The planned study aims to assess whether probiotics improve the quality of life in patients during the early postoperative period following sleeve gastrectomy, and whether they influence the absorption of micro- and macronutrients.

Patients eligible for inclusion will have a BMI of 40 kg/m² or higher and must have successfully completed the qualification process for sleeve gastrectomy. Exclusion criteria include chronic gastrointestinal diseases, antibiotic use within 4 weeks prior to surgery, and lack of consent to participate in the study.

On the day before surgery, a stool sample will be collected from each patient for microbiological analysis to assess the composition of gut bacteria. Patients will then undergo sleeve gastrectomy using a standard surgical technique.

After the operation, participants will be randomized into two groups. The first group will receive probiotics containing Bifidobacterium animalis AMT30, Bifidobacterium breve AMT32, and Lactobacillus plantarum AMT14. These strains are deposited in the Polish Collection of Microorganisms at the Polish Academy of Sciences in Wrocław and are protected by Polish, European, and U.S. patents. The second group will receive a placebo.

As part of follow-up, stool samples will be collected again one month and three months after surgery for comparative microbiological analysis.

Inclusion Criteria:

1. Age over 18 years.
2. BMI over 40 kg/m² or over 35 kg/m² with obesity-related comorbidities.
3. Successful qualification for sleeve gastrectomy.
4. Informed consent to participate in the study.

Exclusion Criteria:

1. Age under 18 years.
2. Chronic gastrointestinal diseases.
3. Use of antibiotic therapy within 4 weeks prior to surgery.
4. Lack of consent to participate in the study.