Postprandial Effect of Olive Leaf Biscuits and Tea Consumption on Blood Biomarkers in Healthy Individuals

This randomized controlled nutritional intervention study aims to investigate the bioactivity of dried olive leaves in biscuit and tea preparations, focusing on their postprandial effects on selected biomarkers and plasma antioxidant status. Healthy volunteers aged 18 to 65 from Limnos, Greece, will participate in the study, held at the Human Nutrition Unit of the University of the Aegean. The study will last 15 days and features a cross-over design involving three groups: Control Group: Consumes biscuits made with butter, flour, sugar, and caramel coloring, along with natural mineral water. Intervention Group A: Receives the same biscuits with added dried olive leaf powder, accompanied by the same water. Intervention Group B: Eats the standard biscuits with olive leaf tea instead of water. On each study day, participants will consume their meal over 15 minutes, followed by the liquid within 10 minutes. After a 7-day washout period, the groups will switch treatments for the second phase. The procedure will be repeated on the 15th day, ensuring that all participants experience each condition. Blood samples will be collected before and at 60, 120, and 240 minutes post-meal for analysis. Statistical processing will then be conducted to evaluate the effects on biomarkers and antioxidant status.