This randomized controlled clinical study investigates the effects of daily synbiotic supplementation (containing Lactobacillus rhamnosus GG and partially hydrolyzed guar gum) in patients who underwent sleeve gastrectomy. 60 participants aged 18-65 with a BMI of 35 or higher were randomly assigned to intervention (n=30) and control (n=30) groups. The intervention group received a 5 g sachet daily for 12 weeks postoperatively, mixed into 200 ml of yogurt and consumed during afternoon snacks. The control group received no supplementation. Anthropometric measurements, biochemical parameters, and gastrointestinal outcomes were assessed at baseline, week 4, and week 12. The aim is to evaluate the influence of probiotic and prebiotic supplementation on gastrointestinal function and biochemical markers in the early postoperative period following bariatric surgery.
Obesity is a growing global health problem, and bariatric surgery particularly sleeve gastrectomy, has become an effective method for long-term weight management. However, postoperative gastrointestinal changes, dysbiosis, and metabolic adaptations remain significant challenges, especially during the initial recovery period. The gut microbiota plays a critical role in digestion, nutrient absorption, immune modulation, and metabolic regulation. Probiotics and prebiotics may contribute to restoring microbial balance, enhancing intestinal barrier integrity, and improving biochemical profiles following surgery. This randomized controlled trial was designed to evaluate the impact of synbiotic supplementation on gastrointestinal symptoms and selected biochemical parameters in patients undergoing sleeve gastrectomy. A total of 60 patients aged 18 to 65 years, with a body mass index (BMI) of 35 or higher, were enrolled. Participants were randomly assigned to two groups in a 1:1 ratio. The intervention group (n = 30) received a 5 g sachet containing maltodextrin (4.9 g) and Lactobacillus rhamnosus GG (1×10⁹ CFU) in a partially hydrolyzed guar gum matrix, administered once daily mixed into 200 ml of yogurt for 12 weeks postoperatively. The control group (n = 30) received no supplementation. In the early postoperative period, patients commonly experience gastrointestinal symptoms such as bloating, gas, and constipation. This study aims to determine whether synbiotic supplementation can alleviate these symptoms and positively affect gastrointestinal function, anthropometric measurements, and specific biochemical markers. Additionally, it explores participants' knowledge and awareness of microbiota-related concepts, including probiotics and prebiotics. Data were collected through validated questionnaires assessing gastrointestinal symptoms, constipation severity, dietary habits, and microbiota-related knowledge. Anthropometric and biochemical assessments were conducted at baseline and at weeks 4 and 12 postoperatively.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
60
This synbiotic intervention aims to minimize postoperative gastrointestinal symptoms in sleeve gastrectomy patients. The 5 g sachet contains: * Partially hydrolyzed guar gum (PHGG; 4.9 g): Clinically shown to reduce diarrhea and improve stool consistency, * Lactobacillus rhamnosus GG (LGG; 1×10⁹ CFU): Evidence-based for alleviating abdominal pain and bloating, * Maltodextrin (0.1 g): Excipient for stability. Administered daily in yogurt for 12 weeks post-surgery, this combination directly targets: ① Diarrhea and constipation (via PHGG's soluble fiber), ② Abdominal pain and bloating (via LGG's anti-inflammatory effects), ③ Overall GI symptom burden. \*\*Distinctive features vs. other studies: * Symptom-specific formulation: PHGG (high-dose fiber) + LGG (symptom-targeted probiotic) synergy, * Surgical context: Optimized for rapid gastric transit post-sleeve gastrectomy, * Delivery innovation: Yogurt matrix protects probiotics against surgical gut pH changes.
Türk Obezite Cerrahisi Vakfı
Ankara, Çankaya, Turkey (Türkiye)
Change in Gastrointestinal Symptom Rating Scale (GSRS) Scores
The Gastrointestinal Symptom Rating Scale (GSRS) was used to evaluate participants' gastrointestinal symptoms before surgery, at 4 weeks post-surgery, and at 12 weeks post-surgery. The scale has five subscales targeting abdominal pain, reflux, diarrhea, indigestion, and constipation. Higher scores on the scale indicate more severe symptoms. Between-group comparisons were conducted using independent t-test and changes over time were analyzed with 2 (group) × 3 (time) repeated measures ANOVA.
Time frame: Baseline, Week 4, Week 12
Constipation Severity Scale (CSS) Score
The Constipation Severity Scale (CSS) was administered to participants before surgery, at 4 weeks post-surgery, and at 12 weeks post-surgery. It is a measure designed to determine the frequency, intensity, and difficulty/strain of bowel movements. The scale consists of 16 questions. The CCS has three subscales: Stool Impaction, Colon Sluggishness, and Pain. The score for the Stool Impaction subscale ranges from 0 to 28, the score for the Colon Sluggishness subscale ranges from 0 to 29, and the score for the Pain subscale ranges from 0 to 16. The total score that can be obtained from the CSS ranges from a minimum of 0 to a maximum of 73. A high score on the scale indicates the severity of the symptoms. Between-group comparisons were conducted using independent t-test and changes over time were analyzed with 2 (group) × 3 (time) repeated measures ANOVA.
Time frame: Baseline, week 4, week 12
Gas/Bloating Scale
The Gas/Bloating Scale was used to determine participants' gas/bloating symptoms before surgery, at 4 weeks post-surgery, and at 12 weeks post-surgery. It is designed to measure the frequency, severity, impact, and discomfort caused by gas/bloating symptoms. The scale consists of 12 questions, with each question scored on a scale from 0 to 4. According to the scoring system, 0 points indicate no symptoms, 1 point indicates minimal symptoms, 2-5 points indicate mild symptoms, 6-13 points indicate moderate symptoms, and 14 or more points indicate severe symptoms. Between-group comparisons were conducted using the chi-square and changes over time were analyzed with 2 (group) × 3 (time) repeated measures ANOVA.
Time frame: Baseline, week 4, week 12
Bristol Stool Consistency Scale
The Bristol Stool Consistency Scale is a scale of stool types ranging from the hardest to the softest. Type 1 stool is considered to be hard, nut-like lumps that are difficult to pass through the intestines. Type 2 stool is also lumpy but sausage-shaped. Types 1 and 2 are considered abnormally hard stools. Type 3 stools have cracks on the surface and are sausage-shaped, Type 4 stools are smooth and soft like a snake, and Type 5 stools are soft pieces with distinct edges and are easy to pass. Types 3, 4, and 5 are generally considered "normal" stool forms. The Friedman test was applied to evaluate the distribution of changes in Bristol scores over time in the study and control groups before surgery, at 4 weeks post-surgery, and at 12 weeks post-surgery. The chi-square test was used to compare the distribution and statistical comparisons of the study and control groups before surgery and at 4 and 12 weeks post-surgery according to the Bristol Stool Consistency Scale.
Time frame: Baseline, week 4, week 12
Change in Blood Glucose and Insulin Parameters
Blood glucose homeostasis was evaluated using fasting glucose (mg/dL), fasting insulin (µIU/mL), and HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) index, calculated using the formula \[fasting blood sugar (mg/dL) x fasting insulin (µIU/mL)/405\]. All values were extracted from clinical records at three time points. These variables were analyzed separately.An independent t-test was used to assess whether there were statistically significant differences between the groups.
Time frame: Baseline, Week 4, Week 12
Change in Lipid Biomarkers
To evaluate the participants' blood lipid profiles, the following parameters were assessed: Cholesterol (mg/dL), HDL (High-Density Lipoprotein) (mg/dL), LDL (Low-Density Lipoprotein) (mg/dL), Triglycerides (mg/dL). Each value was extracted from medical records and analyzed separately. Independent t-tests were used to compare values between intervention and control groups.
Time frame: Baseline, Week 4, Week 12
Change in Liver Function and Related Biochemical Parameters
Liver function and associated biomarkers were evaluated through the following laboratory values: Alanine Aminotransferase - ALT (U/L) Aspartate Aminotransferase - AST (U/L) Gamma-Glutamyl Transferase - GGT (U/L) Values were obtained from participants' medical records and assessed at baseline, 4th and 12th postoperative weeks. Independent t-tests were used to compare values between intervention and control groups.
Time frame: Baseline, Week 4, Week 12
Other biochemical parameters
Serum uric acid (mg/dL) Total Bilirubin (mg/dL) Direct Bilirubin (mg/dL) levels were assessed in all participants at three time points: before surgery, and at 4 and 12 weeks postoperatively. Values were obtained from patient medical records. Differences between intervention and control groups were analyzed using independent t-tests.
Time frame: Baseline, Week 4, Week 12
Change in anthropometric measurements
Anthropometric data were collected at three different time points to assess changes in body composition. Body mass index (BMI) was calculated using the formula kg/m\^2 based on the obtained height and body weight. At each time point (baseline, week 4, week 12), intergroup comparisons were reported using independent t-tests to identify statistically significant differences. Measurements were performed under standard conditions at each time point.
Time frame: Baseline, Week 4, Week 12
Change in Body Composition Parameters
Body composition was evaluated using a standardized protocol and the same device (Tanita MC-780, bioelectrical impedance analyzer) across all time points. The following parameters were assessed: Body weight (kg) Body fat mass (kg) Skeletal muscle mass (kg) Total body water (kg) All values were measured under fasting and standardized conditions. Results were analyzed individually.
Time frame: Baseline, Week 4, Week 12
Change in physical activity levels
Participants' physical activity levels were assessed using the International Physical Activity Questionnaire - Short Form (IPAQ-SF). Scores were calculated in weekly MET-minutes. Higher scores indicate higher activity levels. The Total Physical Activity Score (TPAS) was calculated as Walking (+) Moderate-intensity activity (+) Vigorous-intensity activity score. As a result, physical activity level was classified as: * TPAS \<600 MET: 'Not physically active' * TPAS = 600-3000 MET is defined as 'Low Physical Activity Level' * TPAS ≥ 3000 MET is defined as 'Adequate Physical Activity Level' To assess differences in physical activity levels over time, independent t-tests were used at each time point to compare groups.
Time frame: Baseline, Week 4, Week 12
Baseline group differences in Microbiota Awareness Scores (MAS)
Participants' awareness of concepts such as microbiota, probiotics, and prebiotics was assessed before surgery using the Microbiota Awareness Scale (MAS). The scale includes four subdomains: general knowledge, product knowledge, chronic diseases, and probiotics/prebiotics. A total awareness score was also calculated. Scores range from 18 to 100, with higher scores indicating greater awareness. Differences between the intervention and control groups were analyzed using independent t-tests. Additionally, subgroup comparisons were conducted to evaluate awareness levels across different educational backgrounds.
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Time frame: Baseline only