Saturated fat intake and insulin resistance in men with coronary artery disease. The Stanford Coronary Risk Intervention Project Investigators and Staff

Moderate Consumption of Red Meat, Compared to Soy or Non-Soy Legume, Has No Adverse Effect on Cardio-Metabolic Factors in Patients with Type 2 Diabetes

BACKGROUND

Recently, it has been proposed that red meat consumption could enhance risk of diabetes and worsen lipid profile and glycemic status, in comparison with soy or non-soy legume, but the results of clinical trials are controversial.

OBJECTIVES

This study aimed to compare the effect of red meat, soy bean, and non-soy legume consumption on cardio-metabolic factors in patients with type 2 diabetes.

METHODS

This was a randomized controlled clinical trial which included 75 patients with diabetes, aged 40-65 years. Participants were randomly allocated to receive two servings of red meat (control group), soy bean, or non-soy legume, 3 days a week for 8 weeks. All groups also received a balanced-macronutrients weight maintenance diet. Body composition and cardio-metabolic factors including fasting blood glucose (FBG), fasting insulin, glycated hemoglobin (HbA1c), serum lipids, and blood pressure were measured at baseline and endpoint of the study. Quantitative insulin sensitivity check index (QUICKI) score and Framingham risk score (FRS) were also computed.

RESULTS

We found no significant differences in changes of FBG, fasting insulin, HbA1c, QUICKI score, serum lipids, FRS, and systolic and diastolic blood pressure among the 3 groups. Within group analysis showed that FRS reduced significantly in all groups (P<0.05). In addition, systolic (P=0.01) and diastolic (P=0.03) blood pressure reduced within red meat group.

CONCLUSIONS

Compared to soy bean or non-soy legume, moderate consumption of red meat had no adverse effect on cardio-metabolic factors including FBG, fasting insulin, HbA1C, QUICKI score, total cholesterol, low-density lipoprotein , high-density lipoprotein , and blood pressure in adults with type 2 diabetes.

Invited review: Milk fat globule membrane-A possible panacea for neurodevelopment, infections, cardiometabolic diseases, and frailty

Milk is an evolutionary benefit for humans. For infants, it offers optimal nutrients for normal growth, neural development, and protection from harmful microbes. Humans are the only mammals who drink milk throughout their life. Lipids in colostrum originate mostly from milk fat globule membrane (MFGM) droplets extruded from the mammary gland. The MFGM gained much interest as a potential nutraceutical, due to their high phospholipid (PL), ganglioside (GD), and protein contents. In this review, we focused on health effects of MFGM ingredients and dairy food across the life span, especially on neurodevelopment, cardiometabolic health, and frailty in older adults. The MFGM supplements to infants and children reduced gastrointestinal and respiratory tract infections and improved neurodevelopment due to the higher content of protein, PL, and GD in MFGM. The MFGM formulas containing PL and GD improved brain myelination and fastened nerve conduction speed, resulting in improved behavioral developments. Administration of MFGM-rich ingredients improved insulin sensitivity and decreased inflammatory markers, LDL-cholesterol, and triglycerides by lowering intestinal absorption of cholesterol and increasing its fecal excretion. The MFGM supplements, together with exercise, improved ambulatory activities, leg muscle mass, and muscle fiber velocity in older adults. There are great variations in the composition of lipids and proteins in MFGM products, which make comparisons of the different studies impossible. In addition, investigations of the individual MFGM components are required to evaluate their specific effects and molecular mechanisms. Although we are currently only beginning to understand the possible health effects of MFGM products, the current MFGM supplementation trials as presented in this review have shown significant clinical health benefits across the human life span, which are worth further investigation.

Regional Variations of Insulin Secretion and Insulin Sensitivity in Japanese Participants With Normal Glucose Tolerance

Purpose: Regional differences in dietary patterns in Asian countries might affect the balance of insulin response and sensitivity. However, this notion is yet to be validated. To clarify the regional differences in the insulin response and sensitivity and their relationship to nutrients, we compared the insulin secretory response during an oral glucose tolerance test in Japanese participants. Methods: This observational retrospective cohort study analyzed the data from participants with normal glucose tolerance (NGT) from four distinct areas of Japan with regard to the food environment: Fukushima, Nagano, Tokushima, and Okinawa based on data available in the Japanese National Health Insurance database. Results: Although the glucose levels were comparable among the four regions, the insulin responses were significantly different among the regions. This difference was observed even within the same BMI category. The plot between the insulin sensitivity index (Matsuda index) and insulin_AUC/glucose_AUC or the insulinogenic index showed hyperbolic relationships with variations in regions. The indices of insulin secretion correlated positively with fat intake and negatively with the intake of fish, carbohydrate calories, and dietary fiber. Conclusions: We found that significant regional differences in insulin response and insulin sensitivity in Japanese participants and that nutritional factors may be linked to these differences independently of body size/adiposity. Insulin response and insulin sensitivity can vary among adult individuals, even within the same race and the same country, and are likely affected by environmental/lifestyle factors as well as genetic traits.

Diet pattern may affect fasting insulin in a large sample of black and white adults

OBJECTIVE

Dietary modification of insulin resistance may be a strategy for reducing chronic disease. For this study, we tested the hypothesis that higher fasting insulin, a marker for insulin resistance, would be related to diet patterns with a high proportion of carbohydrates, those with a high glycemic index, and those characterized by added sugar and processed starches.

STUDY DESIGN

Data were analyzed on 13,528 nondiabetic participants of the REasons for Geographic and Ethnic Differences in Stroke (REGARDS), an observational study of adults aged ≥45 years residing in 1855 counties across the continental USA. Information on habitual diet was collected using the Block 98 Food Frequency Questionnaire. Percent energy from carbohydrate, glycemic index, and glycemic load were determined for each participant, as well as adherence to five established diet patterns. Logistic regression was used to examine associations of baseline diet characteristics with odds for high fasting insulin [quartiles 3 and 4 (median = 98.9 pmol/L) vs. quartile 1], after adjusting for covariates.

RESULT

Greater percent carbohydrate, glycemic index, and glycemic load, and adherence to sweets/fat and southern diet patterns, was associated with greater odds for high insulin (P for trend <0.05 to <0.0001), whereas adherence to the plant-based and alcohol/salad patterns was associated with lower odds for high insulin (P for linear trend <0.0001).

CONCLUSION

In conclusion, diet pattern is associated with fasting insulin. Future studies are needed to determine if diet interventions designed to lower insulin, perhaps based on the patterns identified in this study, can improve risk for chronic disease.

Role of diet and lifestyle modification in the management of nonalcoholic fatty liver disease and type 2 diabetes

Nonalcoholic fatty liver disease (NAFLD) is considered as the hepatic evidence of insulin resistance which is the hallmark of type 2 diabetes. NAFLD is considered as the risk factor for developing type 2 diabetes and has a high frequency of occurrence in those with existing type 2 diabetes. Compared with patients with only NAFLD or type 2 diabetes, these patients show a poor metabolic profile and increase mortality. Hence, effective treatment strategies are necessary. Here, we review the role of diet and lifestyle modification in the management of NAFLD and type 2 diabetes. Based on the available studies, it has been shown that the addition of any kind of physical activity or exercise is beneficial for patients with both NAFLD and type 2 diabetes. Proper dietary management leads to weight loss are also effective in improving metabolic parameters in patients with both NAFLD and type 2 diabetes. In conclusion, it is clear that increasing physical activity or exercise is effective in improving metabolic parameters in patients who are suffering with both NAFLD and type 2 diabetes.

Nutrition intake among the Japanese elderly: an intergenerational comparison based on national health and nutrition survey scores

Context: The average Japanese lifespan became the longest in the world in 1986. What factors give the Japanese this longevity? Washoku, or the traditional Japanese diet, is respected globally for its nutritionally-balanced and healthy eating habits. This uniquely Japanese way of eating may be one factor that helps extend the Japanese lifespan. Objective: To explain the nutrition intake characteristics of today's Japanese elderly compared with their children's generation and to discuss the association between nutrition intake and various diseases and health issues in the general adult population. Methods: This study compared the characteristics of nutrition status and nutrition intake among today's elderly and their children's generation by using National Health and Nutrition Survey scores. Results: Japanese elderly had high adequacy in all nutrients as well as a high intake of potatoes, pulses, vegetables, fruits, algae, and fish and shellfish compared with their children's generation. Conclusion: Nutrition intake among the Japanese elderly had the characteristics of washoku, but these characteristics were not passed on to the next generation. Extension of the average lifespan and improved health could be achieved by modifying nutrition intake, even after reaching the age of onset of lifestyle- and age-related diseases, typically the 50s.

Dairy product consumption and its association with metabolic disturbance in a prospective study of urban adults

The role of dairy foods and related nutrients in cardiometabolic health aetiology is poorly understood. We investigated longitudinal associations between the metabolic syndrome (MetS) and its components with key dairy product exposures. We used prospective data from a bi-racial cohort of urban adults (30-64 years at baseline (n 1371)), the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS), in Baltimore City, MD (2004-2013). The average of two 24-h dietary recalls measured 4-10 d apart was computed at baseline (V1) and follow-up (V2) waves. Annual rates of change (Δ) in dairy foods and key nutrients were estimated. Incident obesity, central obesity and the MetS were determined. Among key findings, in the overall urban adult population, both cheese and yogurt (V1 and Δ) were associated with an increased risk of central obesity (hazard ratio (HR) 1·13; 95 % CI 1·05, 1·23 per oz equivalent of cheese (V1); HR 1·21; 95 % CI 1·01, 1·44 per fl oz equivalent of yogurt (V1)]. Baseline fluid milk intake (V1 in cup equivalents) was inversely related to the MetS (HR 0·86; 95 % CI 0·78, 0·94), specifically to dyslipidaemia-TAG (HR 0·89; 95 % CI 0·81, 0·99), although it was directly associated with dyslipidaemia-HDL-cholesterol (HR 1·10; 95 % CI 1·01, 1·21). Furthermore, ΔCa and ΔP were inversely related to dyslipidaemia-HDL and MetS incidence, respectively, whereas Δdairy product fat was positively associated with incident TAG-dyslipidaemia and HDL-cholesterol-dyslipidaemia and the MetS. A few of those associations were sex and race specific. In sum, various dairy product exposures had differential associations with metabolic disturbances. Future intervention studies should uncover how changes in dairy product components over time may affect metabolic disorders.

Three days of a eucaloric, low-carbohydrate/high-fat diet increases insulin clearance in healthy non-obese Japanese men

Metabolic clearance rate of insulin (MCRI) is thought to help maintain glucose homeostasis even in healthy subjects. However, the effect of a low carbohydrate/high fat (LCHF) diet on MCRI in healthy subject remains unclear. To investigate the effect of a 3-day eucaloric LCHF diet on MCRI in healthy subjects, we studied 42 healthy non-obese Japanese men. Each subject consumed a eucaloric LCHF diet for 3 days. Before and after the LCHF diet, intramyocellular lipid (IMCL) levels were measured using ¹H-magnetic resonance spectroscopy, and glucose infusion rate (GIR) and MCRI were evaluated with a euglycemic hyperinsulinemic clamp. The LCHF diet increased MCRI by 10% and decreased steady state serum insulin (SS_SI) and GIR during glucose clamp by 10% and 6%, respectively. To further investigate the role of MCRI, we divided subjects into high-responder (HR) and low-responder (LR) groups based on the median %change in MCRI. The LCHF diet increased IMCL and decreased SS_SI during glucose clamp in the HR group, while those were not altered in the LR group. Our results suggested that a 3-day eucaloric LCHF diet increases MCRI in healthy non-obese Japanese men. This change seemed to be beneficial in terms of maintaining euglycemia during low carbohydrate availability.

A Plant-Based Meal Stimulates Incretin and Insulin Secretion More Than an Energy- and Macronutrient-Matched Standard Meal in Type 2 Diabetes: A Randomized Crossover Study

Diminished postprandial secretion of incretins and insulin represents one of the key pathophysiological mechanisms behind type 2 diabetes (T2D). We tested the effects of two energy- and macronutrient-matched meals: A standard meat (M-meal) and a vegan (V-meal) on postprandial incretin and insulin secretion in participants with T2D. A randomized crossover design was used in 20 participants with T2D. Plasma concentrations of glucose, insulin, C-peptide, glucagon-like peptide-1 (GLP-1), amylin, and gastric inhibitory peptide (GIP) were determined at 0, 30, 60, 120, and 180 min. Beta-cell function was assessed with a mathematical model, using C-peptide deconvolution. Repeated-measures ANOVA was used for statistical analysis. Postprandial plasma glucose responses were similar after both test meals (p = 0.64). An increase in the stimulated secretion of insulin (by 30.5%; 95% CI 21.2 to 40.7%; p < 0.001), C-peptide (by 7.1%; 95% CI 4.1 to 9.9%; p < 0.001), and amylin (by 15.7%; 95% CI 11.8 to 19.7%; p < 0.001) was observed following consumption of the V-meal. An increase in stimulated secretion of GLP-1 (by 19.2%; 95% CI 12.4 to 26.7%; p < 0.001) and a decrease in GIP (by −9.4%; 95% CI −17.3 to −0.7%; p = 0.02) were observed after the V-meal. Several parameters of beta-cell function increased after the V-meal, particularly insulin secretion at a fixed glucose value 5 mmol/L, rate sensitivity, and the potentiation factor. Our results showed an increase in postprandial incretin and insulin secretion, after consumption of a V-meal, suggesting a therapeutic potential of plant-based meals for improving beta-cell function in T2D.

A Plant-Based Meal Increases Gastrointestinal Hormones and Satiety More Than an Energy- and Macronutrient-Matched Processed-Meat Meal in T2D, Obese, and Healthy Men: A Three-Group Randomized Crossover Study

Gastrointestinal hormones are involved in regulation of glucose metabolism and satiety. We tested the acute effect of meal composition on these hormones in three population groups. A randomized crossover design was used to examine the effects of two energy- and macronutrient-matched meals: a processed-meat and cheese (M-meal) and a vegan meal with tofu (V-meal) on gastrointestinal hormones, and satiety in men with type 2 diabetes (T2D, n = 20), obese men (O, n = 20), and healthy men (H, n = 20). Plasma concentrations of glucagon-like peptide -1 (GLP-1), amylin, and peptide YY (PYY) were determined at 0, 30, 60, 120 and 180 min. Visual analogue scale was used to assess satiety. We used repeated-measures Analysis of variance (ANOVA) for statistical analysis. Postprandial secretion of GLP-1 increased after the V-meal in T2D (by 30.5%; 95%CI 21.2 to 40.7%; p < 0.001) and H (by 15.8%; 95%CI 8.6 to 23.5%; p = 0.01). Postprandial plasma concentrations of amylin increased in in all groups after the V-meal: by 15.7% in T2D (95%CI 11.8 to 19.6%; p < 0.001); by 11.5% in O (95%CI 7.8 to 15.3%; p = 0.03); and by 13.8% in H (95%CI 8.4 to 19.5%; p < 0.001). An increase in postprandial values of PYY after the V-meal was significant only in H (by 18.9%; 95%CI 7.5 to 31.3%; p = 0.03). Satiety was greater in all participants after the V-meal: by 9% in T2D (95%CI 4.4 to 13.6%; p = 0.004); by 18.7% in O (95%CI 12.8 to 24.6%; p < 0.001); and by 25% in H (95%CI 18.2 to 31.7%; p < 0.001). Our results indicate there is an increase in gut hormones and satiety, following consumption of a single plant-based meal with tofu when compared with an energy- and macronutrient-matched processed-meat meat and cheese meal, in healthy, obese and diabetic men.

Palmitate and oleate exert differential effects on insulin signalling and glucose uptake in human skeletal muscle cells

Saturated fatty acids are implicated in the development of insulin resistance, whereas unsaturated fatty acids may have a protective effect on metabolism. We tested in primary human myotubes if insulin resistance induced by saturated fatty acid palmitate can be ameliorated by concomitant exposure to unsaturated fatty acid oleate. Primary human myotubes were pretreated with palmitate, oleate or their combination for 12 h. Glucose uptake was determined by intracellular accumulation of [3H]-2-deoxy-d-glucose, insulin signalling and activation of endoplasmic reticulum (ER) stress by Western blotting, and mitochondrial reactive oxygen species (ROS) production by fluorescent dye MitoSOX. Exposure of primary human myotubes to palmitate impaired insulin-stimulated Akt-Ser473, AS160 and GSK-3β phosphorylation, induced ER stress signalling target PERK and stress kinase JNK 54 kDa isoform. These effects were virtually abolished by concomitant exposure of palmitate-treated myotubes to oleate. However, an exposure to palmitate, oleate or their combination reduced insulin-stimulated glucose uptake. This was associated with increased mitochondrial ROS production in palmitate-treated myotubes co-incubated with oleate, and was alleviated by antioxidants MitoTempo and Tempol. Thus, metabolic and intracellular signalling events diverge in myotubes treated with palmitate and oleate. Exposure of human myotubes to excess fatty acids increases ROS production and induces insulin resistance.

Weight Management in Primary Care

BACKGROUND

Obesity is one of the greatest public health challenges worldwide. It is not only a medical but also a philosophical, ecological, economic, sociocultural, and psychological problem as well as a severe consequence of our modern value definition to 'receive more and more'. Therefore, physicians are not able to treat obesity broadly and should not be used as tools to achieve certain weight goals.

METHODS

This article presents an outline of conservative obesity therapy. Using the key words 'obesity', 'diet', and 'exercise', a search was conducted in the PubMed and ScienceDirect databases for the period from 1995 to 2015.

RESULTS/CONCLUSION

The goal of obesity therapy is primarily the reduction of abdominal fat distribution. Only after achieving this main objective, weight loss reduction can be included by changes in eating and activity habits as well as further lifestyle modifications supplemented by weight-reducing medical, invasive, and/or surgical therapy measures in order to reduce obesity-associated comorbidities and to improve quality of life. A reduction of fat intake while avoiding unsaturated fatty acids, an optimization especially of the quality of carbohydrate and protein intake, an increase in physical activity (about 30-60 min per day) with individual adaption, and a personal, ongoing therapeutic leadership is necessary to reach the main goal, i.e. losing 5-15% of the initial weight.

The Evidence Is In: Lifestyle Interventions Can Prevent Diabetes

Early epidemiological and clinical trials suggested that type 2 diabetes could be prevented or delayed by lifestyle modifications. The Finnish Diabetes Prevention Study and the Diabetes Prevention Programs provided conclusive evidence that type 2 diabetes could be prevented or delayed with modest lifestyle changes—5% to 7% loss of body weight and 150 min/week of physical activity. Both used intensive intervention strategies and continued support and follow-up to achieve study goals. Other smaller studies made similar observations. Various medications—metformin, acarbose, troglitazone and pioglitazone, orlistat, and rosiglitazone—and bariatric surgery have also been effective for the prevention or delay of diabetes. Nutrient factors studied include the contribution of a high dietary fat intake, especially saturated fat, to the development of diabetes and increased intake of fiber, whole grains, and alcohol to decreased risk. A review of the evidence led the American Diabetes Association to conclude that lifestyle interventions should be the first choice for prevention or delay of diabetes and that drug therapy should not be a substitute for lifestyle interventions—healthy and appropriate food choices and physical activity.

Factors associated with BMI, underweight, overweight, and obesity among adults in a population of rural south India: a cross-sectional study

BACKGROUND

Overweight, obesity, and related chronic diseases are becoming serious public health concerns in rural areas of India. Compounded with the existing issue of underweight, such concerns expose the double burden of disease and may put stress on rural healthcare. The purpose of this article was to present the prevalence and factors associated with underweight, overweight, and obesity in an area of rural south India.

METHODS

During 2013 and 2014, a random sample of adults aged 20-80 years were selected for participation in a cross-sectional study that collected information on diet (using a food frequency questionnaire), physical activity (using the Global Physical Activity Questionnaire), socioeconomic position (using a wealth index), rurality (using the MSU rurality index), education, and a variety of descriptive factors. BMI was measured using standard techniques. Using a multivariate linear regression analysis and multivariate logistic regression analyses, we examined associations between BMI, overweight, obesity, and underweight, and all potential risk factors included in the survey.

RESULTS

Age and sex-adjusted prevalence of overweight, obesity class I, and obesity class II were 14.9, 16.1, and 3.3 % respectively. Prevalence of underweight was 22.7 %. The following variables were associated with higher BMI and/or increased odds of overweight, obesity class I, and/or obesity class II: Low physical activity, high wealth index, no livestock, low animal fat consumption, high n-6 polyunsaturated fat consumption, television ownership, time spent watching television, low rurality index, and high caste. The following variables were associated with increased odds of underweight: low wealth index, high rurality index, and low intake of n-6 PUFAs.

CONCLUSION

Underweight, overweight, and obesity are prevalent in rural regions of southern India, indicating a village-level dual burden. A variety of variables are associated with these conditions, including physical activity, socioeconomic position, rurality, television use, and diet. To address the both underweight and obesity, policymakers must simultaneously focus on encouraging positive behaviour through education and addressing society-level risk factors that inhibit individuals from achieving optimal health.

Sunflower Oil but Not Fish Oil Resembles Positive Effects of Virgin Olive Oil on Aged Pancreas after Life-Long Coenzyme Q Addition

An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. In this context, it has been reported that different pancreatic compartments from rats were affected according to the fat composition consumed. Since there is a close relationship between mitochondria, oxidative stress and aging, an experimental approach has been developed to gain more insight into this process in the pancreas. A low dosage of coenzyme Q was administered life-long in rats in order to try to prevent pancreatic aging-related alterations associated to some dietary fat sources. According to that, three groups of rats were fed normocaloric diets containing Coenzyme Q (CoQ) for two years, where virgin olive, sunflower, or fish oil was included as unique fat source. Pancreatic samples for microscopy and blood samples were collected at the moment of euthanasia. The main finding is that CoQ supplementation gives different results according to fat used in diet. When sunflower oil was the main fat in the diet, CoQ supplementation seems to improve endocrine pancreas structure and in particular β-cell mass resembling positive effects of virgin olive oil. Conversely, CoQ intake does not seem to improve the structural alterations of exocrine compartment previously observed in fish oil fed rats. Therefore CoQ may improve pancreatic alterations associated to the chronic intake of some dietary fat sources.

A review of potential metabolic etiologies of the observed association between red meat consumption and development of type 2 diabetes mellitus

Epidemiological studies suggest that red and processed meat consumption is related to an increased risk of type 2 diabetes. However, it is not clearly understood which components of red and processed meat contribute to this increased risk. This review examines potential mechanisms addressing the role of saturated fatty acid, sodium, advanced glycation end products (AGEs), nitrates/nitrites, heme iron, trimethylamine N-oxide (TMAO), branched amino acids (BCAAs) and endocrine disruptor chemicals (EDCs) in the development of type 2 diabetes based on data from published clinical trials and animal models. TMAO which is derived from dietary carnitine and choline by the action of bacterial enzymes followed by oxidation in the liver may be a strong candidate molecule mediating the risk of type 2 diabetes. BCAAs may induce insulin resistance via the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal protein S6 kinase β 1 (S6k1)-associated pathways. The increased risk associated with processed meat compared with red meat suggests that there are interactions between the saturated fat, salt, and nitrates in processed meat and iron, AGEs and TMAO. Intervention studies are required to clarify potential mechanisms and explore interactions among components, in order to make firm recommendations on red and processed meat consumption.

Diets high in protein or saturated fat do not affect insulin sensitivity or plasma concentrations of lipids and lipoproteins in overweight and obese adults

BACKGROUND

Previous human studies reported inconsistent effects of dietary protein and branched-chain amino acids (BCAAs) on insulin action and glucose metabolism. Similarly, it is unclear whether saturated fat (SF) intake influences these metabolic variables.

OBJECTIVE

The objective of this study was to test the effects of high [30% of energy (%E)] vs. moderate (20%E) intakes of protein (primarily whey) on insulin action and lipid and lipoprotein concentrations in the context of both high (15%E) and low (7%E) SF diets.

METHODS

The study was conducted as a randomized controlled trial in 158 overweight and obese men and women. After a 4-wk baseline diet [55%E carbohydrate, 15%E protein, 30%E fat (7%E SF)], participants were randomly assigned to 4 wk of either the baseline diet or 1 of 4 test diets containing 35%E carbohydrate and either 20%E or 30%E protein and either 7%E or 15%E SF. Frequently sampled i.v. glucose tolerance tests were administered after each dietary period.

RESULTS

Other than significantly higher fasting glucose concentrations for high vs. moderate protein intakes with a low-fat diet (difference ± SE: 0.47 ± 0.14 mmol/L; P = 0.001), there were no significant effects of dietary protein or SF on glucose metabolism, plasma insulin, or concentrations of lipids and lipoproteins. Changes in plasma BCAAs across all diets were negatively correlated with changes in the metabolic clearance rate of insulin (ρ = -0.18, P = 0.03) and positively correlated with changes in the acute insulin response to glucose (ρ = 0.15, P = 0.05).

CONCLUSIONS

These findings suggest that short-term intake of BCAAs can influence insulin dynamics. However, in this group of overweight and obese individuals, neither high protein nor SF intake affected insulin sensitivity or plasma concentrations of lipids and lipoproteins. This trial was registered at clinicaltrials.gov as NCT00508937.

Differential acute postprandial effects of processed meat and isocaloric vegan meals on the gastrointestinal hormone response in subjects suffering from type 2 diabetes and healthy controls: a randomized crossover study

BACKGROUND

The intake of meat, particularly processed meat, is a dietary risk factor for diabetes. Meat intake impairs insulin sensitivity and leads to increased oxidative stress. However, its effect on postprandial gastrointestinal hormone (GIH) secretion is unclear. We aimed to investigate the acute effects of two standardized isocaloric meals: a processed hamburger meat meal rich in protein and saturated fat (M-meal) and a vegan meal rich in carbohydrates (V-meal). We hypothesized that the meat meal would lead to abnormal postprandial increases in plasma lipids and oxidative stress markers and impaired GIH responses.

METHODS

In a randomized crossover study, 50 patients suffering from type 2 diabetes (T2D) and 50 healthy subjects underwent two 3-h meal tolerance tests. For statistical analyses, repeated-measures ANOVA was performed.

RESULTS

The M-meal resulted in a higher postprandial increase in lipids in both groups (p<0.001) and persistent postprandial hyperinsulinemia in patients with diabetes (p<0.001). The plasma glucose levels were significantly higher after the V-meal only at the peak level. The plasma concentrations of glucose-dependent insulinotropic peptide (GIP), peptide tyrosine-tyrosine (PYY) and pancreatic polypeptide (PP) were higher (p<0.05, p<0.001, p<0.001, respectively) and the ghrelin concentration was lower (p<0.001) after the M-meal in healthy subjects. In contrast, the concentrations of GIP, PYY and PP were significantly lower after the M-meal in T2D patients (p<0.001). Compared with the V-meal, the M-meal was associated with a larger increase in lipoperoxidation in T2D patients (p<0.05).

CONCLUSION/INTERPRETATION

Our results suggest that the diet composition and the energy content, rather than the carbohydrate count, should be important considerations for dietary management and demonstrate that processed meat consumption is accompanied by impaired GIH responses and increased oxidative stress marker levels in diabetic patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01572402.

Linoleate appears to protect against palmitate-induced inflammation in Huh7 cells

Background

Polyunsaturated fatty acids (PUFAs) may protect against metabolic diseases. Although the benefits of the n-3 family of PUFA have been well investigated in nonalcoholic steatohepatitis (NASH), little is known about the effect of the n-6 family. This study examined the effect of linoleate, a member of the n-6 family, on regulation of the palmitate-induced inflammatory cytokine interleukin-8 (IL8) in hepatocytes.

Methods

Huh7 cells and HepG2 cells were cultured with and without free fatty acid treatment (palmitate and linoleate, alone or in combination, 100–1000 μM). Inflammatory pathways, lipid accumulation, apoptosis and cell viability were monitored.

Results

Dose- and time-related changes of IL8 mRNA expression were examined and 9 h treatment with 500 μM palmitate showed the greatest elevation of IL8. Co-treatment with 500 μM palmitate and 400 μM linoleate significantly suppressed IL8 production below that with palmitate alone in both cells (both mRNA and protein). A quantitative measurement for lipid accumulation showed no significant difference between palmitate-treated cells (1.69 ± 0.21), linoleate-treated cells (1.61 ± 0.16) and palmitate and linoleate-treated cells (1.73 ± 0.22, NS, n = 7). The co-treatment with 400 μM linoleate inhibited phospho-c-Jun N-terminal kinase (pJNK) activation and IkBα reduction caused by 500 μM palmitate treatment. Treatment with 400 μM linoleate alone led to IL8 production (5.48 fold change), similar to co-treatment, with no influence on the expression of pJNK/IkBα. The cell viability was similar between treatment with 500 μM palmitate and with both 500 μM palmitate and 400 μM linoleate, showing no significant changes in the expression of cleaved caspase-3.

Conclusions

Linoleate is a potent regulator of the proinflammatory cytokine IL8 via the JNK and nuclear factor kappa B pathways that are involved in the pathophysiology of NASH, suggesting a future recommendation of dietary management.

Dietary habits and behaviors associated with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent causes of health problems in Western (industrialized) countries. Moreover, the incidence of infantile NAFLD is increasing, with some of these patients progressing to nonalcoholic steatohepatitis. These trends depend on dietary habits and life-style. In particular, overeating and its associated obesity affect the development of NAFLD. Nutritional problems in patients with NAFLD include excess intake of energy, carbohydrates, and lipids, and shortages of polyunsaturated fatty acids, vitamins, and minerals. Although nutritional therapeutic approaches are required for prophylaxis and treatment of NAFLD, continuous nutrition therapy is difficult for many patients because of their dietary habits and lifestyle, and because the motivation for treatment differs among patients. Thus, it is necessary to assess the nutritional background and to identify nutritional problems in each patient with NAFLD. When assessing dietary habits, it is important to individually evaluate those that are consumed excessively or insufficiently, as well as inappropriate eating behaviors. Successful nutrition therapy requires patient education, based on assessments of individual nutrients, and continuing the treatment. In this article, we update knowledge about NAFLD, review the important aspects of nutritional assessment targeting treatment success, and present some concrete nutritional care plans which can be applied generally.

Specific plasma lipid classes and phospholipid fatty acids indicative of dairy food consumption associate with insulin sensitivity

BACKGROUND

Reports have suggested that the consumption of dairy foods may reduce risk of type 2 diabetes on the basis of evidence of raised circulating ruminant fatty acids.

OBJECTIVE

We determined whether certain phospholipid species and fatty acids that are associated with full-fat dairy consumption may also be linked to diminished insulin resistance.

DESIGN

Four variables of insulin resistance and sensitivity were defined from oral-glucose-tolerance tests in 86 overweight and obese subjects with metabolic syndrome. Plasma phospholipids, sphingolipids, and fatty acids were determined by using a lipidomic analysis and gas chromatography-mass spectrometry to provide objective markers of dairy consumption. Food records provided information on dairy products. Associations were determined by using linear regression analyses adjusted for potential confounders age, sex, systolic blood pressure, waist:hip ratio, or body mass index (BMI) and corrected for multiple comparisons.

RESULTS

Lysophosphatidylcholine, lyso-platelet-activating factor, and several phospholipid fatty acids correlated directly with the number of servings of full-fat dairy foods. Lysophosphatidylcholine and lyso-platelet-activating factor were also associated directly with insulin sensitivity when accounting for the waist:hip ratio (Matsuda index unadjusted, P < 0.001 for both; adjusted for multiple comparisons, P < 0.02 for both) and inversely with insulin resistance (fasting insulin unadjusted, P < 0.001 for both; adjusted, P = 0.04 and P < 0.05, respectively; homeostasis model assessment of insulin resistance adjusted, P = 0.04 for both; post-glucose insulin area under the plasma insulin curve during the 120 min of the test adjusted, P < 0.01 for both). The substitution of BMI for the waist:hip ratio attenuated associations modestly. Phospholipid fatty acid 17:0 also tended to be associated directly with insulin sensitivity and inversely with resistance.

CONCLUSION

Variables of insulin resistance were lower at higher concentrations of specific plasma phospholipids that were also indicators of full-fat dairy consumption. This trial was registered at clinicaltrials.gov as NCT00163943.

Effect of dietary fatty acid composition on substrate utilization and body weight maintenance in humans

BACKGROUND/PURPOSE

Dietary fat content is a primary factor associated with the increase in global obesity rates. There is a delay in achieving fat balance following exposure to a high-fat (HF) diet (≥ 40% of total energy from fat) and fat balance is closely linked to energy balance. Exercise has been shown to improve this rate of adaptation to a HF diet. Recently, however, the role of dietary fatty acid composition on energy and macronutrient balance has come into question.

METHODS

We chose studies that compared monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA). We have reviewed studies that measured diet-induced thermogenesis (DIT), energy expenditure (EE), or fat oxidation (FOx) in response to a HF meal challenge, or long-term dietary intervention comparing these fatty acids.

RESULTS

While single-meal studies show that SFA induce lower DIT and FOx compared to unsaturated fats, the effect of the degree of unsaturation (MUFA vs. PUFA) appears to yet be determined. Long-term dietary interventions also support the notion that unsaturated fats induce greater EE, DIT, and/or FOx versus SFA and that a high MUFA diet induces more weight loss compared to a high SFA diet. Sex and BMI status also affect the metabolic responses to different fatty acids; however, more research in these areas is warranted.

CONCLUSION

SFA are likely more obesigenic than MUFA, and PUFA. The unsaturated fats appear to be more metabolically beneficial, specifically MUFA ≥ PUFA > SFA, as evidenced by the higher DIT and FOx following HF meals or diets.

High fat diets are associated with higher abdominal adiposity regardless of physical activity in adolescents; the HELENA study

BACKGROUND & AIMS

Failure to attain fat balance may contribute to obesity development even without excessive energy intake. The objective of this study was to examine the associations of dietary macronutrient distribution with abdominal adiposity in adolescents and to evaluate whether these relationships were attenuated by physical activity.

METHODS

A total of 224 Spanish adolescents (51% females, 14.9 ± 1.2 years) were included in the study. Abdominal adiposity in three regions, truncal and total body fat mass (FM) and lean mass (LM) were measured by dual-energy X-ray absorptiometry and thereafter FM index (FMI = FM/height(2)) and FMI/LMI ratio were calculated. The energy derived from fat intake was assessed by two non-consecutive 24 h recalls. Total physical activity (PA) and time spent in moderate-to-vigorous PA (MVPA) and vigorous PA were objectively measured by accelerometry.

RESULTS

We observed that the percent of energy derived from fat intake was significantly associated with FMI and FMI/LMI ratio (Ps = 0.001) and greater amounts of truncal (P = 0.001) and abdominal adiposity in the three regions regardless of age, sex and height (all P ≤ 0.005). The strength of the relationships was not substantially altered by further adjustment for PA, vigorous PA or moderate-to-vigorous PA (Ps ≤ 0.005).

CONCLUSIONS

The percent of energy derived from dietary fat intake is strongly and linearly associated with total, truncal and abdominal adiposity independently of PA in adolescents. These observations implicate the amount of dietary fat intake as a specific risk factor in the excess of abdominal adiposity in adolescence.

Comparative analysis of pancreatic changes in aged rats fed life long with sunflower, fish, or olive oils

An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. We aimed to study the effect of oil consumption on pancreas histology in order to find aging-related signs. To this end, three groups of rats were fed an isocaloric diet for 2 years, where virgin olive, sunflower, or fish oil was included. Pancreatic samples for microscopy and blood samples were collected at the moment of sacrifice. As a result, the sunflower oil-fed rats presented higher β-cell numbers and twice the insulin content than virgin olive oil-fed animals. In addition, rats fed with fish oil developed acinar fibrosis and macrophage infiltrates in peri-insular regions, compared with counterparts fed with virgin olive oil. Inflammation signs were less prominent in the sunflower group. The obtained data emphasize the importance of dietary fatty acids in determining pancreatic structure.

Higher regular fat dairy consumption is associated with lower incidence of metabolic syndrome but not type 2 diabetes

BACKGROUND AND AIMS

Limited evidence suggests habitual dairy consumption to be protective against metabolic syndrome (MetSyn) and type 2 diabetes among older adults. We assessed the association of baseline consumption of dairy products with the incidence of MetSyn and type 2 diabetes among a cohort of Australian adults aged 49 years and over.

METHODS AND RESULTS

A validated 145-item semi-quantitative food frequency questionnaire was used to assess food and nutrient intake at baseline. Ten-year incidence of MetSyn and type 2 diabetes were obtained from 1807 and 1824 subjects respectively. Odds ratios (OR) were calculated by discrete time logistic regression modelling. Compared with subjects in the lowest intake quartile of regular fat dairy products, those in the highest quartile had a 59% lower risk of MetSyn (multivariate adjusted OR: 0.41; 95% CI: 0.23-0.71; p(trend) = 0.004), after adjustment for risk factors. Among obese subjects, an association between a high intake of regular fat dairy foods and reduced risk of type 2 diabetes was also found (age and sex adjusted OR 0.37; 95% CI: 0.16-0.88; p(trend) = 0.030), but the association did not persist after adjustment for additional confounders. There was no association between total dairy consumption and risk of MetSyn or type 2 diabetes.

CONCLUSIONS

We found an inverse association between regular fat dairy consumption and risk of MetSyn among Australian older adults. Further studies are warranted to examine the association between weight status, dairy consumption and risk of type 2 diabetes.

Association between dietary meat consumption and incident type 2 diabetes: the EPIC-InterAct study

AIMS/HYPOTHESIS

A diet rich in meat has been reported to contribute to the risk of type 2 diabetes. The present study aims to investigate the association between meat consumption and incident type 2 diabetes in the EPIC-InterAct study, a large prospective case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

METHODS

During 11.7 years of follow-up, 12,403 incident cases of type 2 diabetes were identified among 340,234 adults from eight European countries. A centre-stratified random subsample of 16,835 individuals was selected in order to perform a case-cohort design. Prentice-weighted Cox regression analyses were used to estimate HR and 95% CI for incident diabetes according to meat consumption.

RESULTS

Overall, multivariate analyses showed significant positive associations with incident type 2 diabetes for increasing consumption of total meat (50 g increments: HR 1.08; 95% CI 1.05, 1.12), red meat (HR 1.08; 95% CI 1.03, 1.13) and processed meat (HR 1.12; 95% CI 1.05, 1.19), and a borderline positive association with meat iron intake. Effect modifications by sex and class of BMI were observed. In men, the results of the overall analyses were confirmed. In women, the association with total and red meat persisted, although attenuated, while an association with poultry consumption also emerged (HR 1.20; 95% CI 1.07, 1.34). These associations were not evident among obese participants.

CONCLUSIONS/INTERPRETATION

This prospective study confirms a positive association between high consumption of total and red meat and incident type 2 diabetes in a large cohort of European adults.

Neuron-specific deletion of peroxisome proliferator-activated receptor delta (PPARδ) in mice leads to increased susceptibility to diet-induced obesity

Central nervous system (CNS) lipid accumulation, inflammation and resistance to adipo-regulatory hormones, such as insulin and leptin, are implicated in the pathogenesis of diet-induced obesity (DIO). Peroxisome proliferator-activated receptors (PPAR α, δ, γ) are nuclear transcription factors that act as environmental fatty acid sensors and regulate genes involved in lipid metabolism and inflammation in response to dietary and endogenous fatty acid ligands. All three PPAR isoforms are expressed in the CNS at different levels. Recent evidence suggests that activation of CNS PPARα and/or PPARγ may contribute to weight gain and obesity. PPARδ is the most abundant isoform in the CNS and is enriched in the hypothalamus, a region of the brain involved in energy homeostasis regulation. Because in peripheral tissues, expression of PPARδ increases lipid oxidative genes and opposes inflammation, we hypothesized that CNS PPARδ protects against the development of DIO. Indeed, genetic neuronal deletion using Nes-Cre loxP technology led to elevated fat mass and decreased lean mass on low-fat diet (LFD), accompanied by leptin resistance and hypothalamic inflammation. Impaired regulation of neuropeptide expression, as well as uncoupling protein 2, and abnormal responses to a metabolic challenge, such as fasting, also occur in the absence of neuronal PPARδ. Consistent with our hypothesis, KO mice gain significantly more fat mass on a high-fat diet (HFD), yet are surprisingly resistant to diet-induced elevations in CNS inflammation and lipid accumulation. We detected evidence of upregulation of PPARγ and target genes of both PPARα and PPARγ, as well as genes of fatty acid oxidation. Thus, our data reveal a previously underappreciated role for neuronal PPARδ in the regulation of body composition, feeding responses, and in the regulation of hypothalamic gene expression.

Metabolic syndrome: definition and therapeutic implications

The collection of impaired glucose metabolism, central obesity, elevated blood pressure, and dyslipidemia is identified as metabolic syndrome (MetS). It is estimated that approximately 25% of the world's population has MetS. In the United States, MetS is more common in men and Hispanics, and its incidence increases with age. Metabolic syndrome increases the risk of developing cardiovascular disease and type 2 diabetes mellitus. The underlying risk factors include insulin resistance and abdominal obesity. Confusion about MetS exists in part due to the lack of a consensus definition and treatment protocol. Treatment of MetS begins with therapeutic lifestyle changes and then pharmacologic treatment of the syndrome's individual components. Effective interventions include diet modification, exercise, and use of pharmacologic agents to treat risk factors. Weight loss and increasing physical activity significantly improve all aspects of MetS. A diet that includes more fruits, vegetables, whole grains, monounsaturated fats, and low-fat dairy products will benefit most patients with MetS. Physicians can be most effective in advising patients by customizing specific lifestyle recommendations after assessing patients for the presence of risk factors.

Effects of polymorphisms in nucleotide-binding oligomerization domains 1 and 2 on biomarkers of the metabolic syndrome and type II diabetes

The innate immune receptor toll-like receptor 4 (TLR4) has been implicated in mediating some of the effects of dietary lipids on inflammation and type 2 diabetes (T2D). Similar to TLR4, the nucleotide-binding oligomerization domains (Nods) 1 and 2 are also proteins of innate immunity, which can respond to lipids and initiate pro-inflammatory signalling that plays a role in the aetiology of T2D. The objective was to determine the effect of Nod1 (Glu266Lys) and Nod2 (Ser268Pro) genotypes on factors associated with the metabolic syndrome (MetS), and whether they modify the association between dietary lipids and biomarkers of the MetS. Men and women (n = 998) between the ages of 20-29 years were genotyped for both polymorphisms, completed a one-month, semiquantitative food frequency questionnaire and provided a fasting blood sample. The Glu266Lys polymorphism in Nod1 was not associated with any of the biomarkers of the MetS, but modified the association between dietary saturated fat (SFA) and insulin sensitivity, as measured by HOMA-IR (p for interaction = 0.04). Individuals with the Glu/Glu or Glu/Lys genotype showed no significant relationship between dietary SFA and HOMA-IR (β = -0.002 ± 0.006, p = 0.77; and β = -0.003 ± 0.006, p = 0.61), while those with the Lys/Lys genotype showed a positive association (β = 0.033 ± 0.02, p = 0.03). The Nod2 Ser268Pro polymorphism was not associated with components of the MetS and did not modify the relationship between dietary lipid intake and the biomarkers of MetS. In summary, the Nod1 Glu266Lys polymorphism modifies the relationship between dietary SFA intake and HOMA-IR, suggesting that Nod1 may act as an intracellular lipid sensor affecting insulin sensitivity.

Foods for the prevention of diabetes: how do they work?

With the diabetes epidemic reaching menacing proportions worldwide, there is an urgent need for the development of cost-efficient prevention strategies to be effective at the population level. Great potential in this direction lies in properly designed, large-scale dietary interventions. The macronutrient composition and the caloric content of our diet are major determinants of glucose homeostasis and there is a continuously growing list of foods, nutrients or individual compounds that have been associated with an increased or reduced incidence of diabetes mellitus. These include fat, carbohydrates, fibre, alcohol, polyphenols and other micronutrients or individual dietary compounds, which have been shown to either promote or prevent a progression towards a (pre-)diabetic state. This review aims to briefly summarize relevant epidemiological data linking foods to diabetes and to provide insights into the mechanisms through which these effects are mediated. These include improvement of insulin sensitivity or promotion of insulin resistance, regulation of inflammatory pathways, regulation of glucose transport and tissue glucose uptake, aggravation or attenuation of postprandial glycaemia/insulinaemia, interactions with hormonal responses and β-cell-dependent mechanisms.

ATF4 deficiency protects mice from high-carbohydrate-diet-induced liver steatosis

Chronic feeding of HCD (high-carbohydrate diet) is one of the major contributors to the prevailing of metabolic diseases. ATF4 (activating transcription factor 4) has been shown to play an important role in the regulation of glucose metabolism and obesity development; however, it is unclear how ATF4(-/-) mice respond to HCD. In the present study, we show that 8 weeks of HCD results in significant higher accumulation of TAGs (triacylglycerols) in livers and impairment in glucose tolerance in ATF4(+/+) mice, but not in ATF4(-/-) mice, compared with those on a normal diet. Meanwhile, energy expenditure is further enhanced by HCD in ATF4(-/-) mice. Moreover, we show that ATF4 deficiency suppresses HCD-induced SCD1 (stearoyl-CoA desaturase 1) expression, furthermore, oral supplementation of the main product of SCD1 oleate (18:1) increases TAG accumulation in livers of ATF4(-/-) mice. Taken together, these results suggest that ATF4 deficiency is protective for HCD-induced hepatic steatosis and impairment of glucose tolerance and insulin sensitivity. Furthermore, the resistance to hepatic steatosis is at least in part due to suppression of SCD1 expression under HCD.

Decreases in dietary glycemic index are related to weight loss among individuals following therapeutic diets for type 2 diabetes

This study assessed the effect of changes in glycemic index (GI) and load (GL) on weight loss and glycated hemoglobin (HbA1c) among individuals with type 2 diabetes beginning a vegan diet or diet following the 2003 American Diabetes Association (ADA) recommendations. The study was a 22-wk, randomized trial of 99 participants with type 2 diabetes who were counseled to follow 1 of 2 diet treatments. GI and GL changes were assessed based on 3-d dietary records. The relationships between GI/GL and changes in weight and HbA1C were calculated. In an intention-to-treat analysis (n = 99), the vegan group reduced GI to a greater extent than the ADA group (P < 0.05), but GL was reduced further in the ADA than the vegan group (P < 0.001). GI predicted changes in weight (P = 0.001), adjusting for changes in fiber, carbohydrate, fat, alcohol, energy intake, steps per day, group, and demographics, such that for every point decrease in GI, participants lost ~0.2 kg (0.44 lb). GI was not a predictor for changes in HbA1C after controlling for weight loss (P = 0.33). Weight loss was a predictor of changes in HbA1C (P = 0.047). GL was not related to weight loss or changes in HbA1C. A low-GI diet appears to be one of the determinants of success of a vegan or ADA diet in reducing body weight among people with type 2 diabetes. The reduction of body weight, in turn, was predictive of decreasing HbA1C.

Effect of dietary consumption of sheep meat on thyroid hormone levels and energy expenditure of Sprague - Dawley rats

The purpose of the present study was to investigate the effects of a sheep meat-based diet on the thyroid hormone concentrations and energy expenditure of Sprague–Dawley rats. The diets, a sheep meat diet (SMD) or a casein control diet (CD), each based on a standard formulation (AIN-93G), contained 18.3% protein, 7.4% fat and 60.0% carbohydrate, and were isocaloric (15.9kJ/g dry matter). Serum tri-iodothryonine (T3), thyroxine (T4), free tri-iodothyronine (FT3) and free thyroxine (FT4) concentrations, oxygen consumption rate (OCR), bodyweight, bodyweight gain and activities of liver sodium–potassium-adenosinetriphosphatase (Na,K-ATPase) and Ca2+-dependent adenosine triphosphatase (Ca-ATPase) were measured. Compared with the CD, the SMD increased the serum FT3 concentration on Day 7 (P = 0.004) and Day 14 (P < 0.001). Serum albumin concentrations, which may influence the amount of thyroid hormones bound, were significantly lower in the SMD group on Day 7 (P < 0.001) and Day 14 (P = 0.02) than those in the CD group. Both liver Na,K-ATPase and Ca-ATPase activities were significantly higher in rats consuming the SMD on Day 7 (P < 0.001, P = 0.001) and Day 14 (P < 0.001, P < 0.001) respectively. OCRs were significantly higher in rats consuming the SMD on Day 6 (P = 0.023) and Day 13 (P = 0.014). Both bodyweight and bodyweight gains were significantly lower in the SMD group. We concluded that sheep meat consumption decreased the serum albumin concentrations, which increased the serum FT3 concentrations. This lead to FT3 promoting the OCRs and the activities of Na,K-ATPase and Ca-ATPase, resulting in reduced bodyweight and bodyweight gain, presumably through greater energy expenditure. Thus, energy expenditure appears to have been enhanced in rats fed the SMD.

Can a Mediterranean diet reduce the effects of lipodystrophy syndrome in people living with HIV? A pilot randomised controlled trial

Background: HIV and highly active antiretroviral therapies have been associated with changes in individuals’ lipid profiles and fat distribution (lipodystrophy). A pilot study was conducted for a randomised controlled trial to evaluate whether lipodystrophy in HIV patients can be controlled by adopting the low-fat and low-cholesterol diet or the modified Mediterranean diet. Methods: Forty-eight HIV patients were randomised into two diet groups. Thirty-six (75%) completed the 1-year pilot study with regular dietetic consultations, during which time lipid levels, weight, body mass index and fat distribution were recorded. Differences between and within groups were determined. Results: Undesirable body fat changes in the low-fat diet group included decreases in tricep skinfold (from 19.9 mm to 15.4 mm (P = 0.03)), hip circumference (from 93.6 cm to 91.7 cm (P = 0.01)) but a significant increase in waist-to-hip ratio (from 0.87 to 0.89 (P = 0.003)). Serum cholesterol increased significantly in the Mediterranean diet group at 9 and 12 months (from 4.6 to 5.06 mmol L−1 (P = 0.03) and 5.12 mmol L−1 (P = 0.01)) with no obvious change in the low-fat diet group. Serum triglyceride levels remained the same in the Mediterranean diet group, whereas it increased from 1.9 to 3.22 mmol L−1 (P = 0.07) in the low-fat diet group. Conclusions: A Mediterranean diet seems to have an advantage over the low-fat diet in maintaining serum triglyceride levels and avoiding lipodystrophy, but this advantage was offset by a rise in cholesterol level. Several procedural and methodological issues were identified which must be rectified before a similar large-scale trial taking place.

Different effects of oleate vs. palmitate on mitochondrial function, apoptosis, and insulin signaling in L6 skeletal muscle cells: role of oxidative stress

The type of free fatty acids (FFAs), saturated or unsaturated, is critical in the development of insulin resistance (IR), since the degree of saturation correlates with IR. We compared the effects of the saturated FFA palmitate, the unsaturated FFA oleate, and a mixture of each on the production of mitochondrial reactive oxygen species (mtROS), mitochondrial DNA (mtDNA) damage, mitochondrial function, apoptosis, and insulin-signaling pathway in skeletal muscle cells. Only palmitate caused a significant increase of mtROS production, which correlated with concomitant mtDNA damage, mitochondrial dysfunction, induction of JNK, apoptosis, and inhibition of insulin signaling. Blocking de novo synthesis of ceramide abolished the effects of palmitate on mtROS production, viability, and insulin signaling. Oleate alone did not cause mtROS generation and mtDNA damage, and its addition to palmitate prevented palmitate-induced mtDNA damage, increased total ATP levels and cell viability, and prevented palmitate-induced apoptosis and inhibition of insulin-stimulated Akt (Ser(473)) phosphorylation. The peroxisome proliferator activator receptor-γ coactivator 1α (PGC-1α) protein level and promoter activity were decreased at concentrations of palmitate ≥0.5 mM, whereas addition of oleate increased both PGC-1α level and promoter activity. Expression of the mitochondrial transcription factor (TFAM) was significantly diminished after palmitate but not oleate treatment. Addition of the ROS scavenger, N-acetylcystein (NAC), to palmitate restored both the expression and promoter activity of PGC-1α as well as TFAM expression. We propose that 1) mtROS generation is the initial event in the induction of mitochondrial dysfunction and consequent apoptosis and the inhibition of insulin signaling and that 2) oleate ameliorates palmitate-induced mitochondrial dysfunction and thus may contribute to the prevention of palmitate-induced IR.

Dietary monounsaturated fatty acids but not saturated fatty acids preserve the insulin signaling pathway via IRS-1/PI3K in rat skeletal muscle

Saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) show different effects on the development of insulin resistance. In this study, we compared the effect of dietary SFA and MUFA on the insulin signaling pathway in the skeletal muscle of a type 2 diabetic animal model. Twenty-nine-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) rats were randomly divided into three groups and fed one of the following diets for 3 weeks; a normal chow diet, an SFA (lard oil) enriched or a MUFA (olive oil) enriched high-fat diet. The vastus lateralis muscle was used for analyses. Insulin tolerance test showed improved insulin sensitivity in rats fed the MUFA diet, as compared to those fed the SFA diet (p < 0.001). The SFA diet reduced IRS-1 expression and phosphorylated PI3K levels in skeletal muscle, as compared with a chow diet (p < 0.001, respectively). On the contrary, muscle IRS-2 expression and phosphorylated ERK1/2 was significantly increased in rats fed the SFA diet (p < 0.001, respectively). Membrane translocation of glucose transporter type 4 decreased in the skeletal muscle of rats fed the SFA diet, as compared to those fed a chow diet (p < 0.001). These changes in insulin signaling pathway in skeletal muscle were not observed in rats fed the MUFA diet. In conclusion, the beneficial effect of dietary MUFA on insulin sensitivity is associated with a conserved IRS-1/PI3K insulin signaling pathway which was altered by dietary SFA.

Nutritional profiles in a public health perspective: a critical review

Nutritional profiling is defined as 'the science of categorizing foods according to their nutritional composition' and it is useful for food labelling and regulation of health claims. The evidence for the link between nutrients and health outcomes was reviewed. A reduced salt intake reduces blood pressure, but only a few randomized controlled trials have verified the effect of salt on overall and cardiovascular mortality. Evidence linking a reduced fat intake with cardiovascular mortality and obesity is generally non-significant. Studies that have examined the relationship between obesity and diet have produced contrasting results. A simulation exercise that demonstrated that the impact of a reduced salt and fat intake on overall mortality would be negligible in the European population was carried out. Consideration of the literature and the results of this simulation exercise suggest that the introduction of nutritional profiles in Europe would be expected to have a very limited impact on health outcomes.

Erythrocyte fatty acid composition and insulin sensitivity in daughters of Type 2 diabetic patients and women with no family history of diabetes

BACKGROUND

There is evidence that the impact of environmental factors on insulin sensitivity is modified by the presence of family history of diabetes.

AIM

To compare the association between the erythrocyte phospholipid fatty acid composition (a biomarker of dietary fatty acids) and insulin sensitivity in daughters of Type 2 diabetic patients with the corresponding association in women without family history of diabetes.

MATERIAL/SUBJECTS AND METHODS

Eighteen offspring of Type 2 diabetic patients [age 30+/-6.5 yr; body mass index (BMI) 22.2+/-2.5 kg/m2; body fat 31.8+/-5.1%] and 18 matched women (age 30.1+/-6.8 yr; BMI 22.2+/-1.8 kg/m2; body fat 32.2+/-6.0%) participated in the study.

RESULTS

Insulin Sensitivity Index (ISI)-Matsuda tended to be lower (p=0.06) in the Offspring than the control group. Weight proportions of erythrocyte phospholipid saturated (SFA), polyunsaturated (PUFA), and monounsaturated fatty acids (MUFA) were similar between the two groups. In the offspring, erythrocyte total SFA were negatively correlated with ISI-Matsuda [r=-0.47, p<0.05), ISI(gly)-Belfiore (r=-0.52, p<0.05) and ISI(ffa)-Belfiore (r=-0.53, p<0.05)], whereas total PUFA were positively correlated with insulin sensitivity [ISI-Matsuda, r=0.46, p<0.05; ISI(gly)-Belfiore, r=0.53, p<0.05; ISI(ffa)-Belfiore, r=0.54, p<0.05]. No significant correlations were observed in the control group.

CONCLUSIONS

The associations between erythrocyte fatty acid composition and insulin sensitivity are distinct between daughters of Type 2 diabetic patients and women without family history of diabetes.

Corn content of French fry oil from national chain vs. small business restaurants

Several issues, ranging from sustainability to health, may interest the consumers in the corn content of their food. However, because restaurants are excluded from the Nutrition Labeling and Education Act of 1990, national chain restaurants provide nonspecific ingredient information and small businesses supply none. We measured the carbon isotope composition of fry oil in French fries purchased from 68 (67%) of the 101 national chain fast food restaurants on Oahu (i.e., McDonald's, Burger King, Wendy's, Arby's, and Jack in the Box), and paired this with a similar number of small businesses (n = 66) to calculate minimum percent contribution of corn to total fry oil. We found that the majority (69%) of the national chain restaurants served fries containing corn oil, whereas this was true for only a minority (20%) of the small businesses. Corn oil is more expensive than soybean oil (for example) when purchased from a small business supplier, suggesting that large-scale corporate agreements are necessary to make corn oil frying cost-effective. When considering French fry oil along with corn-fed beef and chicken, as well as high-fructose corn syrup-sweetened soda, we see the pervasive influence of corn as an ingredient in national chain fast food.

Relationship between n-3 and n-6 plasma fatty acid levels and insulin resistance in coronary patients with and without metabolic syndrome

BACKGROUND AND AIMS

Animal studies show that ecosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are effective for the prevention and treatment of insulin resistance (IR). Data from human studies are contradictory. We sought to determine whether the relationships between plasma n-3 and n-6 polyunsaturated fatty acid (FA) levels and IR differ according to the presence or absence of metabolic syndrome (MS) in a coronary heart disease sample.

METHOD AND RESULTS

Clinical, metabolic parameters, plasma phospholipid FA profiles and indirect measurement of IR (homeostatic model assessment-HOMA) were measured in 734 subjects, 8 weeks following acute coronary syndrome. FA levels and their correlations with IR were compared in subjects with and without MS. MS patients had higher saturated (16:0, 18:0) and n-6 (18:3n-6, 20:3n-6, 22:4n-6, 22:5n-6) FA levels, and lower EPA and DHA levels. HOMA-IR correlated positively with total saturated (r=0.13, P=0.017) and n-6 (r=0.17, P=0.001) FA levels and negatively with total n-3 FA levels (r=-0.13, P=0.012), in MS subjects only. Total n-3 and n-6 FAs and n-6/n-3 ratio were associated with HOMA-IR levels in MS subjects independent of total saturated FA levels, age, sex, sedentary behaviour, smoking, waist circumference, triglycerides, HDL-cholesterol, and systolic blood pressure.

CONCLUSIONS

Relationships between polyunsaturated FA type and IR vary according to the presence or absence of MS. N-3 FAs including EPA and DHA are associated with lower HOMA-IR, while the opposite is true for n-6 FAs. Prospective studies are required to address the potential effects of intermediate dose EPA and DHA on glucose handling in MS patients.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

South Asian diets and insulin resistance

A role of dietary nutrients in relation to insulin resistance has been suggested but conclusive evidence in human beings is lacking. Asian Indians and South Asians are prone to develop insulin resistance and the metabolic syndrome. In the present paper, data pertaining to nutrient intake, insulin resistance and cardiovascular risk factors in Asian Indians and South Asians have been reviewed. In these populations, several dietary imbalances have been reported: low intake of MUFA, n-3 PUFA and fibre, and high intake of fats, saturated fats, carbohydrates and trans-fatty acids (mostly related to the widespread use of Vanaspati, a hydrogenated oil). Some data suggest that these nutrient imbalances are associated with insulin resistance, dyslipidaemia and subclinical inflammation in South Asians. Specifically, in children and young individuals, a high intake of n-6 PUFA is correlated with fasting hyperinsulinaemia, and in adults, high-carbohydrate meal consumption was reported to cause hyperinsulinaemia, postprandial hyperglycaemia and hypertriacylglycerolaemia. Dietary supplementation with n-3 PUFA leads to an improved lipid profile but not insulin sensitivity. Inadequate maternal nutrition in pregnancy, low birth weight and childhood 'catch-up' obesity may be important for the development of the metabolic syndrome and diabetes. Even in rural populations, who usually consume traditional frugal diets, there is an increasing prevalence of cardiovascular risk factors and the metabolic syndrome due to changes in diets and lifestyle. Nationwide community intervention programmes aimed at creating awareness about the consequences of unhealthy food choices and replacing them by healthy food choices are urgently needed in urban and rural populations in India, other countries in South Asia and in migrant South Asians.