Influence of Tea Consumption on Human Glycemic Response

This study aims to investigate the effects of tea and food consumption on postprandial metabolic responses, specifically focusing on blood glucose (glycemia) and blood lipid levels. The primary objective is to generate scientifically grounded insights that can inform consumer education and product communication regarding the metabolic impacts of tea and food intake. The study will recruit healthy male volunteers of Chinese ethnicity, aged 21 to 60 years inclusive. Eligible participants will be required to attend seven study visits: (1) an initial screening session, (2) a 2-hour Oral Glucose Tolerance Test (OGTT), and (3-7) five 3-hour intervention sessions.

During the screening, participants will undergo body composition measurement, and a blood draw to confirm eligibility. Participants will also be provided with standardized dinner meals to be consumed the day before each subsequent visits as their last meal of the day before an overnight fast. In the OGTT session, participants will fast overnight. They will be cannulated and consume a glucose beverage; blood samples will be collected at seven timepoints over two hours to analyze for glucose, insulin, lipids, and other metabolic biomarkers. Each of the five intervention sessions will also require overnight fasting. Participants will consume either: one of two tea beverages, each tea beverage with a standardized meal, or the meal alone. Participants will be cannulated and blood will be drawn at nine timepoints over three hours per session. They will also complete satiety questionnaires at each timepoint. Blood samples will be analyzed for glucose, insulin, lipid panel, hormones, and other metabolic biomarkers to evaluate the postprandial effects of the interventions.

The findings are expected to clarify whether tea modulates postprandial glycemic and lipid responses compared to typical intake conditions. Results may support evidence-based communication about tea's metabolic effects and inform future product development and consumer guidance.

Inclusion criteria

• Male
• Chinese ethnicity
• Ages 21-60 years old (inclusive)
• Healthy
• Weigh at least 50kg
• Must be English-literate and able to give informed consent in English
• Reliable and willing to make themselves available for the duration of the study and are willing to follow study procedures

Exclusion criteria

• Female
• A current smoker, or has smoked in the past 2 years
• Fasting glucose >= 7 mmol/L
• History of type 1/type 2 diabetes
• Regular use of medication that may affect glucose metabolism (e.g., steroids)
• Being diagnosed with cancer, heart disease, stroke, renal failure, serious mental or physical illnesses at the time of recruitment
• History of food allergies to test products (milk tea) i.e. milk allergies, or lactose intolerance
• History of food allergies to any of the ready made meals (such as soy, peanuts, eggs, shellfish etc)
• Have donated blood of more than 500 mL within 8 weeks of study enrolment
• Any other conditions, which, in the opinion of the Investigator would make the subject unsuitable for inclusion or could interfere with the subject participating in or completing the study