Screening of Phytochemical Rich Ingredients as 'Functional Foods' to Improve Cardiometabolic Health

The study will be a non-blinded, randomised crossover trial with each participants testing between 2 to 4 different test ingredients requiring 5 or 9 separate test sessions (depending on how many the participants opt in for) on 9 non-consecutive days. The number of test ingredients that each participant will consume will be determined by the researcher and communicated to the participant. One of the test sessions will be a control session consisting of plain white rice (50 g available carbohydrates), with 20 g green vegetables being consumed with 200 ml of plain water. On the other hand, the test meal ingredients will be added either to the same amount of rice during preparation or will be added to 200 ml of plain water. The participants will be required to finish the meals within 15 minutes of serving. Appropriate food safety guidelines will be adhered to during the preparation and administration of test meals. We will be testing 20 separate food based traditional ingredients at either one or two doses. 20 participants will be recruited for each test food. Assuming that a minimum 2 test ingredients are tested in each participant up to 200 Chinese male participants aged between 21 and 60 years will be recruited from the general public in Singapore with body mass index between18.5 to 25.0 kg/m2, normal blood pressure (<140/90 mmHg), and fasting blood glucose (<7.0 mmol/L). The exclusion criteria are people who smoke, with any metabolic diseases (such as diabetes, hypertension etc), with glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency), with medical conditions and/ or taking medications known to affect glycemia (glucocorticoids, thyroid hormones, thiazide diuretics), intolerances or allergies to any foods, partake in sports at the competitive and/or endurance levels and individual who intentionally restrict food intake. Interested participants will first attend a consent and screening visit following an overnight fast to go over the informed consent procedure and ascertain their suitability to take part in the study. During this visit, the researchers will discuss the study in more detail and go through the participant information sheet and address any queries that the potential participant may have. If participants are willing to proceed, they will then be asked to sign the informed consent form and complete the screening visit forms and questionnaires. If suitable to proceed, they will then undertake the screening visit measurements including height, weight, waist circumference, body impedance and blood pressure measurements. If suitable at this stage, a finger prick blood glucose measurement will be carried out using the HemoCue® device (Helsingborg, Sweden). The visit should last approximately 1.5 hours. During each of the test days, participants will receive test meals in a random order made with up to 4 different food based test ingredients or the control meal (without any test ingredients). Randomisation of test meals will be done using the =RAND() function in Excel. The ingredients will tested in various doses and/or forms of consumption. The participants will arrive at the study centre following an overnight fast. After a 15 minute rest period, they will have a cannula inserted in their arm to obtain blood samples at regular intervals. There will be 9 blood draws in total per test session: Baseline (0 h, before test meal) and 8 blood samples after test meals at 0.25 h, 0.5 h, 0.75 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h and 3.0 h. At each time point, we will collect 3 ml (about half a teaspoon) of blood. Therefore, for each test day, up to 30 ml blood will be taken and for the entire 9 test sessions, around 270 ml of blood will be collected (around 18 tablespoons) or if the participants only opt in for 5 test sessions, they will donate approximately 150 ml of blood (around 10 tablespoons). The blood samples collected at each timepoint will be measured for glucose, insulin and markers related to the intake of the test meal ingredients. At 4 time points (0 h, 1 h, 2 h and 3 h), seated blood pressure measurements will also be undertaken for 3 times, using an automated sphygmomanometer (Omron, Japan) and the average of the final two blood pressure readings will be taken as that given timepoint. Each test day should take no longer than 4 hours to complete. Participants will be asked to refrain from alcohol and exercise the day before each test day. The study will last between 4 and 12 weeks to compete and each test session will be undertaken on non- consecutive days, dependent on the participants' availability. The participants will be asked to continue with their usual lifestyle during their study participation when they are not attending the test sessions.