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Gut microbiome modulates the effects of a personalised postprandial-targeting (PPT) diet on cardiometabolic markers: a diet intervention in pre-diabetes.
Ben-Yacov, O, Godneva, A, Rein, M, Shilo, S, Lotan-Pompan, M, Weinberger, A, Segal, E
Gut. 2023;72(8):1486-1496
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Diet is a major contributor to cardiometabolic health and plays a fundamental role in the prevention, management and even reversal of many chronic diseases. The gut microbiota has a central role in human health and disease. Specifically, its role in cardiometabolic health has been studied extensively in recent years. The aim of this study was to evaluate the interplay between dietary modifications, microbiome composition and cardiometabolic health outcomes. This study was a randomised controlled trial of a 6-month dietary intervention comparing a personalised postprandial-targeting (PPT) diet versus Mediterranean (MED) diet in 200 adults with pre-diabetes. Results showed that: - PPT intervention induced greater changes in multiple dietary features compared with MED intervention. - PPT intervention increased microbiome diversity and richness and exerted specific microbiome species changes that associate with clinical outcomes. - Changes in specific gut microbiome species partially mediated the effects of dietary modifications on clinical outcomes. Authors conclude that the PPT diet prompted greater changes in gut microbiota composition, consistent with overall greater dietary modifications, as compared with the MED intervention.
Abstract
OBJECTIVE To explore the interplay between dietary modifications, microbiome composition and host metabolic responses in a dietary intervention setting of a personalised postprandial-targeting (PPT) diet versus a Mediterranean (MED) diet in pre-diabetes. DESIGN In a 6-month dietary intervention, adults with pre-diabetes were randomly assigned to follow an MED or PPT diet (based on a machine-learning algorithm for predicting postprandial glucose responses). Data collected at baseline and 6 months from 200 participants who completed the intervention included: dietary data from self-recorded logging using a smartphone application, gut microbiome data from shotgun metagenomics sequencing of faecal samples, and clinical data from continuous glucose monitoring, blood biomarkers and anthropometrics. RESULTS PPT diet induced more prominent changes to the gut microbiome composition, compared with MED diet, consistent with overall greater dietary modifications observed. Particularly, microbiome alpha-diversity increased significantly in PPT (p=0.007) but not in MED arm (p=0.18). Post hoc analysis of changes in multiple dietary features, including food-categories, nutrients and PPT-adherence score across the cohort, demonstrated significant associations between specific dietary changes and species-level changes in microbiome composition. Furthermore, using causal mediation analysis we detect nine microbial species that partially mediate the association between specific dietary changes and clinical outcomes, including three species (from Bacteroidales, Lachnospiraceae, Oscillospirales orders) that mediate the association between PPT-adherence score and clinical outcomes of hemoglobin A1c (HbA1c), high-density lipoprotein cholesterol (HDL-C) and triglycerides. Finally, using machine-learning models trained on dietary changes and baseline clinical data, we predict personalised metabolic responses to dietary modifications and assess features importance for clinical improvement in cardiometabolic markers of blood lipids, glycaemic control and body weight. CONCLUSIONS Our findings support the role of gut microbiome in modulating the effects of dietary modifications on cardiometabolic outcomes, and advance the concept of precision nutrition strategies for reducing comorbidities in pre-diabetes. TRIAL REGISTRATION NUMBER NCT03222791.
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Differential Responders to a Mixed Meal Tolerance Test Associated with Type 2 Diabetes Risk Factors and Gut Microbiota-Data from the MEDGI-Carb Randomized Controlled Trial.
Skantze, V, Hjorth, T, Wallman, M, Brunius, C, Dicksved, J, Pelve, EA, Esberg, A, Vitale, M, Giacco, R, Costabile, G, et al
Nutrients. 2023;15(20)
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Type 2 diabetes (T2D) is a growing worldwide health problem. Increased blood sugars and a corresponding increase in the production of the hormone insulin, which functions to lower blood sugar are risk factors for T2D development. However, it has been shown that everyone has an individual response to the food and the production of differing levels of blood sugar and insulin when eating the same meals has been shown. This secondary analysis of a 12-week randomised control trial of 155 individuals aimed to determine relationships between gut microbiota composition and the glucose response to high and low glycaemic index Mediterranean diets. The results identified two distinct types of response amongst the participants. Cluster A individuals had a lower but more rapid glucose response following food and were deemed to have a better glucose control than cluster B individuals. The clusters also differed in the gut microbiota composition. Cluster A had a higher proportion of Clostridium sensu stricto 1 and a lower proportion of Blautia, than cluster B. It was concluded that the glucose response to a standardised meal can differ between individuals and are associated with differing gut microbiota and risk for T2D. This study could be used by healthcare professionals to understand that diet recommendations are not one size fits all and that the recommendation of certain diets may have differing success. Understanding and differentiating individuals and tailor making recommendations may be of benefit, however further understanding is required on different glucose responses following a meal.
Abstract
The global prevalence of type 2 diabetes mellitus (T2DM) has surged in recent decades, and the identification of differential glycemic responders can aid tailored treatment for the prevention of prediabetes and T2DM. A mixed meal tolerance test (MMTT) based on regular foods offers the potential to uncover differential responders in dynamical postprandial events. We aimed to fit a simple mathematical model on dynamic postprandial glucose data from repeated MMTTs among participants with elevated T2DM risk to identify response clusters and investigate their association with T2DM risk factors and gut microbiota. Data were used from a 12-week multi-center dietary intervention trial involving high-risk T2DM adults, comparing high- versus low-glycemic index foods within a Mediterranean diet context (MEDGICarb). Model-based analysis of MMTTs from 155 participants (81 females and 74 males) revealed two distinct plasma glucose response clusters that were associated with baseline gut microbiota. Cluster A, inversely associated with HbA1c and waist circumference and directly with insulin sensitivity, exhibited a contrasting profile to cluster B. Findings imply that a standardized breakfast MMTT using regular foods could effectively distinguish non-diabetic individuals at varying risk levels for T2DM using a simple mechanistic model.
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An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition: An Interim Subgroup Analysis of the PREDIMED-Plus Randomized Clinical Trial.
Konieczna, J, Ruiz-Canela, M, Galmes-Panades, AM, Abete, I, Babio, N, Fiol, M, Martín-Sánchez, V, Estruch, R, Vidal, J, Buil-Cosiales, P, et al
JAMA network open. 2023;6(10):e2337994
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The Mediterranean diet (MedDiet), which focuses on whole grains, lean meat, fruits, vegetables, and low amounts of minimally processed foods has been shown in previous research to improve body composition and decrease fat storage around the middle. This randomised control trial of 1556 older adults aimed to determine the effects of combining a 30% lower energy version of the MedDiet in combination with physical exercise on body composition. After 3 years, the results showed that compared to a normal MedDiet without exercise, the lower energy version in combination with exercise improved body composition by decreasing total fat, and the fat stored around the organs and increasing muscle mass. However, benefits were more pronounced after 1 year and decreased slightly at 3 years. It was concluded that a low energy MedDiet in combination with physical activity may be able to improve the body composition of overweight and older adults with obesity. This study could be used by healthcare professionals to recommend a low energy MedDiet to older adults to promote weight loss, whilst attenuating muscle loss associated with ageing.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The addition of exercise to an energy-reduced diet, which focuses on whole grains, healthy fats, lean protein, and fruits and vegetables can emphasise positive effects on body composition in older adults.
- However, there is a loss of lean mass associated with this type of diet (contrary to author conclusions) and measures should be taken to monitor and increase protein intake to prevent or limit this loss.
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
This study aimed to determine the long-term effects of an energy reduced MedDiet in combination with physical activity on body composition.
Methods
- This is a predetermined 3-year interim analysis of a 6-year single-blind, randomised control trial of 1556 individuals aged 55-75 who are overweight or obese with metabolic syndrome.
- 760 individuals on 30% energy reduced MedDiet with limited processed foods, plus 45 minutes walking 6 days per week and behavioural and motivational support. [Intervention group]
- 761 on standard MedDiet without physical activity. [Control]
Results
Within group comparisons showed that individuals in the intervention group lost (P value represents baseline vs year 3):
- Total fat mass percentage (1-year vs baseline, −1.14%; 95% CI, −1.32% to −0.96%; 3-year vs baseline, −0.52%; 95% CI, −0.71% to −0.33% P=<0.001)
- Absolute visceral fat (1-year vs baseline, −154 g; 95% CI, −191 to −116 g; 3-year vs baseline, −75.1 g, 95% CI, −115 to −35.3 g P=<0.001)
- Absolute total fat after 1 year (mean change at 1 year vs baseline, −1677 g; 95% CI, −1930 to −1424 g) but regained some at year 3 (mean change at 3 years vs baseline, −1018 g; 95% CI, −1280 to −756 g P=<0.001)
- Absolute lean mass (mean change at 1 year vs baseline −300 g; 95% CI, −439 to −162 g) with further losses at year 3 (−626 g; 95% CI, −770 to −483 g P=0.001).
Within group comparisons also showed significantly increased:
- Total lean mass percentage, which was greater at year 1 than year 3 (1-year vs baseline, 1.07%; 95%CI, 0.90%-1.25%; 3-year vs baseline, 0.47%; 95% CI, 0.29%-0.65% P=<0.001).
As a result of total fat loss and some lean mass in the intervention group, the lean:fat mass ratio improved and was unchanged in the control group (between group differences (P=<0.001).
Compared to women, men may find the MedDiet + exercise more beneficial as it was shown that body composition changes were slightly more pronounced in men.
Conclusion
An energy-reduced MedDiet plus exercise emphasised positive changes to body composition compared to standard MedDiet in older adults who are overweight or have obesity.
Clinical practice applications:
- The recommendation of a reduced energy MedDiet in combination with physical activity to older people who are overweight or obese may improve body composition.
- Although lean mass loss slowed between years 1 and 3, other practices should be employed to attenuate the loss of lean mass associated with an energy-reduced MedDiet and ageing.
Considerations for future research:
- The research has not yet concluded but when it does, it will address the incidence of cardiovascular disease along with body composition changes.
- It will also look at long-term effects of the diet to determine longevity.
- Future research could focus on how to limit lean mass loss through the possibility of changing the type of exercise that accompanies the MedDiet.
Abstract
IMPORTANCE Strategies targeting body composition may help prevent chronic diseases in persons with excess weight, but randomized clinical trials evaluating lifestyle interventions have rarely reported effects on directly quantified body composition. OBJECTIVE To evaluate the effects of a lifestyle weight-loss intervention on changes in overall and regional body composition. DESIGN, SETTING, AND PARTICIPANTS The ongoing Prevención con Dieta Mediterránea-Plus (PREDIMED-Plus) randomized clinical trial is designed to test the effect of the intervention on cardiovascular disease prevention after 8 years of follow-up. The trial is being conducted in 23 Spanish research centers and includes men and women (age 55-75 years) with body mass index between 27 and 40 and metabolic syndrome. The trial reported herein is an interim subgroup analysis of the intermediate outcome body composition after 3-year follow-up, and data analysis was conducted from February 1 to November 30, 2022. Of 6874 total PREDIMED-Plus participants, a subsample of 1521 individuals, coming from centers with access to a dual energy x-ray absorptiometry device, underwent body composition measurements at 3 time points. INTERVENTION Participants were randomly allocated to a multifactorial intervention based on an energy-reduced Mediterranean diet (MedDiet) and increased physical activity (PA) or to a control group based on usual care, with advice to follow an ad libitum MedDiet, but no physical activity promotion. MAIN OUTCOMES AND MEASURES The outcomes (continuous) were 3-year changes in total fat and lean mass (expressed as percentages of body mass) and visceral fat (in grams), tested using multivariable linear mixed-effects models. Clinical relevance of changes in body components (dichotomous) was assessed based on 5% or more improvements in baseline values, using logistic regression. Main analyses were performed in the evaluable population (completers only) and in sensitivity analyses, multiple imputation was performed to include data of participants lost to follow-up (intention-to-treat analyses). RESULTS A total of 1521 individuals were included (mean [SD] age, 65.3 [5.0] years; 52.1% men). In comparison with the control group (n=761), participants in the intervention arm (n=760) showed greater reductions in the percentage of total fat (between group differences after 1-year, -0.94% [95% CI, -1.19 to -0.69]; 3 years, -0.38% [95% CI, -0.64 to -0.12] and visceral fat storage after 1 year, -126 g [95% CI, -179 to -73.3 g]; 3 years, -70.4 g [95% CI, -126 to -15.2 g] and greater increases in the percentage of total lean mass at 1 year, 0.88% [95% CI, 0.63%-1.12%]; 3-years 0.34% [95% CI, 0.09%-0.60%]). The intervention group was more likely to show improvements of 5% or more in baseline body components (absolute risk reduction after 1 year, 13% for total fat mass, 11% for total lean mass, and 14% for visceral fat mass; after 3-years: 6% for total fat mass, 6% for total lean mass, and 8% for visceral fat mass). The number of participants needed to treat was between 12 and 17 to attain at least 1 individual with possibly clinically meaningful improvements in body composition. CONCLUSIONS AND RELEVANCE The findings of this trial suggest a weight-loss lifestyle intervention based on an energy-reduced MedDiet and physical activity significantly reduced total and visceral fat and attenuated age-related losses of lean mass in older adults with overweight or obesity and metabolic syndrome. Continued follow-up is warranted to confirm the long-term consequences of these changes on cardiovascular clinical end points. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN89898870.
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A nutritional biomarker score of the Mediterranean diet and incident type 2 diabetes: Integrated analysis of data from the MedLey randomised controlled trial and the EPIC-InterAct case-cohort study.
Sobiecki, JG, Imamura, F, Davis, CR, Sharp, SJ, Koulman, A, Hodgson, JM, Guevara, M, Schulze, MB, Zheng, JS, Agnoli, C, et al
PLoS medicine. 2023;20(4):e1004221
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Self-reported adherence to the Mediterranean diet (MedDiet) has been associated with a lower incidence of type 2 diabetes (T2D). However, as no biological indicators of whether people are really following the MedDiet have been recorded, it is difficult to definitively ascertain any associations. This post-hoc analysis of a randomised control trial and a cohort study aimed to determine indicative nutritional biomarkers associated with the MedDiet and to see if associations exist with the incidence of T2D. The study formulated a biomarker score based on 29 different nutrients that are in abundance in the MedDiet. This score was then applied to an observational study and showed that as the score went up and therefore adherence to the diet, the incidence of T2D went down and vice versa. Higher adherence to the MedDiet resulted in an 11% decrease in the incidence of T2D. It was concluded that adherence to the MedDiet may help to prevent T2D. This study could be used by healthcare professionals to recommend the commencement of the MedDiet in individuals who are risk of its development.
Abstract
BACKGROUND Self-reported adherence to the Mediterranean diet has been modestly inversely associated with incidence of type 2 diabetes (T2D) in cohort studies. There is uncertainty about the validity and magnitude of this association due to subjective reporting of diet. The association has not been evaluated using an objectively measured biomarker of the Mediterranean diet. METHODS AND FINDINGS We derived a biomarker score based on 5 circulating carotenoids and 24 fatty acids that discriminated between the Mediterranean or habitual diet arms of a parallel design, 6-month partial-feeding randomised controlled trial (RCT) conducted between 2013 and 2014, the MedLey trial (128 participants out of 166 randomised). We applied this biomarker score in an observational study, the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study, to assess the association of the score with T2D incidence over an average of 9.7 years of follow-up since the baseline (1991 to 1998). We included 22,202 participants, of whom 9,453 were T2D cases, with relevant biomarkers from an original case-cohort of 27,779 participants sampled from a cohort of 340,234 people. As a secondary measure of the Mediterranean diet, we used a score estimated from dietary-self report. Within the trial, the biomarker score discriminated well between the 2 arms; the cross-validated C-statistic was 0.88 (95% confidence interval (CI) 0.82 to 0.94). The score was inversely associated with incident T2D in EPIC-InterAct: the hazard ratio (HR) per standard deviation of the score was 0.71 (95% CI: 0.65 to 0.77) following adjustment for sociodemographic, lifestyle and medical factors, and adiposity. In comparison, the HR per standard deviation of the self-reported Mediterranean diet was 0.90 (95% CI: 0.86 to 0.95). Assuming the score was causally associated with T2D, higher adherence to the Mediterranean diet in Western European adults by 10 percentiles of the score was estimated to reduce the incidence of T2D by 11% (95% CI: 7% to 14%). The study limitations included potential measurement error in nutritional biomarkers, unclear specificity of the biomarker score to the Mediterranean diet, and possible residual confounding. CONCLUSIONS These findings suggest that objectively assessed adherence to the Mediterranean diet is associated with lower risk of T2D and that even modestly higher adherence may have the potential to reduce the population burden of T2D meaningfully. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12613000602729 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=363860.
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Acute Insulin Secretory Effects of a Classic Ketogenic Meal in Healthy Subjects: A Randomized Cross-Over Study.
Battezzati, A, Foppiani, A, Leone, A, De Amicis, R, Spadafranca, A, Mari, A, Bertoli, S
Nutrients. 2023;15(5)
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The ketogenic diet is a dietary regimen providing very low carbohydrate, high fat, and modest protein. Low carbohydrate and ketogenic diets have become increasingly popular in the treatment of metabolic syndrome, obesity, and type 2 diabetes. The main aim of this study was to measure the insulin secretory response to a typical ketogenic meal providing ~40% of individual energy needs and to compare it to the response to an isocaloric Mediterranean meal in healthy subjects. This study is a randomised cross-over study which enrolled twelve healthy subjects (50/50 female/male), adults with an age range of 19–31 years, and with a normal weight. The participants received mixed standardised meals of different compositions on two different days spaced apart by a washout period of 7 days. Each subject consumed two meals of identical energy content but differing in macronutrient composition. Results show that a Mediterranean meal accounting for 40% of daily dietary intake, requires, for its metabolism, the production of 7.8 ± 0.8 times the amount of insulin compared to fasting values, temporarily spiking the insulin secretory rate to 8.9 ± 1.2-fold the basal values. Authors conclude that a ketogenic meal is disposed of with only a minimal insulin secretory response compared to a Mediterranean meal.
Abstract
The classic ketogenic diet (KD) is a high-fat, low-carbohydrate diet that mimics a starvation state with sufficient caloric intake to sustain growth and development. KD is an established treatment for several diseases, and it is currently evaluated in the management of insulin-resistant states, although insulin secretion after a classic ketogenic meal has never been investigated. We measured the insulin secretion to a ketogenic meal in 12 healthy subjects (50% females, age range 19-31 years, BMI range 19.7-24.7 kg/m2) after cross-over administrations of a Mediterranean meal and a ketogenic meal both satisfying ~40% of an individual's total energy requirement, in random order and separated by a 7-day washout period. Venous blood was sampled at baseline and at 10, 20, 30, 45, 60, 90, 120, and 180 min to measure glucose, insulin, and C-peptide concentrations. Insulin secretion was calculated from C-peptide deconvolution and normalized to the estimated body surface area. Glucose, insulin concentrations, and insulin secretory rate were markedly reduced after the ketogenic meal with respect to the Mediterranean meal: glucose AUC in the first OGTT hour -643 mg × dL-1 × min-1, 95% CI -1134, -152, p = 0.015; total insulin concentration -44,943 pmol/L, 95% CI -59,181, -3706, p < 0.001; peak rate of insulin secretion -535 pmol × min-1 × m-2, 95% CI -763, -308, p < 0.001. We have shown that a ketogenic meal is disposed of with only a minimal insulin secretory response compared to a Mediterranean meal. This finding may be of interest to patients with insulin resistance and or insulin secretory defects.
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Polyphenol Intake in Pregnant Women on Gestational Diabetes Risk and Neurodevelopmental Disorders in Offspring: A Systematic Review.
Salinas-Roca, B, Rubió-Piqué, L, Montull-López, A
Nutrients. 2022;14(18)
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In Europe, gestational diabetes affects approximately 10.9% of pregnant women. According to previous research, the cardiometabolic health of the mother and the mother's dietary habits during pregnancy may affect the foetus' neurodevelopment. Taking polyphenol supplements and eating foods rich in polyphenols is beneficial for promoting health across generations. In this systematic review, fourteen studies were included in order to evaluate the effects of polyphenols on gestational diabetes and mental health in the offspring. A higher prevalence of neurodevelopmental diseases in offspring is associated with gestational diabetes. The results of this systematic review revealed that polyphenol intake during pregnancy might have a beneficial effect on improving cardiometabolic health, reducing inflammation, DNA methylation and oxidative stress, thus reducing the risk of developing fetal neurodevelopmental disorders, such as attention deficit hyperactivity disorder, autism spectrum disorder and learning disorders. There is a need for further robust research, as the existing evidence regarding the safety of long-term polyphenol supplementation and its effects on gestational diabetes and fetal neurodevelopment is very limited. In spite of this, healthcare professionals can use the findings of this systematic review to learn more about the positive health benefits of polyphenols in pregnant women.
Abstract
The intake of foods containing polyphenols can have a protective role to avoid comorbidities during pregnancy and, at the same time, promote transgenerational health. This review aims to describe the effect of polyphenol intake through supplements or polyphenol-rich foods during pregnancy on the incidence and evolution of gestational diabetes mellitus (GDM), as well as the link with the neurodevelopment of the fetus. Using PRISMA procedures, a systematic review was conducted by searching in biomedical databases (PubMed, Cinahl and Scopus) from January to June 2022. Full articles were screened (n = 419) and critically appraised. Fourteen studies were selected and were divided into two different thematic blocks considering (i) the effect of polyphenols in GDM and (ii) the effect of GDM to mental disorders in the offspring. A positive relationship was observed between the intake of polyphenols and the prevention and control of cardiometabolic complications during pregnancy, such as GDM, which could be related to thwarted inflammatory and oxidative processes, as well as neuronal factors. GDM is related to a greater risk of suffering from diseases related to neurodevelopment, such as attention deficit hyperactivity disorder, autism spectrum disorder and learning disorder. Further clinical research on the molecule protective mechanism of polyphenols on pregnant women is required to understand the transgenerational impact on fetal neurodevelopment.
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Effects of personalized diets by prediction of glycemic responses on glycemic control and metabolic health in newly diagnosed T2DM: a randomized dietary intervention pilot trial.
Rein, M, Ben-Yacov, O, Godneva, A, Shilo, S, Zmora, N, Kolobkov, D, Cohen-Dolev, N, Wolf, BC, Kosower, N, Lotan-Pompan, M, et al
BMC medicine. 2022;20(1):56
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Type 2 diabetes mellitus (T2DM) affects around 10% of the global population. The primary goal in its management is to improve glycemic control. Modifying the diet can help, but many patients fail to achieve improvements with diet alone. The aim of the randomized dietary intervention pilot trial is to evaluate the effects of a personalized postprandial-targeting (PPT) diet on glycemic control and metabolic health in 23 adults with newly diagnosed T2DM, as compared to the commonly recommended Mediterranean-style (MED) diet. The PPT diet led to significant lower levels of continuous-glucose-monitoring (CGM)-based measures as compared to the MED diet. In the additional 6-months intervention, metabolic parameters were further improved and 61% of the participants exhibited diabetes remission. Improvements in clinical outcomes were also accompanied by changes in the gut microbiome. These findings may be useful for the design of larger studies in the future that may have implications for dietary advice in clinical practice.
Abstract
BACKGROUND Dietary modifications are crucial for managing newly diagnosed type 2 diabetes mellitus (T2DM) and preventing its health complications, but many patients fail to achieve clinical goals with diet alone. We sought to evaluate the clinical effects of a personalized postprandial-targeting (PPT) diet on glycemic control and metabolic health in individuals with newly diagnosed T2DM as compared to the commonly recommended Mediterranean-style (MED) diet. METHODS We enrolled 23 adults with newly diagnosed T2DM (aged 53.5 ± 8.9 years, 48% males) for a randomized crossover trial of two 2-week-long dietary interventions. Participants were blinded to their assignment to one of the two sequence groups: either PPT-MED or MED-PPT diets. The PPT diet relies on a machine learning algorithm that integrates clinical and microbiome features to predict personal postprandial glucose responses (PPGR). We further evaluated the long-term effects of PPT diet on glycemic control and metabolic health by an additional 6-month PPT intervention (n = 16). Participants were connected to continuous glucose monitoring (CGM) throughout the study and self-recorded dietary intake using a smartphone application. RESULTS In the crossover intervention, the PPT diet lead to significant lower levels of CGM-based measures as compared to the MED diet, including average PPGR (mean difference between diets, - 19.8 ± 16.3 mg/dl × h, p < 0.001), mean glucose (mean difference between diets, - 7.8 ± 5.5 mg/dl, p < 0.001), and daily time of glucose levels > 140 mg/dl (mean difference between diets, - 2.42 ± 1.7 h/day, p < 0.001). Blood fructosamine also decreased significantly more during PPT compared to MED intervention (mean change difference between diets, - 16.4 ± 37 μmol/dl, p < 0.0001). At the end of 6 months, the PPT intervention leads to significant improvements in multiple metabolic health parameters, among them HbA1c (mean ± SD, - 0.39 ± 0.48%, p < 0.001), fasting glucose (- 16.4 ± 24.2 mg/dl, p = 0.02) and triglycerides (- 49 ± 46 mg/dl, p < 0.001). Importantly, 61% of the participants exhibited diabetes remission, as measured by HbA1c < 6.5%. Finally, some clinical improvements were significantly associated with gut microbiome changes per person. CONCLUSION In this crossover trial in subjects with newly diagnosed T2DM, a PPT diet improved CGM-based glycemic measures significantly more than a Mediterranean-style MED diet. Additional 6-month PPT intervention further improved glycemic control and metabolic health parameters, supporting the clinical efficacy of this approach. TRIAL REGISTRATION ClinicalTrials.gov number, NCT01892956.
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Diets for weight management in adults with type 2 diabetes: an umbrella review of published meta-analyses and systematic review of trials of diets for diabetes remission.
Churuangsuk, C, Hall, J, Reynolds, A, Griffin, SJ, Combet, E, Lean, MEJ
Diabetologia. 2022;65(1):14-36
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Type 2 diabetes (T2D) is a global epidemic. Although it is a complex disease, it is mainly driven by weight gain. The benefits of weight loss for T2D are well known, but patients and healthcare practitioners do not have clear guidance as to which dietary strategies may be effective to achieve and to maintain weight loss. The aim of this study is to review a number of studies of weight loss diets in T2D patients to see which ones are the most effective. Also, to see which dietary patterns support type 2 diabetes remission. Greatest weight loss was reported with very low energy diets including formula meal replacements. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets. High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal or no difference from control diets. Diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacements appear to be the most effective. Programmes including a hypocaloric formula ‘total diet replacement’ induction phase were most effective for type 2 diabetes remission. Further research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Authors highlight current evidence on diets for T2D remission is limited but believe remission can be achieved if sufficient weight loss is maintained. The main contributor to HbA1c reduction and remission appears to be weight loss, irrespective of diet type
- Nice Guidelines highlight the remission of diabetes occurs when a patient no longer satisfies the diagnostic criteria, without receiving glucose-lowering medication. By 2019 in one UK GP practice 27% of the practice population with T2D who followed a LCD for 23 months, lost weight and lowered their HbA1c to 48 mmol/mol (NICE target range) in conjunction with prescribed medication
- This review highlights an opportunity for Nutritional Therapy Practitioners to successfully work with LCD approaches to support weight loss and improved HbA1c.
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:
- 19 meta-analyses (MA) on weight-loss diets, involving 23 primary trials were assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies – of Interventions [ROBINS-I]) with GRADE applied
- Weight loss diets in the review included: Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI −3.3, −1.4) greater weight loss over 12–52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3– 2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate)
- Greatest weight loss was reported with very low energy diets (VLED), (400–500 kcal). However, this study found that low-carbohydrate diets (LCD) (21–70g of carbohydrate daily from1000–1500 kcal) were no better for weight loss than higher-carbohydrate/low-fat diets
- Time period of diets / length of observation / intervention: (1) Formula meal replacements (>12–52 wk), (2) LCDs ranged between (>8 wk to 4 years), (3) Very low energy diets (>8–12 wk), (4) High- protein (>4->8 wks), Mediterranean (>4->8 wk), high-monounsaturated-fatty-acid (>2wk), vegetarian (≥3wk) and low-glycaemic-index diets (≥6mo)
- Authors highlight weight reduction is fundamental for T2D management and remission
- This MA found that VLED and formula meal replacement appear the most effective approaches for weight management with T2D by providing less energy than self-administered food-based diets
- Potential pathophysiological mechanisms highlighted by authors are HbA1c reduction and remission which appear to be from weight loss, with only small differences between diet types assessed over 3–12 months, irrespective of diet type
- Study limitations: Many meta-analyses were of ‘low’ and ‘critically low’ AMSTAR 2 quality, predominantly through ‘no protocol reported’ (despite clear and sound methods) and no assessment of publication bias
- Most studies included European participants, such that findings may not be equally applicable to other ethnic and/or deprived communities. Durations of interventions varied, where weight regain is frequent over a longer period. Authors highlight evidence from clinical practice is needed to identify safe and effective approaches to achieve and maintain weight loss
- Authors highlight primary studies should use an RCT design, with data analyses conducted ‘blind’. They should define the intervention clearly (e.g., diets, physical activity, and behavioural and psychological support), and address separately the induction (usually 3–6 months) and maintenance (≥12 months)
- This research received no funding
- The authors declared no conflicts of interest.
Clinical practice applications:
- While this study found a variety of dietary compositions can be used effectively for weight management with T2D, VLED was successfully used to achieve remission for T2D
- Programmes with a ’total diet replacement’ induction phase were the most effective dietary approach for T2D remission (up to 61% of participants at 1 year).
Considerations for future research:
- Authors state future research should provide implementation with optimal support in real-life settings for weight loss, prevention of weight regain and remissions, rather than seek subtle differences from macronutrient compositions
- Future studies should report sufficient detail about macronutrient or micronutrient contents, or prescribed and reported energy intakes, including energy intake of nutrient-restricted diets.
Abstract
AIMS/HYPOTHESIS Weight reduction is fundamental for type 2 diabetes management and remission, but uncertainty exists over which diet type is best to achieve and maintain weight loss. We evaluated dietary approaches for weight loss, and remission, in people with type 2 diabetes to inform practice and clinical guidelines. METHODS First, we conducted a systematic review of published meta-analyses of RCTs of weight-loss diets. We searched MEDLINE (Ovid), PubMed, Web of Science and Cochrane Database of Systematic Reviews, up to 7 May 2021. We synthesised weight loss findings stratified by diet types and assessed meta-analyses quality with A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. We assessed certainty of pooled results of each meta-analysis using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) (PROSPERO CRD42020169258). Second, we conducted a systematic review of any intervention studies reporting type 2 diabetes remission with weight-loss diets, in MEDLINE (via PubMed), Embase and Cochrane Central Register of Controlled Trials, up to 10 May 2021. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies - of Interventions [ROBINS-I]), with GRADE applied (PROSPERO CRD42020208878). RESULTS We identified 19 meta-analyses of weight-loss diets, involving 2-23 primary trials (n = 100-1587), published 2013-2021. Twelve were 'critically low' or 'low' AMSTAR 2 quality, with seven 'high' quality. Greatest weight loss was reported with very low energy diets, 1.7-2.1 MJ/day (400-500 kcal) for 8-12 weeks (high-quality meta-analysis, GRADE low), achieving 6.6 kg (95% CI -9.5, -3.7) greater weight loss than low-energy diets (4.2-6.3 MJ/day [1000-1500 kcal]). Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI -3.3, -1.4) greater weight loss over 12-52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3-2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate). For type 2 diabetes remission, of 373 records, 16 met inclusion criteria. Remissions at 1 year were reported for a median 54% of participants in RCTs including initial low-energy total diet replacement (low-risk-of-bias study, GRADE high), and 11% and 15% for meal replacements and Mediterranean diets, respectively (some concerns for risk of bias in studies, GRADE moderate/low). For ketogenic/very low-carbohydrate and very low-energy food-based diets, the evidence for remission (20% and 22%, respectively) has serious and critical risk of bias, and GRADE certainty is very low. CONCLUSIONS/INTERPRETATION Published meta-analyses of hypocaloric diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacement appear the most effective approaches, generally providing less energy than self-administered food-based diets. Programmes including a hypocaloric formula 'total diet replacement' induction phase were most effective for type 2 diabetes remission. Most of the evidence is restricted to 1 year or less. Well-conducted research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.
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9.
Mediterranean Diet Combined With a Low-Carbohydrate Dietary Pattern in the Treatment of Overweight Polycystic Ovary Syndrome Patients.
Mei, S, Ding, J, Wang, K, Ni, Z, Yu, J
Frontiers in nutrition. 2022;9:876620
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Polycystic ovary syndrome (PCOS) is a common group of endocrine metabolic disorders in women of reproductive age, characterised by polycystic ovarian changes, sporadic ovulation and menstrual disorders. The aim of this study was to combine the Mediterranean diet (MED) model with a low-carbohydrates (LC) dietary model based on energy restriction, compared with a low-fat (LF) dietary model, in order to investigate whether this novel dietary model could provide significant improvements in reproductive endocrine and metabolic levels in overweight patients with PCOS. This study is an open-label, parallel-group randomised controlled trial design for a 12-week intervention with a 4-week follow-up. Seventy-two participants were enrolled for the study. Results showed that the LF and MED/LC dietary models were effective in modifying anthropometric parameters, reproductive endocrine levels, insulin resistance levels and lipid levels in patients with PCOS, with the MED/LC dietary model being more effective and the recovery of menstrual cycles being approximately the same in both groups. Authors conclude that the MED/LC diet model is recommended for the treatment of overweight patients with PCOS.
Abstract
OBJECTIVES To determine the therapeutic effect of a Mediterranean diet (MED) combined with a low-carbohydrate (LC) dietary model in overweight polycystic ovary syndrome (PCOS) patients. METHODS In this 12-week randomized controlled clinical trial, 72 overweight patients with PCOS were randomly assigned to one of two energy-restricted dietary models: the MED/LC diet or the Low fat (LF) diet. After the intervention, the number of the two groups returned to normal menstruation was counted. Body weight, body mass index (BMI), waist circumference, waist-hip ratio (WHR), body fat percentage (BF%), serum fasting insulin(FINS), fasting plasma glucose(FPG), insulin resistance index (HOMA-IR), quantitative insulin sensitivity index (QUIKI), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride (TG), total testosterone (TT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL) were compared between 2 groups before and after intervention. RESULTS MED/LC group had more significant reduction trend in weight (-6.10 ± 1.52 kg vs -4.79 ± 0.97 kg, P < 0.05), BMI (-2.12 ± 0.57 kg/m2 vs -1.78 ± 0.36 kg/m2, P < 0.05), WC (-6.12 ± 5.95 cm vs -3.90 ± 1.58 cm, P < 0.05), WHR (-0.06 ± 0.02 vs -0.03 ± 0.02, P < 0.05), BF% (-2.97% ± 1.78% vs -1.19% ± 0.91%, P < 0.05), TT (-0.20 ± 0.24 ng/mL vs 0.08 ± 0.11 ng/Ml, P < 0.001), LH (-5.28 ± 3.31 mIU/mL vs -3.39 ± 3.64 mIU/mL, P < 0.05), and LH/FSH (-1.18 ± 0.75 vs -0.66 ± 1.05, P < 0.05) compared with the LF group. In addition, FPG (0.05 ± 0.38 mmol/mL vs -0.50 ± 1.01 mmol/mL, P < 0.001), FINS (-4.88 ± 6.11 μU/mL vs -8.53 ± 5.61 μU/mL, P < 0.01), HOMA-IR index (-1.11 ± 1.51 vs -2.23 ± 0.25, P < 0.05), and QUIKI index (0.014 ± 0.016 vs 0.028 ± 0.019, P < 0.05) decreased significantly in the MED/LC group compared with the LF group. Comparing the changes in lipid parameters between the two groups (LF vs MED/LC), significant differences in TG (-0.33 ± 0.32 mmol vs -0.76 ± 0.97 mmol, P < 0.05), TC (-0.40 ± 1.00 mmol vs -1.45 ± 2.00 mmol, P < 0.05), and LDL-C (-0.41 ± 1.05 mmol vs -0.73 ± 0.76 mmol, P < 0.05) were observed. CONCLUSION The results of this study suggest that the MED/LC diet model is a good treatment for overweight PCOS patients, significantly restoring their menstrual cycle, improving their anthropometric parameters and correcting their disturbed endocrine levels, and its overall effectiveness is significantly better than the LF diet model. Therefore, this study recommends that the MED/LC diet model can be used in the clinical treatment of patients with overweight PCOS.
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10.
Nutritional intervention for diabetes mellitus with Alzheimer's disease.
Li, Z, Li, S, Xiao, Y, Zhong, T, Yu, X, Wang, L
Frontiers in nutrition. 2022;9:1046726
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Diabetes Mellitus (DM) affects more than 463 million people worldwide. Similarly, the number of deaths related to Alzheimer’s disease (AD) has increased by 145%. There are several common risk factors for Type 2 Diabetes and AD, including obesity, insulin resistance, and ageing, as well as common pathological mechanisms, including altered insulin signalling, oxidative stress, neuroinflammation, mitochondrial dysfunction, formation of glycated proteins and metabolic syndrome. This review aims to summarize the therapeutic effects of different nutritional therapy strategies on the reduction of DM and AD risk. Controlling blood sugar levels and reducing calorie intake is crucial to preventing diabetes and Alzheimer's disease. The low-carbohydrate, ketogenic, and Mediterranean diets have been found to improve glucose control in people with Type 2 diabetes (T2D). In addition, MIND (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) and a ketogenic diet may improve cognition in AD patients. Lactobacillus, Bifidobacterium probiotics, and prebiotics, such as inulin, may inhibit the progression of T2D and AD diseases by suppressing inflammation and modulating gut microbes. In addition, vitamins A, C, D, E, B6, B12, folate, long-chain polyunsaturated fatty acids, zinc, magnesium, and polyphenols may improve cognitive decline, homocysteine levels, and insulin resistance in AD and T2D patients. Healthcare professionals can use the results of this review to understand the beneficial effects of dietary strategies and multi-nutrient supplementation on DM and AD. However, further robust studies are required to investigate the risk factors and underlying mechanisms behind DM-combined AD progression.
Abstract
The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.