Monounsaturated fatty acid diets improve glycemic tolerance through increased secretion of glucagon-like peptide-1

Photobioreactor systems for mitigating ammonia and carbon dioxide from a broiler house

This study investigated the effectiveness of photobioreactor (PBR) systems in reducing air pollutants emitted from broiler houses. It focused on two microalgae species and one cyanobacteria grown under different media conditions and investigated their ability to mitigate ammonia (NH3) and carbon dioxide (CO2) in the exhaust air of a broiler house. Ankistrodesmus sp. achieved the highest cell concentrations across all experiments, with maximum dry biomass concentration observed under Nitrogen-free Bold's Basal Medium (BBM-N) culture condition. Scenedesmus sp. showed the highest NH3 mitigation efficiency (52.3%) with BBM-N culture, while Synechococcaceae species exhibited the highest CO2 mitigation efficiency (70.8%) with DI-water culture condition. Operating costs for producing 1.0 g L-1day-1 of dry microalgal biomass ranged from 0.10 to 0.35 USD L-1day-1. The cost of removing 1 g of NH3 ranged from $3.53-7.16, while for CO2, it ranged from $0.04-0.59. The study also evaluated the economic feasibility of this approach, demonstrating significant cost savings in biomass and protein production. These findings highlight the potential of PBR systems as a sustainable solution for reducing air pollutants in broiler house environments.

Intestinal Stearoyl-CoA Desaturase-1 Regulates Energy Balance via Alterations in Bile Acid Homeostasis

BACKGROUND & AIMS

Stearoyl-CoA desaturase-1 (SCD1) converts saturated fatty acids into monounsaturated fatty acids and plays an important regulatory role in lipid metabolism. Previous studies have demonstrated that mice deficient in SCD1 are protected from diet-induced obesity and hepatic steatosis due to altered lipid assimilation and increased energy expenditure. Previous studies in our lab have shown that intestinal SCD1 modulates intestinal and plasma lipids and alters cholesterol metabolism. Here, we investigated a novel role for intestinal SCD1 in the regulation of systemic energy balance.

METHODS

To interrogate the role of intestinal SCD1 in modulating whole body metabolism, intestine-specific Scd1 knockout (iKO) mice were maintained on standard chow diet or challenged with a high-fat diet (HFD). Studies included analyses of bile acid content and composition, and metabolic phenotyping, including body composition, indirect calorimetry, glucose tolerance analyses, quantification of the composition of the gut microbiome, and assessment of bile acid signaling pathways.

RESULTS

iKO mice displayed elevated plasma and hepatic bile acid content and decreased fecal bile acid excretion, associated with increased expression of the ileal bile acid uptake transporter, Asbt. In addition, the alpha and beta diversity of the gut microbiome was reduced in iKO mice, with several alterations in microbe species being associated with the observed increases in plasma bile acids. These increases in plasma bile acids were associated with increased expression of TGR5 targets, including Dio2 in brown adipose tissue and elevated plasma glucagon-like peptide-1 levels. Upon HFD challenge, iKO mice had reduced metabolic efficiency apparent through decreased weight gain despite higher food intake. Concomitantly, energy expenditure was increased, and glucose tolerance was improved in HFD-fed iKO mice.

CONCLUSIONS

Our results indicate that deletion of intestinal SCD1 has significant impacts on bile acid homeostasis and whole-body energy balance, likely via activation of TGR5.

Postprandial glycemic response to a high-protein diabetes-specific nutritional shake compared to isocaloric instant oatmeal in people with type 2 diabetes: a randomized, controlled, crossover trial

Introduction

Minimizing postprandial glucose response is an important goal for overall diabetes management. Diabetes-specific nutritional shakes (DSNS) have been clinically shown to minimize postprandial glucose response in people with type 2 diabetes (T2DM) compared to high-glycemic foods. However, it is unknown how a high-protein, low-fat DSNS impacts the GLP-1 response.

Methods

We tested the postprandial glucose, insulin, and GLP-1 response to a high-protein, low-fat diabetes-specific nutritional shake (DSNS-HP) compared to isocaloric instant oatmeal (IOM) in a randomized, controlled, crossover study in adults with T2DM (n = 24). Participants were randomly selected to receive IOM or DSNS-HP on two test days. Glucose, insulin, and total GLP-1 concentration were measured at baseline and 15, 30, 45, 60, 90, 120, 180, and 240 min postprandially.

Results

Compared to IOM, the glucose-positive area under the curve (pAUC) was significantly lower (P = .021). DSNS-HP significantly increased GLP-1 pAUC response by 213% (P <.001) with a corresponding increase in insulin pAUC (P = .033) compared to IOM.

Discussion

A high-protein, low-fat DSNS leads to favorable changes in GLP-1 response and is a suitable option to minimize blood glucose response in people with type 2 diabetes.

Pollutant Gases to Algal Animal Feed: Impacts of Poultry House Exhaust Air on Amino Acid Profile of Algae

Algae provide a rich source of proteins, lipids, vitamins, and minerals, making them valuable feed ingredients in animal nutrition. Beyond their nutritional benefits, algae have been recognized for their potential to mitigate the negative environmental impacts of poultry production. Poultry production is crucial for the global food supply but contributes to environmental concerns, particularly in terms of ammonia and carbon dioxide gas emissions. This study emphasizes the importance of reducing greenhouse gas and ammonia production in poultry operations by utilizing algae species suitable for animal consumption, highlighting the need for sustainable feed sources. This study investigated the effects of poultry exhaust air and culture conditions on the amino acid profiles of three microalgae species, namely, Scenedesmus sp. (AQUAMEB-60), Ankistrodesmus sp. (AQUAMEB-33), and Synechococcaceae (AQUAMEB 32). The experiments were conducted in a commercial broiler farm in Bursa, Turkey, focusing on reducing pollutant gas emissions and utilizing poultry exhaust air in algae cultivation. The highest protein content of 50.4% was observed in the biomass of Synechococcaceae with BBM and DI water. Scenedesmus sp. had the highest carbohydrate content of 33.4% cultivated with DI water. The algae biomass produced from Synechococcaceae growth with DI water was found to have the highest content of essential and nonessential amino acids, except for glutamic acid and glycine. The arsenic, cadmium, and mercury content showed variations within the following respective ranges: 1.076-3.500 mg/kg, 0.0127-0.1210 mg/kg, and 0.1330-0.0124 mg/kg. The overall operating costs for producing 1.0 g L-1 d-1 of dry algal biomass with the existing PBR system were $0.12-0.35 L-1 d-1, $0.10-0.26 L-1 d-1, and $0.11-0.24 L-1 d-1 for Scenedesmus sp., Ankistrodesmus sp., and Synechococcaceae, respectively. The operating cost of producing 1.0 g L-1 d-1 of protein was in the range of $0.25-0.88 L-1 d-1 for the three algae species. The results provide insights into the potential of algae as a sustainable feed ingredient in animal diets, emphasizing both environmental and economic considerations. The results demonstrated a considerable reduction in the production costs of dry biomass and protein when utilizing poultry house exhaust air, highlighting the economic viability and nutritional benefits of this cultivation method.

Effects of energy-restricted diets with or without nuts on weight, body composition and glycaemic control in adults: a scoping review

Energy-restricted (ER) diets promote weight loss and improve body composition and glycaemic control. Nut consumption also improves these parameters. However, less is known about the combined benefit of these two strategies. This scoping review implemented a systematic search of Medline, Embase and Scopus to identify randomised controlled trials evaluating the effect of ER diets with or without nuts on body mass, body composition and glycaemic control in adults. After reviewing titles and abstracts, twenty-nine full-text articles were screened, resulting in seven studies reported in eight papers that met the inclusion criteria. Energy restriction was achieved by prescribing a set energy target or reducing intake by 1000-4200 kJ from daily energy requirements. Interventions ranged from 4 to 52 weeks in duration and contained 42-84 g/d of almonds, peanuts, pistachios or walnuts. While all studies reported that energy restriction resulted in significant weight loss, the addition of nuts to ER diets demonstrated significantly greater weight loss in only approximately half of the included studies (4/7 studies). There was limited evidence to support additional benefits from nuts for body composition measures or glycaemic control. Although improvements in weight loss and glycaemia were not consistent when nuts were included in ER diets, no study revealed an adverse effect of nut consumption on health outcomes. Future studies could explore the effect of consuming different types and amounts of nuts, combined with various levels of energy restriction on weight, body composition and glycaemic control.

Quality of dietary macronutrients is associated with glycemic outcomes in adults with cystic fibrosis

Objective

Poor diet quality contributes to metabolic dysfunction. This study aimed to gain a greater understanding of the relationship between dietary macronutrient quality and glucose homeostasis in adults with cystic fibrosis (CF).

Design

This was a cross-sectional study of N = 27 adults with CF with glucose tolerance ranging from normal (n = 9) to prediabetes (n = 6) to being classified as having cystic fibrosis-related diabetes (CFRD, n = 12). Fasted blood was collected for analysis of glucose, insulin, and C-peptide. Insulin resistance was assessed by Homeostatic Model Assessment for Insulin Resistance (HOMA2-IR). Subjects without known CFRD also underwent a 2-h oral glucose tolerance test. Three-day food records were used to assess macronutrient sources. Dietary variables were adjusted for energy intake. Statistical analyses included ANOVA, Spearman correlations, and multiple linear regression.

Results

Individuals with CFRD consumed less total fat and monounsaturated fatty acids (MUFA) compared to those with normal glucose tolerance (p < 0.05). In Spearman correlation analyses, dietary glycemic load was inversely associated with C-peptide (rho = -0.28, p = 0.05). Total dietary fat, MUFA, and polyunsaturated fatty acids (PUFA) were positively associated with C-peptide (rho = 0.39-0.41, all p < 0.05). Plant protein intake was inversely related to HOMA2-IR (rho = -0.28, p = 0.048). Associations remained significant after adjustment for age and sex.

Discussion

Improvements in diet quality are needed in people with CF. This study suggests that higher unsaturated dietary fat, higher plant protein, and higher carbohydrate quality were associated with better glucose tolerance indicators in adults with CF. Larger, prospective studies in individuals with CF are needed to determine the impact of diet quality on the development of CFRD.

Effect of sesame (Sesamum indicum L.) consumption on glycemic control in patients with type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials

Conflicting evidence exists on the effect of sesame consumption on glucose metabolism in patients with type 2 diabetes (T2D). Therefore, this meta-analysis focuses on the relationship between sesame (Sesamum indicum L.) intervention and glycemic control in patients with T2D. Published literature was retrieved and screened from PubMed, Scopus, ISI Web of Science, and the Cochrane Library up to December 2022. Outcome measures included fasting blood sugar (FBS) concentrations, fasting insulin levels, and hemoglobin A1c (HbA1c) percentage. Pooled effect sizes were reported as weighted mean differences (WMDs) and 95% confidence intervals (CIs). Eight clinical trials (395 participants) were eligible for meta-analyses. Overall, sesame consumption significantly reduced serum FBS (WMD: -28.61 mg/dL, 95% CI: -36.07 to -21.16, p˂0.001; I2  = 98.3%) and HbA1c percentage (WMD: -0.99%, 95% CI: -1.22 to -0.76, p ≤ 0.001; I2  = 65.1%) in patients with T2D. However, sesame consumption did not significantly influence fasting insulin levels (Hedges's: 2.29, 95% CI: -0.06 to 4.63, p = 0.06; I2  = 98.1%). In summary, the current meta-analysis showed a promising effect of sesame consumption on glycemic control through reducing FBS and HbA1c, yet additional prospective studies are recommended, using higher doses and longer intervention period, to confirm the impact of sesame consumption on insulin levels in T2D patients.

Plasma Phospholipid Monounsaturated Fatty Acids and Gestational Diabetes Mellitus: A Longitudinal Study in the NICHD Fetal Growth Studies-Singletons Cohort

Fatty acids (FAs) have been implicated in the development of gestational diabetes mellitus (GDM), but the role of monounsaturated FAs (MUFAs) remains understudied. We investigated the associations of plasma phospholipid MUFAs in early to mid-pregnancy with cardiometabolic biomarkers and GDM risk. From the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies-Singletons cohort (2009-2013), we identified 107 women with GDM according to Carpenter and Coustan criteria and 214 control participants without GDM matched (2:1) on age, race/ethnicity, and gestational week (GW) of blood collection. MUFAs were measured at 10-14, 15-26, 23-31, and 33-39 GWs by gas chromatography mass spectrometry. We found that the concentration of total 18:1 MUFAs was significantly lower among women with GDM than those without GDM at 15-26 GWs. Each SD increment in the level of total 18:1 MUFAs was associated with a 40% lower risk of GDM at 15-26 GWs. Moreover, each SD increment in vaccenic acid (18:1n-7) levels at 10-14 and 15-26 GWs were associated with a 36% and 45% lower risk of GDM, respectively. Our extensive assessments of MUFAs advance our understanding of the unique associations of FA composition with GDM risk, suggesting the potentially beneficial role of MUFAs in GDM pathophysiology.

The Molecular Determinants of Glucagon-like Peptide Secretion by the Intestinal L cell

The intestinal L cell secretes a diversity of biologically active hormones, most notably the glucagon-like peptides, GLP-1 and GLP-2. The highly successful introduction of GLP-1-based drugs into the clinic for the treatment of patients with type 2 diabetes and obesity, and of a GLP-2 analog for patients with short bowel syndrome, has led to the suggestion that stimulation of the endogenous secretion of these peptides may serve as a novel therapeutic approach in these conditions. Situated in the intestinal epithelium, the L cell demonstrates complex relationships with not only circulating, paracrine, and neural regulators, but also ingested nutrients and other factors in the lumen, most notably the microbiota. The integrated input from these numerous secretagogues results in a variety of temporal patterns in L cell secretion, ranging from minutes to 24 hours. This review combines the findings of traditional, physiological studies with those using newer molecular approaches to describe what is known and what remains to be elucidated after 5 decades of research on the intestinal L cell and its secreted peptides, GLP-1 and GLP-2.

Neither Incretin or Amino Acid Responses, nor Casein Content, Account for the Equal Insulin Response Following Iso-Lactose Loads of Natural Human and Cow Milk in Healthy Young Adults

Human milk contains <50% less protein (casein) than cow milk, but is equally effective in insulin secretion despite lower postingestion hyperaminoacidemia. Such potency of human milk might be modulated either by incretins (glucagon-like polypeptide-1,GLP-1); glucose-inhibitory-polypeptide, GIP), and/or by milk casein content. Healthy volunteers of both sexes were fed iso-lactose loads of two low-protein milks, i.e., human [Hum] (n = 8) and casein-deprived cow milk (Cow [↓Cas]) (n = 10), as well as loads of two high-protein milks, i.e., cow (n = 7), and casein-added human-milk (Hum [↑Cas]) (n = 7). Plasma glucose, insulin, C-peptide, incretins and amino acid concentrations were measured for 240′. All milks induced the same transient hyperglycemia. The early [20′−30′] insulin and C-peptide responses were comparable among all milk types apart from the low-protein (Cow [↓Cas]) milk, where they were reduced by <50% (p < 0.05 vs. others). When comparing the two high-protein milks, GLP-1 and GIP [5’−20’] responses with the (Hum [↑Cas]) milk were lower (by ≈2−3 fold, p < 0.007 and p < 0.03 respectively) than those with cow milk, whereas incretin secretion was substantially similar. Plasma amino acid increments largely reflected the milk protein content. Thus, neither casein milk content, nor incretin or amino acid concentrations, can account for the specific potency of human milk on insulin secretion, which remains as yet unresolved.

Consumption of sesame seeds and sesame products has favorable effects on blood glucose levels but not on insulin resistance: A systematic review and meta-analysis of controlled clinical trials

Sesame, with an oily seed containing oil, lignans, and proteins, is a popular plant that has demonstrated health benefits such as antioxidative, antiobesity, and antiinflammatory effects. In this systematic review and meta-analysis, we aimed to summarize the effect of sesame seeds and their consumption compared to a control group on blood glucose and insulin resistance in human adults. PubMed/MEDLINE, SCOPUS, Web of Science, Google Scholar, and EMBASE were searched to identify eligible controlled clinical trials up to February 2021. Finally, eight clinical trials were included in this study. Sesame products used in these trials were sesame oil, sesamin, and tahini, and the duration of the intervention varied from 45 days to 9 weeks. Our results showed the significant positive effects of sesame and its products on fasting blood glucose FBG (weighted mean difference, WMD: -21.31 mg/dl, 95% CI: -41.23, -1.39, p = .036) and HbA1c (WMD: -0.75, 95% CI: -1.16, -0.34, p < .001) levels but results about fasting serum insulin (WMD: 5.51 μU/ml, 95% CI: -2.31, 13.33, p = .167) and HOMA-IR (WMD: -0.07, 95% CI: -0.33, 0.20, p = .617) were not meaningful. Sesame may be considered a beneficial agent for human glucose metabolism and can be a part of glucose-lowering diets.

Effects of consumption of coconut oil or coconut on glycemic control and insulin sensitivity: A systematic review and meta-analysis of interventional trials

BACKGROUND AND AIMS

The often purported claim that coconut fat is beneficial for cardiovascular health and was disputed in several recent meta-analyses. However, the evidence on the effects of coconut fat intake on glycemic control remains equivocal. We conducted a systematic review and meta-analysis in accordance with the PRISMA guidelines to determine the effects of dietary coconut fats on markers of acute and long-term glycemic control.

METHODS AND RESULTS

PubMed, Scopus, ProQuest, and Web-of-Science databases were searched and the records were screened by three independent reviewers to identify interventional studies examining acute and long-term (i.e., >10 days) effects of coconut fat on glycemic control. DerSimonian-Laird random-effects meta-analyses were performed using the meta-package in R (4.0.2). Seven interventional studies on acute effects and 11 interventional studies on long-term effects of coconut fat were included. Meals with coconut fat acutely increased the incremental area under the curve (AUC) of glucose (p = 0.046) and decreased the incremental AUC of insulin (p = 0.037) vs. control meals. Long-term coconut fat intake increased HOMA-IR (p = 0.049), but did not significantly affect fasting glucose, insulin, or HOMA-β vs. control meals.

CONCLUSIONS

Coconut fat in meals seems to be associated with a diminished postprandial insulin response, resulting in a subtle increase in the postprandial glycemic response. Long-term intake of coconut fat seems to increase insulin resistance, yet does not seem to be beneficial for long-term glycemic control. Thus, our results disprove the popular claim that coconut fat improves glycemic control.

REGISTRATION

PROSPERO registry (CRD42020183450).

Nutritional and dietary interventions to prolong renal allograft survival after kidney transplantation

PURPOSE OF REVIEW

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

RECENT FINDINGS

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

SUMMARY

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Effect of pecan nuts and extra-virgin olive oil on glycemic profile and nontraditional anthropometric indexes in patients with coronary artery disease: a randomized clinical trial

BACKGROUND/OBJECTIVES

The influence of cardioprotective foods on nontraditional indexes related to dysglycemia and body fat distribution is unknown in individuals with coronary artery disease (CAD). This study aimed to evaluate the effect of a healthy diet supplemented with pecan nuts or extra-virgin olive oil on glycemic profile and adipose tissue dysfunction assessed by anthropometric indexes in patients with stable CAD.

SUBJECTS/METHODS

In a randomized, pragmatic, parallel clinical trial lasting 12 weeks, 204 individuals were allocated to three interventions: a healthy diet (control group [CG], n = 67), a healthy diet plus 30 g/day of pecan nuts (pecan nut group [PNG], n = 68), or a healthy diet plus 30 mL/day of extra-virgin olive oil (olive oil group [OOG], n = 69). Triglyceride-glucose (TyG) index (primary outcome) and other markers of glycemic profile were evaluated, and nontraditional anthropometric indexes as well. Diet quality was assessed according to the Alternate Healthy Eating Index (mAHEI).

RESULTS

After adjustment for baseline values, use of antidiabetic drugs and insulin, there were no differences in both glycemic and anthropometric profiles according to groups at the end of the study. PNG improved the quality of the diet in comparison to other groups (final mAHEI scores: CG: 19 ± 7.5; PNG: 26 ± 8; OOG: 18.9 ± 6; P < 0.001).

CONCLUSIONS

There was no difference regarding glycemic and anthropometric parameters according to interventions in patients with stable CAD. However, adding pecan nuts to a healthy diet may improve its quality. Further studies must be conducted considering dietary interventions on secondary cardiovascular prevention setting.

CLINICAL TRIALS IDENTIFIER NUMBER

NCT02202265. First Posted: July 2014; Last Update: September 2020.

Alternative Foods in Cardio-Healthy Dietary Models That Improve Postprandial Lipemia and Insulinemia in Obese People

Obesity is one of the major health problems worldwide. Following healthy dietary patterns can be difficult in some countries due to the lack of availability of certain foods; thus, alternative foods are needed. Our aim was to evaluate the effect of a dietary pattern consisting of fruit, avocado, whole grains, and trout (FAWGT) on postprandial insulinemia and lipemia in obese Colombian subjects. A randomized controlled crossover study was conducted, in which 44 subjects with BMI ≥ 30 kg/m² followed either a FAWGT diet or a diet high in saturated fat and rich in processed carbohydrates. Levels of lipids and carbohydrates were measured during the postprandial state. The FAWGT diet reduced fasting insulin, VLDL, and HOMA-IR after 8 weeks (p < 0.05), while there was a lower postprandial increase in TG, VLDL, and insulin levels after both acute and chronic intake of FAWGT diet (p < 0.05). The intake of FAWGT-diet was characterized by high consumption of foods rich in fiber, MUFAs, and vitamins C and E (p < 0.05). The consumption of a diet composed of fruit, avocado, whole grains, and trout has emerged as a valid alternative to the foods included in other heart-healthy diets since it improves postprandial lipemia and insulinemia in obese people and has similar beneficial effects to these healthy models.

The mechanism of increased intestinal palmitic acid absorption and its impact on hepatic stellate cell activation in nonalcoholic steatohepatitis

Dietary palmitic acid (PA) promotes liver fibrosis in patients with nonalcoholic steatohepatitis (NASH). Herein, we clarified the intestinal absorption kinetics of dietary PA and effect of trans-portal PA on the activation of hepatic stellate cells (HSCs) involved in liver fibrosis in NASH. Blood PA levels after meals were significantly increased in patients with NASH compared to those in the control. Expression of genes associated with fat absorption and chylomicron formation, such as CD36 and MTP, was significantly increased in the intestine of NASH model rats compared with that in the controls. Plasma levels of glucagon-like peptide-2, involved in the upregulation of CD36 expression, were elevated in NASH rats compared with those in the controls. Furthermore, portal PA levels after meals in NASH rats were significantly higher than those in control and nonalcoholic fatty liver rats. Moreover, PA injection into the portal vein to the liver in control rats increased the mRNA levels associated with the activation of HSCs. Increased intestinal absorption of diet-derived PA was observed in NASH. Thus, the rapid increase in PA levels via the portal vein to the liver may activate HSCs and affect the development of liver fibrosis in NASH.

Nutrient infusion in the dorsal vagal complex controls hepatic lipid and glucose metabolism in rats

Hypothalamic regulation of lipid and glucose homeostasis is emerging, but whether the dorsal vagal complex (DVC) senses nutrients and regulates hepatic nutrient metabolism remains unclear. Here, we found in rats DVC oleic acid infusion suppressed hepatic secretion of triglyceride-rich very-low-density lipoprotein (VLDL-TG), which was disrupted by inhibiting DVC long-chain fatty acyl-CoA synthetase that in parallel disturbed lipid homeostasis during intravenous lipid infusion. DVC glucose infusion elevated local glucose levels similarly as intravenous glucose infusion and suppressed hepatic glucose production. This was independent of lactate metabolism as inhibiting lactate dehydrogenase failed to disrupt glucose sensing and neither could DVC lactate infusion recapitulate glucose effect. DVC oleic acid and glucose infusion failed to lower VLDL-TG secretion and glucose production in high-fat fed rats, while inhibiting DVC farnesoid X receptor enhanced oleic acid but not glucose sensing. Thus, an impairment of DVC nutrient sensing may lead to the disruption of lipid and glucose homeostasis in metabolic syndrome.

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DVC oleic acid infusion lowers hepatic secretion of VLDL-TG in chow but not HF rats

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Inhibition of ACSL in the DVC negates lipid sensing

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DVC glucose infusion lowers hepatic glucose production in chow but not HF rats

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Inhibition of FXR in the DVC enhances oleic acid but not glucose sensing in HF rats

Effect of high protein and fat diet on postprandial blood glucose levels in children and adolescents with type 1 diabetes in Cairo, Egypt

BACKGROUND AND AIMS

To determine the effect of high protein and high fat meals on post prandial glycemia in patients with type 1 diabetes.

METHODS

This study included 51 children and adolescents with type 1 diabetes who were following up at Diabetes, Endocrine and Metabolism Pediatric Unit (DEMPU), Abo Elrish Children's hospital, Cairo University. Post prandial blood glucose levels were recorded and compared following three breakfast meals with varying protein and fat content (standard carbohydrate meal, high fat meal, and high protein meal) over a period of 5 hours on 3 consecutive days.

RESULTS

High protein meal resulted in hyperglycemia with the peak level at 3.5 hours and continued for 5 hours post prandial while high fat meal caused early hyperglycemia reached the peak at 2 hours then declined towards 5 hours. Comparison of the three different breakfast meals revealed statistically significant difference regarding the postprandial glycemia at 30, 60, 90,120, 180, 210, 240, 270, 300 min.

CONCLUSION

Meals high in protein caused sustained increase in postprandial glucose levels over a period of 5 h. However, high fat meals caused early postprandial hyperglycemia. Protein and fat content of meals affect the timing and values of the peak blood glucose as well as the duration of postprandial hyperglycemia. Therefore, fat/protein unit should be taken in consideration while calculating the bolus insulin dose and anticipating the postprandial glucose response.

Evaluation of the acceptability of low glycaemic index preparations, formulated by replicating traditional Chilean culinary preparations with a high glycaemic index

Introduction

The aim of this study was to determine the acceptability of low glycaemic index (GI) preparations, equivalent to the traditional high GI ones in Chile, elaborated with minimal changes in the ingredients and culinary techniques that significantly diminish the GI and maintain acceptability level. Twelve high-GI traditional lunches and their low GI counterparts were prepared. For 12 days, 20 apparently healthy women randomly tasted 2 paired preparations per day (low and high GI). The attributes of appearance, taste, smell, and texture of salads, main course, and desserts, as well as those of the full lunch, were evaluated using a hedonic scale of 7 and 9 points. Lunches with a high GI (90 ± 20.5 %) were modified by changing types of food ingredients, and/or by using culinary techniques to provide a low-GI counterpart with 47 ± 5.9 % GI (p < 0.001). All the preparations were classified as optimal, exceeding the established cut-off point. The "Legume with CHO" lunch had a higher acceptability level in its low GI version (p = 0.006), while the "Chicken with corn" lunch had it in its high GI version (p = 0.004). There was a preference for low-GI salad appearance (p = 0.003) and dessert flavour (p = 0.024), while high-GI main dishes were better praised for flavour (p = 0.034) and texture (p = 0.012). It is therefore possible to prepare low-GI menus equivalent to their traditional counterparts that are received as generally acceptable, with components and sensory attributes equal to, or even better than typical Chilean cuisine dishes.

The Role of High Fat Diets and Liver Peptidase Activity in the Development of Obesity and Insulin Resistance in Wistar Rats

High-fat diets (HFD) have been widely associated with an increased risk of metabolic disorders and overweight. However, a high intake of sources that are rich in monounsaturated fatty acids has been suggested as a dietary agent that is able to positively influence energy metabolism and vascular function. The main objective of this study was to analyze the role of dietary fats on hepatic peptidases activities and metabolic disorders. Three diets: standard (S), HFD supplemented with virgin olive oil (VOO), and HFD supplemented with butter plus cholesterol (Bch), were administered over six months to male Wistar rats. Plasma and liver samples were collected for clinical biochemistry and aminopeptidase activities (AP) analysis. The expression of inducible nitric oxide synthase (iNOS) was also determined by Western blot in liver samples. The diet supplement with VOO did not induce obesity, in contrast to the Bch group. Though the VOO diet increased the time that was needed to return to the basal levels of plasma glucose, the fasting insulin/glucose ratio and HOMA2-%B index (a homeostasis model index of insulin secretion and valuation of β-cell usefulness (% β-cell secretion)) were improved. An increase of hepatic membrane-bound dipeptidyl-peptidase 4 (DPP4) activity was found only in VOO rats, even if no differences in fasting plasma glucagon-like peptide 1 (GLP-1) were obtained. Both HFDs induced changes in hepatic pyroglutamyl-AP in the soluble fraction, but only the Bch diet increased the soluble tyrosyl-AP. Angiotensinase activities that are implicated in the metabolism of angiotensin II (AngII) to AngIV increased in the VOO diet, which was in agreement with the higher activity of insulin-regulated-AP (IRAP) in this group. Otherwise, the diet that was enriched with butter increased soluble gamma-glutamyl transferase (GGT) and Leucyl-AP, iNOS expression in the liver, and plasma NO. In summary, VOO increased the hepatic activity of AP that were related to glucose metabolism (DPP4, angiotensinases, and IRAP). However, the Bch diet increased activities that are implicated in the control of food intake (Tyrosine-AP), the index of hepatic damage (Leucine-AP and GGT), and the expression of hepatic iNOS and plasma NO. Taken together, these results support that the source of fat in the diet affects several peptidases activities in the liver, which could be related to alterations in feeding behavior and glucose metabolism.

Adipokines and Adipose Tissue-Related Metabolites, Nuts and Cardiovascular Disease

Adipose tissue is a complex structure responsible for fat storage and releasing polypeptides (adipokines) and metabolites, with systemic actions including body weight balance, appetite regulation, glucose homeostasis, and blood pressure control. Signals sent from different tissues are generated and integrated in adipose tissue; thus, there is a close connection between this endocrine organ and different organs and systems such as the gut and the cardiovascular system. It is known that functional foods, especially different nuts, may be related to a net of molecular mechanisms contributing to cardiometabolic health. Despite being energy-dense foods, nut consumption has been associated with no weight gain, weight loss, and lower risk of becoming overweight or obese. Several studies have reported beneficial effects after nut consumption on glucose control, appetite suppression, metabolites related to adipose tissue and gut microbiota, and on adipokines due to their fatty acid profile, vegetable proteins, l-arginine, dietary fibers, vitamins, minerals, and phytosterols. The aim of this review is to briefly describe possible mechanisms implicated in weight homeostasis related to different nuts, as well as studies that have evaluated the effects of nut consumption on adipokines and metabolites related to adipose tissue and gut microbiota in animal models, healthy individuals, and primary and secondary cardiovascular prevention.

Glucagon-like peptide 1 (GLP-1)

BACKGROUND

The glucagon-like peptide-1 (GLP-1) is a multifaceted hormone with broad pharmacological potential. Among the numerous metabolic effects of GLP-1 are the glucose-dependent stimulation of insulin secretion, decrease of gastric emptying, inhibition of food intake, increase of natriuresis and diuresis, and modulation of rodent β-cell proliferation. GLP-1 also has cardio- and neuroprotective effects, decreases inflammation and apoptosis, and has implications for learning and memory, reward behavior, and palatability. Biochemically modified for enhanced potency and sustained action, GLP-1 receptor agonists are successfully in clinical use for the treatment of type-2 diabetes, and several GLP-1-based pharmacotherapies are in clinical evaluation for the treatment of obesity.

SCOPE OF REVIEW

In this review, we provide a detailed overview on the multifaceted nature of GLP-1 and its pharmacology and discuss its therapeutic implications on various diseases.

MAJOR CONCLUSIONS

Since its discovery, GLP-1 has emerged as a pleiotropic hormone with a myriad of metabolic functions that go well beyond its classical identification as an incretin hormone. The numerous beneficial effects of GLP-1 render this hormone an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, and neurodegenerative disorders.

Dietary Patterns Emphasizing the Consumption of Plant Foods in the Management of Type 2 Diabetes: A Narrative Review

The prevalence of type 2 diabetes (T2D) is increasing worldwide. This complex and multifactorial metabolic condition affects both the quality and expectancy of life in adults. Therefore, appropriate lifestyle strategies are needed in order to reduce the burden of T2D. Dietary patterns characterized by a high consumption of fruits, vegetables, whole grains, legumes, nuts, and seeds, and a minimal consumption of animal products, have been suggested as a dietary approach to prevent and control T2D and related micro- and macrovascular complications. This narrative review summarizes epidemiologic and clinical trial evidence on the role of the most widely studied dietary patterns that emphasize the consumption of plant foods [vegetarian, vegan, Mediterranean, and DASH (Dietary Approaches to Stop Hypertension) diets] in the management of T2D and its complications. Furthermore, their potential underlying mechanisms are discussed. Dietary patterns emphasizing the consumption of plant foods appear to confer beneficial effects on glycemic control in different diabetic populations. Several components of these dietary patterns might confer benefits on glycemia and counterbalance the detrimental effects of animal-based foods. The limited evidence on T2D-related complications makes it difficult to draw solid conclusions.

Effect of Oral Nutritional Supplements with Sucromalt and Isomaltulose versus Standard Formula on Glycaemic Index, Entero-Insular Axis Peptides and Subjective Appetite in Patients with Type 2 Diabetes: A Randomised Cross-Over Study

Oral diabetes-specific nutritional supplements (ONS-D) induce favourable postprandial responses in subjects with type 2 diabetes (DM2), but they have not been correlated yet with incretin release and subjective appetite (SA). This randomised, double-blind, cross-over study compared postprandial effects of ONS-D with isomaltulose and sucromalt versus standard formula (ET) on glycaemic index (GI), insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1) and SA in 16 individuals with DM2. After overnight fasting, subjects consumed a portion of supplements containing 25 g of carbohydrates or reference food. Blood samples were collected at baseline and at 30, 60, 90, 120, 150 and 180 min; and SA sensations were assessed by a visual analogue scale on separate days. Glycaemic index values were low for ONS-D and intermediate for ET (p < 0.001). The insulin area under the curve (AUC0-180 min) (p < 0.02) and GIP AUC (p < 0.02) were lower after ONS-D and higher GLP-1 AUC when compared with ET (p < 0.05). Subjective appetite AUC was greater after ET than ONS-D (p < 0.05). Interactions between hormones, hunger, fullness and GI were found, but not within the ratings of SA; isomaltulose and sucromalt may have influenced these factors.

Gut microbiome-Mediterranean diet interactions in improving host health

The gut microbiota plays a fundamental role in host health and disease. Host diet is one of the most significant modulators of the gut microbial community and its metabolic activities. Evidence demonstrates that dietary patterns such as the 'Western diet' and perturbations in gut microbiome (dysbiosis) have strong associations with a wide range of human diseases, including obesity, metabolic syndrome, type-2 diabetes and cardiovascular diseases. However, consumption of Mediterranean-style diets is considered healthy and associated with the prevention of cardiovascular and metabolic diseases, colorectal cancers and many other diseases. Such beneficial effects of the Mediterranean diet might be attributed to high proportion of fibers, mono- and poly-unsaturated fatty acids, antioxidants and polyphenols. Concurrent literature has demonstrated beneficial modulation of the gut microbiome following a Mediterranean-style diet in humans as well as in experimental animal models such as rodents. We recently demonstrated similar positive changes in the gut microbiome of non-human primates consuming a Mediterranean-style diet for long term (30 months). Therefore, it is rational to speculate that this positive modulation of the gut microbiome diversity, composition and function is one of the main factors intermediating the health effects of Mediterranean diet on the host. The present perspective discusses the evidences that the Mediterranean diet induces gut microbiome modulation in rodents, non-human primates and human subjects, and discusses the potential role of gut microbiota and microbial metabolites as one of the fundamental catalysts intermediating various beneficial health effects of Mediterranean diet on the host.

Effects of dietary fat on insulin secretion in subjects with the metabolic syndrome

Objective Impaired insulin secretion and action contribute to the development of type 2 diabetes. Dietary fat modification may improve insulin sensitivity, whereas the effect on insulin secretion is unclear. We investigated the effect of dietary fat modification on insulin secretion in subjects with the metabolic syndrome. Design In a 12-week pan-European parallel, randomized controlled dietary intervention trial (LIPGENE), 486 subjects were assigned to four isoenergetic diets: high-fat diets rich in saturated fat (HSFA) or monounsaturated fat (HMUFA) or low-fat, high-complex carbohydrate diets with (LFHCC n-3) or without (LFHCC control) 1.2 g/day of n-3 PUFA supplementation. Insulin secretion was estimated as acute insulin response to glucose (AIRg) and disposition index (DI), modeled from an intravenous glucose tolerance test. Results There were no overall effect of the dietary intervention on AIRg and DI in the total cohort, in neither the high-fat nor LFHCC groups. We observed significant diet*fasting glucose category interactions for AIRg (P = 0.021) and DI (P = 0.001) in the high-fat groups. In subjects with normal fasting glucose and preserved first phase insulin secretion, the HMUFA diet increased, whereas the HSFA diet reduced AIRg (P = 0.015) and DI (P = 0.010). Conclusions The effects of dietary fat modification on insulin secretion were minor, and only evident in normoglycemic subjects. In this case, the HMUFA diet improved AIRg and DI, as compared to the HSFA diet.

Relationship Between Nut Consumption and Metabolic Syndrome: A Meta-Analysis of Observational Studies

Objective: Our aim was to examine the relationship between nut consumption and metabolic syndrome (MetS). Methods: The electronic databases of PubMed, Web of Science, and Embase were searched up to November 2018 for observational studies on the relationship between nut consumption and MetS. The pooled relative risk (RR) of MetS for the highest versus lowest category of nut consumption, as well as their corresponding 95% confidence intervals (CIs) were calculated. Results: A total of 11 observational studies (6 cross-sectional and 5 prospective cohort studies), which involved a total of 89,224 participants, were identified for this meta-analysis. The overall multivariable adjusted RR showed that nut consumption was negatively associated with MetS (RR = 0.84; 95% CI, 0.76-0.92; p < 0.001). Of interest, subgroup analysis confirmed that such findings existed in tree nuts (RR = 0.97; 95% CI, 0.94-1.00; p = 0.04), but not in peanuts (RR = 1.01; 95% CI, 0.96-1.06; p = 0.68). Conclusions: The existing evidence suggested that nut consumption was negatively associated with MetS. However, such an inverse relationship only existed in tree nuts, not in peanuts. More well-designed studies with detailed specifications of nut varieties are needed to further elaborate the issues examined in this study.

Preventive Effect of Different Wild Pistachio Oils on Oxidative Stress Markers, Liver Enzymes, and Histopathological Findings in a Metabolic Syndrome Model

Background

Wild pistachio (Pistacia Atlantica mutica) species with wide distribution in Iran have different nutrition properties and may have therapeutic effects in metabolic syndrome. Metabolic syndrome, as a prevalent health problem, is a main risk factor for different chronic diseases such as diabetes, fatty liver and cardiovascular diseases. The present study aimed to evaluate the preventive effects of mixture, kernel, and hull oil of wild pistachio (WP) on oxidative stress markers, liver function and histopathological findings in metabolic syndrome induced rats.

Materials and Methods

After oil extraction by cold press method and chemical analysis, rats were divided into 6 groups. Group 1 received normal saline; group 2 received 2cc fructose solution and 0.5cc normal saline; and groups 3, 4, 5 and 6 received 2 cc fructose solution and 0.5 cc sunflower oil, mixture, hull and kernel oils of WP for 10 weeks, respectively. Then, glycemic indices, oxidative stress, liver enzymes and histopathological examination were determined using standard laboratory tests.

Results

WP Kernel and mixture oils notably decreased the fasting blood sugar and insulin resistance compared with the fructose group. Insulin level was significantly increased in the kernel oil group (P<0.05). There was no significant difference in oxidative stress, liver enzymes and histopathology parameters among the groups.

Conclusion

Kernel oil of WP improved hyperglycemia, insulin resistance and insulin secretion, but the changes in oxidative stress markers, liver enzymes and histopathologic results were not significant among the groups.

Dietary Composition and Cardiovascular Risk: A Mediator or a Bystander?

The role of nutrition in the pathogenesis of cardiovascular disease has long been debated. The established notion of the deleterious effects of fat is recently under question, with numerous studies demonstrating the benefits of low-carbohydrate, high-fat diets in terms of obesity, diabetes, dyslipidemia, and metabolic derangement. Monounsaturated and polyunsaturated fatty acids, especially n-3 PUFAs (polyunsaturated fatty acids), are the types of fat that favor metabolic markers and are key components of the Mediterranean Diet, which is considered an ideal dietary pattern with great cardioprotective effects. Except for macronutrients, however, micronutrients like polyphenols, carotenoids, and vitamins act on molecular pathways that affect oxidative stress, endothelial function, and lipid and glucose homeostasis. In relation to these metabolic markers, the human gut microbiome is constantly revealed, with its composition being altered by even small dietary changes and different microbial populations being associated with adverse cardiovascular outcomes, thus becoming the target for potential new treatment interventions. This review aims to present the most recent data concerning different dietary patterns at both the macro- and micronutrient level and their association with atherosclerosis, obesity, and other risk factors for cardiovascular disease.

Wild pistachio (Pistacia atlantica mutica) oil improve metabolic syndrome features in rats with high fructose ingestion

OBJECTIVES

Metabolic syndrome is a multiplex risk factor for diabetes and cardiovascular disease. Since some dietary fats such as mono-unsaturated fatty acids (MUFA) modify metabolic syndrome components the aim of the present study was to evaluate the preventive effects of mixture, kernel and hull oils of wild pistachio (WP) (Pistacia atlantica mutica) as good sources of MUFA on different features of this abnormality in rats under induction.

MATERIALS AND METHODS

In this study rats were randomly assigned to six groups with 12 animals per group. Metabolic syndrome was induced by fructose solution in groups 2, 3, 4, 5, and 6. Group 3 received sunflower oil and groups 4, 5, and 6 received mixture, hull and kernel oils of WP (2 ml/kg/day), respectively, for 10 weeks. Then, lipid profiles, glycemic indices, oxidative stress and inflammatory parameters were measured using standard laboratory tests.

RESULTS

Different forms of WP oil induced hypotriglyceridemia, but the hypocholesterolemia effect was seen only in the mixed and kernel oil groups. Kernel oil also significantly reduced LDL and HDL cholesterol (P<0.05). In addition, mixed and kernel oils notably decreased glycemic indices (fasting blood glucose and insulin resistance) compared with the fructose group. Serum insulin levels were significantly increased in the kernel oil group (P<0.05). All WP oils also significantly decreased inflammation (IL-6).

CONCLUSION

The results showed that the consumption of WP kernel oil may have beneficial effects on preventing hyperglycemia, hypertriglyceridemia, hypercholesterolemia, inflammation and pancreatic secretory disorders.

Methodological Issues in Studying PAHSA Biology: Masking PAHSA Effects

PAHSAs are anti-diabetic and anti-inflammatory lipids. Syed et al. identify numerous experimental differences that likely account for the failure of Pflimlin et al. to observe PAHSA beneficial effects. The differences include different HFDs resulting in minimal/no glucose intolerance, different assay conditions, an LC-MS protocol that was not validated, and use of olive oil, a bioactive nutrient that improves glucose tolerance, as a vehicle.

Lactobacillus gasseri in the Upper Small Intestine Impacts an ACSL3-Dependent Fatty Acid-Sensing Pathway Regulating Whole-Body Glucose Homeostasis

Long-chain acyl-CoA synthetase (ACSL)-dependent upper small intestinal lipid metabolism activates pre-absorptive pathways to regulate metabolic homeostasis, but whether changes in the upper small intestinal microbiota alter specific fatty acid-dependent pathways to impact glucose homeostasis remains unknown. We here first find that upper small intestinal infusion of Intralipid, oleic acid, or linoleic acid pre-absorptively increases glucose tolerance and lowers glucose production in rodents. High-fat feeding impairs pre-absorptive fatty acid sensing and reduces upper small intestinal Lactobacillus gasseri levels and ACSL3 expression. Transplantation of healthy upper small intestinal microbiota to high-fat-fed rodents restores L. gasseri levels and fatty acid sensing via increased ACSL3 expression, while L. gasseri probiotic administration to non-transplanted high-fat-fed rodents is sufficient to restore upper small intestinal ACSL3 expression and fatty acid sensing. In summary, we unveil a glucoregulatory role of upper small intestinal L. gasseri that impacts an ACSL3-dependent glucoregulatory fatty acid-sensing pathway.

Fatty Acids Consumption: The Role Metabolic Aspects Involved in Obesity and Its Associated Disorders

Obesity and its associated disorders, such as insulin resistance, dyslipidemia, metabolic inflammation, dysbiosis, and non-alcoholic hepatic steatosis, are involved in several molecular and inflammatory mechanisms that alter the metabolism. Food habit changes, such as the quality of fatty acids in the diet, are proposed to treat and prevent these disorders. Some studies demonstrated that saturated fatty acids (SFA) are considered detrimental for treating these disorders. A high fat diet rich in palmitic acid, a SFA, is associated with lower insulin sensitivity and it may also increase atherosclerosis parameters. On the other hand, a high intake of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids may promote positive effects, especially on triglyceride levels and increased high-density lipoprotein (HDL) levels. Moreover, polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) are effective at limiting the hepatic steatosis process through a series of biochemical events, such as reducing the markers of non-alcoholic hepatic steatosis, increasing the gene expression of lipid metabolism, decreasing lipogenic activity, and releasing adiponectin. This current review shows that the consumption of unsaturated fatty acids, MUFA, and PUFA, and especially EPA and DHA, which can be applied as food supplements, may promote effects on glucose and lipid metabolism, as well as on metabolic inflammation, gut microbiota, and hepatic metabolism.

Mediterranean Diet and 10-year (2002-2012) Incidence of Diabetes and Cardiovascular Disease in Participants with Prediabetes: The ATTICA study

BACKGROUND

Prediabetes has been related to an increased risk of developing diabetes and cardiovascular disease (CVD).

AIM

The aim of the present study was to examine the effect of the Mediterranean diet on diabetes and CVD risk in subjects with impaired fasting glucose (IFG, i.e. fasting plasma glucose 100-125 mg/dl).

METHODS

During 2001-2002, 3042 men and women (>18y) were enrolled for the study. The participants showed no clinical evidence of CVD or any other chronic disease, and were living in the greater Athens (Greece) area. In 2011 and 2012, the 10-year follow-up examinations were performed, including a working sample of n = 1875 participants without diabetes at baseline. Adherence to the Mediterranean diet at baseline evaluation was assessed using the MedDietScore (range 0-55).

RESULTS

The prediabetic subjects (n = 343) had a significantly higher incidence of diabetes (25% vs. 10%, p < 0.001) and CVD (17.8% vs. 12.3%, p = 0.007) compared with subjects with normal glucose values. A significant trend towards lower diabetes and CVD incidence was observed with medium and high adherence to the Mediterranean diet compared with low adherence (p < 0.001). High adherence to the Mediterranean diet (>35/55 score) was associated with lower 10-year incidence of diabetes and CVD. In multiple logistic regression models, participants with high levels of adherence to the Mediterranean diet were significantly less affected by diabetes and CVD than those with low adherence levels.

CONCLUSION

High adherence to the Mediterranean diet is associated with a low risk of developing diabetes and CVD in prediabetic subjects.

Mediterranean style diet is associated with low risk of new-onset diabetes after renal transplantation

OBJECTIVE

The incidence of new-onset diabetes after transplantation (NODAT) and premature mortality is high in renal transplant recipients (RTR). We hypothesized that a Mediterranean Style diet protects against NODAT and premature mortality in RTR.

RESEARCH DESIGN AND METHODS

A prospective cohort study of adult RTR with a functioning graft for >1 year. Dietary intake was assessed with a 177-item validated food frequency questionnaire. Patients were divided based on a 9-point Mediterranean Style Diet Score (MDS): low MDS (0-4 points) versus high MDS (5-9 points). A total of 468 RTR were eligible for analyses. Logistic multivariable regression analyses were used to study the association of MDS with NODAT and Cox multivariable regression models for the association with all-cause mortality.

RESULTS

Mean±SD age was 51.3±13.2 years and 56.6% were men. About 50% of the patients had a high MDS. During median follow-up of 4.0 (IQR, 0.4-5.4) years, 22 (5%) RTR developed NODAT and 50 (11%) died. High MDS was significantly associated with both a lower risk of NODAT (HR=0.23; 95% CI 0.09 to 0.64; p=0.004) and all-cause mortality (HR=0.51; 95% CI 0.29 to 0.89, p=0.02) compared to low MDS, independent of age and sex. Adjustment for other potential confounders, including total energy intake, physical activity and smoking status, did not materially change the results of the analyses.

CONCLUSIONS

Dietary habits leading to high MDS were associated with lower risk of NODAT. These results suggest that healthy dietary habits are of paramount importance for RTR.

Lipidomic analysis enables prediction of clinical outcomes in burn patients

Recent discoveries have highlighted the novel metabolic functions of adipose tissue in enhancing hypermetabolism after trauma. As the exact function and expression profiles of serum lipids and free fatty acids (FFA) are essentially unknown, we determined the lipidomic expression profile after burn in correlation to clinical outcomes to identify important lipid mediators affecting post-burn outcomes. We conducted a prospective cohort study with 46 adult burn patients and 5 healthy controls at the Ross Tilley Burn Center in Toronto, Canada. Patients were stratified based on major demographic and clinical variables, including age, burn severity, mortality, and sepsis. Serum FFAs and inflammatory markers were measured during acute hospital stay. We found that FFAs were acutely elevated post-burn and returned to baseline over time. Greater burn severity and age were associated with an impaired acute response in unsaturated FFAs and pro-inflammatory cytokines. Elevations in saturated and mono-unsaturated FFAs correlated significantly to increased mortality. In summary, persistent elevation of unsaturated lipids was associated with a functionally altered inflammatory-immunological milieu and worse clinical outcomes. The present lipidomic analysis indicates profound alterations in the lipid profile after burn by characterizing key lipids as potential diagnostic and outcome indicators in critically injured patients.

Blueberries' Impact on Insulin Resistance and Glucose Intolerance

Blueberries are a rich source of polyphenols, which include anthocyanin bioactive compounds. Epidemiological evidence indicates that incorporating blueberries into the diet may lower the risk of developing type 2 diabetes (T2DM). These findings are supported by pre-clinical and clinical studies that have shown improvements in insulin resistance (i.e., increased insulin sensitivity) after obese and insulin-resistant rodents or humans consumed blueberries. Insulin resistance was assessed by homeostatic model assessment-estimated insulin resistance (HOMA-IR), insulin tolerance tests, and hyperinsulinemic-euglycemic clamps. Additionally, the improvements in glucose tolerance after blueberry consumption were assessed by glucose tolerance tests. However, firm conclusions regarding the anti-diabetic effect of blueberries cannot be drawn due to the small number of existing clinical studies. Although the current evidence is promising, more long-term, randomized, and placebo-controlled trials are needed to establish the role of blueberries in preventing or delaying T2DM.

Impact of Diabetes-Specific Nutritional Formulas versus Oatmeal on Postprandial Glucose, Insulin, GLP-1 and Postprandial Lipidemia

Diabetes-specific nutritional formulas (DSNFs) are frequently used as part of medical nutrition therapy for patients with diabetes. This study aims to evaluate postprandial (PP) effects of 2 DSNFs; Glucerna (GL) and Ultra Glucose Control (UGC) versus oatmeal (OM) on glucose, insulin, glucagon-like peptide-1 (GLP-1), free fatty acids (FFA) and triglycerides (TG). After an overnight fast, 22 overweight/obese patients with type 2 diabetes were given 200 kcal of each of the three meals on three separate days in random order. Blood samples were collected at baseline and at 30, 60, 90, 120, 180 and 240 min. Glucose area under the curve (AUC_0–240) after GL and UGC was lower than OM (p < 0.001 for both). Insulin positive AUC_0–120 after UGC was higher than after OM (p = 0.02). GLP-1 AUC_0–120 and AUC_0–240 after GL and UGC was higher than after OM (p < 0.001 for both). FFA and TG levels were not different between meals. Intake of DSNFs improves PP glucose for 4 h in comparison to oatmeal of similar caloric level. This is achieved by either direct stimulation of insulin secretion or indirectly by stimulating GLP-1 secretion. The difference between their effects is probably related to their unique blends of amino acids, carbohydrates and fat.

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.

Gut feedback mechanisms and food intake: a physiological approach to slow carbohydrate bioavailability

Glycemic carbohydrates in foods are an important macronutrient providing the biological fuel of glucose for a variety of physiological processes. A classification of glycemic carbohydrates into rapidly digestible carbohydrate (RDC) and slowly digestible carbohydrate (SDC) has been used to specify their nutritional quality related to glucose homeostasis that is essential to normal functioning of the brain and critical to life. Although there have been many studies and reviews on slowly digestible starch (SDS) and SDC, the mechanisms of their slow digestion and absorption were mostly investigated from the material side without considering the physiological processes of their in vivo digestion, absorption, and most importantly interactions with other food components and the gastrointestinal tract. In this article, the physiological processes modulating the bioavailability of carbohydrates, specifically the rate and extent of their digestion and absorption as well as the related locations, in a whole food context, will be discussed by focusing on the activities of the gastrointestinal tract including glycolytic enzymes and glucose release, sugar sensing, gut hormones, and neurohormonal negative feedback mechanisms. It is hoped that a deep understanding of these physiological processes will facilitate the development of innovative dietary approaches to achieve desired carbohydrate or glucose bioavailability for improved health.

High-Fat Diet and Palmitate Alter the Rhythmic Secretion of Glucagon-Like Peptide-1 by the Rodent L-cell

Secretion of the incretin hormone, glucagon-like peptide-1 (GLP-1), by the intestinal L-cell is rhythmically regulated by an independent molecular clock. However, the impact of factors known to affect the activity of similar cell-autonomous clocks, such as circulating glucocorticoids and high-fat feeding, on GLP-1 secretory patterns remains to be elucidated. Herein the role of the endogenous corticosterone rhythm on the pattern of GLP-1 and insulin nutrient-induced responses was examined in corticosterone pellet-implanted rats. Moreover, the impact of nutrient excess on the time-dependent secretion of both hormones was assessed in rats fed a high-fat, high-sucrose diet. Finally, the effects of the saturated fatty acid, palmitate, on the L-cell molecular clock and GLP-1 secretion were investigated in vitro using murine GLUTag L-cells. Diurnal variations in GLP-1 and insulin nutrient-induced responses were maintained in animals lacking an endogenous corticosterone rhythm, suggesting that glucocorticoids are not the predominant entrainment factor for L-cell rhythmic activity. In addition to hyperglycemia, hyperinsulinemia, insulin resistance, and disorganization of feeding behavior, high-fat high-sucrose-fed rats showed a total abrogation of the diurnal variation in GLP-1 and insulin nutrient-induced responses, with comparable levels of both hormones at the normal peak (5:00 pm) and trough (5:00 am) of their daily pattern. Finally, palmitate incubation induced profound derangements in the rhythmic expression of circadian oscillators in GLUTag L-cells and severely impaired the secretory activity of these cells. Collectively our findings demonstrate that obesogenic diets disrupt the rhythmic activity of the L-cell, partially through a direct effect of specific nutritional components.

Potential mechanism of enhanced postprandial glucagon-like peptide-1 release following treatment with a diacylglycerol acyltransferase 1 inhibitor

Studies have demonstrated that blockade of diacylglycerol acyltransferase 1 (DGAT1) leads to prolonged release of glucagon‐like peptide 1 (GLP‐1) after meal challenge. The current study was undertaken to investigate the mechanism of action underlying the elevated levels of GLP‐1 release following pharmacological inhibition of DGAT1. We utilized a potent, specific DGAT1 inhibitor, compound A, to investigate the changes in intestinal lipid profile in a mouse model after oral administration of the compound and challenge with tracer containing fatty meal. [¹³C₁₈]‐oleic acid and LC‐MS were employed to trace the fate of dietary fatty acids provided as part of a meal challenge in lean mice. Lipid profiles in plasma, proximal to distal segments of intestine, and feces were evaluated at various times following the meal challenge to study the kinetics of fatty acid absorption, synthesis into complex lipids, and excretion. Pharmacological inhibition of DGAT1 led to reduction of postprandial total and newly synthesized triglyceride (TG) excursion and significant increases in TG and FFA levels in the distal portion of intestine enriched with enteroendocrine L cells. Enhanced levels of FFA and cholesteryl ester were observed via fecal fat profiling. DGAT1 inhibition leads to enhancement of carbon flow to the synthesis of phosphatidylcholine within the intestine. DGAT1 inhibition markedly increases levels of TG and FFA in the distal intestine, which could be the predominant contributor to the prolonged and enhanced postprandial GLP‐1 release. Inactivation of DGAT1 could provide potential benefit in the treatment of dysmetabolic diseases.

Lipid-rich diet enhances L-cell density in obese subjects and in mice through improved L-cell differentiation

The enterohormone glucagon-like peptide-1 (GLP-1) is required to amplify glucose-induced insulin secretion that facilitates peripheral glucose utilisation. Alteration in GLP-1 secretion during obesity has been reported but is still controversial. Due to the high adaptability of intestinal cells to environmental changes, we hypothesised that the density of GLP-1-producing cells could be modified by nutritional factors to prevent the deterioration of metabolic condition in obesity. We quantified L-cell density in jejunum samples collected during Roux-en-Y gastric bypass in forty-nine severely obese subjects analysed according to their fat consumption. In mice, we deciphered the mechanisms by which a high-fat diet (HFD) makes an impact on enteroendocrine cell density and function. L-cell density in the jejunum was higher in obese subjects consuming >30 % fat compared with low fat eaters. Mice fed a HFD for 8 weeks displayed an increase in GLP-1-positive cells in the jejunum and colon accordingly to GLP-1 secretion. The regulation by the HFD appears specific to GLP-1-producing cells, as the number of PYY (peptide YY)-positive cells remained unchanged. Moreover, genetically obese ob/ob mice did not show alteration of GLP-1-positive cell density in the jejunum or colon, suggesting that obesity per se is not sufficient to trigger the mechanism. The higher L-cell density in HFD-fed mice involved a rise in L-cell terminal differentiation as witnessed by the increased expression of transcription factors downstream of neurogenin3 (Ngn3). We suggest that the observed increase in GLP-1-positive cell density triggered by high fat consumption in humans and mice might favour insulin secretion and therefore constitute an adaptive response of the intestine to balance diet-induced insulin resistance.

The Anthocyanin Delphinidin 3-Rutinoside Stimulates Glucagon-Like Peptide-1 Secretion in Murine GLUTag Cell Line via the Ca2+/Calmodulin-Dependent Kinase II Pathway

Glucagon-like peptide-1 (GLP-1) is an incretin hormone secreted from enteroendocrine L-cells. Although several nutrients induce GLP-1 secretion, there is little evidence to suggest that non-nutritive compounds directly increase GLP-1 secretion. Here, we hypothesized that anthocyanins induce GLP-1 secretion and thereby significantly contribute to the prevention and treatment of diabetes. Delphinidin 3-rutinoside (D3R) was shown to increase GLP-1 secretion in GLUTag L cells. The results suggested that three hydroxyl or two methoxyl moieties on the aromatic ring are essential for the stimulation of GLP-1 secretion. Notably, the rutinose moiety was shown to be a potent enhancer of GLP-1 secretion, but only in conjunction with three hydroxyl moieties on the aromatic ring (D3R). Receptor antagonist studies revealed that D3R-stimulates GLP-1 secretion involving inositol 1,4,5-trisphosphate receptor-mediated intracellular Ca²⁺ mobilization. Treatment of GLUTag cells with a Ca²⁺/calmodulin-dependent kinaseII (CaMKII) inhibitor (KN-93) abolished D3R-stimulated GLP-1 secretion. In addition, treatment of GLUTag cells with D3R resulted in activation of CaMKII. Pre-treatment of cells with a G protein-coupled receptor (GPR) 40/120 antagonist (GW1100) also significantly decreased D3R-stimulated GLP-1 secretion. These observations suggest that D3R stimulates GLP-1 secretion in GLUTag cells, and that stimulation of GLP-1 secretion by D3R is mediated via Ca²⁺-CaMKII pathway, which may possibly be mediated by GPR40/120. These findings provide a possible molecular mechanism of GLP-1 secretion in intestinal L-cells mediated by foods or drugs and demonstrate a novel biological function of anthocyanins in regards to GLP-1 secretion.

Ghrelin Is a Novel Regulator of GLP-1 Secretion

GLP-1 is a gastrointestinal L-cell hormone that enhances glucose-stimulated insulin secretion. Hence, strategies that prevent GLP-1 degradation or activate the GLP-1 receptor are used to treat patients with type 2 diabetes. GLP-1 secretion occurs after a meal and is partly regulated by other circulating hormones. Ghrelin is a stomach-derived hormone that plays a key role in whole-body energy metabolism. Because ghrelin levels peak immediately before mealtimes, we hypothesized that ghrelin plays a role in priming the intestinal L-cell for nutrient-induced GLP-1 release. The intraperitoneal injection of ghrelin into mice 15 min before the administration of oral glucose enhanced glucose-stimulated GLP-1 release and improved glucose tolerance, whereas the ghrelin receptor antagonist D-Lys GHRP-6 reduced plasma levels of GLP-1 and insulin and diminished oral glucose tolerance. The ghrelin-mediated improvement in glucose tolerance was lost in mice coinjected with a GLP-1 receptor antagonist as well as in Glp1r(-/-) mice lacking the GLP-1 receptor. The impaired oral glucose tolerance in diet-induced obese mice was also improved by ghrelin preadministration. Importantly, ghrelin directly stimulated GLP-1 release from L-cell lines (murine GLUTag, human NCI-H716) through an extracellular signal-related kinase 1/2-dependent pathway. These studies demonstrate a novel role for ghrelin in enhancing the GLP-1 secretory response to ingested nutrients.

Postprandial glucagon-like peptide-1 secretion is increased during the progression of glucose intolerance and obesity in high-fat/high-sucrose diet-fed rats

Glucagon-like peptide-1 (GLP-1) is secreted by distal enteroendocrine cells in response to luminal nutrients, and exerts insulinotropic and anorexigenic effects. Although GLP-1 secretory responses under established obese or diabetic conditions have been studied, it has not been investigated whether or how postprandial GLP-1 responses were affected during the progression of diet-induced obesity. In the present study, a meal tolerance test was performed every week in rats fed a high-fat and high-sucrose (HF/HS) diet to evaluate postprandial glycaemic, insulin and GLP-1 responses. In addition, gastric emptying was assessed by the acetaminophen method. After 8 weeks of HF/HS treatment, portal vein and intestinal mucosa were collected to examine GLP-1 production. Postprandial glucose in response to normal meal ingestion was increased in the HF/HS group within 2 weeks, and its elevation gradually returned close to that of the control group until day 50. Slower postprandial gastric emptying was observed in the HF/HS group on days 6, 13 and 34. Postprandial GLP-1 and insulin responses were increased in the HF/HS group at 7 weeks. Higher portal GLP-1 and insulin levels were observed in the HF/HS group, but mucosal gut hormone mRNA levels were unchanged. These results revealed that the postprandial GLP-1 response to meal ingestion is enhanced during the progression of diet-induced glucose intolerance and obesity in rats. The boosted postprandial GLP-1 secretion by chronic HF/HS diet treatment suggests increased sensitivity to luminal nutrients in the gut, and this may slow the establishment of glucose intolerance and obesity.

Pros and cons of fatty acids in bone biology

Despite the growing interest in deciphering the causes and consequences of obesity-related disorders, the mechanisms linking fat intake to bone behaviour remain unclear. Since bone fractures are widely associated with increased morbidity and mortality, most notably in elderly and obese people, bone health has become a major social and economic issue. Consistently, public health system guidelines have encouraged low-fat diets in order to reduce associated complications. However, from a bone point of view, mechanisms linking fat intake to bone alteration remain quite controversial. Thus, after more than a decade of dedicated studies, this timely review offers a comprehensive overview of the relationships between bone and fatty acids. Using clinical evidences as a starting-point to more complex molecular elucidation, this work highlights the complexity of the system and reveals that bone alteration that cannot be solved simply by taking ω-3 pills. Fatty acid effects on bone metabolism can be both direct and indirect and require integrated investigations. Furthermore, even at the level of a single cell, one fatty acid is able to trigger several different independent pathways (receptors, metabolites…) which may all have a say in the final cellular metabolic response.

Nuts in the prevention and treatment of metabolic syndrome

Nuts are rich in many bioactive compounds that can exert beneficial effects on cardiovascular health. We reviewed the evidence relating nut consumption and the metabolic syndrome (MetS) and its components. Nuts reduce the postprandial glycemic response; however, long-term trials of nuts on insulin resistance and glycemic control in diabetic individuals are inconsistent. Epidemiologic studies have shown that nuts may lower the risk of diabetes incidence in women. Few studies have assessed the association between nuts and abdominal obesity, although an inverse association with body mass index and general obesity has been observed. Limited evidence suggests that nuts have a protective effect on blood pressure and endothelial function. Nuts have a cholesterol-lowering effect, but the relation between nuts and hypertriglyceridemia and high-density lipoprotein cholesterol is not well established. A recent pooled analysis of clinical trials showed that nuts are inversely related to triglyceride concentrations only in subjects with hypertriglyceridemia. An inverse association was found between the frequency of nut consumption and the prevalence and the incidence of MetS. Several trials evaluated the effect of nuts on subjects with MetS and found that they may have benefits in some components. Compared with a low-fat diet, a Mediterranean diet enriched with nuts could be beneficial for MetS management. The protective effects on metabolism could be explained by the modulation of inflammation and oxidation. Further trials are needed to clarify the role of nuts in MetS prevention and treatment.