Standardized Large Yellow Tea Extract for Glucose and Lipid Metabolism in Overweight Adults With Hypertriglyceridemia

This study is a multicenter, prospective, randomized, blinded, parallel-group controlled intervention trial conducted at the First Affiliated Hospital of USTC, Huangshan People's Hospital, and Lu'an People's Hospital in China.

Eligible participants will be adults aged 18 to 60 years who are overweight or obese, defined as a body mass index of at least 24.0 kg/m², and who have elevated fasting triglyceride levels without diagnosed diabetes or major cardiovascular disease. After screening and confirmation of eligibility, participants will be randomized in a 1:2 ratio to the placebo control group or the standardized large yellow tea extract group.

The intervention period will last 12 weeks. Both groups will receive standardized lifestyle guidance covering diet, physical activity, and sleep. Lifestyle-related factors will be assessed using dietary records, the International Physical Activity Questionnaire, and the Pittsburgh Sleep Quality Index. Adherence, concomitant medication use, and adverse events will be monitored throughout the intervention period.

Study visits are planned at screening, baseline, week 4, week 8, and week 12. Fasting blood samples will be collected for efficacy and safety assessments according to the study schedule. The primary efficacy endpoint is the change in fasting triglyceride concentration from baseline to week 12.

Secondary assessments include total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, apolipoprotein A1, apolipoprotein B, fasting plasma glucose, fasting insulin, HOMA-IR, body weight, body mass index, waist circumference, blood pressure, and heart rate. Safety assessments include adverse events, laboratory safety parameters, and tolerability.

Exploratory analyses will investigate changes in plasma and/or urine metabolomic profiles, identify metabolites associated with exposure to large yellow tea extract, and explore associations between candidate biomarkers and triglyceride response.

After completion of the 12-week intervention, participants will continue follow-up through week 24 for evaluation of longer-term safety and changes in glucose and lipid metabolism.

Inclusion criteria

• Voluntarily participates in the study, fully understands the study objectives, procedures, and potential risks, and provides written informed consent.
• Aged 18 to 60 years, either sex.
• Body mass index (BMI) ≥24.0 kg/m², with body weight fluctuation <5% during the previous 3 months.
• Elevated fasting triglyceride (TG) level, consistent with hypertriglyceridemia or a high-normal/elevated triglyceride status.
• General health condition is stable, with no clinically significant abnormalities in vital signs or physical examination as judged by the investigator.
• Baseline laboratory tests show no clinically significant abnormalities; complete blood count, liver function, and renal function are considered acceptable by the investigator for safe participation.
• No diagnosis of diabetes mellitus and no regular use of glucose-lowering medications during the previous 3 months.
• No regular use during the previous month of medications, dietary supplements, or tea extract products that may substantially affect glucose or lipid metabolism.
• Able to understand and comply with the study requirements and willing to complete the 12-week intervention and follow-up, with acceptable anticipated adherence as judged by the investigator.

Exclusion criteria

• Known or suspected allergy to tea, tea polyphenols, caffeine, or any component of the study products, or a history of severe allergic reactions.
• Presence of any of the following cardiovascular or high-risk conditions:

• Established coronary atherosclerotic heart disease, including myocardial infarction, unstable angina, or previous coronary revascularization;
• Cerebrovascular disease, including stroke or transient ischemic attack;
• Peripheral arterial disease;
• Hypertension, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg, or current use of antihypertensive medication;
• Diagnosed type 1 or type 2 diabetes mellitus;
• Other serious cardiovascular or cerebrovascular disease that, in the investigator's judgment, may increase participant risk or interfere with assessment of study outcomes.
• Severe abnormalities of glucose or lipid metabolism, including diabetes mellitus.
• Clinically significant baseline laboratory abnormalities, including ALT or AST >1.5 times the upper limit of normal, total bilirubin >1.5 times the upper limit of normal, significantly reduced renal function, or clinically significant abnormalities in complete blood count as judged by the investigator.
• Use within the previous 3 months of lipid-lowering medications, weight-loss medications, long-term systemic glucocorticoids, or other medications that may substantially affect glucose or lipid metabolism; or regular use within the previous month of high-dose antioxidants, fish oil, plant sterols, tea extracts, or other products that may affect study outcomes.
• Participation in another clinical trial within the previous 3 months, or blood donation/blood loss ≥400 mL within the previous 3 months.
• Pregnant or breastfeeding women, women planning pregnancy during the study, or participants unwilling to use effective contraception when applicable.
• Alcohol abuse, drug abuse, poor anticipated adherence, or any other condition considered by the investigator to make participation inappropriate.