Evaluate the effect of spermidine supplementation on lipid profile changes in individuals with overweight or obesity accompanied by hyperlipidemia. Analyze the impact of spermidine on metabolic parameters and assess the safety of spermidine supplementation, including liver and kidney function, gastrointestinal reactions, and other adverse effects.

This is a single-center, randomized, double-blind, placebo-controlled, parallel-group trial designed to evaluate the efficacy and safety of spermidine supplementation in overweight or obese adults with hyperlipidemia.

A total of 50 eligible participants will be randomly assigned in a 1:1 ratio to either the experimental group (spermidine capsule 10 mg/day) or the control group (placebo capsule, identical in appearance, packaging, and taste). Randomization will be performed by a third-party statistician using a computer-generated random number table with variable block sizes. Allocation concealment will be ensured through sequentially numbered, opaque, sealed envelopes. All outcome assessors, investigators, and participants will be blinded to group assignment throughout the study.

The intervention period lasts 1 month. Participants in the experimental group will take 2 capsules (10 mg total) of spermidine (extracted from North American high-selenium wheat germ, 100:1 concentration process) orally per day after breakfast. The placebo group will receive an identical regimen of microcrystalline cellulose capsules. During the trial, all participants will receive standardized dietary advice designed to avoid high-polyamine foods (e.g., natto, fermented soy products, mushroom, germ products) and maintain stable total energy intake without overeating. They will also be advised to avoid new nutritional supplements and any other weight-loss interventions. Weekly telephone follow-ups will monitor compliance and dietary/exercise logs. Compliance will be assessed by pill counts of returned capsules, with <80% adherence defined as protocol deviation.

Assessments are scheduled at baseline (Day 0) and at study end (Month 1). Baseline evaluations include anthropometric measurements, blood biochemistry, stool sample collection, and questionnaire assessments. At Month 1, all baseline measurements will be repeated, and adverse events will be recorded and assessed for causality using the Naranjo scale. Safety monitoring includes liver and kidney function tests and documentation of gastrointestinal or other adverse reactions throughout the trial.

Primary outcome is the change in triglycerides (TG) from baseline to 1 month. Secondary outcomes include changes in LDL, total cholesterol, weight, BMI, body fat percentage, waist-to-hip ratio, fasting glucose, liver/kidney function parameters, and adverse event rates. Statistical analyses will follow the intention-to-treat principle using SAS 9.4. Primary analysis will employ two independent sample t-tests or Mann-Whitney U tests for between-group comparisons.

Inclusion Criteria:

• Males or females aged 18 to 65 years.
• BMI ≥ 24 kg/m², without severe chronic diseases.
• Not currently using glucose-lowering or lipid-lowering medications.
• Dyslipidemia defined as triglycerides ≥ 1.7 mmol/L or total cholesterol ≥ 5.2 mmol/L.
• No active weight loss or weight gain diet within the past 1 month.
• No special dietary pattern changes (e.g., ketogenic, vegan, high-protein, meal replacement, intermittent fasting) within the past 1 month.
• No use of supplements that may affect polyamine intake (e.g., germ, yeast, fermented extracts, nutritional powders) within the past 2-4 weeks.
• Willing and able to provide signed informed consent.

Exclusion Criteria:

• Diagnosis of acute or severe gastrointestinal disease
• Concurrent participation in any other weight-loss therapy
• Current use of hypoglycemic or lipid-lowering medications
• Participation in any other clinical trial within one month prior to signing the informed consent form
• Pregnancy, lactation, or planning a pregnancy during the trial period
• Known allergy to cellulose or wheat
• History of cancer
• Renal insufficiency, indicated by abnormal serum creatinine levels
• Hepatic impairment, defined as alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >3 × upper limit of normal (ULN), or total bilirubin (TBIL) >3 × ULN
• Any other condition deemed by the investigator as inappropriate for trial participation