study Design
BLIND
The study was a randomised, crossover, three-arm, blind intervention that lasted 8.5 months. After a 2-week run-in, volunteers were randomly allocated to begin consuming GCP, BG or GCP/BG; randomisation was carried out using the MicrosoftAt the beginning and end of each intervention period, volunteers attended the Human Nutrition Unit (HNU) at the Institute of Food Science, Technology and Nutrition (ICTAN). During the two days prior to each visit, participants were instructed to avoid caffeine and to consume a low-polyphenol diet, with special emphasis on the avoidance of foods rich in hydroxycinnamates, such as herbal teas; artichokes; red wine; vegetables; whole-grain cereals; and fruits, including dried fruits, juices and smoothies. Only watermelon, banana, potatoes and cantaloupes were allowed. In each visit, the subjects came to the HNU after an overnight fast. Then, a blood sample was obtained from the cubital vein by a licensed health care professional and collected into tubes without anticoagulant or in EDTA-coated tubes to obtain serum and plasma samples, respectively. In addition, blood pressure was measured, and anthropometric data were collected. SBP, DBP and heart rate were measured in triplicate in the non-prevailing arm with an OMRONParticipants were asked to refrain from changing their dietary and physical activity habits. Diet was monitored by collecting 72 h dietary recall questionnaires (which included two working days and one weekend day), which volunteers completed before each visit to the HNU. Energy and macronutrient and micronutrient intake were calculated using DIAL software for Windows (version 3.0.0.5; Department of Food Science and Nutrition, School of Pharmacy (UCM) and Alce Ingeniería, S.A. Madrid, Spain). 