The goal of this randomized controlled clinical trial is to evaluate whether polysaccharide peptide (PsP) supplementation from Ganoderma lucidum can modulate biomarkers of oxidative stress, inflammation, nicotine exposure, and stress response in adults exposed to cigarette smoke. The study is conducted in adults aged 20-50 years with active or passive exposure to cigarette smoke.

The main questions it aims to answer are:

• Does PsP supplementation change serum malondialdehyde (MDA) and superoxide dismutase (SOD) levels over 8 weeks?
• Does PsP supplementation affect serum interleukin-6 (IL-6), nitric oxide (NO), cotinine, nicotinic acetylcholine receptor (nAChR), and cortisol levels?

Researchers will compare participants receiving PsP supplementation with those receiving a placebo to evaluate differences in changes in the specified biomarkers.

Participants will:

• Be randomly assigned to receive PsP capsules (500 mg/day) or placebo for 8 weeks
• Provide fasting blood samples at baseline and at the end of the intervention
• Maintain usual lifestyle habits while avoiding antioxidant supplements during the study period

Cigarette smoke exposure is associated with increased oxidative stress and inflammatory responses, largely mediated by excessive production of reactive oxygen species. These processes contribute to elevated levels of lipid peroxidation products and proinflammatory cytokines, as well as measurable biomarkers of nicotine exposure and stress-related physiological responses. Individuals with active or passive exposure to cigarette smoke may therefore experience sustained biochemical alterations linked to oxidative and inflammatory burden.

Polysaccharide peptide (PsP) derived from Ganoderma lucidum is composed primarily of β-(1,3)/(1,6)-D-glucans and peptide fractions that have demonstrated antioxidant and immunomodulatory activity in experimental and preclinical studies. Despite growing interest in PsP as a functional nutritional supplement, clinical evidence evaluating its effects on oxidative stress and inflammation in smoke-exposed human populations remains limited.

This randomized, single-blind, placebo-controlled clinical trial is designed to assess the effects of PsP supplementation on selected serum biomarkers related to oxidative stress, inflammation, nicotine exposure, and stress response. Eligible participants are adults aged 20-50 years with documented active or passive exposure to cigarette smoke. Participants are randomly assigned in a 1:1 ratio to receive either PsP supplementation or a visually identical placebo for a period of 8 weeks.

Participants assigned to the intervention group receive PsP capsules at a total daily dose of 500 mg, administered as one 250 mg capsule twice daily. Each capsule contains standardized amounts of total polysaccharides, including β-glucans, and peptide fractions. The control group receives placebo capsules containing inert excipients with no known biological activity. All study products meet applicable pharmacopeial standards for quality and safety. Adherence to the intervention is monitored through capsule counts and participant-maintained compliance logs.

Fasting blood samples are collected at baseline and at the end of the intervention period. Serum is separated and stored under controlled conditions until analysis. Laboratory assessments are planned using validated analytical methods to quantify biomarkers of oxidative stress, antioxidant activity, inflammation, nicotine exposure, receptor-related parameters, and stress-related hormones.

The primary outcome measures include changes in serum malondialdehyde (MDA) and superoxide dismutase (SOD) concentrations from baseline to week 8. Secondary outcome measures include changes in serum interleukin-6 (IL-6), nitric oxide (NO), cotinine, nicotinic acetylcholine receptor (nAChR) levels, and cortisol concentrations over the same period.

The planned statistical analysis includes descriptive summaries of baseline characteristics and inferential analyses to compare changes in outcome measures between study groups and within groups over time. Appropriate statistical methods are prespecified to account for baseline variability. All analyses are conducted using two-tailed tests with a prespecified level of statistical significance.

Inclusion Criteria:

1. Male or female adults aged 18 to 60 years.
2. Has smoked regularly for at least the past 12 months.
3. Able and willing to provide written informed consent.
4. Agrees to maintain usual smoking habits during the study period.
5. Able to comply with study procedures and visits.

Exclusion Criteria:

1. Current use of antioxidant supplements, vitamins, herbal supplements, or mushroom- derived products within the last 4 weeks.
2. Diagnosis of chronic inflammatory disease, autoimmune disease, diabetes mellitus, cardiovascular disease, chronic kidney disease, chronic liver disease, or cancer.
3. Acute illness, infection, or fever within the last 14 days.
4. Regular use of anti-inflammatory drugs (NSAIDs, corticosteroids) within the last 4 weeks.
5. Participation in another clinical study within the past 30 days.
6. Pregnant or breastfeeding.
7. Known allergy to Ganoderma lucidum or mushroom-derived compounds.
8. Alcohol dependence or substance abuse other than tobacco.

Individual participant data (IPD) will not be shared because the study does not include a data-sharing plan in the ethics approval or informed consent. Data contain sensitive biomarker and smoking-related information that may pose a re-identification risk for participants. Therefore, IPD will not be made publicly available.

Participants were blinded to group allocation, with PsP and placebo capsules identical in appearance and packaging. Investigators conducting laboratory analyses were also blinded to group assignments.