Probiotics' effect on visceral and subcutaneous adipose tissue: a systematic review of randomized controlled trials

Visceral Fat-Reducing Effect of Novel Dietary Intervention Program: A Randomized Controlled Trial in Japanese Males

Background/Objectives: Reducing visceral fat is a critical factor in preventing obesity-related health complications. In this study, we evaluated the effectiveness of our previously reported novel dietary intervention program, "Optimized Nutri-Dense Meals", designed according to the Dietary Reference Intakes (DRIs) in Japan in reducing visceral fat. Method: This open-label, randomized controlled trial included 100 Japanese males with obesity or overweight. In total, 50 participants were assigned to a control group that continued their usual diets, and the other 50 consumed test meals twice per week for four weeks (test group). Result: The primary outcome, visceral fat area, significantly decreased in the test group compared to that in the control group (-7.5 cm2, confidence interval [CI]: -14.3 to -0.6). In addition, we measured the changes in gut flora and work productivity. The abundance of Bifidobacterium (+1.5%, CI: 0.3-2.7) and Christensenellaceae (+0.4%, CI: 0.01-0.8) increased significantly in the test group compared with those in the control group. Work Limitation Questionnaire Japanese version scores representing presenteeism also significantly increased in the test group (+1.2 points, CI: 0.2-2.3) compared with the control group. Conclusions: These findings suggest that dietary interventions based on Japanese DRIs can effectively decrease visceral fat and improve health outcomes over the short term without the need for a complete dietary overhaul.

Effect of Bifidobacterium Intake on Body Weight and Body Fat in Overweight and Obese Adult Subjects: A Systematic Review and Meta-Analysis

This systematic review aimed to assess the impact of Bifidobacterium genus probiotics on body weight and body composition parameters in overweight and obese individuals.

A systematic search for randomized controlled trials was conducted in MEDLINE, EMBASE, LILACS, and Google Scholar databases until April 17, 2023. The inclusion criteria required the trials to involve Bifidobacterium genus probiotics interventions and the evaluation of obesity-related anthropometric and body composition outcomes in overweight or obese subjects. Studies were excluded when involving obese individuals with genetic syndromes or pregnant women, as well as probiotic mixture interventions. The revised Cochrane risk-of-bias tool for randomized trials was utilized to assess the quality of the included studies. A random-effects meta-analysis was performed using the mean difference between endpoint measurements and change from baseline for body mass index, body weight, body fat mass, body fat percentage, waist circumference, waist-to-hip ratio, and visceral fat area.

From 1,527 retrieved reports, 11 studies (911 subjects) were included in this review. Bifidobacterium probiotics administration resulted in significant reductions in body fat mass (MD = -0.64 kg, 95% CI: -1.09, -0.18, p = 0.006), body fat percentage (MD = -0.64%, 95% CI: -1.18, -0.11, p = 0.02), waist circumference (MD = -1.39 cm, 95% CI: -1.99, -0.79, p < 0.00001), and visceral fat area (MD = -4.38 cm2, 95% CI: -7.24, -1.52, p = 0.003). No significant differences were observed for body mass index, body weight, or waist-to-hip ratio.

This systematic review suggests that Bifidobacterium genus probiotics may contribute to managing overweight and obesity by reducing body fat mass, body fat percentage, waist circumference, and visceral fat area. Further research is required to understand strain and species interactions, optimal dosages, and effective delivery methods for probiotics in obesity management. This review was pre-registered under the PROSPERO record CRD42022370057.

Accounting for the health risk of probiotics

Probiotics have long been associated with a myriad of health benefits, so much so that their adverse effects whether mild or severe, are often neglected or overshadowed by the enormous volume of articles describing their beneficial effects in the current literature. Recent evidence has demonstrated several health risks of probiotics that warrant serious reconsideration of their applications and further investigations. This review aims to highlight studies that report on how probiotics might cause opportunistic systemic and local infections, detrimental immunological effects, metabolic disturbance, allergic reactions, and facilitating the spread of antimicrobial resistance. To offer a recent account of the literature, articles within the last five years were prioritized. The narration of these evidence was based on the nature of the studies in the following order of preference: clinical studies or human samples, in vivo or animal models, in situ, in vitro and/or in silico. We hope that this review will inform consumers, food scientists, and medical practitioners, on the health risks, while also encouraging research that will focus on and clarify the adverse effects of probiotics.

Evaluating probiotic efficacy on weight loss in adults with overweight through a double-blind, placebo-controlled randomized trial

The aim was to assess the weight-reducing effects of various doses of a probiotic dietary supplement and evaluate the tolerance and safety of increased dosage. A 3-month double-blinded, randomized, placebo-controlled trial, followed by a 3-month open phase, was conducted at Karolinska Institutet, Sweden. The probiotic compound AB001 was tested at two doses (single and double) and compared with placebo during the blinded phase, and at triple dose during the open phase. Eighty-one volunteers, 18-45 years old, with overweight were included. The primary outcome was change in weight. Secondary outcomes were changes in; BMI, waist circumference, blood pressure, blood lipids, glucose metabolism, liver enzymes, vitamin levels, and bowel habits. After 3 months (n = 81), no difference in weight, BMI, waist circumference, blood pressure, or biomarkers were observed between the groups. Forty-five individuals continued with triple dose. The group with initial single dose decreased 0.93 ± 4.73 kg (p = 0.34), and the group with double dose initially decreased 1.93 ± 3.70 kg (p = 0.027). Reported changes in bowel habits and gastro-intestinal problems were similar for all doses. The results indicate that a long-term use of at least double dose AB001 may be more beneficial for weight loss than lower doses. However, in the double blinded phase, no differences between groups were found. The probiotic compound AB001 was well tolerated and can safely be used up to double dose for 90 days followed by triple dose for 90 days.Trial registration: Clinicaltrial.gov NCT04897698, registered on 21 May 2021.

The Effect of Microbiome Therapies on Waist Circumference, a Measure of Central Obesity, in Patients with Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Microbiome therapies (probiotic, prebiotic, and synbiotics) have been proposed as adjuvants in the control of central obesity; however, their results for patients with type 2 diabetes (T2D) remain inconclusive.

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the effect of microbiome therapies on central obesity as measured by waist circumference (WC), and to evaluate the effect of microbiome therapies for glycemic parameters (fasting glucose [FPG], fasting insulin [FPI], hemoglobin A1c [HbA1c], and insulin resistance [HOMA1-IR]) in patients with T2D.

METHODS

SCOPUS, Pubmed, EBSCO, and LILACS databases were searched for studies that investigated the effect of microbiome therapies on WC up to June 1, 2022. Heterogeneity was determined using Cochran's Q test and quantified using the inconsistency index. The random effects model was used to calculate the pooled difference in means (DM) and 95% confidence intervals (95%CI). Egger's test and Beggs-Muzamar's test were used to assess publication bias.

RESULTS

Fifteen reports were included (443 treated and 387 controls). Overall, a significant decrease in WC was found (DM = -0.97 cm; 95% confidence interval [95%CI] = -1.74 to -0.20; P = 0.014); however, when stratified by type of microbiome therapy, only probiotics significantly decreased WC (DM = -0.62 cm; 95%CI = -1.00 to -0.24; P = 0.002). No effect was observed for prebiotics and synbiotics. With respect to glycemic parameters, HbA1c, FPG, and HOMA1-IR significantly decrease with microbiome therapies (P ≤ 0.001). When stratified by the type of therapy, for probiotic treatments, HbA1c, FPG, and HOMA1-IR scores decrease (P < 0.001). For prebiotic treatments, HbA1c and FPG (P ≤ 0.001) levels decrease, whereas FPI increased (P = 0.012). Synbiotic treatments were only associated with an increase in FPI (P = 0.031).

CONCLUSION

Findings indicate that using probiotics alone improved WC in patients with T2D. Both probiotics and prebiotics decreased HbA1c and FPG; however, prebiotics and synbiotics resulted in an increase in FPI. The formulation of the therapy (single vs multi) had no difference on the effect.