The protective effect of the Mediterranean diet on endothelial resistance to GLP-1 in type 2 diabetes: a preliminary report

Mediterranean diet in the targeted prevention and personalized treatment of chronic diseases: evidence, potential mechanisms, and prospects

The prevalence of chronic diseases is currently a major public health issue worldwide and is exploding with the population growth and aging. Dietary patterns are well known to play a important role in our overall health and well-being, and therefore, poor diet and malnutrition are among the most critical risk factors for chronic disease. Thus, dietary recommendation and nutritional supplementation have significant clinical implications for the targeted treatment of some of these diseases. Multiple dietary patterns have been proposed to prevent chronic disease incidence, like Dietary Approaches to Stop Hypertension (DASH) and Diabetes Risk Reduction Diet (DRRD). Among them, the MedDiet, which is one of the most well-known and studied dietary patterns in the world, has been related to a wide extent of health benefits. Substantial evidence has supported an important reverse association between higher compliance to MedDiet and the risk of chronic disease. Innovative strategies within the healthcare framework of predictive, preventive, and personalized medicine (PPPM/3PM) view personalized dietary customization as a predictive medical approach, cost-effective preventive measures, and the optimal dietary treatment tailored to the characteristics of patients with chronic diseases in primary and secondary care. Through a comprehensive collection and review of available evidence, this review summarizes health benefits of MedDiet in the context of PPPM/3PM for chronic diseases, including cardiovascular disease, hypertension, type 2 diabetes, obesity, metabolic syndrome, osteoporosis, and cancer, thereby a working hypothesis that MedDiet can personalize the prevention and treatment of chronic diseases was derived.

Mediterranean diet effects on vascular health and serum levels of adipokines and ceramides

BACKGROUND

A randomized clinical trial to evaluate the effect of a Mediterranean-style diet on vascular health indices such as endothelial function indices, serum lipid and ceramide plasma and some adipokine serum levels. We recruited all consecutive patients at high risk of cardiovascular diseases admitted to the Internal Medicine and Stroke Care ward at the University Hospital of Palermo between September 2017 and December 2020.

MATERIALS AND METHODS

The enrolled subjects, after the evaluation of the degree of adherence to a dietary regimen of the Mediterranean-style diet, were randomised to a Mediterranean Diet (group A) assessing the adherence to a Mediterranean-style diet at each follow up visit (every three months) for the entire duration of the study (twelve months) and to a Low-fat diet (group B) with a dietary "counselling" starting every three months for the entire duration of the study (twelve months).The aims of the study were to evaluate: the effects of adherence to Mediterranean Diet on some surrogate markers of vascular damage, such as endothelial function measured by means of the reactive hyperaemia index (RHI) and augmentation index (AIX), at the 6-(T1) and 12-month (T2) follow-ups; the effects of adherence to Mediterranean Diet on the lipidaemic profile and on serum levels of ceramides at T1 and T2 follow-ups; the effects of adherence to Mediterranean Diet on serum levels of visfatin, adiponectin and resistin at the 6- and 12-month follow-ups.

RESULTS

A total of 101 patients were randomised to a Mediterranean Diet style and 52 control subjects were randomised to a low-fat diet with a dietary "counselling". At the six-month follow-up (T1), subjects in the Mediterranean Diet group showed significantly lower mean serum total cholesterol levels, and significantly higher increase in reactive hyperaemia index (RHI) values compared to the low-fat diet group. Patients in the Mediterranean Diet group also showed lower serum levels of resistin and visfatin at the six-month follow-up compared to the control group, as well as higher values ​​of adiponectin, lower values of C24:0, higher values of C22:0 and higher values of the C24:0/C16:0 ratio. At the twelve-month follow-up (T2), subjects in the Mediterranean Diet group showed lower serum total cholesterol levels and lower serum LDL cholesterol levels than those in the control group. At the twelve-month follow-up, we also observed a further significant increase in the mean RHI in the Mediterranean Diet group, lower serum levels of resistin and visfatin, lower values of C24:0 and of C:18:0,and higher values of the C24:0/C16:0 ratio.

DISCUSSION

The findings of our current study offer a further possible explanation with regard to the beneficial effects of a higher degree of adherence to a Mediterranean-style diet on multiple cardiovascular risk factors and the underlying mechanisms of atherosclerosis. Moreover, these findings provide an additional plausible interpretation of the results from observational and cohort studies linking high adherence to a Mediterranean-style diet with lower total mortality and a decrease in cardiovascular events and cardiovascular mortality.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04873167. https://classic.clinicaltrials.gov/ct2/show/NCT04873167.

Association Between Dietary Habits and Type 2 Diabetes Mellitus in Thai Adults: A Case-Control Study

Background

The prevalence of T2DM is escalating in Thailand affecting over 10% of adults aged 20-79 years old. It is imperative to identify modifiable risk factors that can potentially help mitigate the risk of developing diabetes.

Objective

This study aimed to investigate the relationship between dietary habits and type 2 diabetes in Chiang Mai, Thailand.

Methods

This case-control study involved 300 individuals aged 25-74 years residing in Chiang Mai, Thailand including 150 newly diagnosed T2DM patients (cases) and 150 community residents without diabetes (controls). Dietary habits were assessed based on Food Frequency Questionnaire (FFQ). Socio-demographic characteristics and anthropometric information of the participants were collected. Data analysis was performed using the STATA-17.

Results

The case group participants were older and had a higher proportion of males compared to the control group. The case group exhibited a significantly higher consumption of meat, beans, nuts, soft drinks, and topping seasonings (p<0.001), conversely, a lower intake of vegetables (p<0.001), fruits (p=0.006), fish, rice (p<0.001), eggs (p=0.032), milk products, coffee, and tea (p<0.001) compared to the control group. Furthermore, the case group demonstrated a higher level of certain dietary practices such as a greater frequency of having meals with family, not removing visible fat from food (p<0.001), and eating snacks between meals compared to controls. Multiple logistic regression analysis showed that after adjusting for potential confounding factors not removing visible fat from food (aOR 5.61, 95% CI: 2.29-13.7, p<0.001) and using topping seasonings (aOR 3.52 95% CI: 1.69-7.32 p=0.001) were significantly associated with the risk of T2DM, whereas daily vegetable intake (aOR 0.32 95% CI: 0.15-0.68 p=0.003) was inversely associated with T2DM.

Conclusion

The study findings caution against the consumption of food rich in fat and using salty seasonings, while advocating for an increased intake of vegetables to prevent the prevalence of T2DM.

Association between dietary phytochemical index and risk of benign prostatic hyperplasia: a case-control study

BACKGROUND

Dietary intake of phytochemicals has been associated with a reduced risk of chronic diseases, but research on their relationship with benign prostatic hyperplasia (BPH) is limited. This case-control study aimed to investigate the association between a Dietary Phytochemical Index (DPI) and BPH risk in a Middle-Eastern population.

METHODS

The study recruited 112 BPH patients and 112 age-matched healthy controls (40-75 years) from Al-Zahra Hospital Clinic in Isfahan, Iran between 2021 and 2022. Dietary intake was assessed using a validated food-frequency questionnaire, and DPI was calculated as the ratio of energy intake from phytochemical-rich foods to total daily energy intake. Logistic regression analysis was performed, adjusting for potential confounders.

RESULTS

In the crude model, participants in the highest DPI tertile had a 70% lower odds of BPH compared to those in the lowest tertile (OR:0.3, 95% CI 0.15-0.61, P-trend = 0.001). After adjusting for confounders, this inverse association remained significant (OR:0.23, 95% CI 0.15-0.63, P-trend = 0.001). Participants with higher DPI consumed more whole grains (p = 0.02), nuts (p < 0.001), legumes (p = 0.02), fruits (p < 0.001), vegetables (p < 0.001), olives and oilve products (p = 0.02), and tomato and its products (p < 0.001) in their diet compared to the lowest tertile. However, red meat (p = 0.03) and refined grains (p < 0.001) were consumed in higher amounts in the lowest tertile compared to the highest DPI tertile.

CONCLUSIONS

This study demonstrates a protective association between DPI and BPH risk in the Middle-Eastern population. Encouraging higher intake of phytochemical-rich foods may help reduce the risk of BPH, highlighting the relevance of nutritional science in promoting prostate health.

Roles of mitochondrial dynamics and mitophagy in diabetic myocardial microvascular injury

Myocardial microvessels are composed of a monolayer of endothelial cells, which play a crucial role in maintaining vascular barrier function, luminal latency, vascular tone, and myocardial perfusion. Endothelial dysfunction is a key factor in the development of cardiac microvascular injury and diabetic cardiomyopathy. In addition to their role in glucose oxidation and energy metabolism, mitochondria also participate in non-metabolic processes such as apoptosis, intracellular ion handling, and redox balancing. Mitochondrial dynamics and mitophagy are responsible for regulating the quality and quantity of mitochondria in response to hyperglycemia. However, these endogenous homeostatic mechanisms can both preserve and/or disrupt non-metabolic mitochondrial functions during diabetic endothelial damage and cardiac microvascular injury. This review provides an overview of the molecular features and regulatory mechanisms of mitochondrial dynamics and mitophagy. Furthermore, we summarize findings from various investigations that suggest abnormal mitochondrial dynamics and defective mitophagy contribute to the development of diabetic endothelial dysfunction and myocardial microvascular injury. Finally, we discuss different therapeutic strategies aimed at improving endothelial homeostasis and cardiac microvascular function through the enhancement of mitochondrial dynamics and mitophagy.

Effect of Diet and Oxidative Stress in the Pathogenesis of Lymphoproliferative Disorders

Lymphomas are a heterogeneous group of pathologies that result from clonal proliferation of lymphocytes. They are classified into Hodgkin lymphoma and non-Hodgkin lymphoma; the latter develops as a result of B, T, or NK cells undergoing malignant transformation. It is believed that diet can modulate cellular redox state and that oxidative stress is implicated in lymphomagenesis by acting on several biological mechanisms; in fact, oxidative stress can generate a state of chronic inflammation through the activation of various transcription factors, thereby increasing the production of proinflammatory cytokines and causing overstimulation of B lymphocytes in the production of antibodies and possible alterations in cellular DNA. The purpose of our work is to investigate the results of in vitro and in vivo studies on the possible interaction between lymphomas, oxidative stress, and diet. A variety of dietary regimens and substances introduced with the diet that may have antioxidant and antiproliferative effects were assessed. The possibility of using nutraceuticals as novel anticancer agents is discussed; although the use of natural substances in lymphoma therapy is an interesting field of study, further studies are needed to define the efficacy of different nutraceuticals before introducing them into clinical practice.

Nutriepigenomics in Environmental-Associated Oxidative Stress

Complex molecular mechanisms define our responses to environmental stimuli. Beyond the DNA sequence itself, epigenetic machinery orchestrates changes in gene expression induced by diet, physical activity, stress and pollution, among others. Importantly, nutrition has a strong impact on epigenetic players and, consequently, sustains a promising role in the regulation of cellular responses such as oxidative stress. As oxidative stress is a natural physiological process where the presence of reactive oxygen-derived species and nitrogen-derived species overcomes the uptake strategy of antioxidant defenses, it plays an essential role in epigenetic changes induced by environmental pollutants and culminates in signaling the disruption of redox control. In this review, we present an update on epigenetic mechanisms induced by environmental factors that lead to oxidative stress and potentially to pathogenesis and disease progression in humans. In addition, we introduce the microenvironment factors (physical contacts, nutrients, extracellular vesicle-mediated communication) that influence the epigenetic regulation of cellular responses. Understanding the mechanisms by which nutrients influence the epigenome, and thus global transcription, is crucial for future early diagnostic and therapeutic efforts in the field of environmental medicine.

Different Dietary Approaches, Non-Alcoholic Fatty Liver Disease and Cardiovascular Disease: A Literature Review

Non-alcoholic fatty liver disease (NAFLD) is the first cause of chronic liver disease and is also associated with other harmful entities such as obesity, metabolic syndrome, dyslipidemia, and diabetes. NAFLD is a significant public health concern worldwide, impacting individuals of all ages, and its prevalence is projected to increase in the near future due to its connection with obesity. Intrinsic (genetics) and external (lifestyle) factors may also modulate NAFLD, and, in turn, may partly explain the observed relationship between NAFLD and cardiovascular disease (CVD). Although many drugs are been tested to treat NAFLD, to date, no drug has indication to specifically treat this disorder. Thus, the current management of NAFLD relies on lifestyle modifications and specifically on weight loss, physical activity, and the intake of a healthy diet. In the present narrative review, we will discuss the effects of certain dietary patterns on NAFLD incidence and progression.

Mediterranean Diet and its Effect on Endothelial Function: A Meta-analysis and Systematic Review

BACKGROUND

Endothelial dysfunction serves as an early marker for the risk of cardiovascular disease (CVD); therefore, it is a site of therapeutic interventions to reduce the risk of CVD.

AIMS

To examine the effect of the Mediterranean diet (MedDiet), as an intervention, on structural and functional parameters of endothelial function, and how it may reduce the risk of CVD and associated mortality.

METHODS

Medline database was searched for randomized controlled trials. Random-effects meta-analysis was conducted on 21 independent datasets. Meta-regression and subgroup analysis were performed to assess whether the effect of MedDiet was modified by health status (healthy subjects or with increased CVD risk), type of MedDiet intervention (alone or combined), type of parameter (functional or structural), study design (cross-over or parallel), BMI, age, and study duration. Our study used sample size, mean, and standard deviation of endothelial function measurements for both MedDiet intervention and control in the analyses.

RESULTS

Inverse relationship between endothelial function and intake of MedDiet was observed (SMD: 0.34; 95% CI: 0.16, 0.52; P = 0.0001). Overall, MedDiet increased FMD by 1.39% (95% CI: 0.47, 2.19; P < 0.001). There was a significant improvement in endothelial function in both healthy patients and in those with an increased risk of CVD. No significant variation was observed in the effects of MedDiet on endothelial function, due to study design or type of intervention.

CONCLUSIONS

These findings support that MedDiet can reduce the risk of CVD by improving endothelial function.

Comparative efficacy of different eating patterns in the management of type 2 diabetes and prediabetes: An arm-based Bayesian network meta-analysis

AIMS/INTRODUCTION

Diet therapy is a vital approach to manage type 2 diabetes and prediabetes. However, the comparative efficacy of different eating patterns is not clear enough. We aimed to compare the efficacy of various eating patterns for glycemic control, anthropometrics, and serum lipid profiles in the management of type 2 diabetes and prediabetes.

MATERIALS AND METHODS

We conducted a network meta-analysis using arm-based Bayesian methods and random effect models, and drew the conclusions using the partially contextualized framework. We searched twelve databases and yielded 9,534 related references, where 107 studies were eligible, comprising 8,909 participants.

RESULTS

Eleven diets were evaluated for 14 outcomes. Caloric restriction was ranked as the best pattern for weight loss (SUCRA 86.8%) and waist circumference (82.2%), low-carbohydrate diets for body mass index (81.6%), and high-density lipoprotein (84.0%), and low-glycemic-index diets for total cholesterol (87.5%) and low-density lipoprotein (86.6%). Other interventions showed some superiorities, but were imprecise due to insufficient participants and needed further investigation. The attrition rates of interventions were similar. Meta-regression suggested that macronutrients, energy intake, and weight may modify outcomes differently. The evidence was of moderate-to-low quality, and 38.2% of the evidence items met the minimal clinically important differences.

CONCLUSIONS

The selection and development of dietary strategies for diabetic/prediabetic patients should depend on their holistic conditions, i.e., serum lipid profiles, glucometabolic patterns, weight, and blood pressure. It is recommended to identify the most critical and urgent metabolic indicator to control for one specific patient, and then choose the most appropriate eating pattern accordingly.

The Effect of Dietary Patterns on Inflammatory Biomarkers in Adults with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Some evidence supports the fact that chronic low-grade inflammation contributes to the physiopathology of type 2 diabetes mellitus (T2DM), and circulating markers of inflammation (e.g., C-reactive protein (CRP), pro- and anti-inflammatory biomarkers (e.g., adiponectin), and endothelial function markers could indicate an ongoing pathology. Following certain dietary patterns (DPs) may result in favorable changes in inflammatory biomarkers. The overarching aim of this systematic review and meta-analysis is to explore the inflammatory effect of healthy DPs on inflammatory biomarkers in adults with T2DM. A systematic search of the literature was conducted using the electronic databases MEDLINE, SCOPUS, and Cochrane Central Register of Controlled Trials. A total of 10 randomized controlled clinical trials (RCTs) were analyzed. In our linear meta-analysis, the random-effects model was applied to estimate standardized mean differences (SMD) to associate the effect of the interventions. Dietary Approaches to Stop Hypertension (DASH), Diabetes UK healthy eating, Mediterranean Diet (MD), Diabetes Prevention Program (DPP), and the American Heart Association’s Therapeutic Lifestyle Changes diet were associated with a significant reduction in CRP (SMD: −0.83, 99% CI −1.49, −0.17, p < 0.001; I2 94%), while plasma levels of adiponectin were significantly higher with the intake of MD, DPP, and Diabetes UK healthy eating (SMD: 0.81, 99% CI 0.06,1.56, p < 0.005; I2 96%), both of which indicate less inflammation. Sensitivity analyses were carried out, and potential publication bias was examined. In conclusion, low- moderate-quality evidence from RCTs suggests that, for the DPs evaluated, there are favorable changes in CRP and adiponectin.

Does the Mediterranean diet reduce the odds of diabetic nephropathy in women? A case–control study

Background

In recent decades, the prevalence of chronic diseases such as diabetes is increasing. One of the major complications of diabetes is diabetic nephropathy (DN), so it is important to find a way that can delay or control the onset of DN. Therefore, in this study, we investigated the relationship between the Mediterranean diet (MED) and the odds of DN.

Methods

This case–control study was performed among 210 women (30–65 years) who were referred to the Kowsar Diabetes Clinic in Semnan, Iran. Biochemical variables and anthropometric measurements were assessed. The food frequency questionnaire (FFQ) was used to calculate dietary intakes. Data from dietary intakes based on the FFQ were used to evaluate the MED score. Logistic regression was used to examine the associations.

Results

Our results showed that in the crude model with higher adherence to the MED (OR: 0.272; 95% CI: 0.154, 0.481; P = 0.001), the odds of DN has reduced by 73%, and in model 1, after controlling for potential confounders, with higher adherence to the MED (OR: 0.239; 95% CI: 0.128, 0.447; P = 0.001), the odds of DN has reduced by 76% compared to low adherence. Also, in model 1, significant associations were observed between high consumption of grains (OR: 0.360; 95% CI: 0.191, 0.676; P = 0.001), legumes (OR: 0.156; 95% CI: 0.083, 0.292; P = 0.001), vegetables (OR: 0.273; 95% CI: 0.149, 0.501; P = 0.001), fruits (OR: 0.179; 95% CI: 0.093, 0.347; P = 0.001), fish (OR: 0.459; 95% CI: 0.254, 0.827; P = 0.01), and reduced odds of DN (P &lt; 0.05).

Conclusion

We observed that with higher adherence to the MED, the odds of DN had reduced through mechanisms. However, additional studies are needed to confirm these findings.

Impulsiveness in children with attention-deficit/hyperactivity disorder after an 8-week intervention with the Mediterranean diet and/or omega-3 fatty acids: A randomised clinical trial

INTRODUCTION

The Barratt Impulsiveness Scale (BIS) is a self-administered instrument designed to assess the personality/behavioural construct of impulsiveness. Impulsiveness has been associated with several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). This study assesses the progression of impulsive behaviour in children with ADHD after an 8-week dietary intervention with the Mediterranean diet and/or omega-3 fatty acid supplementation, by using a version of the 11-item BIS adapted for children (BIS-11c).

METHODS

This cross-sectional study includes 60 children with ADHD from the region of Madrid, Spain. Participants were divided into 4 groups, with one control group (G1) and 3 intervention groups (Mediterranean diet [G2]; omega-3 supplementation [G3]; and Mediterranean diet plus omega-3 supplementation [G4]). A personalised Mediterranean diet was designed for members of groups 2 and 4. The BIS-11c was administered to determine the level of impulsiveness, and the KIDMED test was used to assess adherence to the Mediterranean diet.

RESULTS

The supplementation group showed a fairly significant decrease in the total BIS-11c (P=.049). Total cognitive score slightly decreased in the diet and supplementation groups. Only the control group showed a considerable decrease in the total motor score. Total nonplanning scores were lower in all groups after the intervention. Baseline and final BIS-11c scores were positively correlated with treatments (r>0.9).

CONCLUSION

An intake of 550mg EPA fatty acid and 225mg DHA fatty acid per day for 8 weeks is associated with less marked impulsive behaviour in children with ADHD. A Mediterranean diet may improve BIS scores, although our results are not conclusive in this population.

Recent Advances in Lipases and Their Applications in the Food and Nutraceutical Industry

Lipases are efficient enzymes with promising applications in the nutraceutical and food industry, as they can offer high yields, pure products under achievable reaction conditions, and are an environmentally friendly option. This review addresses the production of high-value-added compounds such as fatty acid esters, with the potential to be used as flavoring agents or antioxidant and antimicrobial agents, as well as structured lipids that offer specific functional properties that do not exist in nature, with important applications in different food products, and pharmaceuticals. In addition, the most recent successful cases of reactions with lipases to produce modified compounds for food and nutraceuticals are reported.

Application of Mediterranean Diet in Cardiovascular Diseases and Type 2 Diabetes Mellitus: Motivations and Challenges

Objective: Cardiovascular disease (CVD) is the leading cause of disability and death in many countries. Together with CVD, Type 2 diabetes mellitus (T2DM) accounts for more than 80% of all premature non-communicable disease deaths. The protective effect of the Mediterranean diet (MedDiet) on CVD and its risk factors, including T2DM, has been a constant topic of interest. Notwithstanding, despite the large body of evidence, scientists are concerned about the challenges and difficulties of the application of MedDiet. This review aims to explore the motivations and challenges for using MedDiet in patients with CVD and T2DM. Design: An electronic search was conducted for articles about MedDiet published in PubMed, ScienceDirect, Scopus, and Web of Science up to December 2021, particularly on CVD and T2DM patients. From a total of 1536 studies, the final eligible set of 108 studies was selected. Study selection involved three iterations of filtering. Results: Motivation to apply MedDiet was driven by the importance of studying the entire food pattern rather than just one nutrient, the health benefits, and the distinct characteristics of MedDiet. Challenges of the application of MedDiet include lacking universal definition and scoring of MedDiet. Influences of nutritional transition that promote shifting of traditional diets to Westernized diets further complicate the adherence of MedDiet. The challenges also cover the research aspects, including ambiguous and inconsistent findings, the inexistence of positive results, limited evidence, and generalization in previous studies. The review revealed that most of the studies recommended that future studies are needed in terms of health benefits, describing the potential benefits of MedDiet, identifying the barriers, and mainly discussing the effect of MedDiet in different populations. Conclusions: In general, there is consistent and strong evidence that MedDiet is associated inversely with CVD risk factors and directly with glycemic control. MedDiet is the subject of active and diverse research despite the existing challenges. This review informs the health benefits conferred by this centuries-old dietary pattern and highlights MedDiet could possibly be revolutionary, practical, and non-invasive approach for the prevention and treatment CVD and T2DM.

Positive Effects of Extra-Virgin Olive Oil Supplementation and DietBra on Inflammation and Glycemic Profiles in Adults With Type 2 Diabetes and Class II/III Obesity: A Randomized Clinical Trial

Background

Evidence on the effects of dietary interventions on inflammatory markers in individuals with obesity and type 2 diabetes mellitus (T2DM) is scarce. Our study evaluated the effects of extra-virgin olive oil alone and in combination with a traditional Brazilian diet on inflammatory markers and glycemic profiles in adults with both T2DM and class II/III obesity.

Methods

Adults aged 18-64 years with T2DM and class II/III obesity were randomized into two intervention groups: 1) extra-virgin olive oil only and 2) extra-virgin olive oil + a traditional Brazilian diet (OliveOil+DietBra). Data on sociodemographic characteristics, lifestyle, anthropometry, biochemical markers and inflammatory markers were collected. The primary outcomes were glycemic parameters and inflammatory markers. The body mass index (BMI) and weight were the secondary outcomes.

Results

Forty individuals with T2DM and class II/III obesity were enrolled, and 34 (85%) completed the intervention course. The intake of olive oil was 37.88 ± 12.50 mL/day in the olive oil group and 37.71 ± 12.23 mL/day in the OliveOil+DietBra group, with no significant difference between groups (p = 0.484). Compared to the olive oil only group, the OliveOil+DietBra group had significantly lower levels of fasting insulin (p = 0.047) at the end of the intervention, whereas the other glycemic parameters were not altered. In the OliveOil+DietBra group, serum levels of inflammatory cytokines, IL-1α (p = 0.006) and adiponectin (p = 0.049) were lower and those of TNFα were higher (p = 0.037). There was a significant reduction in BMI and weight compared to the baseline values in the OliveOil+DietBra group (p = 0.015).

Conclusions

The intervention with OliveOil+DietBra effectively decreased the levels of fasting insulin, IL-1α and adiponectin, suggesting its beneficial role in improving the inflammatory profiles and fasting insulin levels in adults with class II/III obesity and T2DM.

Clinical Trial Registration

ClinicalTrials.gov, identifier: NCT02463435.

Nitrotyrosine, Nitrated Lipoproteins, and Cardiovascular Dysfunction in Patients with Type 2 Diabetes: What Do We Know and What Remains to Be Explained?

Diabetes mellitus (DM) is a strong risk factor for the development of cardiovascular diseases (CVDs), which are the most important cause of morbidity and mortality in the population of patients living with DM. DM is associated with lipid metabolism disorders characterized by a decrease in the high-density lipoprotein blood concentration, an increase in the triglyceride blood concentration, and the presence of modified lipoproteins not routinely measured in clinical practice. Nitrated lipoproteins are produced by the nitration of the tyrosyl residues of apolipoproteins by myeloperoxidase. There is some evidence from the research conducted showing that nitrated lipoproteins may play a role in the development of cardiovascular dysfunction, but this issue requires further investigation. It was found that the nitration of HDL particles was associated with a decrease in caspase-3 and paraoxonase-1 activity, as well as a decrease in the activity of cholesterol transport via ABCA1, which reduces the protective effect of HDL particles on the cardiovascular system. Less information has been collected about the role of nitrated LDL particles. Thus far, much more information has been obtained on the relationship of nitrotyrosine expression with the presence of cardiovascular risk factors and the development of cardiovascular dysfunction. The purpose of this paper is to provide an extensive review of the literature and to present the most important information on the current state of knowledge on the association between nitrotyrosine and nitrated lipoproteins with dysfunction of the cardiovascular system, especially in patients living with DM. Moreover, directions for future research in this area were discussed.

Lower miR-21/ROS/HNE levels associate with lower glycemia after habit-intervention: DIAPASON study 1-year later

Background

The prevalence of prediabetes is increasing in the global population and its metabolic derangements may expose to a higher risk to develop type 2 diabetes (T2D) and its cardiovascular burden. Lifestyle modifications might have considerable benefits on ameliorating metabolic status. Alternative biomarkers, such as circulating miR-21, has been recently discovered associated with dysglycemia. Here we evaluated, in a longitudinal cohort of dysglycemic population the relation between the circulating miR-21/ROS/HNE levels and the habit-intervention (HI) after 1 year of follow-up.

Methods

1506 subjects from DIAPASON study were screened based on the Findrisc score. Of them, 531 subjects with Findrisc ≥ 9 were selected for dysglycemia (ADA criteria) and tested for circulating miR-21, ROS and HNE levels, as damaging-axis. 207 subjects with dysglycemia were re-evaluated after 1-year of habit intervention (HI). Repeated measures tests were used to evaluate changes from baseline to 1-year of follow-up. The associations between glycemic parameters and miR-21/ROS/HNE were implemented by linear regression and logistic regression models.

Results

After HI, we observed a significant reduction of miR-21/ROS/HNE axis in dysglycemic subjects, concomitantly with ameliorating of metabolic parameters, including insulin resistance, BMI, microalbuminuria, reactive hyperemia index and skin fluorescence. Significant positive interaction was observed between miR-21 axis with glycaemic parameters after HI. Lower miR-21 levels after HI, strongly associated with a reduction of glycemic damaging-axis, in particular, within-subjects with values of 2hPG < 200 mg/dL.

Conclusions

Our findings demonstrated that HI influenced the epigenetic changes related to miR-21 axis, and sustain the concept of reversibility from dysglycemia. These data support the usefulness of novel biological approaches for monitoring glycemia as well as provide a screening tool for preventive programmes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01465-0.

The Impact of Diet on Bone and Fracture Risk in Diabetes

PURPOSE OF REVIEW

The purpose of this review is to summarize the recently published scientific evidence on the effects of diet on diabetes and skeletal health.

RECENT FINDINGS

The impact of diet on overall health has been a growing topic of interest among researchers. An inappropriate eating habit is a relatively modified risk factor for diabetes in adults. Parallel with the significant increase in the incidence of diabetes mellitus worldwide, many studies have shown the benefits of lifestyle modifications, including diet and exercise for people with, or at risk of developing, diabetes. In the last years, accumulating evidence suggests that diabetes is a risk factor for bone fragility. As lifestyle intervention represents an effective option for diabetes management and treatment, there is potential for an effect on bone health. Healthy lifestyle is critical to prevent bone fragility. However, more studies are needed to fully understand the impact of diet and weight loss on fracture risk in diabetics.

Impulsiveness in children with attention-deficit/hyperactivity disorder after an 8-week intervention with the Mediterranean diet and/or omega-3 fatty acids: a randomised clinical trial

INTRODUCTION

The Barratt Impulsiveness Scale (BIS) is a self-administered instrument designed to assess the personality/behavioural construct of impulsiveness. Impulsiveness has been associated with several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). This study assesses the progression of impulsive behaviour in children with ADHD after an 8-week dietary intervention with the Mediterranean diet and/or omega-3 fatty acid supplementation, by using a version of the 11-item BIS adapted for children (BIS-11c).

METHODS

This cross-sectional study includes 60 children with ADHD from the region of Madrid, Spain. Participants were divided into 4 groups, with one control group and 3 intervention groups (Mediterranean diet; omega-3 supplementation; and Mediterranean diet plus omega-3 supplementation). A personalised Mediterranean diet was designed for members of groups 2 and 4. The BIS-11c was administered to determine the level of impulsiveness, and the KIDMED test was used to assess adherence to the Mediterranean diet.

RESULTS

The supplementation group showed a fairly significant decrease in the total BIS-11c (P = .049). Total cognitive score slightly decreased in the diet and supplementation groups. Only the control group showed a considerable decrease in the total motor score. Total nonplanning scores were lower in all groups after the intervention. Baseline and final BIS-11c scores were positively correlated with treatments (r > 0.9).

CONCLUSION

An intake of 550 mg EPA fatty acid and 225 mg DHA fatty acid per day for 8 weeks is associated with less marked impulsive behaviour in children with ADHD. A Mediterranean diet may improve BIS scores, although our results are not conclusive in this population.

Effects of a Mediterranean diet on blood pressure: a systematic review and meta-analysis of randomized controlled trials and observational studies

OBJECTIVE

To conduct a systematic review and meta-analysis investigating effects of MedDiet on blood pressure in randomized controlled trials (RCTs) and associations of MedDiet with risk of hypertension in observational studies.

METHODS

PubMed, The Cochrane Library and EBSCOhost were searched from inception until January 2020 for studies that met the following criteria: participants aged at least 18 years, RCTs investigating effects of a MedDiet versus control on BP, observational studies exploring associations between MedDiet adherence and risk of hypertension. Random-effects meta-analyses were conducted. Meta-regression and subgroup analyses were performed for RCTs to identify potential effect moderators.

RESULTS

Nineteen RCTs reporting data on 4137 participants and 16 observational studies reporting data on 59 001 participants were included in the meta-analysis. MedDiet interventions reduced SBP and DBP by a mean -1.4 mmHg (95% CI: -2.40 to -0.39 mmHg, P = 0.007, I2 = 53.5%, Q = 44.7, τ2 = 1.65, df = 19) and -1.5 mmHg (95% CI: -2.74 to -0.32 mmHg, P = 0.013, I2 = 71.5%, Q = 51.6, τ2 = 4.72, df = 19) versus control, respectively. Meta-regression revealed that longer study duration and higher baseline SBP was associated with a greater decrease in BP, in response to a MedDiet (P < 0.05). In observational studies, odds of developing hypertension were 13% lower with higher versus lower MedDiet adherence (95% CI: 0.78--0.98, P = 0.017, I2 = 69.6%, Q = 41.1, τ2 = 0.03, df = 17).

CONCLUSION

Data suggest that MedDiet is an effective dietary strategy to aid BP control, which may contribute towards the lower risk of CVD reported with this dietary pattern. This study was registered with PROSPERO: CRD42019125073.

Mediterranean diet and blood pressure reduction in adults with and without hypertension: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

It is unclear whether the Mediterranean diet (MedDiet) has a favorable effect on blood pressure (BP) levels because among randomized controlled trials (RCTs) investigating the MedDiet-mediated BP reduction significant methodological and clinical differences are observed. The purpose of this study was to comprehensively assess the MedDiet BP-effect compared to the usual diet or another dietary intervention (e.g. low-fat diet) in adults with and without hypertension, accounting for methodological and clinical confounders.

METHODS

We systematically searched Medline and the Cochrane Collaboration Library databases and identified 35 RCTs (13,943 participants). Random-effects model was used to calculate the mean attained systolic BP (SBP) and diastolic BP (DBP) differences during follow-up. Subgroup and meta-regression analyses were also conducted.

RESULTS

Compared to the usual diet and all other active intervention diets the MedDiet reduced SBP and DBP (difference in means: -1.5 mm Hg; 95% CI: -2.8, -0.1; P = 0.035, and -0.9 mm Hg; 95% CI: -1.5, -0.3; P = 0.002, respectively). Compared only to the usual diet the MedDiet reduced SBP and DBP, while compared to all other active intervention diets or only to the low-fat diet the MedDiet did not reduce SBP and DBP. The MedDiet reduced DBP levels to a higher extent in trials with mean baseline SBP ≥130 mm Hg, while both SBP and DBP were reduced more in trials with a mean follow-up period ≥16 weeks. The quality of evidence was rated as moderate for both outcomes according to the grading of recommendations, assessment, development and evaluation (GRADE) approach.

CONCLUSIONS

The adoption of the MedDiet was accompanied by a relatively small, but yet significant BP reduction, while higher baseline SBP levels and longer follow-up duration enhanced the BP-lowering effect of the intervention. This meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO) as CRD42020167308.

REGISTRY NUMBER

CRD42020167308.

High variability of food and nutrient intake exists across the Mediterranean Dietary Pattern-A systematic review

A Mediterranean style dietary pattern (MDP) is considered beneficial for health. The MD Score (MDS) definition has evolved, resulting in considerable variability in the foods and nutrients associated with MDS adherence. We systematically investigated food and nutrient composition of the MD between studies, countries, and methods of classifying the MDS. We searched Embase for MD systematic reviews and selected observational studies reporting intakes of foods, macronutrients, or micronutrients by categories of MDS adherence. The percentage differences in food and nutrient intakes between categories of high and low adherence to the MDS were calculated for each study. A total of 369 full-text primary papers were reviewed from the included systematic reviews and 74 papers selected (66 adults, 8 children). We found considerable differences in MDS definitions and scoring criteria. Between-study variation in food intake between high- and low-adherence MDS adherence categories ranged from a mean of -23% for meat, to 119% for fruit, and 278% for fish. Greater variability was evident in non-Mediterranean than Mediterranean regions. We conclude that few studies report food and nutrient intakes across the range of the MDP in adults and even fewer in children. The considerable variability in the foods and nutrients reported makes comparison of results from studies and translation into dietary guidelines difficult. We recommend that future publications of MD studies include full details of the range of food and nutrient intakes across the distribution of MD adherence in order to facilitate translation into health policy and practice.

Analysis of the intricate effects of polyunsaturated fatty acids and polyphenols on inflammatory pathways in health and disease

Prevention and treatment of non-communicable diseases (NCDs), including cardiovascular disease, diabetes, obesity, cancer, Alzheimer's and Parkinson's disease, arthritis, non-alcoholic fatty liver disease and various infectious diseases; lately most notably COVID-19 have been in the front line of research worldwide. Although targeting different organs, these pathologies have common biochemical impairments - redox disparity and, prominently, dysregulation of the inflammatory pathways. Research data have shown that diet components like polyphenols, poly-unsaturated fatty acids (PUFAs), fibres as well as lifestyle (fasting, physical exercise) are important factors influencing signalling pathways with a significant potential to improve metabolic homeostasis and immune cells' functions. In the present manuscript we have reviewed scientific data from recent publications regarding the beneficial cellular and molecular effects induced by dietary plant products, mainly polyphenolic compounds and PUFAs, and summarize the clinical outcomes expected from these types of interventions, in a search for effective long-term approaches to improve the immune system response.

Mediterranean Diet Effects on Type 2 Diabetes Prevention, Disease Progression, and Related Mechanisms. A Review

The search for a quality diet has grown over the past decade. Diet is considered one of the pillars for the prevention and progression of several diseases, among them: diabetes. Type 2 diabetes (T2D) is an epidemic of western countries that increases the vulnerability of other diseases, such as cardiovascular and cancer. T2D is associated with lifestyle and diet. The traditional Mediterranean diet has proven its benefits over several cardiovascular risk factors, and specifically on diabetes. This review compiles recent published evidence on the effects of the Mediterranean diet on the incidence and progression of type 2 diabetes (T2D) and its relation with several other cardiovascular healthy diets. We will also focus on how the Mediterranean diet could play a role in T2D-related mechanisms, such as anti-inflammatory or antioxidant compounds, glucagon-like peptide agonist compounds, and changes in gut microbiota. Each component of the Mediterranean diet could be involved in processes related to diabetes homeostasis, many of them sharing common physio-pathological pathways. The importance of this diet within the set of habits of a healthy lifestyle must be emphasized.

Mediterranean Diet and Endothelial Function: A Review of its Effects at Different Vascular Bed Levels

The Mediterranean diet has recently been the focus of considerable attention as a palatable model of a healthy diet. Its influence on many cardiovascular risk factors, combined with its proven effect in reducing the risk of cardiovascular events in primary prevention, has boosted scientific interest in this age-old nutritional model. Many of the underlying mechanisms behind its health-giving effects have been revealed, from the modulation of the microbiota to the function of high-density lipoproteins (HDL), and it seems to deliver its health benefits mainly by regulating several key mechanisms of atherosclerosis. In this review, we will review the evidence for its regulation of endothelial function, a key element in the early and late stages of atherosclerosis. In addition, we will assess studies which evaluate its effects on the functioning of different arterial territory vessels (mainly the microvascular, peripheral and central vascular beds), focusing mainly on the capillary, brachial and carotid arteries. Finally, we will evaluate the molecular mechanisms which may be involved.

Type 2 Diabetes Mellitus in Class II and III Obesity: Prevalence, Associated Factors, and Correlation between Glycemic Parameters and Body Mass Index

Despite the worldwide growth of class II and III obesity, the factors associated with type 2 diabetes mellitus (T2DM) in these obese individuals are not widely understood. Moreover, no study has investigated these associations in South America. Our study aimed to investigate the prevalence of T2DM and its associated factors, with an emphasis on biochemical parameters and eating habits, in class II and III obese individuals. We also aimed to analyze the correlation between glycemic parameters and body mass index (BMI). Baseline data from a randomized clinical trial (DieTBra Trial) of 150 class II and III obese individuals (BMI > 35 kg/m2) was used. An accelerometer, Food Frequency Questionnaire, and bioimpedance analysis were used to assess physical activity levels, eating habits, and body composition, respectively. Blood was collected after 12 h of fasting. Hierarchical multivariate Poisson regression was performed, and prevalence ratios (PRs) were calculated. Correlations between glycemic parameters (fasting blood glucose, glycosylated hemoglobin, homeostasis model assessment of insulin resistance (HOMA-IR), and insulin) and BMI were also analyzed. The prevalence of T2DM was 40.0% (95% CI, 32.1-48.3), high fasting blood glucose level was 19.33% (95% CI, 13.3-26.6), and high glycosylated hemoglobin was 32.67% (95% CI, 25.2-40.8). Age ≥ 50 years (PR = 3.17, 95% CI, 1.26-7.98) was significantly associated with T2DM; there was a positive linear trend between age and T2DM (p = 0.011). Multivariate analysis showed an association with educational level (PR = 1.49, 1.07-2.09, p = 0.018), nonconsumption of whole grains daily (PR = 1.67, 1.00-2.80, p = 0.049), and high HOMA-IR (PR = 1.54, 1.08-2.18, p = 0.016). We found a high prevalence of T2DM and no significant correlations between BMI and glycemic parameters.

Effects of Olive Oil on Blood Pressure: Epidemiological, Clinical, and Mechanistic Evidence

The increasing access to antihypertensive medications has improved longevity and quality of life in hypertensive patients. Nevertheless, hypertension still remains a major risk factor for stroke and myocardial infarction, suggesting the need to implement management of pre- and hypertensive patients. In addition to antihypertensive medications, lifestyle changes, including healthier dietary patterns, such as the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean diet, have been shown to favorably affect blood pressure and are now recommended as integrative tools in hypertension management. An analysis of the effects of nutritional components of the Mediterranean diet(s) on blood pressure has therefore become mandatory. After a literature review of the impact of Mediterranean diet(s) on cardiovascular risk factors, we here analyze the effects of olive oil and its major components on blood pressure in healthy and cardiovascular disease individuals and examine underlying mechanisms of action. Both experimental and human studies agree in showing anti-hypertensive effects of olive oil. We conclude that due to its high oleic acid and antioxidant polyphenol content, the consumption of olive oil may be advised as the optimal fat choice in the management protocols for hypertension in both healthy and cardiovascular disease patients.

Mediterranean Diet Increases Endothelial Function in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease.

OBJECTIVE

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function.

METHODS

Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants.

RESULTS

Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P <0.001; I2 = 73.68%]. MedDiet interventions improved flow-mediated dilation (FMD)-the reference method for noninvasive, clinical measurement of endothelial function-by 1.66% (absolute change; 95% CI: 1.15, 2.17; P <0.001; I2 = 0%). Effects of the MedDiet on endothelial function were not modified by health status, type of intervention, study duration, study design, BMI, or age of participants (P >0.05).

CONCLUSIONS

MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188.

Cardioprotective Effect of Olive Oil Against Ischemia Reperfusion-induced Cardiac Arrhythmia in Isolated Diabetic Rat Heart

Background

Olive oil is rich in monounsaturated fatty acids and has been reported for a variety of beneficial cardiovascular effects, including blood pressure lowering, anti-platelet, anti-diabetic, and anti-inflammatory effects. Diabetes is a major risk factor for cardiac dysfunctions, and olive oil prevents diabetes-induced adverse myocardial remodeling.

Objective

The study aimed to evaluate the effects of olive oil against streptozotocin-induced cardiac dysfunction in animal models of diabetes and ischemia and reperfusion (I/R)-induced cardiac arrhythmias.

Methods

Diabetes was induced in male rats with a single intraperitoneal injection of streptozotocin (60 mg/kg i.p), rats were treated for five, 15, or 56 days with olive oil (1 ml/kg p.o). Control animals received saline. Blood glucose and body weight were monitored every two weeks. At the end of the treatment, rats were sacrificed and hearts were isolated for mounting on Langedorff’s apparatus. The effect of olive oil on oxidative stress and histopathological changes in the cardiac tissues were studied.

Results

The initial blood glucose and body weight were not significantly different in the control and olive-treated animals. Streptozotocin (60 mg/kg i.p) caused a significant increase in the blood glucose of animals as compared to saline-treated animals. The control, saline-treated diabetic animals exhibited a 100% incidence of I/R-induced ventricular fibrillation, which was reduced to 0% with olive oil treatment. The protective effects of olive oil were evident after 15 and 56 days of treatment. Diltiazem, a calcium channel blocker (1 µm/L) showed similar results and protected the I/R-induced cardiac disorders. The cardiac tissues isolated from diabetic rats exhibited marked pathological changes in the cardiomyocytes, including decreased glutathione (GSH) and increased oxidative stress (malondialdehyde; MDA). Pretreatment of animals with olive oil (1 ml/kg p.o) increased GSH and decreased MDA levels. Olive oil also improved the diabetic-induced histopathological changes in the cardiomyocytes.

Conclusion

Olive oil possesses cardiac protective properties against I/R-induced cardiac arrhythmias in rats. It attenuated oxidative stress and diabetes-induced histopathological changes in cardiac tissues. The observed cardiac protectiveness of olive oil in the present investigation may be related to its antioxidant potential.

Relationship Between Oxidative Stress, ER Stress, and Inflammation in Type 2 Diabetes: The Battle Continues

Type 2 diabetes (T2D) is a metabolic disorder characterized by hyperglycemia and insulin resistance in which oxidative stress is thought to be a primary cause. Considering that mitochondria are the main source of ROS, we have set out to provide a general overview on how oxidative stress is generated and related to T2D. Enhanced generation of reactive oxygen species (ROS) and oxidative stress occurs in mitochondria as a consequence of an overload of glucose and oxidative phosphorylation. Endoplasmic reticulum (ER) stress plays an important role in oxidative stress, as it is also a source of ROS. The tight interconnection between both organelles through mitochondrial-associated membranes (MAMs) means that the ROS generated in mitochondria promote ER stress. Therefore, a state of stress and mitochondrial dysfunction are consequences of this vicious cycle. The implication of mitochondria in insulin release and the exposure of pancreatic β-cells to hyperglycemia make them especially susceptible to oxidative stress and mitochondrial dysfunction. In fact, crosstalk between both mechanisms is related with alterations in glucose homeostasis and can lead to the diabetes-associated insulin-resistance status. In the present review, we discuss the current knowledge of the relationship between oxidative stress, mitochondria, ER stress, inflammation, and lipotoxicity in T2D.

Improving the scientific rigour of nutritional recommendations for adults with type 2 diabetes: A comprehensive review of the American Diabetes Association guideline-recommended eating patterns

AIMS

The global rate of type 2 diabetes (T2D) continues to rise. Guidelines that influence the worldwide treatment of this disease are central to changing this trajectory. We sought in this review to evaluate the appropriateness of sources cited in the American Diabetes Association's (ADA) guidelines on eating patterns for T2D management, identify additional relevant sources, and evaluate the evidence.

MATERIALS AND METHODS

We reviewed the evidence behind the ADA's recommendations on eating patterns in the 2018 and 2019 ADA Standards of Care and the 2014 ADA Nutrition Therapy Recommendations for Adults with Diabetes. Additionally, we conducted a comprehensive search to identify any additional studies not included in the cited evidence. To determine appropriateness of inclusion in the guidelines, the following criteria were applied: 1) it was a clinical trial or systematic review/meta-analysis of clinical trials; 2) it involved persons with T2D; 3) one of the study arms followed one of the eating patterns currently recommended; 4) its reported outcomes included glycaemic control; 5) outcomes were reported separately for persons with T2D.

RESULTS

We found a wide variation in the evidence for each eating pattern. Issues that have hampered the guideline process include: lack of a rigorous literature review, resulting in the omission of pertinent studies; an overreliance on prospective cohort studies; inconsistent standards for evidence; inclusion of studies not on persons with T2D; and bias.

CONCLUSIONS

The ADA Guidelines recommended eating patterns fall short of rigorous standards of scientific review according to state-of-the-art systematic review and guideline creation practices.

Is olive oil good for you? A systematic review and meta-analysis on anti-inflammatory benefits from regular dietary intake

The prevalence of non-communicable diseases is rapidly increasing, and evidence shows that diet and lifestyle are key areas of intervention to decrease their burden. Olive oil is considered one of the key nutritional components responsible for the benefits of the Mediterranean diet, which is characterized by the use of olive oil in meals as the main source of fat; a high consumption of water, fruits, nuts, vegetables, legumes, whole grains, spices, and herbs; a moderate consumption of dairy products (mainly cheese and yogurt), fish, poultry, and red wine; and a reduced consumption of red meat and processed foods. The aim of this review was to summarize evidence from randomized controlled trials on the effect of regular dietary intake of olive oil on three inflammatory markers: C-reactive protein, interleukin-6, and tumor necrosis factor-α. Reviewed RCTs reveal beneficial effects of olive oil by reducing levels of inflammation markers. Olive oil taken on a regular basis can be a good dietary fat alternative, especially to manage IL-6. However, further research is required to clarify the effects of olive oil consumption on inflammation, comparing to other fats. Moreover, olive oil daily dosage, different time-lenght intervention and follow-up periods should be taken into consideration.

Role of diet in type 2 diabetes incidence: umbrella review of meta-analyses of prospective observational studies

OBJECTIVE

To summarise the evidence of associations between dietary factors and incidence of type 2 diabetes and to evaluate the strength and validity of these associations.

DESIGN

Umbrella review of systematic reviews with meta-analyses of prospective observational studies.

DATA SOURCES

PubMed, Web of Science, and Embase, searched up to August 2018.

ELIGIBILITY CRITERIA

Systematic reviews with meta-analyses reporting summary risk estimates for the associations between incidence of type 2 diabetes and dietary behaviours or diet quality indices, food groups, foods, beverages, alcoholic beverages, macronutrients, and micronutrients.

RESULTS

53 publications were included, with 153 adjusted summary hazard ratios on dietary behaviours or diet quality indices (n=12), food groups and foods (n=56), beverages (n=10), alcoholic beverages (n=12), macronutrients (n=32), and micronutrients (n=31), regarding incidence of type 2 diabetes. Methodological quality was high for 75% (n=115) of meta-analyses, moderate for 23% (n=35), and low for 2% (n=3). Quality of evidence was rated high for an inverse association for type 2 diabetes incidence with increased intake of whole grains (for an increment of 30 g/day, adjusted summary hazard ratio 0.87 (95% confidence interval 0.82 to 0.93)) and cereal fibre (for an increment of 10 g/day, 0.75 (0.65 to 0.86)), as well as for moderate intake of total alcohol (for an intake of 12-24 g/day v no consumption, 0.75 (0.67 to 0.83)). Quality of evidence was also high for the association for increased incidence of type 2 diabetes with higher intake of red meat (for an increment of 100 g/day, 1.17 (1.08 to 1.26)), processed meat (for an increment of 50 g/day, 1.37 (1.22 to 1.54)), bacon (per two slices/day, 2.07 (1.40 to 3.05)), and sugar sweetened beverages (for an increase of one serving/day, 1.26 (1.11 to 1.43)).

CONCLUSIONS

Overall, the association between dietary factors and type 2 diabetes has been extensively studied, but few of the associations were graded as high quality of evidence. Further factors are likely to be important in type 2 diabetes prevention; thus, more well conducted research, with more detailed assessment of diet, is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018088106.

Impact of different dietary approaches on blood lipid control in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis

The aim of this study was to assess the effects of different dietary approaches on low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride (TG) levels in patients with type 2 diabetes (T2D) by applying network meta-analysis (NMA). Systematic electronic and hand searches were conducted until January 2018. Randomized controlled trials (RCTs) with an intervention period of ≥ 12 weeks, focussing on adults with T2D, and comparing dietary approaches regarding LDL, HDL or TGs, were included. For each outcome measure, random effects NMA was performed in order to determine the effect of each dietary approach compared to every other dietary intervention. Mean differences (MDs) and 95% confidence intervals (95% CIs) were calculated, and for the ranking, the surface under the cumulative ranking curves (SUCRA) was determined. Additionally, the credibility of evidence was evaluated. 52 RCTs (44 for LDL, 48 for HDL and 52 for TGs) comparing nine dietary approaches (low fat, vegetarian, Mediterranean, high protein, moderate carbohydrate, low carbohydrate, control, low glycaemic index/glycaemic load and Palaeolithic diet) enrolling 5360 T2D patients were included. The vegetarian diet most effectively reduced LDL levels [MD (95% CI): - 0.33 (- 0.55, - 0.12) mmol/L; compared to the control diet]. The Mediterranean diet beneficially raised HDL [MD (95% CI): 0.09 (0.04, 0.15) mmol/L] and decreased TG levels [MD (95% CI): - 0.41 (- 0.72, - 0.10) mmol/L] compared to the control diet. The Mediterranean diet was the most effective dietary approach to manage diabetic dyslipidaemia altogether (SUCRA: 79%). The overall findings are mainly limited by low credibility of evidence.

Dietary approaches to stop hypertension, mediterranean dietary pattern, and diabetic nephropathy in women with type 2 diabetes: A case-control study

BACKGROUND AND AIMS

The association between dietary habits and kidney function in patients with type 2 diabetes (T2D) has been poorly investigated. We aimed to test the relationship between adherences to the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean dietary pattern (Med diet) and likelihood of diabetic nephropathy (DN) in women with T2D.

METHODS

In a case-control study, 105 women with T2D and DN (albumin-creatinine ratio ≥ 30 mg/g, mean age: 55.3 ± 7.0 years; diabetes duration: 7.6 ± 2.2 years), and 105 controls with T2D and without DN (mean age: 55.4 ± 7.1 years; diabetes duration: 7.6 ± 2.1 years) who attended at Kowsar diabetes clinic in Semnan, Iran were matched for age and diabetes duration. Dietary intakes were assessed using a validated 147-item semiquantitative food frequency questionnaire. The DASH and Med diet scores were calculated using the methods developed by Fung and Trichopoulou, respectively. A generalized estimating equation model was used to examine the relationship between dietary scores and odds of DN across tertiles of dietary patterns scores.

RESULTS

Type 2 diabetic women with moderate and high Med diet scores had 62% and 86% lower odds of DN in comparison with low adherent (ORs: 0.38, 95%CI: 0.20, 0.73; and 0.14, 95%CI: 0.06, 0.33; respectively). A moderate adherence to the DASH diet was not associated with risk of DN, but a significant inverse relationship was found in those with high adherence (OR: 0.71, 95%CI: 0.57, 0.90).

CONCLUSIONS

Adherence to the DASH and Med diets was inversely and dose-dependently associated with risk of DN. Further observational studies are needed to confirm the present results.

Adherence to Mediterranean Diet, Malnutrition, Length of Stay and Mortality in Elderly Patients Hospitalized in Internal Medicine Wards

: This investigation aimed to explore the adherence to a Mediterranean Diet and its relationship with length of stay and in-hospital mortality, circulating interleukins, body composition, and frailty, in elderly patients hospitalized in internal medicine wards. Thus, a cross-sectional study in 194 acute hospitalized, community-dwelling elderly patients was performed. Adherence to a Mediterranean Diet was evaluated by the Italian Mediterranean Index (IMI). Length of stay, but not in-hospital mortality rate, was higher in patients with a low IMI score, as compared to subjects with high IMI score. Markers of systemic inflammation, as well as circulating interleukin-6 and tumor necrosis factor alpha, were higher in patients with a low IMI score, with respect to patients with high IMI score. Furthermore, patients with low IMI score had increased fat mass and reduced lean mass, together with a higher prevalence of frailty, as compared to those presenting with high IMI score. In a multivariate logistic regression model, an IMI score < 3 resulted as an independent predictor of longer length of stay. In conclusion, low adherence to a Mediterranean Diet in elderly patients hospitalized in internal medicine wards is associated with higher length of stay and related to unfavorable changes in circulating pro-inflammatory markers and body composition.

Effects of Mediterranean Diet and Physical Activity on Pulmonary Function: A Cross-Sectional Analysis in the ILERVAS Project

A few studies showed that both adherence to Mediterranean diet (MedDiet) and physical activity practice have a positive impact on pulmonary function in subjects with lung disease. These associations are not well studied in subjects free from lung disease. In a cross-sectional study conducted in 3020 middle-aged subjects free of lung disease, adherence to the MedDiet using the Mediterranean Diet Adherence Screener, and physical activity practice using the International Physical Activity Questionnaire short form were recorded. Respiratory function was assessed using forced spirometry and the results were evaluated according to the Global initiative for Chronic Obstructive Lung Disease. Logistic regression models were used to analyze the associations between adherence to the MedDiet and physical activity practice with the presence of ventilatory defects. Participants with a high adherence to MedDiet, in comparison to those with low adherence, had both higher forced vital capacity (FVC; 100 (87–109) vs. 94 (82–105) % of predicted, p = 0.003) and forced expired volume in the first second (FEV1; 100 (89–112) vs. 93 (80–107) % of predicted, p < 0.001). According to their degree of physical activity, those subjects with a high adherence also had both higher FVC (100 (88–107) vs. 94 (83–105) % of predicted, p = 0.027) and FEV1 (100 (89–110) vs. 95 (84–108) % of predicted, p = 0.047) in comparison with those with low adherence. The multivariable logistic regression models showed a significant and independent association between both low adherence to MedDiet and low physical activity practice, and the presence of altered pulmonary patterns, with differences between men and women. However, no joint effect between adherence to MedDiet and physical activity practice on respiratory function values was observed. Low adherence to MedDiet and low physical activity practice were independently associated with pulmonary impairment. Therefore, the lung mechanics seem to benefit from heart-healthy lifestyle behaviors.

Differences in the interpretation of a modernized Mediterranean diet prescribed in intervention studies for the management of type 2 diabetes: how closely does this align with a traditional Mediterranean diet?

PURPOSE AND METHODS

Adherence to Mediterranean diet (MedDiet) is associated with the prevention and management of type 2 diabetes mellitus (T2DM). However, in intervention studies, there is discordance in the interpretation of a MedDiet. The purpose of this paper was to examine, synthesize, and develop a narrative review, exploring the qualitative differences in the interpretation of a modernized MedDiet prescribed as an intervention in clinical trials for the management of T2DM, and how closely this aligns with a traditional MedDiet. The 'traditional' MedDiet is often described as a dietary pattern high in unprocessed plant foods (fruits, vegetables, legumes, nuts, wholegrain cereals, and olive oil); moderate consumption of wine; low moderate in fish/shellfish; and an infrequent consumption of red meat, animal fats, vegetable oils, and processed foods.

RESULTS AND CONCLUSIONS

Synthesis of the reviewed literature demonstrates considerable variation in the qualitative interpretation of a MedDiet. We also identified inadequate reporting of MedDiet interventions, despite a number of studies referring to their intervention as a 'traditional' MedDiet. The majority of studies emphasized the same key dietary components and principles: an increased intake of vegetables, wholegrains, and the preferential consumption of white meat in substitute of red and processed meat and abundant use of olive oil. However, the reporting of specific dietary recommendations for fruit, legumes, nuts, bread, red wine, and fermentable dairy products were less consistent or not reported. Irrespective of the discordance in the interpretation of a MedDiet, a number of studies included in the present review reported improved glycaemic control and favorable cardiovascular outcomes with adherence to a Mediterranean-style diet. Nevertheless, greater clarity and depth of reporting amongst intervention studies is warranted for the refinement of a modernized MedDiet definition that is distinct from a prudent dietary pattern.

Dietary Pattern and Macronutrients Profile on the Variation of Inflammatory Biomarkers: Scientific Update

It is known that the dietary pattern and macronutrients profile may influence the expression and secretion of inflammatory biomarkers, and the low-grade inflammation is associated with the manifestation of noncommunicable chronic diseases. Therefore, this review aimed to present and discuss the role of dietary patterns and macronutrients on the variation of inflammatory markers related to NCD risk. Scientific evidences within the last five years based on clinical trials, case-controls, cohorts, and cross-sectional studies indicate that normocaloric, carbohydrate-moderated, low-glycemic index, protein-moderated, monounsaturated and polyunsaturated fatty acid-rich, omega-3, and low-saturated fat diets display positive effects on the inflammatory state, both in healthy individuals and in those with cardiovascular risk, although the second group seems to benefit more from changes in the dietary profile.

A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus

The aim of the present study is to assess the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus using a systematic review of the literature. Electronic and hand searches were performed until July 2017. The inclusion criteria were defined as follows: (1) randomized trial with a dietary approach; (2) adults with type 2 diabetes mellitus; (3) outcome either HbA1c (%) and/or fasting glucose (mmol/l); (4) minimum intervention period of 12 weeks. For each outcome measure, random effects network meta-analysis was performed in order to determine the pooled effect of each intervention relative to each of the other interventions. A total of 56 trials comparing nine dietary approaches (low-fat, Vegetarian, Mediterranean, high-protein, moderate-carbohydrate, low-carbohydrate, control, low GI/GL, Palaeolithic) enrolling 4937 participants were included. For reducing HbA1c, the low-carbohydrate diet was ranked as the best dietary approach (SUCRA: 84%), followed by the Mediterranean diet (80%) and Palaeolithic diet (76%) compared to a control diet. For reducing fasting glucose, the Mediterranean diet (88%) was ranked as the best approach, followed by Palaeolithic diet (71%) and Vegetarian diet (63%). The network analysis also revealed that all dietary approaches significantly reduce HbA1c (− 0.82 to − 0.47% reduction) and fasting glucose (− 1.61 to − 1.00 mmol/l reduction) compared to a control diet. According to the network meta-analysis the Mediterranean diet is the most effective and efficacious dietary approach to improve glycaemic control in type 2 diabetes patients.

Correlation between Oxidative Stress, Nutrition, and Cancer Initiation

Inadequate or excessive nutrient consumption leads to oxidative stress, which may disrupt oxidative homeostasis, activate a cascade of molecular pathways, and alter the metabolic status of various tissues. Several foods and consumption patterns have been associated with various cancers and approximately 30-35% of the cancer cases are correlated with overnutrition or malnutrition. However, several contradictory studies are available regarding the association between diet and cancer risk, which remains to be elucidated. Concurrently, oxidative stress is a crucial factor for cancer progression and therapy. Nutritional oxidative stress may be induced by an imbalance between antioxidant defense and pro-oxidant load due to inadequate or excess nutrient supply. Oxidative stress is a physiological state where high levels of reactive oxygen species (ROS) and free radicals are generated. Several signaling pathways associated with carcinogenesis can additionally control ROS generation and regulate ROS downstream mechanisms, which could have potential implications in anticancer research. Cancer initiation may be modulated by the nutrition-mediated elevation in ROS levels, which can stimulate cancer initiation by triggering DNA mutations, damage, and pro-oncogenic signaling. Therefore, in this review, we have provided an overview of the relationship between nutrition, oxidative stress, and cancer initiation, and evaluated the impact of nutrient-mediated regulation of antioxidant capability against cancer therapy.

MECHANISMS IN ENDOCRINOLOGY: Nutrition as a mediator of oxidative stress in metabolic and reproductive disorders in women

Nutrition can generate oxidative stress and trigger a cascade of molecular events that can disrupt oxidative and hormonal balance. Nutrient ingestion promotes a major inflammatory and oxidative response at the cellular level in the postprandial state, altering the metabolic state of tissues. A domino of unfavorable metabolic changes is orchestrated in the main metabolic organs, including adipose tissue, skeletal muscle, liver and pancreas, where subclinical inflammation, endothelial dysfunction, mitochondrial deregulation and impaired insulin response and secretion take place. Simultaneously, in reproductive tissues, nutrition-induced oxidative stress can potentially violate delicate oxidative balance that is mandatory to secure normal reproductive function. Taken all the above into account, nutrition and its accompanying postprandial oxidative stress, in the unique context of female hormonal background, can potentially compromise normal metabolic and reproductive functions in women and may act as an active mediator of various metabolic and reproductive disorders.

Effect of plant-based diets on obesity-related inflammatory profiles: a systematic review and meta-analysis of intervention trials

Plant-based dietary interventions have been proposed to reduce obesity induced chronic low-grade inflammation and hence prevent chronic disease risk; however, human evidence remains unclear. This systematic review and meta-analysis of intervention trials aimed to assess the effect of plant-based diets on obesity-related inflammatory biomarker profiles. Medline, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for articles published until January 2016 and mean differences in biomarkers of inflammatory status were assessed for: C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-ɑ), soluble intercellular adhesion molecule 1 (sICAM), leptin, adiponectin and resistin. Of initially identified 2,583 publications, 29 met the meta-analysis inclusion criteria [a total of 2,689 participants]. Consumption of plant-based diets was associated with a reduction in the mean concentrations of the following biomarkers: CRP [effect size, -0.55 mg/l, 95% confidence intervals (CI): -0.78; -0.32, I²  = 94.4%], IL-6 [effect size, -0.25 ng/l, 95% CI: -0.56; 0.06, I²  = 74%], and, to some degree, sICAM (-25.07 ng/ml [95% CI: -52.32; 2.17, I²  = 93.2%]). No substantial effects were revealed for TNF-ɑ, resistin, adiponectin and leptin. Plant-based diets are associated with an improvement in obesity-related inflammatory profiles and could provide means for therapy and prevention of chronic disease risk.

Palaeolithic diet decreases fasting plasma leptin concentrations more than a diabetes diet in patients with type 2 diabetes: a randomised cross-over trial

Background

We have previously shown that a Palaeolithic diet consisting of the typical food groups that our ancestors ate during the Palaeolithic era, improves cardiovascular disease risk factors and glucose control compared to the currently recommended diabetes diet in patients with type 2 diabetes. To elucidate the mechanisms behind these effects, we evaluated fasting plasma concentrations of glucagon, insulin, incretins, ghrelin, C-peptide and adipokines from the same study.

Methods

In a randomised, open-label, cross-over study, 13 patients with type 2 diabetes were randomly assigned to eat a Palaeolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts, or a diabetes diet designed in accordance with current diabetes dietary guidelines during two consecutive 3-month periods. The patients were recruited from primary health-care units and included three women and 10 men [age (mean ± SD) 64 ± 6 years; BMI 30 ± 7 kg/m²; diabetes duration 8 ± 5 years; glycated haemoglobin 6.6 ± 0.6 % (57.3 ± 6 mmol/mol)] with unaltered diabetes treatment and stable body weight for 3 months prior to the start of the study. Outcome variables included fasting plasma concentrations of leptin, adiponectin, adipsin, visfatin, resistin, glucagon, insulin, C-peptide, glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1 and ghrelin. Dietary intake was evaluated by use of 4-day weighed food records.

Results

Seven participants started with the Palaeolithic diet and six with the diabetes diet. The Palaeolithic diet resulted in a large effect size (Cohen’s d = −1.26) at lowering fasting plasma leptin levels compared to the diabetes diet [mean difference (95 % CI), −2.3 (−5.1 to 0.4) ng/ml, p = 0.023]. No statistically significant differences between the diets for the other variables, analysed in this study, were observed.

Conclusions

Over a 3-month study period, a Palaeolithic diet resulted in reduced fasting plasma leptin levels, but did not change fasting levels of insulin, C-peptide, glucagon, incretins, ghrelin and adipokines compared to the currently recommended diabetes diet.

Trial registration: ClinicalTrials.gov NCT00435240

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0398-1) contains supplementary material, which is available to authorized users.

Oleic acid stimulates glucagon-like peptide-1 release from enteroendocrine cells by modulating cell respiration and glycolysis

OBJECTIVE

Glucagon-like peptide-1 (GLP-1) is a potent satiating and incretin hormone released by enteroendocrine L-cells in response to eating. Dietary fat, in particular monounsaturated fatty acids, such as oleic acid (OA), potently stimulates GLP-1 secretion from L-cells. It is, however, unclear whether the intracellular metabolic handling of OA is involved in this effect.

METHODS

First we determined the optimal medium for the bioenergetics measurements. Then we examined the effect of OA on the metabolism of the immortalized enteroendocrine GLUTag cell model and assessed GLP-1 release in parallel. We measured oxygen consumption rate and extracellular acidification rate in response to OA and to different metabolic inhibitors with the Seahorse extracellular flux analyzer.

RESULTS

OA increased cellular respiration and potently stimulated GLP-1 release. The fatty acid oxidation inhibitor etomoxir did neither reduce OA-induced respiration nor affect the OA-induced GLP-1 release. In contrast, inhibition of the respiratory chain or of downstream steps of aerobic glycolysis reduced the OA-induced GLP-1 release, and an inhibition of the first step of glycolysis by addition of 2-deoxy-d-glucose even abolished it.

CONCLUSION

These findings indicate that an indirect stimulation of glycolysis is crucial for the OA-induced release of GLP-1.

Interleukin-6 predicts inflammation-induced increase of Glucagon-like peptide-1 in humans in response to cardiac surgery with association to parameters of glucose metabolism

Objective

Glucagon-like peptide-1 (GLP-1) is an incretin hormone, which gets secreted in response to nutritional stimuli from the gut mediating glucose-dependent insulin secretion. Interestingly, GLP-1 was recently found to be also increased in response to inflammatory stimuli in an interleukin 6 (IL-6) dependent manner in mice. The relevance of this finding to humans is unknown but has been suggested by the presence of high circulating GLP-1 levels in critically ill patients that correlated with markers of inflammation. This study was performed to elucidate, whether a direct link exists between inflammation and GLP-1 secretion in humans.

Research design and methods

We enrolled 22 non-diabetic patients scheduled for cardiac surgery as a reproducible inflammatory stimulus with repeated blood sampling before and after surgery.

Results

Mean total circulating GLP-1 levels significantly increased in response to surgery from 25.5 ± 15.6 pM to 51.9 ± 42.7 pM which was not found in a control population. This was preceded by an early rise of IL6, which was significantly associated with GLP-1 under inflammatory but not basal conditions. Using repeated measure ANCOVA, IL6 best predicted the observed kinetics of GLP-1, followed by blood glucose concentrations and cortisol plasma levels. Furthermore, GLP-1 plasma concentrations significantly predicted endogenous insulin production as assessed by C-peptide concentrations over time, while an inverse association was found for insulin infusion rate.

Conclusion

We found GLP-1 secretion to be increased in response to inflammatory stimuli in humans, which was associated to parameters of glucose metabolism and best predicted by IL6.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0330-8) contains supplementary material, which is available to authorized users.

Effects of Olive Oil on Markers of Inflammation and Endothelial Function-A Systematic Review and Meta-Analysis

The aim of the present systematic review was to synthesize data from randomized controlled trials investigating the effects of olive oil on markers of inflammation or endothelial function. Literature search in electronic databases Cochrane Trial Register, EMBASE, and MEDLINE was performed. Thirty studies enrolling 3106 participants fulfilled the selection criteria. Pooled effects of different interventions were assessed as mean difference using a random effects model. Olive oil interventions (with daily consumption ranging approximately between 1 mg and 50 mg) resulted in a significantly more pronounced decrease in C-reactive protein (mean difference: −0.64 mg/L, (95% confidence interval (CI) −0.96 to −0.31), p < 0.0001, n = 15 trials) and interleukin-6 (mean difference: −0.29 (95% CI −0.7 to −0.02), p < 0.04, n = 7 trials) as compared to controls, respectively. Values of flow-mediated dilatation (given as absolute percentage) were significantly more increased in individuals subjected to olive oil interventions (mean difference: 0.76% (95% CI 0.27 to 1.24), p < 0.002, n = 8 trials). These results provide evidence that olive oil might exert beneficial effects on endothelial function as well as markers of inflammation and endothelial function, thus representing a key ingredient contributing to the cardiovascular-protective effects of a Mediterranean diet. However, due to the heterogeneous study designs (e.g., olive oil given as a supplement or as part of dietary pattern, variations in control diets), a conservative interpretation of the results is necessary.

Isocaloric substitution of carbohydrates with protein: the association with weight change and mortality among patients with type 2 diabetes

Background

The health impact of dietary replacement of carbohydrates with protein for patients with type 2 diabetes is still debated. This study aimed to investigate the association between dietary substitution of carbohydrates with (animal and plant) protein and 5-year weight change, and all-cause and cardiovascular (CVD) mortality risk in patients with type 2 diabetes.

Methods

The study included 6,107 diabetes patients from 15 European cohorts. Patients with type 1 diabetes were excluded. At recruitment, validated country-specific food-frequency questionnaires were used to estimate dietary intake. Multivariable adjusted linear regression was used to examine the associations between dietary carbohydrate substitution with protein and 5-year weight change, and Cox regression to estimate hazard ratios (HRs) for (CVD) mortality.

Results

Annual weight loss of patients with type 2 diabetes was 0.17 (SD 1.24) kg. After a mean follow-up of 9.2 (SD 2.3)y, 787 (13%) participants had died, of which 266 (4%) deaths were due to CVD. Substitution of 10 gram dietary carbohydrate with total (ß = 187 [75;299]g) and animal (ß = 196 [137;254]g) protein was associated with mean 5-year weight gain. Substitution for plant protein was not significantly associated with weight change (β = 82 [−421;584]g). Substitution with plant protein was associated with lower all-cause mortality risk (HR = 0.79 [0.64;0.97]), whereas substitution with total or animal protein was not associated with (CVD) mortality risk.

Conclusions

In diabetes patients, substitution with plant protein was beneficial with respect to weight change and all-cause mortality as opposed to substitution with animal protein. Therefore, future research is needed whether dietary guidelines should not actively promote substitution of carbohydrates by total protein, but rather focus on substitution of carbohydrates with plant protein.