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Gut microbiome-related effects of berberine and probiotics on type 2 diabetes (the PREMOTE study).
Zhang, Y, Gu, Y, Ren, H, Wang, S, Zhong, H, Zhao, X, Ma, J, Gu, X, Xue, Y, Huang, S, et al
Nature communications. 2020;11(1):5015
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Berberine, which is a naturally occurring alkaloid found in plants, has been traditionally used as a remedy to protect against Type 2 diabetes and other metabolic disorders. It is important to study how berberine affects the human gut microbiome, specifically in regard to its impact on short-chain fatty acid and bile acid metabolism, due to its low oral bioavailability. The PREMOTE study investigated the glycaemic lowering effects of individual and combination of berberine and probiotics in newly diagnosed Type 2 Diabetes patients. This randomised, double-blinded, placebo-controlled trial included four hundred and nine Type 2 diabetic patients and randomly assigned them (1:1:1:1 ratio) to receive berberine alone, berberine combined with probiotics, probiotics alone or a placebo for twelve weeks. A combination of berberine plus probiotics and berberine alone significantly improved glycated haemoglobin levels compared to the placebo and probiotics alone treatment. The antidiabetic effects of berberine could be due to the Ruminococcus bromii abundance followed by the berberine treatment and its ability to inhibit deoxycholic acid biotransformation. Further robust studies are required to consider the therapeutic application of berberine and probiotics in a general population due to the limitations of the present study. However, healthcare professionals can use the results of this trial to understand the mechanism behind the anti-diabetic effects of berberine and probiotics.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The use of berberine, as a specific antimicrobial agent, along with high strength probiotics may be beneficial for managing blood glucose and potentially other metabolic health markers alongside diet and lifestyle modifications
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
Dysbiosis of the human gut microbiome has been associated with the development of type 2 diabetes (T2D). Research has found that, in part, mechanisms of action for the antidiabetic medications, Metformin and Acarbose, include alterations in the gut microbiome as well as the inhibition of bile acid (BA) metabolism and signalling. Remedies targeting the gut microbiota for treatment of T2D and other metabolic diseases have therefore been investigated.
Berberine (BBR) has been used in Indian Ayurvedic and Traditional Chinese Medicine to treat metabolic conditions for hundreds of years. Probiotics have also been extensively researched for their potential metabolic benefits. This randomised, double-blind, placebo-controlled trial aimed to investigate whether BBR and probiotics may be effective in managing T2D.
Methods
A total of 409 participants aged 42-61 years were recruited from 20 medical centres in China. All patients were newly diagnosed (<12 months) with T2D and had no previous antidiabetic medication history. Participants were randomised into 4 groups; Probiotics and BBR, BBR only, probiotics only or a placebo for 12 weeks. Subgroup analysis was also completed for those aged >50 and >54.
Dosage of BBR was 0.6 g prior to a meal, twice daily. 4 g of powdered multi-strain probiotics including 9 strains of lactic acid bacteria were taken at bedtime. All participants were given a 7-day broad-spectrum antibiotic treatment immediately prior to baseline. 391 people completed the trial. The primary outcome measurement was glycaemic haemoglobin (HbA1c). Secondary evaluations of additional metabolic markers included fasting and post-load plasma glucose (FPG, PPG), homeostasis assessment model index for insulin resistance (HOMA-IR), total cholesterol (TC), high density lipoprotein cholesterol (HDL-c), low density lipoprotein cholesterol (LDL-c) and serum triglycerides (TG).
Results
Results showed a reduction in glycaemic haemoglobin (HbA1c) for both the BBR plus probiotics group (least squares mean [95% CI] -1.04 [-1-19, -0.89]% ) and the BBR only group (-.99 [-1.16, 0.83]%). The results for these groups were significantly greater than the probiotics alone (-0.53 {-068, -0.37]%) and the placebo groups (0.59 [-0.75, -0.44]%).
Secondary metabolic evaluations for FPG and PPG, TC, LDL -c and TGs also showed similar improvements in the BBR and BBR plus probiotic groups only. Additionally, in the >50 and >54 subgroups BBR and probiotics marginally improved the HOMA-IR.
Metagenomic and metabolomic analysis of the gut microbiome was also undertaken after a one-week pre-treatment with antibiotics immediately prior to the trial and at week 13. These results showed that the blood glucose lowering effects of BBR may be due to decreased deoxycholic acid species (DCA) biotransformation by ruminococcus bromii.
Higher levels of adverse gastrointestinal side effects were reported in the BBR treatment groups, however, the authors reported that this did not affect glycemic control outcomes.
Conclusion
This study found that BBR had an antidiabetic effect through microbial alterations in the human gut microbiome
The authors declare no conflicts of interest.
Clinical practice applications:
- 600mg of BBR twice daily prior to a meal plus a multi-strain (lactic acid) probiotic of >50 billion colony forming units (CFU) for 12 weeks may be effective in lowering HbA1c in T2D clients diagnosed within the previous 12 months
- Further research is needed for clients with longer term T2D diagnosis
- Insulin resistance may be marginally improved in clients >50
- Practitioners should be aware that in this study, adverse gastrointestinal side effects were more likely to be be experienced with the use of BBR
Considerations for future research:
The authors reported several limitations to this study:
- A population of Chinese people living in China may not be generalisable to other ethnic/racial populations
- The study was over a short duration. Longer studies are needed to confirm the results
- Participants had newly diagnosed T2D and had not received any previous medications. Future studies should include patients with a longer diagnosis time
- Records should be kept of any additional lifestyle changes made by the participants
- Adverse reactions were experienced in the BBR groups, in this study. It was reported that the gut microbiome and anti-diabetic effects were not affected, however, this may be something to be considered in longer trials.
Abstract
Human gut microbiome is a promising target for managing type 2 diabetes (T2D). Measures altering gut microbiota like oral intake of probiotics or berberine (BBR), a bacteriostatic agent, merit metabolic homoeostasis. We hence conducted a randomized, double-blind, placebo-controlled trial with newly diagnosed T2D patients from 20 centres in China. Four-hundred-nine eligible participants were enroled, randomly assigned (1:1:1:1) and completed a 12-week treatment of either BBR-alone, probiotics+BBR, probiotics-alone, or placebo, after a one-week run-in of gentamycin pretreatment. The changes in glycated haemoglobin, as the primary outcome, in the probiotics+BBR (least-squares mean [95% CI], -1.04[-1.19, -0.89]%) and BBR-alone group (-0.99[-1.16, -0.83]%) were significantly greater than that in the placebo and probiotics-alone groups (-0.59[-0.75, -0.44]%, -0.53[-0.68, -0.37]%, P < 0.001). BBR treatment induced more gastrointestinal side effects. Further metagenomics and metabolomic studies found that the hypoglycaemic effect of BBR is mediated by the inhibition of DCA biotransformation by Ruminococcus bromii. Therefore, our study reports a human microbial related mechanism underlying the antidiabetic effect of BBR on T2D. (Clinicaltrial.gov Identifier: NCT02861261).
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Gut feelings: A randomised, triple-blind, placebo-controlled trial of probiotics for depressive symptoms.
Chahwan, B, Kwan, S, Isik, A, van Hemert, S, Burke, C, Roberts, L
Journal of affective disorders. 2019;253:317-326
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Depression is a debilitating psychiatric disorder that is the leading cause of disability world-wide. Multiple causes of depression have been identified, including genetic, neurological, inflammatory, personality, cognitive, and environmental factors. The aim of this study was to investigate the effectiveness of the multispecies probiotic Ecologic® Barrier for reducing symptoms in adults with mild to severe levels of depression. The study was a triple-blinded parallel, placebo-controlled randomised clinical trial. Participants were randomly allocated into two groups; probiotic and placebo. 71 participants with depressive symptoms were recruited and allocated sequentially over 12 months. Results indicate that all participants across both probiotic and placebo groups exhibited a reduction in depressive symptoms over the time-period of the trial. Thus, the routine involved with daily preparation and consumption of the probiotic and scheduled appointments, as well as involvement in these behaviours with the aim of seeking improvement in depressive symptoms had positive impacts on mood, irrespective of whether the probiotic or placebo was consumed. Authors conclude that their findings offer evidence to indicate that probiotic consumption can exert change on cognitive patterns associated with depression.
Expert Review
Conflicts of interest:
None
Take Home Message:
- This study offers evidence to indicate that probiotic consumption can exert change on cognitive patterns associated with depression.
- The study suggests that probiotics, rather than having a direct effect on depressive symptoms, potentially act on immune system activity, inflammation and gut barrier integrity which contribute to the expression of depression.
- Probiotics may be a useful adjunct to potentiate the effects of other therapies, such as CBT.
- This study points to the validity of managing physical health as part of mental health treatment.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
With evidence suggesting that decreased gut barrier function and inflammation are correlated with depression, this study set out to determine the effect of consumption of probiotic supplements on depressive symptoms from a sample of 71 participants with depression. The study was a triple-blinded parallel, placebo-controlled randomised clinical trial conducted over 8 weeks in Australia. Pre and post intervention measures of symptoms and vulnerability markers of depression as well as gut microbiota were compared alongside psychological variables and gut microbiota composition to non-depressed, placebo and probiotic groups. All the clinical trial participants demonstrated an improvement in symptoms – participants in the probiotic group demonstrated a significantly greater reduction in cognitive reactivity compared with the placebo group. Probiotics did not significantly alter the microbiota of depressed individuals, however a significant correlation was found between Ruminococcus gnavus and one of the metrics for depression.
Clinical practice applications:
This study was small and carried out over a short period of time. While significant results were found, which signify potential considerations for clinical practice, the results from this study do not offer evidence that the probiotics used had a direct effect on depressive symptoms – they suggest that probiotics potentially act on cognitive processes contributing to depression which may include immune system activity, inflammation, and gut barrier integrity. Overall, this study offers evidence to indicate that probiotic consumption can exert change on cognitive patterns associated with depression. In clinical practice, probiotics may be a useful adjunct to potentiate the effects of therapies, such as CBT. Finally, the use of probiotics promotes the concept of managing physical health as part of mental health treatment.
Considerations for future research:
These preliminary results are promising and offer a number of future research and clinical avenues to build upon. The results do however, indicate that a longer trial may be needed to fully assess the effects of probiotics on mood and the mechanisms by which probiotics may be influencing this. The study also suggests that further research using a range of concentrations in a dose response study may be warranted to determine the optimal dose; a greater dose over a longer period may produce detectable changes in microbiota as well as further differences in psychological data.
Abstract
BACKGROUND Depression is the leading cause of disability worldwide; with evidence suggesting that decreased gut barrier function and inflammation are correlated with depressive symptoms. We conducted a clinical trial to determine the effect of consumption of probiotic supplements (Winclove's Ecologic® Barrier) on depressive symptoms in a sample of participants with mild to severe depression. METHOD 71 participants were randomly allocated to either probiotic or placebo, which was, consumed daily over eight weeks. Pre- and post-intervention measures of symptoms and vulnerability markers of depression as well as gut microbiota composition were compared. Clinical trial participants were also compared on psychological variables and gut microbiota composition to a non-depressed group (n = 20). RESULTS All clinical trial participants demonstrated improvement in symptoms, suggesting non-specific therapeutic effects associated with weekly monitoring visits. Participants in the probiotic group demonstrated a significantly greater reduction in cognitive reactivity compared with the placebo group, particularly in the mild/moderate subgroup. Probiotics did not significantly alter the microbiota of depressed individuals, however, a significant correlation was found between Ruminococcus gnavus and one depression metric. LIMITATIONS There was a high attrition rate, which may be attributed to weekly monitoring visits. Additionally, modulation of the gut microbiota may need more specific testing to distinguish subtle changes. CONCLUSIONS While microbiota composition was similar between all groups, probiotics did affect a psychological variable associated with susceptibility to depression. Further research is needed to investigate how probiotics can be utilised to modify mental wellbeing, and whether they can act as an adjunct to existing treatments.
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A structured weight loss program increases gut microbiota phylogenetic diversity and reduces levels of Collinsella in obese type 2 diabetics: A pilot study.
Frost, F, Storck, LJ, Kacprowski, T, Gärtner, S, Rühlemann, M, Bang, C, Franke, A, Völker, U, Aghdassi, AA, Steveling, A, et al
PloS one. 2019;14(7):e0219489
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The global obesity epidemic is a major cause of the increase in type 2 diabetes mellitus (T2DM) and ensuing cardiovascular disease. The causes of obesity are complex ,and it has been shown that changes in the microbiome are associated with obesity. The microbiome can be altered through dietary intervention and weight loss. The aim of this open label pilot study was to investigate the microbiome of obese patients with T2DM during a weight loss programme. During the first six weeks the diet consisted of formula drink providing 800kcal per day, followed by nine weeks during which a regular diet of 1,200-1,500kcal per day was reintroduced, depending on the individuals’ needs. All participants lost weight continuously over the 15 weeks, from an average BMI of 39.6 at the start to 33.1 at the end of the programme. This was accompanied with an improvement in glucose metabolism, total and LDL cholesterol and uric acid levels, but not HDL cholesterol or triglycerides. All participants experienced changes in their microbiome towards greater diversity after the first six weeks of the low-calorie formula diet but these changes were partially reversed at the end of the study period at 15 weeks. A particular type of bacteria, Collinsella, which has been associated with poor metabolic health, was the only type found to remain reduced at the end of the 15 weeks, an 8.4-fold decrease. The authors hypothesise that this reduction in Collinsella may be associated with the improvement of metabolic factor in these patients at the end of the study.
Abstract
The global obesity epidemic constitutes a major cause of morbidity and mortality challenging public health care systems worldwide. Thus, a better understanding of its pathophysiology and the development of novel therapeutic options are urgently needed. Recently, alterations of the intestinal microbiome in the obese have been discussed as a promoting factor in the pathophysiology of obesity and as a contributing factor to related diseases such as type 2 diabetes and metabolic syndrome. The present pilot study investigated the effect of a structured weight loss program on fecal microbiota in obese type 2 diabetics. Twelve study subjects received a low-calorie formula diet for six weeks, followed by a nine week food reintroduction and stabilization period. Fecal microbiota were determined by 16S rRNA gene sequencing of stool samples at baseline, after six weeks and at the end of the study after fifteen weeks. All study subjects lost weight continuously throughout the program. Changes in fecal microbiota were most pronounced after six weeks of low-calorie formula diet, but reverted partially until the end of the study. However, the gut microbiota phylogenetic diversity increased persistently. The abundance of Collinsella, which has previously been associated with atherosclerosis, decreased significantly during the weight loss program. This study underlines the impact of dietary changes on the intestinal microbiome and further demonstrates the beneficial effects of weight loss on gut microbiota. Trial registration: ClinicalTrials.gov NCT02970838.
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Dietary supplementation with inulin-propionate ester or inulin improves insulin sensitivity in adults with overweight and obesity with distinct effects on the gut microbiota, plasma metabolome and systemic inflammatory responses: a randomised cross-over trial.
Chambers, ES, Byrne, CS, Morrison, DJ, Murphy, KG, Preston, T, Tedford, C, Garcia-Perez, I, Fountana, S, Serrano-Contreras, JI, Holmes, E, et al
Gut. 2019;68(8):1430-1438
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Literature shows that higher intakes of dietary fibre are associated with a reduced risk of type 2 diabetes. The main aim of this study was to elucidate the underlying mechanisms behind improvements in glucose homeostasis following long-term delivery of propionate (a short-chain fatty acid produced by human gut microbiota in response to dietary fibre) to the human colon. The study is a randomised, double-blind, placebo-controlled cross over trial. Fourteen participants randomly received 20 g/day of a low-fermentable fibre control, a high-fermentable fibre control and inulin-propionate ester (IPE) for 42 days each. Results indicate that stool concentrations of short-chain fatty acids were not different following the three supplementation periods. Furthermore, dietary supplementation with 20 g/day IPE promoted no superior impacts on measures of glucose homeostasis compared with inulin (high-fermentable fibre), yet both IPE and inulin improved insulin resistance relative to cellulose (low-fermentable fibre). Authors conclude that manipulating the colonic fermentation profile of a dietary fibre in favour of propionate promotes selective effects on the mechanisms that contribute to metabolic dysregulation.
Abstract
OBJECTIVE To investigate the underlying mechanisms behind changes in glucose homeostasis with delivery of propionate to the human colon by comprehensive and coordinated analysis of gut bacterial composition, plasma metabolome and immune responses. DESIGN Twelve non-diabetic adults with overweight and obesity received 20 g/day of inulin-propionate ester (IPE), designed to selectively deliver propionate to the colon, a high-fermentable fibre control (inulin) and a low-fermentable fibre control (cellulose) in a randomised, double-blind, placebo-controlled, cross-over design. Outcome measurements of metabolic responses, inflammatory markers and gut bacterial composition were analysed at the end of each 42-day supplementation period. RESULTS Both IPE and inulin supplementation improved insulin resistance compared with cellulose supplementation, measured by homeostatic model assessment 2 (mean±SEM 1.23±0.17 IPE vs 1.59±0.17 cellulose, p=0.001; 1.17±0.15 inulin vs 1.59±0.17 cellulose, p=0.009), with no differences between IPE and inulin (p=0.272). Fasting insulin was only associated positively with plasma tyrosine and negatively with plasma glycine following inulin supplementation. IPE supplementation decreased proinflammatory interleukin-8 levels compared with cellulose, while inulin had no impact on the systemic inflammatory markers studied. Inulin promoted changes in gut bacterial populations at the class level (increased Actinobacteria and decreased Clostridia) and order level (decreased Clostridiales) compared with cellulose, with small differences at the species level observed between IPE and cellulose. CONCLUSION These data demonstrate a distinctive physiological impact of raising colonic propionate delivery in humans, as improvements in insulin sensitivity promoted by IPE and inulin were accompanied with different effects on the plasma metabolome, gut bacterial populations and markers of systemic inflammation.
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Mixed Spices at Culinary Doses Have Prebiotic Effects in Healthy Adults: A Pilot Study.
Lu, QY, Rasmussen, AM, Yang, J, Lee, RP, Huang, J, Shao, P, Carpenter, CL, Gilbuena, I, Thames, G, Henning, SM, et al
Nutrients. 2019;11(6)
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An increasing body of evidence suggests that the gut microbiota has a profound impact on human health. While the microbiome of a healthy individual is relatively stable, gut microbial dynamics can be influenced by host lifestyle and dietary choices. The aim of this study was to investigate the effects of mixed spices (cinnamon, oregano, ginger, black pepper, and cayenne pepper) at culinary doses consumed over 2 weeks in a standardized 5g capsule on the production of gut microbiota and short-chain fatty acids The study is a randomised, placebo-controlled, double-blind pilot study carried out with a total of 31 healthy women and men aged between 18 and 65. The subjects were randomly allocated to one of the two intervention groups. Results indicate that daily intake of 5g of mixed spices for 2 weeks in healthy subjects resulted in a significant reduction in the relative abundance of the phylum Firmicutes (bacteria), and a trend of increasing in phylum Bacteroidetes (bacteria) as compared with a matched control group. Authors conclude that a mixture of spices at culinary doses affects the composition of gut microbiota.
Abstract
Spices were used as food preservatives prior to the advent of refrigeration, suggesting the possibility of effects on microbiota. Previous studies have shown prebiotic activities in animals and in vitro, but there has not been a demonstration of prebiotic or postbiotic effects at culinary doses in humans. In this randomized placebo-controlled study, we determined in twenty-nine healthy adults the effects on the gut microbiota of the consumption daily of capsules containing 5 g of mixed spices at culinary doses by comparison to a matched control group consuming a maltodextrin placebo capsule. The 16S ribosomal RNA sequencing data were used for microbial characterization. Spice consumption resulted in a significant reduction in Firmicutes abundance (p < 0.033) and a trend of enrichment in Bacteroidetes (p < 0.097) compared to placebo group. Twenty-six operational taxonomic units (OTUs) were different between the spice and placebo groups after intervention. Furthermore, there was a significant negative correlation between fecal short-chain fatty acid propionate concentration and Firmicutes abundance in spice intervention group (p < 0.04). The production of individual fecal short-chain fatty acid was not significantly changed by spice consumption in this study. Mixed spices consumption significantly modified gut microbiota, suggesting a prebiotic effect of spice consumption at culinary doses.
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Role of whole grains versus fruits and vegetables in reducing subclinical inflammation and promoting gastrointestinal health in individuals affected by overweight and obesity: a randomized controlled trial.
Kopf, JC, Suhr, MJ, Clarke, J, Eyun, SI, Riethoven, JM, Ramer-Tait, AE, Rose, DJ
Nutrition journal. 2018;17(1):72
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Poor diet is the leading risk factor for premature death and disability in the United States. Poor diets lead to metabolic syndrome and its associated diseases such as heart disease and diabetes. The purpose of this study was to determine the impact of increasing intake of wholegrains or fruit and vegetables against a typical Western diet on inflammatory makers and gut microbiota composition. The study was a randomized, parallel arm feeding trial which enrolled fifty-two participants. The subjects were randomized into three groups (control, wholegrains, and fruit and vegetables). Results indicate that the wholegrain and fruit and vegetable diets had significant positive impacts on inflammatory markers. Interestingly, while both treatment groups decreased inflammatory markers, each decreased a different biomarker. The treatments induced individualised changes in microbiota composition such that treatment group differences were not identified. Authors conclude that wholegrain and fruit and vegetable diets have a positive impact on metabolic health in individuals affected by overweight or obesity.
Abstract
BACKGROUND Whole grains (WG) and fruits and vegetables (FV) have been shown to reduce the risk of metabolic disease, possibly via modulation of the gut microbiota. The purpose of this study was to determine the impact of increasing intake of either WG or FV on inflammatory markers and gut microbiota composition. METHODS A randomized parallel arm feeding trial was completed on forty-nine subjects with overweight or obesity and low intakes of FV and WG. Individuals were randomized into three groups (3 servings/d provided): WG, FV, and a control (refined grains). Stool and blood samples were collected at the beginning of the study and after 6 weeks. Inflammatory markers [tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), lipopolysaccharide binding protein (LBP), and high sensitivity C-reactive protein (hs-CRP)] were measured. Stool sample analysis included short/branched chain fatty acids (S/BCFA) and microbiota composition. RESULTS There was a significant decrease in LBP for participants on the WG (- 0.2 μg/mL, p = 0.02) and FV (- 0.2 μg/mL, p = 0.005) diets, with no change in those on the control diet (0.1 μg/mL, p = 0.08). The FV diet induced a significant change in IL-6 (- 1.5 pg/mL, p = 0.006), but no significant change was observed for the other treatments (control, - 0.009 pg/mL, p = 0.99; WG, - 0.29, p = 0.68). The WG diet resulted in a significant decrease in TNF-α (- 3.7 pg/mL; p < 0.001), whereas no significant effects were found for those on the other diets (control, - 0.6 pg/mL, p = 0.6; FV, - 1.4 pg/mL, p = 0.2). The treatments induced individualized changes in microbiota composition such that treatment group differences were not identified, except for a significant increase in α-diversity in the FV group. The proportions of Clostridiales (Firmicutes phylum) at baseline were correlated with the magnitude of change in LBP during the study. CONCLUSIONS These data demonstrate that WG and FV intake can have positive effects on metabolic health; however, different markers of inflammation were reduced on each diet suggesting that the anti-inflammatory effects were facilitated via different mechanisms. The anti-inflammatory effects were not related to changes in gut microbiota composition during the intervention, but were correlated with microbiota composition at baseline. TRIAL REGISTRATION ClinicalTrials.gov , NCT02602496 , Nov 4, 2017.
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Bread Affects Clinical Parameters and Induces Gut Microbiome-Associated Personal Glycemic Responses.
Korem, T, Zeevi, D, Zmora, N, Weissbrod, O, Bar, N, Lotan-Pompan, M, Avnit-Sagi, T, Kosower, N, Malka, G, Rein, M, et al
Cell metabolism. 2017;25(6):1243-1253.e5
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Bread is a key ingredient of the human diet. Wheat is the most commonly used cereal for baking bread. The aim of this study was to compare the effects of traditionally milled and prepared whole-grain sourdough bread and industrial white bread made from refined wheat on multiple clinical and disease markers and on the composition and function of the gut microbiome. The study is a randomized crossover trial with 20 healthy subjects. Participants received either industrial white bread made from mostly refined wheat flour or a sourdough-leavened bread made from whole-grain wheat flour. Results indicate that there were no significant differences on a broad array of clinical parameters between the two 1-week-long dietary interventions. Additionally, gut microbiome analysis showed that the microbiota composition remained generally stable and person specific throughout the trial. Authors conclude that their study underlines the importance of personalisation in dietary recommendations as the interpersonal variation in the effect of bread would allow the personalisation of bread-related nutritional recommendations and optimisation of food choices worldwide.
Abstract
Bread is consumed daily by billions of people, yet evidence regarding its clinical effects is contradicting. Here, we performed a randomized crossover trial of two 1-week-long dietary interventions comprising consumption of either traditionally made sourdough-leavened whole-grain bread or industrially made white bread. We found no significant differential effects of bread type on multiple clinical parameters. The gut microbiota composition remained person specific throughout this trial and was generally resilient to the intervention. We demonstrate statistically significant interpersonal variability in the glycemic response to different bread types, suggesting that the lack of phenotypic difference between the bread types stems from a person-specific effect. We further show that the type of bread that induces the lower glycemic response in each person can be predicted based solely on microbiome data prior to the intervention. Together, we present marked personalization in both bread metabolism and the gut microbiome, suggesting that understanding dietary effects requires integration of person-specific factors.
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Functional interactions between the gut microbiota and host metabolism.
Tremaroli, V, Bäckhed, F
Nature. 2012;489(7415):242-9
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This literature review aims to discuss evidence for the role of the gut microbiota in metabolism and possible links to obesity. Obesity and caloric intake can influence the microbiota, but whether the reverse is true in humans remains unclear. Much of the mechanisms have been determined in rodents, determining similar pathways in humans is difficult. The interplay of diet, host and gut microbiota may cause increased gut permeability (leaky gut) that could lead to an increase in inflammation that may cause obesity, fatty liver disease and insulin resistance. It is increasingly accepted that gut microbiota can contribute to diseases such as obesity, diabetes and cardiovascular disease, but exactly how and by how much remains unclear. Evidence for treating the microbiota to help with these metabolic diseases, either by pre- or probiotic supplementation, is building. However, double-blind, placebo-controlled studies are required to determine effects. The influence of the gut microbiota is a promising area, but one that needs further research.
Abstract
The link between the microbes in the human gut and the development of obesity, cardiovascular disease and metabolic syndromes, such as type 2 diabetes, is becoming clearer. However, because of the complexity of the microbial community, the functional connections are less well understood. Studies in both mice and humans are helping to show what effect the gut microbiota has on host metabolism by improving energy yield from food and modulating dietary or the host-derived compounds that alter host metabolic pathways. Through increased knowledge of the mechanisms involved in the interactions between the microbiota and its host, we will be in a better position to develop treatments for metabolic disease.