How quitting smoking affects metabolism and gut bacteria in people in long-term addiction treatment

Metabolomic and Gut Microbial Biomarkers of Smoking Cessation Treatment in Long-term Drug Therapy: A Randomized Controlled Trial

Not applicable Interventional Sigmund Freud PrivatUniversitat · NCT06803706

This study will test whether a six-week quit-smoking program improves emotional control, confidence, and reduces cravings in adults with substance use disorders by changing metabolic markers and gut bacteria.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment150 (estimated)
Ages18 Years and up
SexAll
SponsorSigmund Freud PrivatUniversitat Academic / other
Locations3 sites (Fehring and 2 other locations)
Trial IDNCT06803706 on ClinicalTrials.gov

What this trial studies

Participants in therapeutic communities who are receiving long-term drug therapy will take part in a six-week cognitive-behavioral smoking cessation program while researchers collect behavioral measures, blood/urine metabolomics, and stool samples for gut microbiome analysis. The study compares psychobehavioral outcomes (emotional regulation, self-efficacy, craving) before and after the intervention and links those changes to shifts in metabolic and microbiome profiles. Participants with recent antibiotic or probiotic use and certain medical conditions are excluded to reduce confounding effects on the microbiome. The goal is to identify biological signatures that accompany successful smoking cessation in people with substance use disorders.

Who should consider this trial

Good fit: Adults (18+) with a diagnosed substance use disorder who are German-speaking, willing to quit smoking, and enrolled in long-term drug therapy within the participating therapeutic communities are ideal candidates.

Not a fit: Individuals with acute psychosis or suicidal tendencies, significant cardiovascular or severe medical/neurological illnesses, pregnancy or breastfeeding, recent antibiotic/probiotic use, or recent major gastrointestinal surgery are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, the approach could show that quitting smoking improves emotional regulation and reduces craving in people with SUD, potentially informing integrated treatments that target metabolism or the microbiome.

How similar studies have performed: Previous observational work has linked microbiome and metabolic profiles to addiction and smoking, but interventional tests of smoking cessation's effects on microbiome and metabolome in people with SUD are still limited.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria: Informed consent, a diagnosis of a form of substance use disorder (F1x.x) by a licensed psychiatrist according to ICD-10, minimum age of 18 years, sufficient knowledge of the German language, willingness to quit smoking.

Inclusion criteria years: minimum age of 18 years. -

Exclusion Criteria: lack of consent, age below 18, inability to provide informed consent, acute psychotic symptoms or acute suicidal tendencies, cardiovascular disease, pregnancy or breastfeeding, severe mental or organic illnesses (such as epilepsy, brain tumors, recent major surgery), tumor diseases, dementia (Mini Mental Score \<20), severe autoimmune diseases or immunosuppression, acute infections, or acute diarrhea, prior gastrointestinal surgery (except appendectomy), probiotic intake within the last 6 months, or those consuming dietary supplements, probiotics, antibiotics, or prebiotic supplements during the study, prior participation in a smoking cessation programme.

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Where this trial is running

Fehring and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Substance Use DisorderAlcohol Use DisorderNicotine AddictionHealthy Adult ParticipantsMetabolomicsGut microbiomeSubstance use disordernicotine addiction
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.