Postprandial monocyte activation in response to meals with high and low glycemic loads in overweight women

Monocyte Trafficking and Polarization Contribute to Sex Differences in Meta-Inflammation

Obesity is associated with systemic inflammation and immune cell recruitment to metabolic tissues. Sex differences have been observed where male mice challenged with high fat diet (HFD) exhibit greater adipose tissue inflammation than females demonstrating a role for sex hormones in differential inflammatory responses. Circulating monocytes that respond to dietary lipids and chemokines and produce cytokines are the primary source of recruited adipose tissue macrophages (ATMs). In this study, we investigated sexual dimorphism in biological pathways in HFD-fed ATMs from male and female mice by RNA-seq. We also conducted chemotaxis assays to investigate sex differences in the migration of monocytes isolated from bone marrow from male and female mice toward a dietary saturated lipid - palmitate (PA), and a chemokine - monocyte chemoattractant protein 1 (MCP1), factors known to stimulate myeloid cells in obesity. ATM RNA-Seq demonstrated sex differences of both metabolic and inflammatory activation, including pathways for chemokine signaling and leukocyte trans-endothelial migration. In vivo monocyte transfer studies demonstrated that male monocytes traffic to female adipose tissue to generate ATMs more readily. In chemotaxis assays, lean male monocytes migrated in greater numbers than females toward PA and MCP1. With short-term HFD, male and female monocytes migrated similarly, but in chronic HFD, male monocytes showed greater migration than females upon PA and MCP1 stimulation. Studies with monocytes from toll-like receptor 4 knockout mice (Tlr4^-/- ) demonstrated that both males and females showed decreased migration than WT in response to PA and MCP1 implying a role for TLR4 in monocyte influx in response to meta-inflammation. Overall, these data demonstrate the role of sexual dimorphism in monocyte recruitment and response to metabolic stimuli that may influence meta-inflammation in obesity.

Excess palmitate induces decidual stromal cell apoptosis via the TLR4/JNK/NF-kB pathways and possibly through glutamine oxidation

During gestation, excess palmitate (PA) is enriched in decidua. Both excess PA and decidual dysfunctions are associated with numerous adverse pregnancy outcomes such as gestational diabetes, preeclampsia and preterm birth and intrauterine growth restriction. Here, mRNA data about the effects of PA were collected from multiple databases and analyzed. Human decidual tissues were obtained from clinically normal pregnancies, terminated for non-medical reasons, during the first trimester, and decidual stromal cells (DSCs) were isolated and exposed to PA, alone or together with the inhibitors of Toll-like receptor 4 (TLR4), Jun N-terminal kinase (JNK), nuclear factor-kappa-gene binding (NF-kB) or glutamine (GLN) oxidation. Furthermore, DSCs were transfected with lentiviral particles overexpressing human TLR4. We demonstrate that excess PA interacting with its receptor TLR4 disturbs DSC hemostasis during the first trimester. Specifically, high PA signal induced DSC apoptosis and formed an inflammatory program (elevated interleukin-1 beta and decreased interleukin-10) via the activation of TLR4/JNK/NF-kB pathways. A complexed cross-talk was found between TLR4/JNK/NF-kB signals and PA deposition in DSCs. Besides, under an excess PA environment, GLN oxidation was significantly enhanced in DSCs and the suppression of GLN oxidation further augmented PA-mediated DSC apoptosis and inflammatory responses. In conclusion, excess PA induces apoptosis and inflammation in DSCs via the TLR4/JNK/NF-kB pathways, which can be augmented by the suppression of GLN oxidation.

Breakfast can Affect Routine Hematology and Coagulation Laboratory Testing: An Evaluation on Behalf of COLABIOCLI WG-PRE-LATAM

Laboratories worldwide perform both hematological and coagulation testing on patients avoiding fasting time. In 2017, the Latin America Confederation of Clinical Biochemistry (COLABIOCLI) commissioned the Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) to study preanalytical variability and establish guidelines for preanalytical procedures to be applied by clinical laboratories and health care professionals. This study, on behalf of COLABIOCLI WG-PRE-LATAM, aims to evaluate the effect of the breakfast on routine hematology and coagulation laboratory testing. We studied 20 healthy volunteers who consumed a breakfast containing a standardized amount of carbohydrates, proteins, and lipids. We collected blood specimens for routine hematology and coagulation laboratory testing before breakfast and 1, 2, and 4 hours thereafter. Significant differences between samples were assessed by the Wilcoxon ranked-pairs test. Statistically significant differences ( p  < 0.05) between basal and 4 hours after the breakfast were observed for red blood cells, hemoglobin, hematocrit, mean corpuscular volume, white blood cells, neutrophils, lymphocytes, monocytes, mean platelet volume, and activated partial thromboplastin time. In conclusion, the significant variations observed in several hematological parameters, and activated partial thromboplastin time due to breakfast feeding demonstrate that the fasting time needs to be carefully considered prior to performing routine hematological and coagulation testing to avoid interpretive mistakes of test results, and to guarantee patient safety. Therefore, COLABIOCLI WG-PRE-LATAM encourages laboratory quality managers to standardize the fasting requirements in their laboratory, i.e., 12 hours.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

The purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk.

Is palmitate truly proinflammatory? Experimental confounders and context-specificity

Based primarily on cell culture results, saturated fatty acids (SFAs) are proposed to promote inflammation and contribute to metabolic dysfunction through Toll-like receptor activation. Studies are often complicated by a requirement for carriers (e.g., BSA) or solvents (e.g., ethanol) to increase SFA solubility. To ascertain whether these factors influence interpretations of SFA-associated inflammation activity, we measured responses of RAW264.7 monocyte/macrophages and C₂C₁₂ myotubes to various BSA, ethanol, and cyclodextrin (alternative FA carrier) conditions. Fatty acid-free, low-endotoxin BSA preparations (0.33% to 2% wt/vol) activated whereas 0.5-1.0% ethanol inhibited RAW264.7 TNFα release. Ethanol modestly increased IL-6 secretion in C₂C₁₂ myotubes. Cyclodextrins (0.3-6.0 mM) were tested as alternative carriers of palmitate, but their usefulness was limited due to toxicity and solubility issues. Using a lower-inflammation BSA source and no ethanol, ∼24-h sodium palmitate treatment (≤600 µM) failed to trigger RAW264.7 TNFα release and, in fact, significantly dampened BSA-induced inflammation by >50%. In C₂C₁₂ myotubes, only high palmitate concentrations (500-600 µM) elicited IL-6 secretion (>2.5-fold increase). Acute palmitate (200 or 500 µM) treatment did not activate MAP kinase pathways above that of fresh BSA-containing media alone in either cell type. These results highlight the importance of experimental conditions in studies exploring SFA inflammation effects. The limited (or even anti-inflammatory) effects of palmitate that we observed indicate that immunomodulatory effects of SFAs are context-specific. Thus, caution is needed when interpreting the literature related to putative proinflammatory effects of SFA.

Diabetes-mediated myelopoiesis and the relationship to cardiovascular risk

Diabetes is the greatest risk factor for the development of cardiovascular disease, which, in turn, is the most prevalent cause of mortality and morbidity in diabetics. These patients have elevations in inflammatory monocytes, a factor consistently reported to drive the development of atherosclerosis. In preclinical models of both type 1 and type 2 diabetes, studies have demonstrated that the increased production and activation of monocytes is driven by enhanced myelopoiesis, promoted by factors, including hyperglycemia, impaired cholesterol efflux, and inflammasome activation, that affect the proliferation of bone marrow precursor cells. This suggests that continued mechanistic investigations of the enhanced myelopoiesis and the generation of inflammatory monocytes are timely, from the dual perspectives of understanding more deeply the underlying bases of diabetes pathophysiology and identifying therapeutic targets to reduce cardiovascular risk in these patients.

Leucocyte-bound apolipoprotein B in the circulation is inversely associated with the presence of clinical and subclinical atherosclerosis

BACKGROUND

Atherosclerosis is a pro-inflammatory condition, in which leucocyte activation plays an important role. The interaction between circulating leucocytes and apolipoprotein (apo) B-containing lipoproteins results in pro-inflammatory changes of these cells. We aimed to evaluate the relationship between apo B bound to circulating leucocytes and atherosclerosis.

METHODS

Apo B on circulating leucocytes was measured by flow cytometry in subjects with and without cardiovascular disease (CVD), expressed as mean fluorescent intensity in arbitrary units (au). Carotid intima-media thickness (cIMT) was measured using B-mode ultrasound. Data are given as median (interquartile range).

RESULTS

A total of 396 subjects were included, of whom 183 had a history of CVD. Compared to subjects without CVD, patients with CVD had lower apo B bound to neutrophils (12·7 au (9·8-16·2) and 14·2 au (10·1-17·5), respectively, P = 0·038) and to monocytes (2·5 au (1·7-3·1) and 2·7 (1·9-3·6) au, respectively, P = 0·025). No differences were found for lymphocyte-bound apo B. Neutrophil- and monocyte-bound apo B were inversely correlated with cIMT (Spearman's rho: -0·123, P = 0·017 and -0·108, P = 0·035, respectively). Both monocyte- and neutrophil-bound apo B were inversely associated with different factors related to the metabolic syndrome, such as body mass index, triglycerides and complement C3. There was a positive association between erythrocyte-bound apo B and apo B bound to each of the leucocyte classes, possibly reflecting a similar mechanism. Discontinuation of statins in 54 subjects did not influence leucocyte-bound apo B.

CONCLUSION

Unexpectedly, the presence of noninternalized apo B-containing lipoproteins on circulating neutrophil and monocyte membranes may represent a protective mechanism against atherosclerosis.

Coronary leukocyte activation in relation to progression of coronary artery disease

Leukocyte activation has been linked to atherogenesis, but there is little in vivo evidence for its role in the progression of atherosclerosis. We evaluated the predictive value for progression of coronary artery disease (CAD) of leukocyte activation markers in the coronary circulation. Monocyte and neutrophil CD11b, neutrophil CD66b expression and intracellular neutrophil myeloperoxidase (MPO) in the coronary arteries were determined by flow cytometry in patients undergoing coronary angiography. The primary outcome included fatal and nonfatal myocardial infarction or arterial vascular intervention due to unstable angina pectoris. In total 99 subjects who were included, 70 had CAD at inclusion (26 patients had single-vessel disease, 18 patients had twovessel disease and 26 patients had three-vessel disease). The median follow-up duration was 2242 days (interquartile range: 2142-2358). During follow-up, 13 patients (13%) developed progression of CAD. Monocyte CD11b, neutrophil CD11b and CD66b expression and intracellular MPO measured in blood obtained from the coronary arteries were not associated with the progression of CAD. These data indicate that coronary monocyte CD11b, neutrophil CD11b and CD66b expression and intracellular MPO do not predict the risk of progression of CAD.

Potential Drug Combinations to Reduce Cardiovascular Disease Burden in Diabetes

The major cause of death and complications in patients with type 2 diabetes (T2DM) is cardiovascular disease (CVD). More than 60% of all patients with T2DM die of CVD, and an even greater percentage have serious complications. The impact of glucose lowering on cardiovascular complications is a hotly debated issue and recent large clinical trials reported no significant decrease in cardiovascular events with intensive glucose control. Risk remains high even after correcting diabetes-associated dyslipidemia with drugs such as fibrates and niacin. Data from several clinical studies show that postprandial glucose and lipids have a strong predictive value on myocardial infarction (MI) and mortality. However, strategies to reduce postprandial hyperglycemia and/or lipemia through increased utilization of glucose and/or triglycerides (TG) have been shown to not be effective in reducing the CVD burden. In this review, I discus the preferred ways to reduce postprandial glucose and TG with combinations of currently marketed drugs with potential benefit in CVD.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.

Effects of a Macro-Nutrient Preload on Type 2 Diabetic Patients

AIMS

Macro-nutrient preloads given 30 min before regular meals may improve metabolism. The aim was to investigate how type 2 diabetic patients react to a preload consisting of a blend of macro-nutrients with a low-glycemic index (Inzone Preload(®)).

METHODS

In a before-after study design, 30 subjects with type 2 diabetes mellitus (T2DM) were enrolled in a 12-week program. All subjects were given Inzone Preload (43% proteins, 29% carbohydrates, 10% lipids, and 9% fibers, 71 kcal), 30 min before each meal during 12 weeks. Fasting glucose and postprandial 2 h glucose were monitored every second week. Body weight (BW) and waist circumference were measured each month. Fasting plasma glucose, glycosylated hemoglobin, serum lipids, fasting insulin, C-reactive protein, and homeostasis model assessment were evaluated before and after the intervention. Subjective appetite was monitored using visual analogue scales after the Inzone Preload.

RESULTS

The dietary intervention significantly influenced several metabolic parameters compared to base line. Inzone Preload treatment reduced mean postprandial plasma glucose levels (12.2 ± 1.2 vs. 10.5 ± 2.0 mmol/L), HbA1c (7.4 ± 0.3 vs. 7.1 ± 0.2%), mean total cholesterol (4.8 ± 0.9 vs. 4.3 ± 0.8 mmol/L), low-density lipoprotein cholesterol (2.8 ± 0.6 vs. 2.5 ± 0.4 mmol/L), and CRP (1.5 ± 1.4 vs. 0.7 ± 0.7 mg/L). BW loss of more than 3% was seen in 13 participants (43%). Feelings of satiety were significantly higher after Inzone Preload than after habitual breakfast (p < 0.05). No significant changes in fasting blood glucose, high-density lipoprotein and total triacylglycerol, HOMA-IR, and HOMA-β were observed.

CONCLUSION

A macro-nutrient preload treatment reduces postprandial glucose, inflammatory markers, and serum lipids in patients with T2DM. Approximately half of the study group also displayed reduced BW.

Glycemic index, glycemic load, and pulse wave reflection in adults

BACKGROUND AND AIMS

Diets with a high glycemic index (GI), high glycemic load (GL), or both, increase the risk of cardiovascular disease. This study examined the association of GI and GL in a regular diet with the peripheral augmentation index (i.e., a marker of vascular aging) in a sample of adults.

METHODS AND RESULTS

Cross-sectional study. The findings presented in this manuscript are a subanalysis of the EVIDENT study whose purpose was to analyze the relationship between lifestyle and arterial aging. For the sample population, 1553 individuals aged 20-80 years were selected through random sampling from the patients of general practitioners at six health centers in Spain. GI and GL for each patient's diet were calculated from a previously validated, semi-quantitative, 137-item food frequency questionnaire. The peripheral augmentation index corrected for a heart rate of 75 bpm (PAIx75) was measured with pulse-wave application software (A-Pulse CASP). Based on a risk factor adjusted regression model, for every 5 unit increase in GI, the PAIx75 increased by 0.11 units (95% CI: 0.04-0.19). Similarly, for every increase in 10 units in GL, the PAIx75 increased by 1.13 (95% CI: 0.21-2.05). High PAIx75 values were observed in individuals with diets in the third GI tertile (i.e., the highest), and lower PAIx75 values in those with diets in the first tertile (i.e., the lowest), (93.1 vs. 87.5, respectively, p = 0.001).

CONCLUSIONS

GI and GL were directly associated with PAIx75 values in adults without cardiovascular diseases regardless of age, gender, physical activity, and other confounders.

Sweet potato [Ipomoea batatas (L.) Lam. "Tainong 57"] starch improves insulin sensitivity in high-fructose diet-fed rats by ameliorating adipocytokine levels, pro-inflammatory status, and insulin signaling

The aim of this study was to investigate the effects of low-glycemic index (GI) sweet potato starch on adipocytokines, pro-inflammatory status, and insulin signaling in the high-fructose diet-induced insulin-resistant rat. We randomly divided 24 insulin-resistant rats and 16 normal rats into two groups fed a diet containing 575 g/kg of starch: a low-GI sweet potato starch (S) or a high-GI potato starch (P). The four experimental groups were labeled as follows: insulin-resistant P (IR-P), insulin-resistant S (IR-S), normal P (N-P) and normal S (N-S). After 4 wk on the experimental diets, an intraperitoneal glucose tolerance test (IPGTT) was conducted, and the homeostasis model assessment (HOMA), adipocytokines, pro-inflammatory cytokines levels, and insulin signaling-related protein expression were measured. The homeostasis model assessment values were significantly lower in the IR-S than in the IR-P group, suggesting that insulin sensitivity was improved among sweet potato starch-fed rats. Levels of tumor necrosis factor-α, interleukin-6, resistin, and retinol binding protein-4 were significantly lower in the IR-S versus the IR-P group, indicating an improvement of pro-inflammatory status in sweet potato starch-fed rats. The sweet potato starch diet also significantly enhanced the protein expression of phospho-Tyr-insulin receptor substrate-1 and improved the translocation of glucose transporter 4 in the skeletal muscle. Our results illustrated that sweet potato starch feeding for 4 wk can improve insulin sensitivity in insulin-resistant rats, possibly by improving the adipocytokine levels, pro-inflammatory status, and insulin signaling.

Acute intake of a high-fructose diet alters the balance of adipokine concentrations and induces neutrophil influx in the liver

The postprandial state is a period of metabolic fluxes, biosynthesis and oxidative metabolism. A considerable amount is known about the inflammatory response to the chronic consumption of fructose, but little is known about its effects in the postprandial state. The aim of the present study was to investigate the inflammatory effects of a single meal containing fructose on healthy mice. Male BALB/c and LysM-eGFP mice at 12-14 weeks were divided into three groups: fasted, control (mice fed with a sucrose-containing diet) and fructose (mice fed with a fructose-containing diet). One, 2 or 4 h postprandial, the BALB/c mice were killed, and samples were collected. LysM-eGFP mice were submitted to intravital microscopy. The fed mice showed a low-grade inflammatory response apart from dietary composition, which was characterized by increased numbers of leukocytes and high serum concentrations of pentraxin 3, leptin and resistin. TNF-α and CCL2 concentrations rose in the liver after the meal. IL-6 concentration increased and IL-10 decreased in the adipose tissue of the fed mice. Mice fed with the fructose-containing diet showed an intensification of the inflammatory response. Furthermore, the adiponectin concentration dropped, and the liver influx of neutrophils increased after fructose intake. Overall, this study showed a rapid increase in the systemic and tissue-specific immune response after a balanced meal. The study also showed an increased neutrophil influx in liver associated with an imbalance of adipokine concentrations and an increase of cytokine in the liver and adipose tissue following a fructose-containing meal.

A low-glycemic load diet reduces serum C-reactive protein and modestly increases adiponectin in overweight and obese adults

Low-glycemic load (GL) diets improve insulin resistance and glucose homeostasis in individuals with diabetes. Less is known about whether low-GL diets, independent of weight loss, improve the health profile for persons without diabetes or other preexisting conditions. We conducted a randomized, cross-over feeding study testing low- compared to High-GL diets on biomarkers of inflammation and adiposity in healthy adults. Eighty participants (n = 40 with BMI 18.5-24.9 kg/m²; n = 40 with BMI 28.0-40.0 kg/m²) completed two 28-d feeding periods in random order where one period was a high-GL diet (mean GL/d = 250) and the other a low-GL diet (mean GL/d = 125). Diets were isocaloric with identical macronutrient content (as percent energy). All food was provided and participants maintained weight and usual physical activity. Height, weight, and DXA were measured at study entry and weight assessed again thrice per week. Blood was drawn from fasting participants at the beginning and end of each feeding period and serum concentrations of high-sensitivity CRP, serum amyloid A, IL-6, leptin, and adiponectin were measured. Linear mixed models tested the intervention effect on the biomarkers; models were adjusted for baseline biomarker concentrations, diet sequence, feeding period, age, sex, and body fat mass. Among participants with high-body fat mass (>32.0% for males and >25.0% for females), the low-GL diet reduced CRP (P = 0.02) and marginally increased adiponectin (P = 0.06). In conclusion, carbohydrate quality, independent of energy, is important. Dietary patterns emphasizing low-GL foods may improve the inflammatory and adipokine profiles of overweight and obese individuals.

Plasma interleukin-1β concentrations are closely associated with fasting blood glucose levels in healthy and preclinical middle-aged nonoverweight and overweight Japanese men

Plasma interleukin (IL)-1β and IL-6 are markers that predict the risk of inflammation in diabetes. In the current study, we examined the relationship between fasting glucose and plasma inflammatory cytokines (IL-1β and IL-6) concentrations in healthy and preclinical middle-aged Japanese men (mean ± SD, 58.7 ± 7.8 years old) divided according to body mass index (<25 kg/m(2), nonoverweight group; ≥25 kg/m(2), overweight group). We conducted a cross-sectional study of 413 healthy and preclinical men aged 40 to 69 years who participated in health checkups in Japan. We measured their clinical parameters, lifestyle factors, and plasma IL-1β and IL-6 concentrations. Participants were classified according to their fasting blood glucose levels, and we compared their plasma cytokine levels. Plasma IL-1β and IL-6 levels in nonoverweight subjects were positively and strongly associated with fasting blood glucose and hemoglobin A(1c); in contrast, these cytokines were strongly associated with homeostasis model assessment of insulin resistance and fasting glucose in overweight subjects. Significant positive associations between plasma IL-1β and glucose concentrations were observed within the groups classified according to glucose concentrations, after adjustment for age and body mass index. The results of our current study show that plasma IL-1β levels are strongly associated with fasting blood glucose concentrations in healthy and preclinical nonoverweight and overweight Japanese men.

Time-dependent changes in the expression of lymphocyte and monocyte cell adhesion molecules after meals of different composition

The objective of the present study was to compare the acute effect of meals of different composition on the expression of adhesion molecules that play a key role in leucocyte trafficking. A total of twenty apparently healthy subjects randomly consumed three isoenergetic meals 1 week apart: enriched in carbohydrates (CHO), enriched in monounsaturated fat and enriched in saturated fat. Blood samples were obtained before the meals and at 2, 4, 6, 8 and 10 h after meal ingestion. Samples were analysed for LDL resistance to Cu-mediated oxidation and for the surface expression on peripheral blood mononuclear cells (PBMC) of CD62L, CD162, CD11a, CD11b, CD49d and CD54 by flow cytometry. The present results showed that there were no changes in LDL susceptibility to oxidation within and among the meals. After the CHO-enriched meal, there was a time-dependent increased expression of CD162, CD49d, CD11a and CD54 on PBMC that returned to basal values after 8-10 h. These changes were significantly greater than the ones observed after the consumption of the monounsaturated fat- and the saturated fat-enriched meals and were more evident in lymphocytes than in monocytes. In conclusion, acute ingestion of a CHO-enriched meal induces higher increases of lymphocyte activation markers than fat-enriched meals. These results suggest that long-term consumption of CHO-enriched diets may be associated with a sustained pro-inflammatory state.

Effects of glycemic load on metabolic risk markers in subjects at increased risk of developing metabolic syndrome

BACKGROUND

Epidemiologic studies suggest that diets with a low glycemic index (GI) or glycemic load (GL) are associated with a decreased risk of developing metabolic syndrome. Intervention studies are inconsistent, however, possibly due to differences in macronutrient and fiber compositions of the experimental diets.

OBJECTIVE

We tested side-by-side test foods with similar macronutrient and fiber compositions but with different sucrose-flour ratios or carbohydrate source to determine the effects of different GIs and GLs on metabolic risk markers in overweight subjects.

DESIGN

Overweight men (n = 9) and women (n = 6) received in random order for 11 wk 4 test foods with an increased GI or a decreased GI (69 compared with 40, 86 compared with 48, 63 compared with 37, and 51 compared with 20, respectively). There was a GL difference of 32 units between the 2 interventions.

RESULTS

At the end of the 11-wk intervention periods, the decreased GL test foods did not change fasting plasma glucose (mean +/- SD: 5.83 +/- 0.6 compared with 5.94 +/- 0.6 mmol/L) or insulin (8.3 +/- 2.8 compared with 9.8 +/- 5.1 mU/L) concentrations compared with increased GL test foods. Serum total cholesterol (5.56 +/- 0.90 compared with 5.76 +/- 1.04 mmol/L), LDL-cholesterol (3.57 +/- 0.72 compared with 3.68 +/- 0.80 mmol/L), HDL-cholesterol (1.21 +/- 0.38 compared with 1.24 +/- 0.37 mmol/L), and triacylglycerol (1.61 +/- 0.77 compared with 1.78 +/- 1.04 mmol/L) concentrations were also not significantly different for decreased and increased GL test foods, respectively. Finally, proinflammatory (high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-alpha, monocyte chemoattractant protein 1) and prothrombotic (plasminogen activator inhibitor 1) markers were not affected. Glucose and lipids were also analyzed after 1 and 5 wk of intervention and were not affected by the intervention.

CONCLUSION

When incorporated into a habitual diet, consumption of test foods with a decreased GL does not ameliorate metabolic risk markers in overweight subjects.

Effects of low- and high-glycemic index/glycemic load diets on coronary heart disease risk factors in overweight/obese men

Chronic insulin resistance contributes to subclinical inflammation, thrombosis/impaired fibrinolysis, and dyslipidemia. The effect of dietary carbohydrate, specifically of glycemic index (GI) and glycemic load (GL), on established and emerging coronary heart disease risk factors has not been elucidated fully. We conducted a randomized crossover feeding study of matched diets differing only in GI and GL in 24 overweight or obese but otherwise healthy men to investigate the effects on insulin sensitivity, inflammation, thrombosis/fibrinolysis, lipoproteins/lipids, and body composition. All meals for the high- and low-GI/GL diets were prepared in a metabolic kitchen. Each participant consumed both diets in random order for 4 weeks each, with a 4-week washout period in between. Each participant underwent a frequently sampled intravenous glucose tolerance test for assessment of insulin sensitivity; blood sampling for the measurement of inflammatory markers, coagulation factors, and lipoproteins/lipids; and dual-energy x-ray absorptiometry for assessment of body composition at the beginning and end of each dietary period. There were no statistically significant differences in glucose metabolism factors, inflammatory markers, or coagulation factors after 4 weeks on the high- and low-GI/GL diets. The high-GI/GL diet resulted in a slightly greater reduction in fat mass and a slightly greater increase in lean mass compared with the low-GI/GL diet. The high-GI/GL diet resulted in significant, but unexpected, reductions in total and low-density lipoprotein cholesterol, whereas high-density lipoprotein cholesterol concentration was significantly reduced on the high-GI/GL diet compared with the low-GI/GL diet. Overall, high- and low-GI/GL diets of 4 weeks' duration had no consistent effects on coronary heart disease risk factors in this group of overweight/obese men.

Effects of glycemic load on metabolic health and type 2 diabetes mellitus

A large body of epidemiologic evidence has demonstrated that the combination of a Western diet and lifestyle is primarily responsible for the increased metabolic disease risk, such as obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome, noted in society today. Thus finding optimal intervention strategies to combat these growing epidemics is imperative. Despite some controversy, a growing body of literature indicates that one aspect of diet that likely affects phenotypic outcomes and metabolic disease risk is the glycemic load (GL). This brief review will provide an overview of the GL concept, discuss epidemiologic work investigating relationships between both GL and metabolic risk factors, as well as intervention studies that have assessed the impact of GL on phenotypic outcomes related to T2DM and cardiovascular disease. Overall, a low dietary GL may be protective against metabolic disease and should be considered as a healthful dietary component.

High-fat, energy-dense, fast-food-style breakfast results in an increase in oxidative stress in metabolic syndrome

The metabolic syndrome (MetS) is associated with an increased incidence of diabetes and coronary heart disease. Postprandial lipemia is a prominent feature of dyslipidemia in both type 2 diabetes mellitus and MetS and is also associated with coronary heart disease. Oxidative stress and inflammation are pivotal in all stages of atherosclerosis; however, there is a paucity of data on postprandial oxidative stress and inflammation in subjects with MetS. Thus, the primary aim of this study was to compare the postprandial effects of an energy-dense, high-fat, fast-food-style (FFS) meal with an American Heart Association (AHA)-recommended heart-healthy meal on biomarkers of oxidative stress and inflammation in subjects with MetS. A total of 11 subjects with MetS completed the study. Glucose levels were significantly increased 2 hours after both FFS and AHA diets (P < .0001), and high-density lipoprotein cholesterol levels significantly decreased in FFS diet but not in the AHA diet (P for interaction < .05). Total triglyceride levels significantly increased postprandially only in the FFS meal but not in the AHA meal (P for interaction = .03). Plasma thiobarbituric acid reactive substances and malondialdehyde + hydroxynonenal increased significantly with time in both dietary groups, and the postprandial increase was greater in the FFS diet compared to the AHA diet (P < .0005). Serum high-sensitivity C-reactive protein, interleukin 6, and tumor necrosis factor levels did not change with time or dietary treatment. The postprandial increase in interleukin 1b was significantly higher with the FFS meal, thus resulting in significant differences between both treatments (P for interaction = .03). Thus, in subjects with MetS, consumption of an energy-dense, fatty meal (FFS breakfast) results in increased postprandial oxidative stress compared to a heart-healthy meal (AHA).

Inflammation markers are modulated by responses to diets differing in postprandial insulin responses in individuals with the metabolic syndrome

BACKGROUND

Inflammation may be a mechanism by which high postprandial insulin and glucose responses increase the risk of type 2 diabetes mellitus.

OBJECTIVE

We hypothesized that dietary carbohydrates characterized by different postprandial insulin responses may differentially modify cytokine concentrations in plasma and gene expression in subcutaneous adipose tissue.

DESIGN

Individuals (n = 47) with the metabolic syndrome were randomly assigned to a 12-wk diet with oat and wheat bread and potato (high postprandial insulin response) or rye bread and pasta (low postprandial insulin response). Postprandial glucose and insulin responses to the oat and wheat bread meal and to the rye bread meal were determined in 19 individuals before intervention.

RESULTS

During the 12-wk diet, the change in the gene expression of interleukin (IL)-10 receptor alpha and tumor necrosis factor-alpha in subcutaneous adipose tissue differed between the groups (P = 0.002 and P = 0.083, respectively). Moreover, the change in fasting plasma concentrations of IL-1beta and IL-6 differed between the groups (P = 0.020 and P = 0.055, respectively). In the postprandial challenge, the insulin response to the rye bread meal was lower than that to the oat and wheat bread meal (P < 0.001), whereas there were no differences in the mean blood glucose response. In contrast, plasma glucose concentrations decreased more below fasting concentrations 2.5-3 h after the oat and wheat bread meal than after the rye bread meal. A late postprandial rebound of free fatty acids was detected after the oat and wheat bread meal (P = 0.048).

CONCLUSIONS

Long-term intake of cereal foods with differing postprandial insulin responses may be a factor that modulates the inflammatory status in individuals with the metabolic syndrome.

The metabolic syndrome in relation with the glycemic index and the glycemic load

The metabolic syndrome (MS) is a clustering of metabolic abnormalities that increases the risk to develop chronic diseases such as cardiovascular disease and type 2 diabetes mellitus. Although its precise aetiology is unknown, dietary habits play a major role. Nowadays, more and more attention is paid to the glycemic index (GI) and the glycemic load (GL) of a diet. The GI of a food is a value based on the average increase in blood glucose levels occurring when a 50 g carbohydrate portion of that food is consumed. The GL accounts for the amount of carbohydrate per serving. From reviewing the current literature, we conclude that for healthy and/or overweight subjects the importance of low GI or GL diets in relation to the metabolic syndrome has not been established. One of the reasons is that the diets used in the intervention studies frequently not only differed in GI or GL, but also in fibre, protein and/or fat content. In some of the prospective cohort studies, effects of GI or GL attenuated or even disappeared after correcting for fibre intake. This makes it impossible to ascribe the possible beneficial metabolic effects of low GI or GL diets unequivocally to the GI or GL. The question, therefore, remains open on to what components of the metabolic syndrome are specifically affected by the GI per se. To answer this question, controlled longer-term intervention studies are needed to monitor the effects of the GI on the various components of the metabolic syndrome.