The purpose of this study is to evaluate the effect of prebiotic or synbiotic supplementation on inflammatory response and indicators of nutritional status in patients with morbid obesity. Study hypothesis: Supplementation of 12 g/day of fructooligosaccharides (prebiotic) or 12 g/day of fructooligosaccharides + strains of lactobacilli and bifidobacteria (synbiotic) during 30 days promotes reduction of plasma/serum levels of acute phase proteins, cytokines, metabolic and anthropometric parameters in individuals with BMI ≥ 40kg/m².

The purpose of this study is to evaluate the effect of prebiotic or synbiotic supplementation on inflammatory response and indicators of nutritional status in patients with morbid obesity. Adult individuals of both sexes with morbid obesity (body mass index ≥ 40 kg/m²) will be invited to participate in this randomized, placebo-controlled, triple-blind study. The participants will be divided into three groups: G1 - control group (placebo), G2 - prebiotic group and G3 - synbiotic group. The study will consist of four experimental time points: M0 - baseline and start of supplementation; M1 - after fifteen days of the first outpatient visit and fifteen days after the start of supplementation with prebiotic, synbiotic or placebo; M2 - after thirty days from the first outpatient visit and end of supplementation with prebiotic, synbiotic and placebo; and M3 - time after sixty days from the first outpatient visit. At all time points the inflammatory response will be assessed by determination of plasma cytokines (IL-1, IL-6, IL-10, TNF) and acute phase proteins (c-reactive protein and albumin), besides the evaluation of laboratory and anthropometric indicators of nutritional status. The primary endpoint will be the reduction in concentrations of inflammatory markers (cytokines and acute phase proteins).

Investigators expect to contribute with new information in this field of knowledge, which may facilitate the clinical application of these results.

Inclusion Criteria:

• Age greater than 18 years and less than 60 years
• Body mass index (BMI)≥40kg/m2

Exclusion Criteria:

• Previous gastrointestinal diseases (e.g. cancer and inflammatory bowel disease)
• Intolerances and/or food allergies (e.g. lactose intolerance and celiac disease)
• Current use of anti-inflammatory drugs and/or antibiotics and/or immunosuppressants
• Regular use of laxatives and/or appetite suppressants
• Current or previous use (up to one month) of prebiotics, probiotics, synbiotics or products enriched with these food compounds
• Intolerance to prebiotic and/or probiotic and/or synbiotic
• Following a diet for weight loss in the last three months
• Pregnant or breastfeeding
• Following unusual diets (e.g. vegetarian, macrobiotic)
• Alcohol dependence and/or illicit drugs dependence
• Smokers

Study participants and researchers were masked over consumption and distribution of supplementation, respectively. Laboratory technicians who performed the blood collection were also masked as to the distribution of supplementation. Supplements and placebo were pre-packaged by the supplier in opaque and closed sachets with randomization codes, being identical in physical appearance, taste and color. Supplement identification codes were only disclosed by the supplier after statistical analysis of study data.