This randomized controlled clinical study aims to evaluate the effect of Modified Huanglian Wendan Decoction on oxidative stress in patients with metabolic syndrome. A total of 180 patients with metabolic syndrome from The First Affiliated Hospital of Heilongjiang University of Chinese Medicine will be assigned to a control group or an observation group at a 1:1 ratio. Participants in both groups will receive lifestyle intervention and standard therapy, including antihypertensive, hypoglycemic, and lipid-lowering treatment. Participants in the observation group will additionally receive Modified Huanglian Wendan Decoction for 3 months. The study will compare changes in oxidative stress indicators, obesity-related parameters, blood pressure, glucose and lipid metabolism, and insulin resistance before and after treatment.

Metabolic syndrome is a cluster of metabolic abnormalities characterized by obesity, hypertension, dyslipidemia, impaired glucose metabolism, and insulin resistance. Oxidative stress is considered an important mechanism involved in the development and progression of metabolic syndrome. Traditional Chinese medicine may provide additional therapeutic benefits through multi-component and multi-target regulation.

This study is a single-center, randomized controlled clinical study conducted at The First Affiliated Hospital of Heilongjiang University of Chinese Medicine. A total of 180 eligible patients with metabolic syndrome will be enrolled and randomly assigned to a control group or an observation group in a 1:1 ratio. Randomization will be performed using a random number table or randomization software by an independent staff member who is not involved in participant recruitment, treatment, or statistical analysis.

All participants will receive lifestyle intervention, including health education, lifestyle modification, appropriate aerobic exercise, a low-salt and low-fat diet, reduced cholesterol intake, and increased dietary fiber intake. Participants in the control group will receive standard therapy, including valsartan capsules, metformin hydrochloride tablets, and atorvastatin calcium tablets. Participants in the observation group will receive Modified Huanglian Wendan Decoction in addition to the same lifestyle intervention and standard therapy used in the control group. The decoction will be administered orally twice daily for 3 months.

Outcome assessments will be performed at baseline and after 3 months of treatment. The primary outcomes are oxidative stress indicators, including malondialdehyde, superoxide dismutase, glutathione, glutathione peroxidase, catalase, and reactive oxygen species. Secondary outcomes include waist circumference, body mass index, waist-to-hip ratio, waist-to-height ratio, systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting insulin, fasting plasma glucose, 2-hour postprandial glucose, glycated hemoglobin, homeostasis model assessment of insulin resistance, triglyceride-glucose index, and triglyceride to high-density lipoprotein cholesterol ratio.

The purpose of this study is to assess the clinical efficacy and safety of Modified Huanglian Wendan Decoction in patients with metabolic syndrome and to provide clinical evidence for traditional Chinese medicine in the management of metabolic syndrome and oxidative stress.

Inclusion Criteria:

• Patients aged 18 to 75 years.
• Male or female patients.
• Patients diagnosed with metabolic syndrome according to applicable clinical diagnostic criteria.
• Patients treated in the outpatient department or inpatient ward of The First Affiliated Hospital of Heilongjiang University of Chinese Medicine.
• Patients who are able to understand the study procedures and cooperate with treatment, examinations, and follow-up.
• Patients who voluntarily participate in the study and sign the written informed consent form.

Exclusion Criteria:

• Patients with severe diseases of vital organs or systems, including severe cardiovascular, hepatic, renal, neurological, or hematopoietic diseases.
• Patients with malignant tumors, autoimmune diseases, acute infectious diseases, or severe psychiatric disorders.
• Pregnant or lactating women, or women planning pregnancy during the study period.
• Patients with known allergy or intolerance to any study medication or herbal components used in this study.
• Patients who have recently participated in another clinical study or are receiving other treatments that may affect the study outcomes.
• Patients with poor compliance who cannot take the study medication regularly or complete follow-up.
• Patients judged by the investigators to be unsuitable for participation in this study for any other reason.

Individual participant data will not be shared publicly because the study data contain personal health information, laboratory test results, treatment information, and oxidative stress-related outcomes from patients with metabolic syndrome. All study data will be de-identified and managed by the research team in accordance with the approved protocol, informed consent, ethical approval, and institutional data protection requirements.

This is an open-label study. Blinding of participants and investigators is not feasible because the observation group will receive Modified Huanglian Wendan Decoction in addition to standard therapy, while the control group will receive standard therapy only. Standardized data collection procedures will be used to reduce potential bias.