Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common chronic liver condition linked to excess body fat, high blood lipids, and other metabolic problems. Taiwan green propolis is a natural health product collected by bees from plants, which has shown potential benefits for blood lipids and body fat in laboratory and animal studies. However, its effects in people with MASLD have not been well established in clinical trials.

This study is a double-blind, randomized, placebo-controlled trial enrolling up to 60 adults with MASLD at Dalin Tzu Chi Hospital in Taiwan. Eligible participants are randomly assigned in a 1:1 ratio to receive either Taiwan green propolis capsules or matching placebo capsules for 12 weeks. Participants take 2 capsules before breakfast and 2 capsules before dinner each day (4 capsules per day total). Neither participants nor the research team know which capsules are being taken until the study ends.

The study measures changes in blood lipids (triglycerides, total cholesterol, LDL-C, and HDL-C), body fat percentage, body weight, waist circumference, liver enzymes, blood sugar levels, inflammatory markers, and health-related quality of life. Liver fat and scarring are assessed by abdominal ultrasound before and after the intervention. Gut microbiota samples are also collected. Assessments are conducted at baseline, at 4 weeks, 8 weeks, 12 weeks (end of intervention), and at follow-up visits 2 weeks and 12 weeks after the intervention ends.

The goal of this study is to provide scientific evidence on whether Taiwan green propolis can safely and effectively improve blood lipids, body fat, and metabolic health in people with MASLD, and to explore the relationship between physiological improvements and health behavior changes.

Participants are enrolled at Dalin Tzu Chi Hospital (Dalin Township, Chiayi County, Taiwan). Random allocation is performed using a computer-generated random number sequence with a 1:1 male-to-female ratio, further stratified by physiological life stage (reproductive age, middle age, perimenopausal/menopausal, and elderly). Allocation concealment is achieved using sequentially numbered opaque sealed envelopes, which are opened in order after informed consent is obtained.

Intervention arm: Taiwan green propolis capsules (propolis extract), 2 capsules before breakfast and 2 capsules before dinner (4 capsules/day) for 12 consecutive weeks. Capsules may be stored at room temperature.

Placebo arm: Capsules containing edible dextrin with vitamin B2 (approximately 0.1 mg/capsule), identical in appearance and administration schedule to the propolis capsules.

Both participants and all research personnel involved in assessment and data collection are blinded to group assignment throughout the study period.

Assessment schedule:

• Baseline: Anthropometrics (height, weight, BMI, waist/hip circumference), skinfold thickness at 7 sites, blood pressure, heart rate, full blood lipid panel, liver enzymes (AST/ALT/GGT), fasting glucose, HbA1c, complete blood count, biochemistry (albumin, BUN, creatinine, uric acid), thyroid function (TSH, T3, free T4), inflammatory cytokines (IL-6, IL-8, IL-1beta), body composition by bioelectrical impedance (InBody), abdominal ultrasound (hepatic steatosis and fibrosis grading), fecal specimen, and all questionnaires.
• Weeks 4 and 8: Anthropometrics, skinfold thickness, blood pressure, body composition, blood lipid panel, liver enzymes, fasting glucose, HbA1c, biochemistry, ESAS-R. Inflammatory cytokines added at Week 8.
• Week 12 (end of intervention): Full assessment as baseline, except thyroid function; all questionnaires repeated; dietary and activity diary (3 days).
• Week 14 (2 weeks post-intervention): Anthropometrics, blood lipid panel, ESAS-R.
• Week 24 (12 weeks post-intervention): Full assessment as baseline; all questionnaires; fecal specimen.

Questionnaires administered include: General questionnaire, Health Belief Model questionnaire, International Physical Activity Questionnaire (IPAQ Taiwan short form), EQ-5D-5L, Dietary Behavior Scale, and Edmonton Symptom Assessment System-Revised (ESAS-R).

Standard care including dietary counseling and appropriate physical activity is provided to all participants throughout the study, regardless of group assignment.

Primary statistical analyses will use intention-to-treat principles. Mixed-effects models for repeated measures (MMRM) or analysis of covariance (ANCOVA) will compare changes from baseline between groups for primary and secondary outcomes. Descriptive statistics will be reported for all variables.

Inclusion Criteria:

• Adults aged 18 to 80 years

• Diagnosis of hepatic steatosis (fatty liver) confirmed by abdominal ultrasound, PLUS at least one of the following metabolic risk factors:

  1. Overweight or obesity: BMI >= 23 kg/m^2
  2. Elevated waist circumference: >= 90 cm in men or >= 80 cm in women (South Asian and Chinese criteria)
  3. Dysglycemia or type 2 diabetes: prediabetes (HbA1c 5.7-6.4%, or fasting glucose 100-125 mg/dL, or OGTT 2-hour glucose 140-199 mg/dL) OR type 2 diabetes (HbA1c >= 6.5%, or fasting glucose >= 126 mg/dL, or OGTT 2-hour glucose >= 200 mg/dL, or current pharmacological treatment for type 2 diabetes)
  4. Elevated triglycerides: >= 150 mg/dL or currently on lipid-lowering therapy
  5. Low HDL-C: <= 39 mg/dL in men or <= 50 mg/dL in women, or currently on lipid-lowering therapy
  6. Elevated blood pressure: >= 130/85 mmHg or currently on antihypertensive treatment

Exclusion Criteria:

• Known allergy to honey, propolis, multiple pollens, or alcohol
• Psychiatric disorder or cognitive impairment
• Currently pregnant or breastfeeding
• Significant endocrine abnormality, or major disease of the heart, liver (other than MASLD), or kidney
• Difficulty swallowing capsules
• Dementia, impaired consciousness, or inability to respond to questionnaires

Both participants and investigators are blinded to group assignment throughout the intervention period. Allocation concealment is maintained using sequentially numbered opaque sealed envelopes opened only after informed consent is obtained. The placebo capsules are identical in appearance, packaging, and administration schedule to the active intervention capsules.