Effects of oral supplementation with probiotics or synbiotics in overweight and obese adults: a systematic review and meta-analyses of randomized trials.

CONTEXT: Recent evidence suggests that modulation of the gut microbiota may contribute to body weight control. OBJECTIVE: This systematic review aimed to assess the effects of oral supplementation with probiotics or synbiotics on body weight, body mass index (BMI), and waist circumference in overweight and obese adults (BMI ≥ 25 kg/m2). DATA SOURCES: Five electronic databases-PubMed, Embase, Cochrane Library/CENTRAL, LILACS, and Web of Science-were searched from inception to August 2017. No language restrictions were applied. STUDY SELECTION: Randomized and quasi-randomized parallel trials that assessed the effects of oral supplementation with probiotics or synbiotics vs any other intervention but bariatric surgery or fecal transplantation in overweight or obese adults were selected. DATA EXTRACTION: Three teams of 2 authors independently assessed risk of bias and extracted data from the included trials. Data were pooled using inverse-variance random-effects meta-analyses. The quality of evidence was assessed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. RESULTS: Nineteen randomized trials (28 publications, 1412 participants) were included. There were no differences in mean body weight change [mean difference (MD), -0.54 kg; 95%CI, -1.09 to 0.01; I2 = 0%; moderate quality of evidence) or mean BMI change (MD, -0.19 kg/m2; 95%CI, -0.43 to 0.04; I2 = 51%; low quality of evidence) between groups who received probiotics or synbiotics and control groups. Oral supplementation with probiotics or synbiotics reduced mean waist circumference compared with control (MD, -0.82 cm; 95%CI, -1.43 to -0.21; I2 = 46%; low quality of evidence). CONCLUSIONS: The findings suggest that oral supplementation with probiotics or synbiotics has a small effect to reduce waist circumference but no effect on body weight or BMI, although the quality of evidence is low to moderate. Therefore, the current evidence is not definitive. Large-scale trials are needed and may help to better inform clinical practice. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42018075126.

Probiotics for inflammatory bowel diseases: a promising adjuvant treatment.

Inflammatory bowel diseases (IBD) encompass ulcerative colitis (UC), Crohn's disease (CD) and indeterminate colitis (IC), characterising chronic inflammation in the gastrointestinal tract, associated with changes in the immune system and in the intestinal microbiota. Thus, probiotics may offer an alternative or adjuvant approach to conventional therapy. The present review aims to summarise the mechanisms of action of probiotics in IBD and their therapeutic effects. Most of the studies suggest that probiotics are effective in the treatment of UC, especially when several strains are concomitantly administered. Species of Lactobacillus and Bifidobacterium genres are the most commonly used, and some studies even indicate that it is possible to replace medical therapy with probiotic supplementation. Regarding CD, the results of clinical trials are controversial and do not support the use of probiotics in this disease. In conclusion, probiotic supplementation is a promising adjuvant treatment in UC, but not in CD.

Immunomodulatory role of branched-chain amino acids.

Branched-chain amino acids (BCAAs) have been associated with immunomodulation since the mid-1970s and 1980s and have been used in the nutritional therapy of critically ill patients. Evidence shows that BCAAs can directly contribute to immune cell function, aiding recovery of an impaired immune system, as well as improving the nutritional status in cancer and liver diseases. Branched-chain amino acids may also play a role in treatment of patients with sepsis or trauma, contributing to improved clinical outcomes and survival. Branched-chain amino acids, especially leucine, are activators of the mammalian target of rapamycin (mTOR), which, in turn, interacts with several signaling pathways involved in biological mechanisms of insulin action, protein synthesis, mitochondrial biogenesis, inflammation, and lipid metabolism. Although many in vitro and human and animal model studies have provided evidence for the biological activity of BCAAs, findings have been conflicting, and the mechanisms of action of these amino acids are still poorly understood. This review addresses several aspects related to BCAAs, including their transport, oxidation, and mechanisms of action, as well as their role in nutritional therapy and immunomodulation.