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The Effect of Regular Consumption of Reformulated Breads on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Schadow, AM, Revheim, I, Spielau, U, Dierkes, J, Schwingshackl, L, Frank, J, Hodgson, JM, Moreira-Rosário, A, Seal, CJ, Buyken, AE, et al
Advances in nutrition (Bethesda, Md.). 2023;14(1):30-43
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The metabolic effect of bread depends on several qualitative aspects ranging from the type of grain, the amount of carbohydrates, levels of other nutrients, as well as the chemical structure and processing. The aim of this study was to assess the certainty of the evidence and to investigate the overall effect of regular consumption of reformulated breads on glycaemic control in the following groups: a) healthy adults; b) those at risk of developing cardiometabolic disease (e.g., having hypertension, hyperglycaemia, hypercholesterolemia and/or overweight/obesity); and c) those with manifest type 2 diabetes mellitus (T2DM). This study is a systematic review and meta-analysis of 22 studies and 23 distinct study populations. All studies were randomised controlled trials, 12 of which had a crossover design and 10 had a parallel design. In total, 1037 participants were included. These provided 669 and 595 data points for intervention and control comparisons, respectively. Results show a beneficial effect of reformulated bread variants on fasting blood glucose concentrations. This benefit may be more pronounced among people with manifest T2DM (low certainty of evidence). Authors conclude that bread quality is relevant for metabolic health among adults and that future studies should address its relevance among people at risk of T2DM.
Expert Review
Conflicts of interest:
None
Take Home Message:
This study’s findings suggest the effect of reformulated breads high in dietary fibre, whole grains, and/or functional ingredients may be more beneficial than regular breads on fasting blood glucose concentrations in adults, primarily among those with T2DM. Reformulated breads however, did not lower fasting insulin concentrations, HOMA-IR and HbA1C when compared to regular bread.
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:
Overview
This study evaluated the effect of regular consumption of “reformulated breads” on glycemic control among healthy adults, adults at cardiometabolic risk or with manifest T2DM in 22 RCTs with 1037 participants. Compared with “regular” or comparator bread, consumption of reformulated intervention breads yielded lower fasting blood glucose concentrations only among people with T2DM (low certainty of evidence), yet no differences in fasting insulin, HOMA-IR, HbA1c, or postprandial glucose response were identified.
[*’reformulated bread’ as defined by the World Health Organisation of altering the processing or composition of a food to improve its nutritional profile, and contained whole-grains and dietary fibre]
Results
Sub group analysis revealed that the effect of reformulated breads high in dietary fibre, whole grains, and/or functional ingredients on lowering fasting blood glucose was confined to participants with T2DM, with no significant effect among participants without T2DM (0.68 mmol/L; 95% CI: 1.11, 0.36; I2 1⁄4 57% and 0.04 mmol/L; 95% CI: 0.13, 0.05; I2 1⁄4 25%, respectively; P < 0.001).
Subgroup analyses by continent revealed a more pronounced effect on fasting blood glucose concentrations in studies conducted in Asia and the Middle East compared with studies conducted in Europe, North America, and Oceania (MD: 0.84 mmol/L; 95% CI: 1.35, 0.33; I2 1⁄4 52% and MD: 0.04 mmol/L; 95% CI: 0.10, 0.03; I2 1⁄4 0%, respectively; P < 0.001)
Additional subgroup analyses found that the type of control bread, but not the type of intervention bread, affected the pooled effect estimate of fasting blood glucose concentration (P 1⁄4 0.03), with the largest difference reported in studies not describing the control bread used.
Limitations
Publication bias was considered negligible for the studies included in this meta-analysis, and the risk of bias assessment revealed that most of the studies had some concerns of risk of bias. One author is a member of the International Carbohydrate Quality Consortium and another is a member of the GRADE working group.
Strengths
This systematic review and meta-analysis include the focus on high-quality intervention studies (i.e., RCTs using either crossover or parallel design) and the inclusion of longer-term studies (>2 wk) to address the effectiveness of regular bread replacement for glycemic control in everyday life.
Clinical practice applications:
- This data suggests that bread quality is relevant for metabolic health among adults at risk of T2DM. In particular, reformulated breads were found to have a more beneficial impact than regular breads on fasting blood glucose concentrations in adults with TsDM. However, consumption of the reformulated bread (enriched with dietary fiber, whole grains, or functional ingredients) did not lower fasting insulin concentrations compared with the control breads (MD: 1.59 pmol/L; 95% CI: 5.78, 2.59; moderate certainty of evidence)
- Consumption of the reformulated bread did not lower HOMA-IR compared with the control breads (MD: 0.09; 95% CI: 0.35, 0.22; moderate certainty of evidence)
- Consumption of the reformulated bread did not lower HbA1c concentrations compared with the control bread (0.14; 95% CI: 0.39, 0.10; P 1⁄4 0.195; very low certainty of evidence).
Considerations for future research:
- Longer intervention periods may be required to determine the beneficial effects on the HbA1c concentrations and to elicit changes in markers of insulin resistance
- Future studies should use the 2022 WHO standardised HbA1c diagnostic reference criterion for diabetes mellitus
- Improvements in specific outcomes may also be linked to defined groups within populations such as persons with manifest T2DM.
- The type of reformulation of the bread may be an important factor but differ considerably around the world
Abstract
Bread is a major source of grain-derived carbohydrates worldwide. High intakes of refined grains, low in dietary fiber and high in glycemic index, are linked with increased risk for type 2 diabetes mellitus (T2DM) and other chronic diseases. Hence, improvements in the composition of bread could influence population health. This systematic review evaluated the effect of regular consumption of reformulated breads on glycemic control among healthy adults, adults at cardiometabolic risk or with manifest T2DM. A literature search was performed using MEDLINE, Embase, Web of Science and the Cochrane Central Register of Controlled Trials. Eligible studies employed a bread intervention (≥2 wk) in adults (healthy, at cardiometabolic risk or manifest T2DM) and reported glycemic outcomes (fasting blood glucose, fasting insulin, HOMA-IR, HbA1c, and postprandial glucose responses). Data were pooled using generic inverse variance with random-effects model and presented as mean difference (MD) or standardized MD between treatments with 95% CIs. Twenty-two studies met the inclusion criteria (n = 1037 participants). Compared with "regular" or comparator bread, consumption of reformulated intervention breads yielded lower fasting blood glucose concentrations (MD: -0.21 mmol/L; 95% CI: -0.38, -0.03; I2 = 88%, moderate certainty of evidence), yet no differences in fasting insulin (MD: -1.59 pmol/L; 95% CI: -5.78, 2.59; I2 = 38%, moderate certainty of evidence), HOMA-IR (MD: -0.09; 95% CI: -0.35, 0.23; I2 = 60%, moderate certainty of evidence), HbA1c (MD: -0.14; 95% CI: -0.39, 0.10; I2 = 56%, very low certainty of evidence), or postprandial glucose response (SMD: -0.46; 95% CI: -1.28, 0.36; I2 = 74%, low certainty of evidence). Subgroup analyses revealed a beneficial effect for fasting blood glucose only among people with T2DM (low certainty of evidence). Our findings suggest a beneficial effect of reformulated breads high in dietary fiber, whole grains, and/or functional ingredients on fasting blood glucose concentrations in adults, primarily among those with T2DM. This trial was registered at PROSPERO as CRD42020205458.
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Anti-aging Effects of Calorie Restriction (CR) and CR Mimetics based on the Senoinflammation Concept.
Kim, DH, Bang, E, Jung, HJ, Noh, SG, Yu, BP, Choi, YJ, Chung, HY
Nutrients. 2020;12(2)
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Low grade, systemic, chronic inflammation is a feature of ageing and underlies many age-related chronic diseases states. As cells age their capacity to proliferate declines, which is referred to as cell senescence. Such senescent cells release multiple inflammatory markers contributing to a pro-inflammatory state. This is further aggravated by elevated oxidative stress and a reduced capacity to manage it, eventually leading to improper gene regulation and DNA damage. To define this age-related, complex inflammatory phenomena the authors introduced the term senoinflammation. A well-established intervention to reverse or slow down the ageing process and many ageing-associated diseases is calorie restriction (CR), by means of reducing overall caloric intake without malnutrition. CR exhibits potent anti-inflammatory effects, reduces age-associated oxidative stress, improves age-related metabolic dysregulation and enhances favourable gene expression. This review summarises how CR and CR-mimicking substances exert their anti-inflammatory effect and some of the cellular mechanism involved and may be of interest to those who are looking to get a more detailed understanding on ageing, inflammation and the benefits of CR.
Abstract
Chronic inflammation, a pervasive feature of the aging process, is defined by a continuous, multifarious, low-grade inflammatory response. It is a sustained and systemic phenomenon that aggravates aging and can lead to age-related chronic diseases. In recent years, our understanding of age-related chronic inflammation has advanced through a large number of investigations on aging and calorie restriction (CR). A broader view of age-related inflammation is the concept of senoinflammation, which has an outlook beyond the traditional view, as proposed in our previous work. In this review, we discuss the effects of CR on multiple phases of proinflammatory networks and inflammatory signaling pathways to elucidate the basic mechanism underlying aging. Based on studies on senoinflammation and CR, we recognized that senescence-associated secretory phenotype (SASP), which mainly comprises cytokines and chemokines, was significantly increased during aging, whereas it was suppressed during CR. Further, we recognized that cellular metabolic pathways were also dysregulated in aging; however, CR mimetics reversed these effects. These results further support and enhance our understanding of the novel concept of senoinflammation, which is related to the metabolic changes that occur in the aging process. Furthermore, a thorough elucidation of the effect of CR on senoinflammation will reveal key insights and allow possible interventions in aging mechanisms, thus contributing to the development of new therapies focused on improving health and longevity.
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Link between gut microbiota and health outcomes in inulin -treated obese patients: Lessons from the Food4Gut multicenter randomized placebo-controlled trial.
Hiel, S, Gianfrancesco, MA, Rodriguez, J, Portheault, D, Leyrolle, Q, Bindels, LB, Gomes da Silveira Cauduro, C, Mulders, MDGH, Zamariola, G, Azzi, AS, et al
Clinical nutrition (Edinburgh, Scotland). 2020;39(12):3618-3628
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A global obesity epidemic has become a growing concern today. Modifying the microbial population in our gut has been identified as a nutritional intervention strategy for managing obesity. Fermentable dietary fibres such as inulin-type fructans may alter the microbial population in the gut. In this randomised, single-blind, multicentric, placebo-controlled study, researchers examined the effect of 16g/d native inulin supplementation with inulin-rich vegetables on obesity and gut bacteria composition over three months in 106 Caucasian subjects. Furthermore, the study examined the synergistic effects of metformin and inulin on gut microbial composition. 75% of the participants lost body weight after taking inulin and making dietary changes. In addition, BMI, fat mass and other metabolic markers decreased in this group. Combined with inulin, metformin showed gut microbial modulation, although an increase in Bifidobacterium species was less noticeable. Supplementing inulin with inulin-rich vegetables caused uncomfortable side effects such as bloating and flatulence. Even though subjects showed a reduction in side effects after the first month of supplementation, it should be considered when making intervention decisions for people prone to digestive issues. Nutrition practitioners can use these results when developing obesity intervention strategies.
Abstract
BACKGROUND The gut microbiota is altered in obesity and is strongly influenced by nutrients and xenobiotics. We have tested the impact of native inulin as prebiotic present in vegetables and added as a supplement on gut microbiota-related outcomes in obese patients. Metformin treatment was analyzed as a potential modulator of the response. METHODS A randomized, single-blinded, multicentric, placebo-controlled trial was conducted in 150 obese patients who received 16 g/d native inulin versus maltodextrin, coupled to dietary advice to consume inulin-rich versus -poor vegetables for 3 months, respectively, in addition to dietary caloric restriction. Anthropometry, diagnostic imaging (abdominal CT-scan, fibroscan), food-behavior questionnaires, serum biology and fecal microbiome (primary outcome; 16S rDNA sequencing) were analyzed before and after the intervention. RESULTS Both placebo and prebiotic interventions lowered energy intake, BMI, systolic blood pressure, and serum γ-GT. The prebiotic induced greater weight loss and additionally decreased diastolic blood pressure, AST and insulinemia. Metformin treatment compromised most of the gut microbiota changes and metabolic improvements linked to prebiotic intervention. The prebiotic modulated specific bacteria, associated with the improvement of anthropometry (i.e. a decrease in Desulfovibrio and Clostridium sensu stricto). A large increase in Bifidobacterium appears as a signature of inulin intake rather than a driver of prebiotic-linked biological outcomes. CONCLUSIONS Inulin-enriched diet is able to promote weight loss in obese patients, the treatment efficiency being related to gut microbiota characteristics. This treatment is more efficacious in patients who did not receive metformin as anti-diabetic drugs prior the intervention, supporting that both drug treatment and microbiota might be taken into account in personalized nutrition interventions. Registered under ClinicalTrials.gov Identifier no NCT03852069.
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Consumption of a Beverage Containing Aspartame and Acesulfame K for Two Weeks Does Not Adversely Influence Glucose Metabolism in Adult Males and Females: A Randomized Crossover Study.
Kim, Y, Keogh, JB, Clifton, PM
International journal of environmental research and public health. 2020;17(23)
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Artificial sweeteners gained popularity in the past decade, especially in the food industry. Up until recently, people generally considered it a better option to decrease sugar consumption and reduce obesity and Type 2 Diabetes. This randomised crossover study looked at the adverse effects of two commonly used artificial sweeteners on normal-weight subjects, overweight and obese subjects. A total of 39 healthy subjects without Type 2 Diabetes participated in this study. For two weeks, participants consumed 0.6 litres of a commercially branded soft drink containing acesulfame K and aspartame to assess the effects of the ingredients on glucose homeostasis. During the two-week treatment period, the healthy subjects did not show any significant detrimental impact of artificially sweetened beverages on glucose, insulin and insulin sensitivity. However, the study population was small, and the study was conducted only for a relatively short period. Therefore, further, longer-term robust studies are required to estimate the significance of the detrimental effect of artificially sweetened beverages on glucose homeostasis. Nevertheless, this study can help healthcare practitioners understand the short-term impact of artificial sweeteners, keeping in mind that further research is needed to investigate the effects.
Abstract
There is an association between the consumption of artificial sweeteners and Type 2 diabetes in cohort studies, but intervention studies do not show a clear elevation of blood glucose after the use of artificial sweeteners. The objective of this study was to examine whether two commonly used artificial sweeteners had an adverse effect on glucose control in normal-weight subjects, and in overweight and obese subjects when consumed for 2 weeks. In the study, 39 healthy subjects (body-mass index, kg/m2) (18-45) without Type 2 diabetes with an age of 18-75 years were randomly assigned to 0.6 L/day of an artificially sweetened soft drink containing acesulfame K (950) and aspartame (951) or 0.6 L/day of mineral water for 2 weeks each in a crossover study. There was a 4 week washout period with no drinks consumed. Glucose levels were read by a continuous glucose monitor (CGM) during each 2 week period. A 75 g oral glucose-tolerance test (OGTT) was performed at the beginning and end of each intervention period. Blood samples were collected at baseline, and 1 and 2 h for glucose and insulin. A 2 week intake of artificially sweetened beverage (ASB) did not alter concentrations of fasting glucose and fasting insulin, the area under the curve (AUC) for OGTT glucose and insulin, the incremental area under the curve (iAUC) for OGTT glucose and insulin, the homeostatic model assessment for insulin resistance (HOMA-IR), and the Matsuda index compared with the baseline and with the changes after a 2 week intake of mineral water. Continuous 2 week glucose concentrations were not significantly different after a 2 week intake of ASB compared with a 2 week intake of mineral water. This study found no harmful effect of the artificially sweetened soft drink containing acesulfame K (950) and aspartame (951) on glucose control when consumed for 2 weeks by people without Type 2 diabetes.
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The Effectiveness of Intermittent Fasting to Reduce Body Mass Index and Glucose Metabolism: A Systematic Review and Meta-Analysis.
Cho, Y, Hong, N, Kim, KW, Cho, SJ, Lee, M, Lee, YH, Lee, YH, Kang, ES, Cha, BS, Lee, BW
Journal of clinical medicine. 2019;8(10)
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Calorie restriction (CR) is known to reduce body weight and to improve various cardiovascular risk factors. Due to the many difficulties in sustaining daily CR, intermittent fasting (IF) has been proposed as an alternative strategy for achieving and maintaining weight reduction. The aim of this study was to investigate the effectiveness of IF on weight loss and glucose metabolism by analysing the effect size of previous studies among the general population without diabetes mellitus. A total of 12 studies were included in this study. The total number of participants was 545 (261 in the intervention group and 284 in the control group). Study analysis indicates an improvement in glycaemic control and insulin resistance through IF diet as compared with a non-fasting control group. Lean mass was relatively conserved in the IF diet group however, no significant weight reduction was identified. Authors conclude that IF diet may improve fat distribution in the general population without chronic metabolic disease.
Abstract
The effects of an intermittent fasting diet (IFD) in the general population are still controversial. In this study, we aimed to systematically evaluate the effectiveness of an IFD to reduce body mass index and glucose metabolism in the general population without diabetes mellitus. Cochrane, PubMed, and Embase databases were searched to identify randomized controlled trials and controlled clinical trials that compared an IFD with a regular diet or a continuous calorie restriction diet. The effectiveness of an IFD was estimated by the weighted mean difference (WMD) for several variables associated with glucometabolic parameters including body mass index (BMI) and fasting glucose. The pooled mean differences of outcomes were calculated using a random effects model. From 2814 studies identified through a literature search, we finally selected 12 articles (545 participants). Compared with a control diet, an IFD was associated with a significant decline in BMI (WMD, -0.75 kg/m2; 95% CI, -1.44 to -0.06), fasting glucose level (WMD, -4.16 mg/dL; 95% CI, -6.92 to -1.40), and homeostatic model assessment of insulin resistance (WMD, -0.54; 95% CI, -1.05 to -0.03). Fat mass (WMD, -0.98 kg; 95% CI, -2.32 to 0.36) tended to decrease in the IFD group with a significant increase in adiponectin (WMD, 1008.9 ng/mL; 95% CI, 140.5 to 1877.3) and a decrease in leptin (WMD, -0.51 ng/mL; 95% CI, -0.77 to -0.24) levels. An IFD may provide a significant metabolic benefit by improving glycemic control, insulin resistance, and adipokine concentration with a reduction of BMI in adults.
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Dietary Protein Consumption and the Risk of Type 2 Diabetes: ADose-Response Meta-Analysis of Prospective Studies.
Fan, M, Li, Y, Wang, C, Mao, Z, Zhou, W, Zhang, L, Yang, X, Cui, S, Li, L
Nutrients. 2019;11(11)
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Diabetes mellitus is considered a serious public health issue worldwide with the vast majority of patients having type 2 diabetes (T2D). Dietary factors are major behavioural factors that can influence the risk for T2D. The aim of this study was to quantify the relationship between protein consumption and high-protein food intake with T2D risk and to identify optimal food types for a low T2D risk. This study is a meta-analysis which included 60 articles consisting of 72 studies for quantitative synthesis. Results indicate that total and animal protein intake increase the risk of T2D incidence, whereas plant protein intake lowers this risk. Furthermore, the consumption of red meat, processed meat, milk, and eggs are positively linked with an increased risk of T2D incidence; only yoghurt consumption lowered the incidence of T2D. Authors conclude that selecting specific optimal protein intakes can lead to a significant decrease in the risk for T2D.
Abstract
The relationship between dietary protein consumption and the risk of type 2 diabetes (T2D) has been inconsistent. The aim of this meta-analysis was to explore the relations between dietary protein consumption and the risk of T2D. We conducted systematic retrieval of prospective studies in PubMed, Embase, and Web of Science. Summary relative risks were compiled with a fixed effects model or a random effects model, and a restricted cubic spline regression model and generalized least squares analysis were used to evaluate the diet-T2D incidence relationship. T2D risk increased with increasing consumption of total protein and animal protein, red meat, processed meat, milk, and eggs, respectively, while plant protein and yogurt had an inverse relationship. A non-linear association with the risk for T2D was found for the consumption of plant protein, processed meat, milk, yogurt, and soy. This meta-analysis suggests that substitution of plant protein and yogurt for animal protein, especially red meat and processed meat, can reduce the risk for T2D.
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Intermittent Fasting in Cardiovascular Disorders-An Overview.
Malinowski, B, Zalewska, K, Węsierska, A, Sokołowska, MM, Socha, M, Liczner, G, Pawlak-Osińska, K, Wiciński, M
Nutrients. 2019;11(3)
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Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. IF has gained popularity in recent years with people wanting to lose weight, and it may have many long-term health benefits. In this review, the authors looked at human and animal studies using variations of IF including time restricted eating (TRE), where eating is confined within a specific window during the day (for example 8 hours eating and 16 hours fasting), and alternate day fasting (ADF), where a day of eating normally is alternated with a day of either fasting entirely, or significant calorie restriction. The authors found that IF is related to many beneficial effects on the cardiovascular system, involving atherosclerosis progression, benefits for diabetes mellitus type 2 such as improved glucose metabolism and insulin sensitivity, lowering of blood pressure, and other cardiovascular risk factors (such as lipid profile and inflammation). It is currently unclear whether the benefits of IF are solely due to weight loss or other mechanisms. The success of every type of diet depends on compliance, and IF seems to be as easy or easier to follow than more traditional diets for many people. Fasting is not recommended for people with hormonal imbalances, pregnant and breastfeeding women, and diabetics. People with eating disorders and underweight people are also not recommended to use the intermittent fasting diet. In recent years, the IF diet and its varieties have become increasingly popular. This diet not only serves to reduce body weight but seems to have other long-term health benefits. However, individuals’ current health and situation should be considered before commencing the IF diet.
Abstract
Intermittent fasting is a form of time restricted eating (typically 16 h fasting and 8 h eating), which has gained popularity in recent years and shows promise as a possible new paradigm in the approach to weight loss and the reduction of inflammation, and has many potential long term health benefits. In this review, the authors will incorporate many aspects of fasting, mainly focusing on its effects on the cardiovascular system, involving atherosclerosis progression, benefits for diabetes mellitus type 2, lowering of blood pressure, and exploring other cardiovascular risk factors (such as lipid profile and inflammation).