Chronic constipation is a common gastrointestinal disease with a global prevalence of about 15%, significantly affecting daily life and quality of life. Traditional treatments primarily rely on laxatives, which may lead to adverse effects with prolonged use, while surgical interventions have limited patient acceptance. Recent studies indicate that gut microbiota therapies-including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT)-can effectively manage chronic constipation. This study aims to investigate the safety and efficacy of FMT combined with a prebiotic nutritional intervention (using a co-localization strategy) in the treatment of functional constipation. Additionally, the investigators will explore changes in fecal microbiota and metabolomic profiles following the treatment.

Inclusion Criteria:

1. Age: 18 to 70.

2. Diagnostic criteria: Functional constipation (FC) in accordance with Rome IV criteria, which should meet the following conditions:

   • Symptom requirements: The following at least 2 items should occur in ≥25% of bowel movements: a. Straining during defecation; b. Hard stool (Bristol Stool Classification score 1-2); c. Feeling of incomplete evacuation; d. Rectal obstruction sensation; e. Need for finger assistance during defecation; f. Spontaneous bowel movements <3 times per week.
   • It is rare to have loose stools without laxatives.
   • Exclusion of irritable bowel syndrome (IBS): IBS diagnosis criteria not meeting Rome IV.
   • Disease course requirements: Symptoms persist for at least 6 months and meet the above criteria within the last 3 months.

3. Traditional treatment methods (dietary intervention, at least two laxatives or probiotics) are ineffective.

Exclusion Criteria:

1. Pregnancy or lactation.
2. Unable to take the intervention product or complete the examination as required.
3. Language expression disorder or mental illness.
4. Physical examination showed severe liver and kidney dysfunction.
5. Acute gastrointestinal disease within 4 weeks.
6. Constipation caused by surgery in the past 4 weeks.
7. History or abnormal examination: cancer, severe enteritis, intestinal obstruction, inflammatory bowel disease, hypothyroidism, mental illness, stroke, heart disease, cirrhosis, renal failure, hematopoietic system diseases, organic bowel disease suggested by colonoscopy or imaging.
8. Participation in other clinical trials within 3 months prior to enrollment.
9. Other health problems are not suitable for participation in the study.