The effects of probiotic bacteria on glycaemic control in overweight men and women: a randomised controlled trial

Clinical and metabolic response to probiotic supplementation in patients with rheumatoid arthritis: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

This study was performed to determine the effects of probiotic supplementation on clinical and metabolic status of patients with rheumatoid arthritis (RA).

METHODS

Sixty patients with RA aged 25-70 years were assigned into two groups to receive either probiotic capsules (n = 30) or placebo (n = 30) in this randomized, double-blind, placebo-controlled trial. The patients in the probiotic group received a daily capsule that contained three viable and freeze-dried strains: Lactobacillus acidophilus (2 × 10(9) colony-forming units [CFU]/g), Lactobacillus casei (2 × 10(9) CFU/g) and Bifidobacterium bifidum (2 × 10(9) CFU/g) for 8 weeks. The placebo group took capsules filled with cellulose for the same time period. Fasting blood samples were taken at the beginning and the end of the study to quantify related markers.

RESULTS

After 8 weeks of intervention, compared with the placebo, probiotic supplementation resulted in improved Disease Activity Score of 28 joints (DAS-28) (-0.3 ± 0.4 vs. -0.1 ± 0.4, P = 0.01). In addition, a significant decrease in serum insulin levels (-2.0 ± 4.3 vs. +0.5 ± 4.9 μIU/mL, P = 0.03), homeostatic model assessment-B cell function (HOMA-B) (-7.5 ± 18.0 vs. +4.3 ± 25.0, P = 0.03) and serum high-sensitivity C-reactive protein (hs-CRP) concentrations (-6.66 ± 2.56 vs. +3.07 ± 5.53 mg/L, P < 0.001) following the supplementation of probiotics compared with the placebo. Subjects who received probiotic capsules experienced borderline statistically significant improvement in total- (P = 0.09) and low-density lipoprotein-cholesterol levels (P = 0.07) compared with the placebo.

CONCLUSION

Overall, the results of this study indicated that taking probiotic supplements for 8 weeks among patients with RA had beneficial effects on DAS-28, insulin levels, HOMA-B and hs-CRP levels.

GUT MICROBIOTA, PREBIOTICS, PROBIOTICS, AND SYNBIOTICS IN MANAGEMENT OF OBESITY AND PREDIABETES: REVIEW OF RANDOMIZED CONTROLLED TRIALS

OBJECTIVE

To review the data from randomized controlled trials (RCTs) for the roles of microbiota, pre-, pro- and synbiotics in metabolic conditions (obesity, prediabetes, and diabetes mellitus type 2 [DM2]).

METHODS

Primary literature was reviewed on the topics including RCTs of pre-, pro- and synbiotics use for metabolic disease.

RESULTS

Gut bacteria (microbiota) benefit digestion and have multiple other functions. Microbiota could increase harvesting of energy from the food and cause subclinical inflammation seen in metabolic disorders. Diet-related interventions including prebiotics, probiotics, and synbiotics (combining pre-and probiotics) may benefit metabolic conditions. Prebiotics are complex carbohydrates (i.e., dietary fiber). Results of RCTs of prebiotics suggested a neutral effect on body weight, decreased fasting and postprandial glucose, and improved insulin sensitivity and lipid profile. Some inflammation markers were reduced, sometimes substantially (20-30%). RCTs for probiotics demonstrated significant but small effects on body weight (<3%) and metabolic parameters. The effect was seen mostly with fermented milk or yogurt compared to capsule form, consumption for at least 8 weeks, and use of multiple rather than a single bacterial strain. Changes in microbiota were seen at times with both pre- and probiotics. Pickled and fermented foods, particularly vegetables and beans, could serve as a dietary source of pre-, pro-, and synbiotics. These foods showed possible benefits for morbidity and mortality in prospective cohort studies.

CONCLUSION

Pre-, pro-, and synbiotics could prove useful, but further research is needed to clarify their clinical relevance for the prevention and management of metabolic disease.

ABBREVIATIONS

A1c = glycohemoglobin A1c CI = confidence interval CVD = cardiovascular disease GMB = gut (large bowel) microbiota DM2 = diabetes mellitus type 2 HOMA-IR = homeostatic model assessment of insulin resistance LDL = low-density lipoprotein LPS = lipopolysaccharide NAFLD = nonalcoholic fatty liver disease RCT = randomized controlled trial SMD = standardized mean difference TG = triglycerides.

Effects of Probiotics and Synbiotics on Obesity, Insulin Resistance Syndrome, Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease: A Review of Human Clinical Trials

The use of probiotics and synbiotics in the prevention and treatment of different disorders has dramatically increased over the last decade. Both probiotics and synbiotics are well known ingredients of functional foods and nutraceuticals and may provide beneficial health effects because they can influence the intestinal microbial ecology and immunity. The present study reviews the effects of probiotics and synbiotics on obesity, insulin resistance syndrome (IRS), type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) in human randomized clinical trials. Select probiotics and synbiotics provided beneficial effects in patients with obesity, mainly affecting the body mass index and fat mass. Some probiotics had beneficial effects on IRS, decreasing the cell adhesion molecule-1 levels, and the synbiotics decreased the insulin resistance and plasma lipid levels. Moreover, select probiotics improved the carbohydrate metabolism, fasting blood glucose, insulin sensitivity and antioxidant status and also reduced metabolic stress in subjects with T2D. Some probiotics and synbiotics improved the liver and metabolic parameters in patients with NAFLD. The oral intake of probiotics and synbiotics as co-adjuvants for the prevention and treatment of obesity, IRS, T2D and NAFLD is partially supported by the data shown in the present review. However, further studies are required to understand the precise mechanism of how probiotics and synbiotics affect these metabolic disorders.

Impact of the gut microbiota on inflammation, obesity, and metabolic disease

The human gut harbors more than 100 trillion microbial cells, which have an essential role in human metabolic regulation via their symbiotic interactions with the host. Altered gut microbial ecosystems have been associated with increased metabolic and immune disorders in animals and humans. Molecular interactions linking the gut microbiota with host energy metabolism, lipid accumulation, and immunity have also been identified. However, the exact mechanisms that link specific variations in the composition of the gut microbiota with the development of obesity and metabolic diseases in humans remain obscure owing to the complex etiology of these pathologies. In this review, we discuss current knowledge about the mechanistic interactions between the gut microbiota, host energy metabolism, and the host immune system in the context of obesity and metabolic disease, with a focus on the importance of the axis that links gut microbes and host metabolic inflammation. Finally, we discuss therapeutic approaches aimed at reshaping the gut microbial ecosystem to regulate obesity and related pathologies, as well as the challenges that remain in this area.

Glucose- and glycaemic factor-lowering effects of probiotics on diabetes: a meta-analysis of randomised placebo-controlled trials

This meta-analysis examined the effect of probiotics on glucose and glycaemic factors in diabetes and its associated risk factors. All randomised-controlled trials published in English in multiple databases from January 2000 to June 2015 were systematically searched. Only studies that addressed glucose- and glycaemic-related factors as outcome variables were included. The main outcomes of interest in trials were mean changes in glucose, HbA1c, insulin and homoeostasis model assessment-estimated insulin resistance (HOMA-IR). Using the Physiotherapy Evidence Database (PEDro) scale to assess the quality of studies, a total of eleven studies with 614 subjects were included. The pooled mean difference and effect size with a 95% CI were extracted using a random-effect model. It was found that there are statistically significant pooled mean differences between the probiotics and the placebo-controlled groups on the reduction of glucose (-0·52 mmol/l, 95% CI -0·92, -0·11 mmol/l; P=0·01) and HbA1c (-0·32%, 95% CI -0·57, -0·07%; P=0·01). There was no statistically significant pooled mean difference between the probiotics and the placebo-controlled groups on the reduction of insulin (-0·48 µIU/ml, 95% CI -1·34, 0·38 µIU/ml; P=0·27) and HOMA-IR (pooled effect of -0·44, 95% CI -1·57, 0·70; P=0·45). Meta-regression analysis identified that probiotics had significant effects on reduction of glucose, HbA1c, insulin and HOMA-IR in participants with diabetes, but not in participants with other risk factors. The present meta-analysis suggested that probiotics may be used as an important dietary supplement in reducing the glucose metabolic factors associated with diabetes.

Establishing a causal link between gut microbes, body weight gain and glucose metabolism in humans - towards treatment with probiotics

Changes in the gut microbiota are associated with metabolic disorders, such as overweight and elevated blood glucose. Mouse studies have shown that gut microbiota can regulate metabolism with a mechanism related to gut barrier function. An impaired gut barrier permits the translocation of bacteria and their components which, when in contact with the sub-mucosal immune system, evoke metabolic inflammation and distract signalling in metabolically active tissues. Despite thorough research of the topic in animals, the hypothesis is yet to be proven in humans. Cross-sectional studies have shown that certain bacterial populations - such as Akkermansia muciniphila, Faecalibacterium prausnitzii, Methanobrevibacter smithii and Christensenellaceae - are better represented in lean individuals compared to those who are overweight or metabolically unhealthy. Although these differences reflect those seen in mice, it is possible that they are caused by different dietary or other lifestyle habits. Diet has an indisputable influence on gut microbiota making it very difficult to draw conclusions on microbiota-host interactions from cross-sectional studies. Certain research areas do, however, indicate that gut microbiota could causally influence metabolism. Several studies show that antibiotic use in infancy increases body weight in later childhood. Also, probiotics are emerging as a potential therapy for metabolic syndrome. In fact, a handful of human studies and numerous animal studies show promise for probiotics in reducing blood glucose levels or improving insulin sensitivity. For weight management human evidence is scarcer. Nevertheless, it is becoming increasingly recognised that gut microbiota plays a part regulating metabolism, also in humans, which gives rise to novel opportunities for preventative and treatment strategies.

Effect of Probiotics on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials

BACKGROUND

Previous clinical trials indicate that probiotic consumption may improve blood glucose control, however, results from randomized trials on glycemic control have been inconsistent.

OBJECTIVE

To investigate the effects of probiotics on glycemic control in a systematic review and meta-analysis of randomized controlled trials.

DATA SOURCES

PubMed, Embase, Cochrane Library, and Clinicaltrial.gov through October 2014.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted relevant data and assessed study quality and risk of bias. Data were pooled using a random-effects model and expressed as mean differences (MD) with 95% CI. Heterogeneity was assessed (Cochran Q-statistic) and quantified (I2).

RESULTS

Seventeen randomized controlled trials were included, in which 17 fasting blood glucose (n = 1105), 11 fasting plasma insulin (n = 788), 8 homeostasis model assessment of insulin resistance (n = 635) comparisons were reported. Probiotic consumption, compared with placebo, significantly reduced fasting glucose (MD = -0.31 mmol/L; 95% CI 0.56, 0.06; p = 0.02), fasting plasma insulin (MD = -1.29 μU/mL; 95% CI -2.17, -0.41; p = 0.004), and HOMA-IR (MD = 0.48; 95% CI -0.83, -0.13; p = 0.007).

CONCLUSIONS

Probiotic consumption may improve glycemic control modestly. Modification of gut microbiota by probiotic supplementation may be a method for preventing and control hyperglycemia in clinical practice.

The effect of yoghurt and its probiotics on blood pressure and serum lipid profile; a randomised controlled trial

BACKGROUND AND AIMS

Despite strong mechanistic data, and promising results from in vitro and animal studies, the ability of probiotic bacteria to improve blood pressure and serum lipid concentrations in humans remains uncertain. The aim of this study was to determine the effect of Lactobacillus acidophilus La5 and Bifidobacterium animalis subsp lactis Bb12, provided in either yoghurt or capsule form, on home blood pressure and serum lipid profile.

METHODS AND RESULTS

Following a 3-week washout period, 156 overweight men and women over 55 y were randomized to a 6-week double-blinded, factorial, parallel study. The four intervention groups were: A) probiotic yoghurt plus probiotic capsules; B) probiotic yoghurt plus placebo capsules; C) control milk plus probiotic capsules; and D) control milk plus placebo capsules. Each probiotic test article provided a minimum L. acidophilus La5 and B. animalis subsp. lactis Bb12 dose of 3.0 × 10⁹ CFU/d. Home blood pressure monitoring, consisting of 7-day bi-daily repeat measurements, were collected at baseline and week 6. Fasting total cholesterol, low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC), and serum triglyceride were performed at baseline and week 6. When compared to control milk, probiotic yoghurt did not significantly alter blood pressure, heart rate or serum lipid concentrations (P > 0.05). Similarly, when compared to placebo capsules, supplementation with probiotic capsules did not alter blood pressure or concentrations of total cholesterol LDLC, HDLC, or triglycerides (P > 0.05).

CONCLUSIONS

The probiotic strains L. acidophilus La5 and B. animalis subsp. lactis Bb12 did not improve cardiovascular risk factors.