Dietary fat, insulin sensitivity and the metabolic syndrome

The effects of short-term high-fat feeding on exercise capacity: multi-tissue transcriptome changes by RNA sequencing analysis

BACKGROUND

The effects of short-term high fat diets on physiology are elusive and the molecular changes following fat overconsumption remain largely unknown. In this study, we aimed to evaluate exercise capacity in mice fed with a high fat diet (HFD) for 3 days and investigate the molecular mechanisms in the early response to high-fat feeding.

METHODS

Exercise capacity was assessed by weight-loaded swimming test in mice fed a control diet (10 kcal% fat) or a HFD (60 kcal% fat) for 3 days. Global gene expression of ten important tissues (brain, heart, liver, spleen, lung, kidney, stomach, duodenum, skeletal muscle and blood) was analyzed using RNA Sequencing.

RESULTS

A HFD for just 3 days can induce 71% decrease of exercise performance prior to substantial weight gain (P <0.01). Principle component analysis revealed that differential gene expression patterns existed in the ten tissues. Out of which, the brain, spleen and lung were demonstrated to have more pronounced transcriptional changes than other tissues. Biological process analysis for differentially expressed genes in the brain, spleen and lung showed that dysregulation of peripheral and central immune response had been implicated in the early stage of HFD exposure. Neurotransmission related genes and circulatory system process related genes were significantly down-regulated in the brain and lung, respectively.

CONCLUSIONS

Our findings provide new insights for the deleterious effects of high-fat feeding, especially revealing that the lung maybe as a new important target attacked by short-term high-fat feeding.

Elevated C-Peptides, Abdominal Obesity, and Abnormal Adipokine Profile are Associated With Higher Gleason Scores in Prostate Cancer

BACKGROUND

Prostate cancer development is associated with numerous lifestyle factors (i.e., physical activity, nutrition intake) and metabolic perturbations. These factors have been studied independently; here, we used an integrative approach to characterize these lifestyle and metabolic parameters in men undergoing diagnostic prostate biopsies.

METHODS

We prospectively evaluated 51 consecutive men for body composition, metabolic factors including glucose- and lipid-related measures, as well as lifestyle factors prior to prostate biopsy. Evaluations were performed in a blinded manner and were subsequently related to biopsy outcomes for: (i) presence or absence of cancer; and (ii) where cancer was present, Gleason score.

RESULTS

Serum C-peptide concentrations were significantly greater in participants with Gleason scores ≥4 + 3 (2.8 ± 1.1 ng/ml) compared to those with Gleason 3 + 3 (1.4 ± 0.6 ng/ml) or Gleason 3 + 4 (1.3 ± 0.8 ng/ml, P = 0.002), suggesting greater insulin secretion despite lack of differences in fasting glucose concentrations. Central adiposity, measured by waist circumference, was significantly greater in participants with Gleason ≥4 + 3 (110.1 ± 7.4 cm) compared to those with Gleason 3 + 4 (102.0 ± 9.5 cm, P = 0.028). Men with Gleason ≥4 + 3 also had significantly greater leptin concentrations than those with lower Gleason scores (Gleason ≥4 + 3: 15.6 ± 3.3 ng/ml vs. Gleason 3 + 4: 8.1 ± 8.1 ng/ml, P < 0.05) and leptin:adiponectin ratio (Gleason ≥4 + 3: 9.7 ± 6.1 AU, Gleason 3 + 4: 2.9 ± 3.2, Gleason 3 + 3: 2.4 ± 2.1 AU, P = 0.013).

CONCLUSIONS

We profiled a cluster of obesity-related metabolic perturbations (C-peptide, central adiposity, leptin, and leptin:adiponectin ratios) which may associate with more aggressive prostate cancer histology. Prostate 77:211-221, 2017. © 2016 Wiley Periodicals, Inc.

Impact of dietary fat composition on prediabetes: a 12-year follow-up study

Objective

Dietary fatty acid composition likely affects prediabetic conditions such as isolated impaired fasting glucose (IFG) or impaired glucose tolerance (IGT); however, this risk has not been evaluated in a large population nor has it been followed prospectively.

Design

Diet, physical activity, anthropometric, socio-economic and blood glucose data from the Atherosclerosis Risk in Communities (ARIC) study were obtained from BioLINCC. Cox proportional hazards regression models were used to evaluate associations of dietary SFA, MUFA, PUFA,n-3 fatty acid (FA) andn-6 FA intakes with incidence of one (isolated IFG) or two (IFG with IGT) prediabetic conditions at the end of 12-year follow-up.

Setting

Study volunteers were from counties in North Carolina, Mississippi, Minnesota and Maryland, USA.

Subjects

Data from 5288 volunteers who participated in the ARIC study were used for all analyses reported herein.

Results

The study population was 62% male and 84 % white, mean age 53·5 (sd5·7) years and mean BMI 26·2 (sd4·6) kg/m2. A moderately high intake of dietary MUFA (10–15 % of total daily energy) was associated with a 10 % reduced risk of isolated IFG incidence, while a high intake ofn-3 FA (>0·15 % of total daily energy) was associated with a 10 % increase in risk. Curiously, moderately high intake ofn-6 PUFA (4–5 % of total daily energy) was associated with a 12 % reduction in IFG and IGT incidence.

Conclusions

MUFA,n-3 andn-6 FA contribute differently to the development of isolated IFGv. IFG with IGT; and their mechanism may be more complex than originally proposed.

Influence of Antioxidants on Leptin Metabolism and its Role in the Pathogenesis of Obesity

Obesity is associated with low-grade inflammation. Leptin, a hormone made by fat cells regulates appetite and hunger and thus food intake behavior. Interestingly, , food preservatives like sodium sulfite and sodium benzoate and also natural colorant and spice compounds such as curcumin were found to decrease the release of leptin in murine 3T3-L1 adipocytes, after co-incubation with LPS, which was added to mimic the pro-inflammatory status in obesity. Several of these compounds are well known food antioxidants.Whilst reducing oxidation events is beneficial in states of elevated oxidative stress, overexposure to food antioxidant can lead to adverse effects. There are hints from in vivo data, that antioxidant stress in younger age plays a role in the development of adiposity in later life. The insufficient exposure to oxidizing compounds like reactive oxygen species (ROS) cannot only cause an insufficient burning of calories but there is also a link to the regulation of food intake behavior. If the in vitro findings can be extrapolated to the in vivo situation, consumption of antioxidant supplemented food could lead to decreased leptin release and contribute to an obesogenic environment. This aspect sheds some new critical light on the potential role of an antioxidant-enriched nutrition in the obesity epidemic during the past few centuries. Doing sports could represent not only a proper strategy to initiate physiological ROS production and burning of calories, but also may shift the hormone milieu towards a reduction of hunger feelings and thus reduce appetite and food intake.

Dietary intake and prospective changes in cardiometabolic risk factors in children and youth

Only few studies examined the effect of diet on prospective changes in cardiometabolic (CM) risk factors in children and youth despite its importance for understanding the role of diet early in life for cardiovascular disease in adulthood. To test the hypothesis that dietary intake is associated with prospective changes in CM risk factors, we analyzed longitudinal observations made over a period of 2 years among 448 students (aged 10-17 years) from 14 schools in Canada. We applied mixed effect regression to examine the associations of dietary intake at baseline with changes in body mass index, waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP), and insulin sensitivity score between baseline and follow-up while adjusting for age, sex, and physical activity. Dietary fat at baseline was associated with increases in SBP and DBP z scores (per 10 g increase in dietary fat per day: β = 0.03; p < 0.05) and WC (β = 0.31 cm; p < 0.05) between baseline and follow-up. Every additional gram of sodium intake at baseline was associated with an increase in DBP z score of 0.04 (p < 0.05) between baseline and follow-up. Intake of sugar, vegetables and fruit, and fibre were not associated with changes in CM risk factors in a statistically significant manner. Our findings suggest that a reduction in the consumption of total dietary fat and sodium may contribute to the prevention of excess body weight and hypertension in children and youth, and their cardiometabolic sequelae later in life.

Intake of different types of dairy and its prospective association with risk of type 2 diabetes: The Rotterdam Study

BACKGROUND AND AIMS

The prevalence of type 2 diabetes (T2DM) is increasing. Several studies have suggested a beneficial effect of several major dairy nutrients on insulin production and sensitivity. Conversely, harmful effects have been suggested as well. This study aimed to investigate the impact of the full-range of dairy products and its association with incidence T2DM in Dutch adults aged ≥55 years participating in the Rotterdam Study.

METHODS AND RESULTS

Dairy intake was assessed with a validated FFQ, including total, skimmed, semi-skimmed, full-fat, fermented, and non-fermented dairy, and subclasses of these product groups. Verified prevalent and incident diabetes were documented. Cox proportional hazards regression and spline regression were used to analyse data, adjusting for age, sex, alcohol, smoking, education, physical activity, body mass index, intake of total energy, energy-adjusted meat, and energy-adjusted fish intake. Median total dairy intake was 398 g/day (IQR 259-559 g/day). Through 9.5 ± 4.1 years of follow-up, 393 cases of incident T2DM were reported. Cox and spline regression did not point towards associations of total dairy consumption, dairy consumption based on fat content, non-fermented or fermented dairy consumption, or individual dairy product consumption with incident T2DM. The HR for total dairy intake and T2DM was 0.93 (95% CI: 0.70-1.23) in the upper quartile (P-for trend 0.76).

CONCLUSIONS

This prospective cohort study did not point towards an association between dairy consumption and T2DM.

Evaluation of fish oil-rich in MUFAs for anti-diabetic and anti-inflammation potential in experimental type 2 diabetic rats

The advantages of monounsaturated fatty acids (MUFAs) on insulin resistance and type 2 diabetes mellitus (T2DM) have been well established. However, the molecular mechanisms of the anti-diabetic action of MUFAs remain unclear. This study examined the anti-hyperglycemic effect and explored the molecular mechanisms involved in the actions of fish oil- rich in MUFAs that had been acquired from hybrid catfish (Pangasius larnaudii×Pangasianodon hypophthalmus) among experimental type 2 diabetic rats. Diabetic rats that were fed with fish oil (500 and 1,000 mg/kg BW) for 12 weeks significantly reduced the fasting plasma glucose levels without increasing the plasma insulin levels. The diminishing levels of plasma lipids and the muscle triglyceride accumulation as well as the plasma leptin levels were identified in T2DM rats, which had been administrated with fish oil. Notably, the plasma adiponectin levels increased among these rats. The fish oil supplementation also improved glucose tolerance, insulin sensitivity and pancreatic histological changes. Moreover, the supplementation of fish oil improved insulin signaling (p-Akt^Ser473 and p-PKC-ζ/λ^Thr410/403), p-AMPK^Thr172 and membrane GLUT4 protein expressions, whereas the protein expressions of pro-inflammatory cytokines (TNF-α and nuclear NF-κB) as well as p-PKC-θ^Thr538 were down regulated in the skeletal muscle. These data indicate that the effects of fish oil-rich in MUFAs in these T2DM rats were partly due to the attenuation of insulin resistance and an improvement in the adipokine imbalance. The mechanisms of the anti-hyperglycemic effect are involved in the improvement of insulin signaling, AMPK activation, GLUT4 translocation and suppression of pro-inflammatory cytokine protein expressions.

Attenuation of diet-induced obesity and induction of white fat browning with a chemical inhibitor of histone deacetylases

BACKGROUND/OBJECTIVES

In the last decade, a strict link between epigenetics and metabolism has been demonstrated. Histone deacetylases (HDACs) have emerged as key epigenetic regulators involved in metabolic homeostasis in normal and pathologic conditions. Here we investigated the effect of the class I HDAC inhibitor MS-275 in a model of obesity induced by a high-fat diet (HFD).

METHODS

C57BL6/J male mice were fed HFD for 17 weeks and then randomized in two groups, treated intraperitoneally with vehicle dimethylsulfoxide (DMSO) or with the class I selective HDAC inhibitor MS-275 every other day for 22 days. Glucose tolerance test and measurement of body temperature during cold exposure were performed. Adipose tissues and liver were phenotypically characterized through histological analysis. Gene and protein expression analysis of brown and white adipose tissues (WATs) were performed.

RESULTS

MS-275 treated mice showed 10% reduction of body weight, lower adipocyte size and improved glucose tolerance. Inhibition of class I HDAC determined reduction of adipocyte size and of fat mass, paralleled by higher expression of adipose functionality markers and by increased rate of lipolysis and fatty acid β-oxidation. MS-275 also promoted thermogenic capacity, related to 'browning' of visceral and subcutaneous WAT, showing increased expression of uncoupling protein 1. In brown adipose tissue, we observed limited effects on gene expression and only reduction of brown adipocyte size.

CONCLUSIONS

This study provides evidence that class I HDAC inhibition stimulated functionality and oxidative potential of adipose tissue, improving glucose tolerance and ameliorating the metabolic profile in diet-induced obese mice.

The effects of high-fat diets composed of different animal and vegetable fat sources on the health status and tissue lipid profiles of male Japanese quail (Coturnix coturnix japonica)

Objective

The current study aimed to investigate the impact of high-fat diets composed of different animal and vegetable fat sources on serum metabolic health markers in Japanese quail, as well as the overall lipid content and fatty acid profiles of the edible bird tissues following significantly increased dietary lipid supplementation.

Methods

Fifty seven male quail were divided into six groups and fed either a standard diet or a diet enriched with one of five different fats (22% coconut oil, lard, palm oil, soybean oil, or sunflower oil) for 12 weeks. The birds were subjected to an oral glucose tolerance test following the feeding period, after which they were euthanized and blood, liver, breast, and thigh muscle samples collected. Total fat content and fatty acid profiles of the tissue samples, as well as serum uric acid, triglyceride, cholesterol, total protein, albumin, aspartate transaminase, and total bilirubin concentrations were assessed.

Results

High-fat diet feeding had no significant effects on the glucose tolerance of the birds. Dietary fatty acid profiles of the added fats were reflected in the lipid profiles of both the liver and breast and thigh muscle tissues, indicating successful transfer of dietary fatty acids to the edible bird tissues. The significantly increased level of lipid inclusion in the diets of the quail used in the present study was unsuccessful in increasing the overall lipid content of the edible bird tissues. Serum metabolic health markers in birds on the high-fat diets were not significantly different from those observed in birds on the standard diet.

Conclusion

Thus, despite the various high-fat diets modifying the fatty acid profile of the birds’ tissues, unlike in most mammals, the birds maintained a normal health status following consumption of the various high-fat diets.

Prevalence and comorbidities of double diabetes

BACKGROUND

A growing number of people with type 1 diabetes (T1DM) are identified with features of metabolic syndrome (MS) known as "double diabetes", but epidemiologic data on the prevalence of MS in T1DM and its comorbidities are still lacking. Aim of this cross sectional study is to better estimate the prevalence of MS in T1DM, and to assess its association with comorbidities.

METHODS

Data of 31,119 persons with autoimmune diabetes mellitus were analysed for signs of MS and presence of late complications. Double diabetes was defined as T1DM coexisting with MS (obesity, hypertension, dyslipidemia). Multiple linear or logistic regression analyses were performed to identify associations between double diabetes and late complications.

RESULTS

25.5% (n=7926) of persons with T1DM presented additionally the MS. Persons with double diabetes showed significantly more macrovascular comorbidities (coronary heart disease 8.0% versus 3.0% w/o MS, stroke 3.6% versus 1.6%, diabetic foot syndrome 5.5% versus 2.1%). Also microvascular diseases were increased in people with double diabetes (retinopathy 32.4% versus 21.7%, nephropathy 28.3% versus 17.8%). Both macrovascular and microvascular comorbidities were increased independent of glucose control, even if patients with good metabolic control (HbA1c <7.0%, 53mmol/mol) showed significantly less macrovascular (coronary heart disease 2.3% versus 1.8%, p<0.0001) and microvascular problems (retinopathy 8.7% versus 6.6%, p<0.0001).

CONCLUSIONS

Double diabetes seems to be an independent and important risk factor for persons with T1DM in developing macrovascular and microvascular comorbidities. Therefore, patients should be identified and development of MS should be avoided. Longterm studies are needed to observe the effect of insulin resistance on patients with autoimmune diabetes.

FGF21 improves cognition by restored synaptic plasticity, dendritic spine density, brain mitochondrial function and cell apoptosis in obese-insulin resistant male rats

Fibroblast growth factor 21 (FGF21) is an endocrine hormone which exerts beneficial effects on metabolic regulation in obese and diabetic models. However, the effect of FGF21 on cognition in obese-insulin resistant rats has not been investigated. We hypothesized that FGF21 prevented cognitive decline in obese-insulin resistant rats by improving hippocampal synaptic plasticity, dendritic spine density, brain mitochondrial function and brain FGF21 signaling as well as decreasing brain cell apoptosis. Eighteen male Wistar rats were divided into two groups, and received either a normal diet (ND) (n=6) or a high fat diet (HFD) (n=12) for 12weeks. At week 13, the HFD-fed rats were subdivided into two subgroups (n=6/subgroup) to receive either vehicle or recombinant human FGF21 (0.1mg/kg/day) for four weeks. ND-fed rats were given vehicle for four weeks. At the end of the treatment, cognitive function, metabolic parameters, pro-inflammatory markers, brain mitochondrial function, cell apoptosis, hippocampal synaptic plasticity, dendritic spine density and brain FGF21 signaling were determined. The results showed that vehicle-treated HFD-fed rats developed obese-insulin resistance and cognitive decline with impaired hippocampal synaptic plasticity, decreased dendritic spine density, brain mitochondrial dysfunction and increased brain cell apoptosis. Impaired brain FGF 21 signaling was found in these obese-insulin resistant rats. FGF21-treated obese-insulin resistant rats had improved peripheral insulin sensitivity, increased hippocampal synaptic plasticity, increased dendritic spine density, restored brain mitochondrial function, attenuated brain cells apoptosis and increased brain FGF21 signaling, leading to a prevention of cognitive decline. These findings suggest that FGF21 treatment exerts neuroprotection in obese-insulin resistant rats.

Exercise and diet in the management of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition worldwide, and is projected to become the leading cause for liver transplantation in the United States as early as 2020. The mainstay of treatment remains lifestyle modification with diet and exercise recommendations, as although some pharmacological treatments such as glitazones and Vitamin E have shown benefit, there are concerns regarding long term safety. The evidence base for dietary interventions in NAFLD such as the Mediterranean diet, omega-3 polyunsaturated fatty acids and coffee is mainly derived from observational data with questionable validity. Where trials exist, they have shown benefit for surrogate outcomes such as hepatic steatosis and insulin resistance, but no trials have been conducted with salient clinical outcomes such as reduction in progression to chronic liver disease. Benefit in surrogate outcomes has also been seen for aerobic, anaerobic and combined modality exercise but it remains unclear if one type is superior. Furthermore, a reduction in sedentary time appears equally important. To provide a sound evidence base for lifestyle recommendations to people with NAFLD, longer duration trials of standardized dietary or exercise interventions, and testing various doses, types and with liver related outcomes, are essential.

Consumo alimentar dos portadores de Doença Hepática Gordurosa Não Alcoólica: comparação entre a presença e a ausência de Esteatoepatite Não Alcoólica e Síndrome Metabólica

RESUMO Objetivo O objetivo desse estudo foi avaliar o consumo alimentar de portadores de Doença Hepática Gordurosa Não Alcoólica, comparar com as recomendações nutricionais diárias e analisar a correlação da dieta com a presença de Síndrome Metabólica e com a gravidade da doença, uma vez que estudos sobre os hábitos alimentares dos portadores de Doença Hepática Gordurosa Não Alcoólica ainda são escassos na literatura. Métodos Nesse estudo foram avaliados, inicialmente, 158 pacientes com diagnóstico de Doença Hepática Gordurosa Não Alcoólica. Analisou-se exames laboratoriais, biópsia hepática, dados antropométricos e consumo dietético (registro alimentar de três dias). Dentre os pacientes avaliados, alguns já haviam sido orientados nutricionalmente e foram divididos em dois grupos: "sem dieta" e "com dieta". Para o cálculo de comparações de médias entre os grupos estudados, empregou-se o teste t de Student, considerando o nível de significância de 5% (a£0,05). Resultados Do total inicial de participantes, 59 apresentavam modificação significativa da dieta a partir de alguma orientação nutricional prévia e, por isso, foram excluídos da análise. Dos 99 pacientes restantes, quando confrontados com a ingestão dietética recomendada, 26% apresentavam maior ingestão energética e 80%, de ácidos graxos saturados, além de deficiente ingestão de ácidos graxos poli-insaturados e monoinsaturados, fibras e vitamina E, confirmando estudos prévios nessa mesma população. Entretanto, não foram encontradas diferenças significativas na dieta desses pacientes quando divididos de acordo com a presença ou ausência de Síndrome Metabólica e Esteatoepatite Não Alcoólica. Conclusão Esses dados, à luz dos conhecimentos atuais, sugerem que a dieta, especialmente quando rica em ácidos graxos saturados e deficiente em fibras e vitaminas antioxidantes, pode ter importante papel no aparecimento da Doença Hepática Gordurosa Não Alcoólica, mas que outros fatores exercem papel mais relevante na sua progressão para a Esteatoepatite Não Alcoólica.

Effects of an High-Fat Diet Enriched in Lard or in Fish Oil on the Hypothalamic Amp-Activated Protein Kinase and Inflammatory Mediators

The high fat diet (HFD) rich in lard induces obesity, inflammation and oxidative stress, and the deregulation of hypothalamic nuclei plays an important role in this mechanism. One important factor involved in the food intake and inflammation is adenosine monophosphate-dependent kinase (AMPK), a serine/threonine kinase activated by phosphorylation. Omega (ω)3-polyunsaturated fatty acids (PUFA) are dietary compounds known to attenuate the obesity-related diseases, although the molecular mechanisms underlying their actions in the hypothalamus are not completely understood. We hypothesized that the beneficial effects of PUFA may be mediated by AMPK in the hypothalamus. To this aim, rats were fed a control diet (CD), or isocaloric HFD containing either fish oil (FD; rich in ω3-PUFA) or lard for 6 weeks, and the activation of AMPK, inflammatory state (IKKβ, TNF-α) and oxidative stress were analyzed in the hypothalamus. In addition, we also studied serum lipid profile, homeostatic model assessment (HOMA) index, and pro-inflammatory parameters. Our results showed, at the hypothalamic level of LD-fed rats, an increase of AMPK activation, inflammation and oxidative stress, while no modifications were detected in FD-fed animals compared to CD. In addition body weight gain, serum lipid profile, pro-inflammatory parameters and insulin resistance were reduced in FD animals compared to LD. In conclusion, our data indicate that the substitution of saturated by unsaturated fatty acids in the diet has beneficial effects on modulation of hypothalamic inflammation and function in obesity, underlying, at hypothalamic level, the interaction among insulin and/or leptin resistance, AMPK activation and hyperphagia.

Nutrient intake and cerebral metabolism in healthy middle-aged adults: Implications for cognitive aging

OBJECTIVES

Growing evidence suggests dietary factors influence cognition, but the effects of nutrient intake on cerebral metabolism in adults are currently unknown. The present study investigated the relationship between major macronutrient intake (fat, carbohydrate, and protein) and cerebral neurochemical profiles in middle-aged adults.

METHODS

Thirty-six adults recorded dietary intake for 3 days prior to completing cognitive testing and a proton magnetic resonance spectroscopy (¹H-MRS) scan. ¹H-MRS of occipitoparietal gray matter was used to assess glutamate (Glu), N-acetyl-aspartate (NAA), choline (Cho), and myo-inositol (mI) relative to creatine (Cr) levels.

RESULTS

Regression analyses revealed that high intake of polyunsaturated fatty acids (PUFAs) was associated with lower cerebral Glu/Cr (P = 0.005), and high intake of saturated fat (SFA) was associated with poorer memory function (P = 0.030) independent of age, sex, education, estimated intelligence, total caloric intake, and body mass index.

DISCUSSION

In midlife, greater PUFA intake (ω-3 and ω-6) may be associated with lower cerebral glutamate, potentially indicating more efficient cellular reuptake of glutamate. SFA intake, on the other hand, was linked with poorer memory performance. These results suggest that dietary fat intake modification may be an important intervention target for the prevention of cognitive decline.

Dietary Fat Intake During Adolescence and Breast Density Among Young Women

BACKGROUND

Lack of association between fat intake and breast cancer risk in cohort studies might be attributed to the disregard of temporal effects during adolescence when breasts develop and are particularly sensitive to stimuli. We prospectively examined associations between adolescent fat intakes and breast density.

METHOD

Among 177 women who participated in the Dietary Intervention Study in Children, dietary intakes at ages 10-18 years were assessed on five occasions by 24-hour recalls and averaged. We calculated geometric mean and 95% confidence intervals for MRI-measured breast density at ages 25-29 years across quartiles of fat intake using linear mixed-effect regression.

RESULTS

Comparing women in the extreme quartiles of adolescent fat intakes, percent dense breast volume (%DBV) was positively associated with saturated fat (mean = 16.4% vs. 21.5%; Ptrend < 0.001). Conversely, %DBV was inversely associated with monounsaturated fat (25.0% vs. 15.8%; Ptrend < 0.001) and the ratio of polyunsaturated fat to saturated fat (P/S ratio; 19.1% vs. 14.3%; Ptrend < 0.001). When examining intake by pubertal stages, %DBV was inversely associated with intake of polyunsaturated fat (20.8% vs. 16.4%; Ptrend = 0.04), long-chain omega-3 fat (17.8% vs. 15.8%; Ptrend < 0.001), and P/S ratio (22.5% vs. 16.1%; Ptrend < 0.001) before menarche, but not after. These associations observed with %DBV were consistently observed with absolute dense breast volume but not with absolute nondense breast volume.

CONCLUSIONS

In our study, adolescent intakes of higher saturated fat and lower mono- and polyunsaturated fat are associated with higher breast density measured approximately 15 years later.

IMPACT

The fat subtype composition in adolescent diet may be important in early breast cancer prevention. Cancer Epidemiol Biomarkers Prev; 25(6); 918-26. ©2016 AACR.

Long-Term High Fat Diet Has a Profound Effect on Body Weight, Hormone Levels, and Estrous Cycle in Mice

Background

Obesity causes several health complications along with disruption of the reproductive system. The aim of the current study was to determine how long-term intake of very high fat diet (VHFD) changes the hormonal milieu, affecting the cellular morphology and reproductive cycle in female mice.

Material/Methods

Mice were fed on normal diet (ND) and VHFD for 2 weeks, 12 weeks, and 25–27 weeks. We assessed changes in body weight, food consumption, energy intake, cellular and tissue morphology, hormonal levels (leptin, insulin, and estradiol), and vaginal smears were performed at various time points to determine the length and cellularity at each stage of the estrous cycle.

Results

Mice fed on VHFD showed a significant increase in weight gain, reduction in food intake, and increase in energy intake compared to animals fed on ND, indicating that the caloric density of the diet is responsible for the differences in weight gain. Hormonal analysis showed hyperleptinemia, hyperinsulinemia, and increases in estrogen levels, along with increases in size of the islet of Langerhans and adipocytes. After 25–27 weeks, all animals fed on VHFD showed complete acyclicity; elongation of phases (e.g., diestrous), skipping of phases (e.g., metestrous), or a combination of both, indicating disruption in the reproductive cycle. Quantitative analysis showed that in the diestrous phase there was a 70% increase in cell count in VHFD compared to animals fed on ND.

Conclusions

The above results show that morphological and hormonal changes caused by VHFD probably act via negative feedback to the hypothalamic-pituitary axis to shut down reproduction, which has a direct effect on the estrous cycle, causing acyclicity in mice.

Chronic pancreatitis and the composition of plasma phosphatidylcholine fatty acids

Chronic pancreatitis (CP) is an irreversible inflammatory disorder characterized by the destruction of both exocrine and endocrine tissue. There is growing evidence that dysregulation of fatty acid (FA) metabolism is connected with many diseases; however, there are few data concerning FA composition in CP. Therefore, we analyzed FA profiles in plasma phosphatidylcholines in 96 patients with CP and in 108 control subjects (CON). The patients with CP had, in comparison with CON, increased sum of monounsaturated FA (ΣMUFA) and decreased content of polyunsaturated FA (PUFA) in both n-6 and n-3 families. Moreover, CP patients had increased indexes for delta-9, delta-6 desaturases, and fall in activity of delta-5 desaturase. Increased ratio of 16:1n-7/18:2n-6 (marker of essential n-6 FA deficiency), was more prevalent among CP patients. These changes implicated decreased fat intake, including n-3 as well as n-6 PUFA, and intrinsic changes in FA metabolism due to the alteration of delta desaturase activities.

Low-Density Lipoprotein Receptor-Related Protein-1 Protects Against Hepatic Insulin Resistance and Hepatic Steatosis

Low-density lipoprotein receptor-related protein-1 (LRP1) is a multifunctional uptake receptor for chylomicron remnants in the liver. In vascular smooth muscle cells LRP1 controls reverse cholesterol transport through platelet-derived growth factor receptor β (PDGFR-β) trafficking and tyrosine kinase activity. Here we show that LRP1 regulates hepatic energy homeostasis by integrating insulin signaling with lipid uptake and secretion. Somatic inactivation of LRP1 in the liver (hLRP1KO) predisposes to diet-induced insulin resistance with dyslipidemia and non-alcoholic hepatic steatosis. On a high-fat diet, hLRP1KO mice develop a severe Metabolic Syndrome secondary to hepatic insulin resistance, reduced expression of insulin receptors on the hepatocyte surface and decreased glucose transporter 2 (GLUT2) translocation. While LRP1 is also required for efficient cell surface insulin receptor expression in the absence of exogenous lipids, this latent state of insulin resistance is unmasked by exposure to fatty acids. This further impairs insulin receptor trafficking and results in increased hepatic lipogenesis, impaired fatty acid oxidation and reduced very low density lipoprotein (VLDL) triglyceride secretion.

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Hepatic LRP1 deficiency in a mouse model (hLRP1KO) predisposes to diet-induced insulin resistance, dyslipidemia, and obesity.

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Insulin resistance in the hLRP1KO mouse results from reduced cell surface expression of insulin receptor (IR) and impaired translocation of glucose transporter 2 (GLUT2).

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Excess fatty acids in hLRP1KO mice shift hepatic fatty acid metabolism from an oxidative to a synthetic state, resulting in hepatic steatosis.

LRP1 is a multifunctional transmembrane receptor with essential functions in lipoprotein metabolism and subcellular receptor tyrosine kinase trafficking. A mouse model of hepatic LRP1 deficiency integrates the hallmark findings in Metabolic Syndrome - insulin resistance, dyslipidemia, and hepatic steatosis - with impaired glucose metabolism and altered hepatic fatty acid metabolism as a consequence of reduced insulin receptor trafficking and signaling. These findings underscore the central role of LRP1 in overall energy homeostasis, and specifically liver glucose and fatty acid metabolism.

Effect of an avocado oil-enhanced diet ( Persea americana ) on sucrose-induced insulin resistance in Wistar rats

A number of studies have been conducted to evaluate the effects of vegetable oils with varying percentages of monounsaturated and polyunsaturated fatty acids on insulin resistance. However, there is no report on the effect of avocado oil on this pathologic condition. The aim of this work was to evaluate the effect of avocado oil on sucrose-induced insulin resistance in Wistar rats. An experimental study was carried out on Wistar rats that were randomly assigned into six groups. Each group received a different diet over an 8-week period (n = 11 in each group): the control group was given a standard diet, and the other five groups were given the standard feed plus sucrose with the addition of avocado oil at 0%, 5%, 10%, 20%, and 30%, respectively. Variables were compared using Student t test and analysis of variance. Statistically significant difference was considered when p < 0.05. Rats that were given diets with 10% and 20% avocado oil showed lower insulin resistance (p = 0.022 and p = 0.024, respectively). Similar insulin resistance responses were observed in the control and 30% avocado oil addition groups (p = 0.85). Addition of 5–30% avocado oil lowered high sucrose diet-induced body weight gain in Wistar rats. It was thus concluded that glucose tolerance and insulin resistance induced by high sucrose diet in Wistar rats can be reduced by the dietary addition of 5–20% avocado oil.

Gender Differences in Dietary Patterns and Their Association with the Prevalence of Metabolic Syndrome among Chinese: A Cross-Sectional Study

Few studies have investigated gender differences in dietary intake. The objective of this cross-sectional study was to examine gender differences in dietary patterns and their association with the prevalence of metabolic syndrome. The food intakes of 3794 subjects enrolled by a two-stage cluster stratified sampling method were collected using a valid semi-quantitative food frequency questionnaire (FFQ). Metabolic syndrome (MetS) was defined according to the International Diabetes Federation (IDF) and its prevalence was 35.70% in the sample (37.67% in men and 24.67% in women). Dietary patterns were identified using factor analysis combined with cluster analysis and multiple group confirmatory factor analysis was used to assess the factorial invariance between gender groups. The dominating dietary pattern for men was the “balanced” dietary pattern (32.65%) and that for women was the “high-salt and energy” dietary pattern (34.42%). For men, the “animal and fried food” dietary pattern was related to higher risk of MetS (odds ratio: 1.27; 95% CI: 1.01–1.60), after adjustment for age, marital status, socioeconomic status and lifestyle factors. For women, the “high-salt and energy” dietary pattern was related to higher risk of MetS (odds ratio: 2.27; 95% CI: 1.24–4.14). We observed gender differences in dietary patterns and their association with the prevalence of MetS. For men, the “animal and fried food” dietary pattern was associated with enhancive likelihood of MetS. For women, it was the “high-salt and energy” dietary pattern.

Meat and milk intake in the rice-based Korean diet: impact on cancer and metabolic syndrome

Over a few decades, Korean diet has changed from traditional diet, mainly composed of rice and vegetables, to Westernised diet rich, in meat and milk, along with the economic development and globalisation. Increasing prevalence of diet-related chronic diseases such as cancer and metabolic syndrome (MetS) is becoming a heavy burden to society and requires further attention. In this review, the association of meat and milk consumption with cancer and MetS among Koreans was discussed. Previous meta-analyses showed that meat intake was positively associated with increased risk of cancers, especially colon, as well as obesity and type 2 diabetes mellitus, and that the intake of milk and dairy products was negatively associated with colorectal cancer, obesity, and type 2 diabetes mellitus, based on studies conducted mostly in Western countries. In Korea and other Asian countries, the association of meat and milk intake with cancers were inconclusive and varied by types of cancers. Conversely, milk intake was negatively associated with MetS risk as reported in Western countries. The difference in results between Korea and Western countries might come from the differences in dietary patterns and study designs. Most Koreans still maintain traditional dietary pattern, although rapid change towards Westernised diet is underway among the younger age group. Randomised clinical trials or prospective cohort studies with consideration of combined effects of various dietary factors in Korea and other Asian countries are needed to elucidate the impact of meat and milk or related dietary patterns in their diet.

Bromocriptine-QR therapy for the management of type 2 diabetes mellitus: developmental basis and therapeutic profile summary

An extended series of studies indicate that endogenous phase shifts in circadian neuronal input signaling to the biological clock system centered within the hypothalamic suprachiasmatic nucleus (SCN) facilitates shifts in metabolic status. In particular, a diminution of the circadian peak in dopaminergic input to the peri-SCN facilitates the onset of fattening, insulin resistance and glucose intolerance while reversal of low circadian peak dopaminergic activity to the peri-SCN via direct timed dopamine administration to this area normalizes the obese, insulin resistant, glucose intolerant state in high fat fed animals. Systemic circadian-timed daily administration of a potent dopamine D2 receptor agonist, bromocriptine, to increase diminished circadian peak dopaminergic hypothalamic activity across a wide variety of animal models of metabolic syndrome and type 2 diabetes mellitus (T2DM) results in improvements in the obese, insulin resistant, glucose intolerant condition by improving hypothalamic fuel sensing and reducing insulin resistance, elevated sympathetic tone, and leptin resistance. A circadian-timed (within 2 hours of waking in the morning) once daily administration of a quick release formulation of bromocriptine (bromocriptine-QR) has been approved for the treatment of T2DM by the U.S. Food and Drug Administration. Clinical studies with such bromocriptine-QR therapy (1.6 to 4.8 mg/day) indicate that it improves glycemic control by reducing postprandial glucose levels without raising plasma insulin. Across studies of various T2DM populations, bromocriptine-QR has been demonstrated to reduce HbA1c by -0.5 to -1.7. The drug has a good safety profile with transient mild to moderate nausea, headache and dizziness as the most frequent adverse events noted with the medication. In a large randomized clinical study of T2DM subjects, bromocriptine-QR exposure was associated with a 42% hazard ratio reduction of a pre-specified adverse cardiovascular endpoint including myocardial infarction, stroke, hospitalization for congestive heart failure, revascularization surgery, or unstable angina. Bromocriptine-QR represents a novel method of treating T2DM that may have benefits for cardiovascular disease as well.

Heterozygous caveolin-3 mice show increased susceptibility to palmitate-induced insulin resistance

Insulin resistance and diabetes are comorbidities of obesity and affect one in 10 adults in the United States. Despite the high prevalence, the mechanisms of cardiac insulin resistance in obesity are still unclear. We test the hypothesis that the insulin receptor localizes to caveolae and is regulated through binding to caveolin-3 (CAV3). We further test whether haploinsufficiency forCAV3 increases the susceptibility to high-fat-induced insulin resistance. We used in vivo and in vitro studies to determine the effect of palmitate exposure on global insulin resistance, contractile performance of the heart in vivo, glucose uptake in the heart, and on cellular signaling downstream of theIR We show that haploinsufficiency forCAV3 increases susceptibility to palmitate-induced global insulin resistance and causes cardiomyopathy. On the basis of fluorescence energy transfer (FRET) experiments, we show thatCAV3 andIRdirectly interact in cardiomyocytes. Palmitate impairs insulin signaling by a decrease in insulin-stimulated phosphorylation of Akt that corresponds to an 87% decrease in insulin-stimulated glucose uptake inHL-1 cardiomyocytes. Despite loss of Akt phosphorylation and lower glucose uptake, palmitate increased insulin-independent serine phosphorylation ofIRS-1 by 35%. In addition, we found lipid induced downregulation ofCD36, the fatty acid transporter associated with caveolae. This may explain the problem the diabetic heart is facing with the simultaneous impairment of glucose uptake and lipid transport. Thus, these findings suggest that loss ofCAV3 interferes with downstream insulin signaling and lipid uptake, implicatingCAV3 as a regulator of theIRand regulator of lipid uptake in the heart.

The involvement of ginseng berry extract in blood flow via regulation of blood coagulation in rats fed a high-fat diet

Background

The present study investigated the effect of ginseng berry hot water extract (GBx) on blood flow via the regulation of lipid metabolites and blood coagulation in rats fed a high-fat diet (HFD).

Methods

Sixty rats were divided into five groups in descending order of body weight. Except for the control group, the other four groups were fed a HFD containing 45% kcal from fat for 11 wk without GBx. GBx groups were then additionally treated by gastric gavage with GBx dissolved in distilled water at 50 (GBx 50) mg/kg, 100 (GBx 100) mg/kg, or 150 (GBx 150) mg/kg body weight for 6 wk along with the HFD. To investigate the effects of GBx on rats fed a HFD, biochemical metabolite, blood coagulation assay, and histological analysis were performed.

Results

In the experiments to measure the serum levels of leptin and apolipoprotein B/A, GBx treatment attenuated the HFD-induced increases in these metabolites (p < 0.05). Adiponectin and apolipoprotein E levels in GBx-treated groups were significantly higher than the HFD group. Prothrombin time and activated partial thromboplastin time were increased in all GBx-treated groups. In the GBx-treated groups, the serum levels of thromboxane A₂ and serotonin were decreased and concentrations of serum fibrinogen degradation products were increased (p < 0.05). Moreover, histomorphometric dyslipidemia-related atherosclerotic changes were significantly improved by treatment with GBx.

Conclusion

These results suggest the possibility that GBx can ameliorate blood flow by decreasing intima-media thickness via the regulation of blood coagulation factors related to lipid metabolites in rats fed a HFD.

Is the metabolic syndrome inversely associates with butter, non-hydrogenated- and hydrogenated-vegetable oils consumption: Tehran lipid and glucose study

AIM

The aim of this study was to investigate the association between hydrogenated- (HVOs) and non-hydrogenated vegetable oils (non-HVOs) and butter and the metabolic syndrome (MetS) after 3-years of follow-up in adults.

METHODS

This study was conducted between 2006-2008 and 2009-2011 within the framework of the Tehran Lipid and Glucose Study, on 1582 adults, aged 19-84 years. Intakes of HVOs, non-HVOs and butter were assessed by a validated semi-quantitative food frequency questionnaire. Based on the consumption of food rich in fat including HVOs, non-HVOs and butter, participants were categorized to consumers and non-consumers.

RESULTS

Of 1582 participants during a 3-year follow-up, 15.2% developed MetS. Non-consumption of butter was associated with lower MetS risk compared with its consumption. Among consumers of food rich in fat, intake of HVOs and butter were associated with an increased risk of MetS; ORs in the final multivariate model were 2.70 (95% CI: 1.52-4.78) for HVOs and 2.03 (95% CI: 1.20-3.41) for butter, in the highest, compared to the lowest category of dietary intakes. Intake of non-HVOs was not associated with risk of MetS.

CONCLUSIONS

Consumption of HVOs and butter were positively associated with an increase risk of MetS.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Deregulated Lipid Sensing by Intestinal CD36 in Diet-Induced Hyperinsulinemic Obese Mouse Model

The metabolic syndrome (MetS) greatly increases risk of cardiovascular disease and diabetes and is generally associated with abnormally elevated postprandial triglyceride levels. We evaluated intestinal synthesis of triglyceride-rich lipoproteins (TRL) in a mouse model of the MetS obtained by feeding a palm oil-rich high fat diet (HFD). By contrast to control mice, MetS mice secreted two populations of TRL. If the smaller size population represented 44% of total particles in the beginning of intestinal lipid absorption in MetS mice, it accounted for only 17% after 4 h due to the secretion of larger size TRL. The MetS mice displayed accentuated postprandial hypertriglyceridemia up to 3 h due to a defective TRL clearance. These alterations reflected a delay in lipid induction of genes for key proteins of TRL formation (MTP, L-FABP) and blood clearance (ApoC2). These abnormalities associated with blunted lipid sensing by CD36, which is normally required to optimize jejunal formation of large TRL. In MetS mice CD36 was not downregulated by lipid in contrast to control mice. Treatment of controls with the proteosomal inhibitor MG132, which prevented CD36 downregulation, resulted in blunted lipid-induction of MTP, L-FABP and ApoC2 gene expression, as in MetS mice. Absence of CD36 sensing was due to the hyperinsulinemia in MetS mice. Acute insulin treatment of controls before lipid administration abolished CD36 downregulation, lipid-induction of TRL genes and reduced postprandial triglycerides (TG), while streptozotocin-treatment of MetS mice restored lipid-induced CD36 degradation and TG secretion. In vitro, insulin treatment abolished CD36-mediated up-regulation of MTP in Caco-2 cells. In conclusion, HFD treatment impairs TRL formation in early stage of lipid absorption via insulin-mediated inhibition of CD36 lipid sensing. This impairment results in production of smaller TRL that are cleared slowly from the circulation, which might contribute to the reported association of CD36 variants with MetS risk.

Normocaloric Diet Restores Weight Gain and Insulin Sensitivity in Obese Mice

An increased incidence of obesity is registered worldwide, and its association with insulin resistance and type 2 diabetes is closely related with increased morbidity and mortality for cardiovascular diseases. A major clinical problem in the management of obesity is the non-adherence or low adherence of patients to a hypocaloric dietetic restriction. In this study, we evaluated in obese mice the effects of shifting from high-calorie foods to normal diet on insulin sensitivity. Male C57BL/6JOlaHsd mice (n = 20) were fed with high fat diet (HFD) for a 24-week period. Afterward, body weight, energy, and food intake were measured in all animals, together with parameters of insulin sensitivity by homeostatic model assessment of insulin resistance and plasma glucose levels in response to insulin administration. Moreover, in half of these mice, Glut4 mRNA levels were measured in muscle at the end of the high fat treatment, whereas the rest of the animals (n = 10) were shifted to normocaloric diet (NCD) for 10 weeks, after which the same analyses were carried out. A significant reduction of body weight was found after the transition from high to normal fat diet, and this decrease correlated well with an improvement in insulin sensitivity. In fact, we found a reduction in serum insulin levels and the recovery of insulin responsiveness in terms of glucose disposal measured by insulin tolerance test and Glut4 mRNA and protein expression. These results indicate that obesity-related insulin resistance may be rescued by shifting from HFD to NCD.

Dietary fat intake and its association with risk of selected components of the metabolic syndrome among rural South Indians

CONTEXT

There is limited literature on the dietary fat intake of rural Indian populations, particularly in relation to the risk of metabolic syndrome (MS).

AIM

This study aims to assess the dietary fat intake and analyze its association with the risk of selected components of the MS among rural population in the state of Tamil Nadu.

SETTINGS AND DESIGN

Adults (n = 27012) ≥20 years of age were recruited from the rural component of the Chennai Urban Rural Epidemiological Study, a cross-sectional study conducted in 42 villages in Kanchipuram District of Tamil Nadu.

SUBJECTS AND METHODS

Using a validated food frequency questionnaire, data were obtained on the fat intake among 6907 adults. Anthropometric and clinical measures were collected using standard methods. The components of the MS assessed were abdominal obesity, hypertension, and impaired fasting glucose. All analyses were performed using SPSS software (version 20).

RESULTS

Prevalence of abdominal obesity, hypertension, and impaired fasting glucose were significantly higher in the highest quintile of fat intake (33%, P < 0.001; 39%, P = 0.04, and 23.3%, P = 0.003, respectively). Highest intake of fat was also significantly associated with risk of abdominal obesity (P < 0.001), hypertension (P = 0.04), and impaired fasting glucose (P = 0.01). Sunflower oil as the main cooking oil was significantly associated with a higher risk of these components of the MS (P for trend <0.001) compared to traditional oils and palmolein.

CONCLUSIONS

Higher dietary fat was significantly associated with risk of components of the MS and use of sunflower oil as main cooking oil increased metabolic risk in rural South Indians.

Virgin coconut oil maintains redox status and improves glycemic conditions in high fructose fed rats

Virgin Coconut Oil (VCO), extracted from fresh coconut kernel possess similar fatty acid composition to that of Copra Oil (CO), a product of dried kernel. Although CO forms the predominant dietary constituent in south India, VCO is being promoted for healthy life due to its constituent antioxidant molecules. High fructose containing CO is an established model for insulin resistance and steatohepatitis in rodents. In this study, replacement of CO with VCO in high fructose diet markedly improved the glucose metabolism and dyslipidemia. The animals fed VCO diet had only 17 % increase in blood glucose level compared to CO fed animals (46 %). Increased level of GSH and antioxidant enzyme activities in VCO fed rats indicate improved hepatic redox status. Reduced lipid peroxidation and carbonyl adducts in VCO fed rats well corroborate with the histopathological findings that hepatic damage and steatosis were comparatively reduced than the CO fed animals. These results suggest that VCO could be an efficient nutraceutical in preventing the development of diet induced insulin resistance and associated complications possibly through its antioxidant efficacy.

Sex hormones and macronutrient metabolism

The biological differences between males and females are determined by a different set of genes and by a different reactivity to environmental stimuli, including the diet, in general. These differences are further emphasized and driven by the exposure to a different hormone flux throughout the life.

These differences have not been taken into appropriate consideration by the scientific community. Nutritional sciences are not immune from this “bias” and when nutritional needs are concerned, females are considered only when pregnant, lactating or when their hormonal profile is returning back to “normal,” i.e., to the male-like profile.

The authors highlight some of the most evident differences in aspects of biology that are associated with nutrition.

This review presents and describes available data addressing differences and similarities of the “reference man” vs. the “reference woman” in term of metabolic activity and nutritional needs. According to this assumption, available evidences of sex-associated differences of specific biochemical pathways involved in substrate metabolism are reported and discussed. The modulation by sexual hormones affecting glucose, amino acid and protein metabolism and the metabolization of nutritional fats and the distribution of fat depots, is considered targeting a tentative starting up background for a gender concerned nutritional science.

Deleterious effects of lard-enriched diet on tissues fatty acids composition and hypothalamic insulin actions

Altered tissue fatty acid (FA) composition may affect mechanisms involved in the control of energy homeostasis, including central insulin actions. In rats fed either standard chow or a lard-enriched chow (high in saturated/low in polyunsaturated FA, HS-LP) for eight weeks, we examined the FA composition of blood, hypothalamus, liver, and retroperitoneal, epididymal and mesenteric adipose tissues. Insulin-induced hypophagia and hypothalamic signaling were evaluated after intracerebroventricular insulin injection. HS-LP feeding increased saturated FA content in adipose tissues and serum while it decreased polyunsaturated FA content of adipose tissues, serum, and liver. Hypothalamic C20:5n-3 and C20:3n-6 contents increased while monounsaturated FA content decreased. HS-LP rats showed hyperglycemia, impaired insulin-induced hypophagia and hypothalamic insulin signaling. The results showed that, upon HS-LP feeding, peripheral tissues underwent potentially deleterious alterations in their FA composition, whist the hypothalamus was relatively preserved. However, hypothalamic insulin signaling and hypophagia were drastically impaired. These findings suggest that impairment of hypothalamic insulin actions by HS-LP feeding was not related to tissue FA composition.

Nutritional Modulation of Non-Alcoholic Fatty Liver Disease and Insulin Resistance

Non-alcoholic fatty liver disease (NAFLD) covers a spectrum of disorders ranging from simple steatosis (non-alcoholic fatty liver, NAFL) to non-alcoholic steatohepatitis (NASH) and cirrhosis. NAFL increases the risk of liver fibrosis. If the liver is fatty due to causes of insulin resistance such as obesity and physical inactivity, it overproduces glucose and triglycerides leading to hyperinsulinemia and a low high-density lipoprotein (HDL) cholesterol concentration. The latter features predispose to type 2 diabetes and cardiovascular disease (CVD). Understanding the impact of nutritional modulation of liver fat content and insulin resistance is therefore of interest for prevention and treatment of NAFLD. Hypocaloric, especially low carbohydrate ketogenic diets rapidly decrease liver fat content and associated metabolic abnormalities. However, any type of caloric restriction seems effective long-term. Isocaloric diets containing 16%-23% fat and 57%-65% carbohydrate lower liver fat compared to diets with 43%-55% fat and 27%-38% carbohydrate. Diets rich in saturated (SFA) as compared to monounsaturated (MUFA) or polyunsaturated (PUFA) fatty acids appear particularly harmful as they increase both liver fat and insulin resistance. Overfeeding either saturated fat or carbohydrate increases liver fat content. Vitamin E supplementation decreases liver fat content as well as fibrosis but has no effect on features of insulin resistance.

The association of cardiovascular risk factors with saturated fatty acids and fatty acid desaturase indices in erythrocyte in middle-aged Korean adults

BACKGROUND

The quality of dietary fats is associated with risk of cardiovascular diseases (CVD). We aimed to investigate the association between fatty acids in erythrocyte membrane phospholipids and CVD risk factors in middle-aged Korean adults.

METHODS

Fifty-five middle-aged adults who underwent health examinations were included in this retrospective and cross-sectional study. Anthropometry, serum lipids, clinical parameters, and erythrocyte membrane phospholipid fatty acid data were obtained from a registry.

RESULTS

The proportion of C14:0 and C16:0 was greatly elevated in high quartile groups for triglyceride (TG) and systolic and diastolic blood pressure groups (SBP and DBP) (p = 0.042, p = 0.021, or p = 0.008 respectively) compared to low quartile groups. While C16:1n7 and/or C18:1n9 were positively associated with CVD risk factors, the delta 9 desaturase activity index (D9D) (C18:1n9/C18:0) was only significantly increased in high quartile groups for TG and blood pressures (p = 0.001, p = 0.002 or p = 0.003). Conversely, TG and blood pressures showed inverse relationships with C20:4n6 or D5D (C20:4n6/C20:3n6). C18:3n6 and/or D6D (C18:3n6/C18:2n6) were positively associated with insulin resistance and diabetic parameters. Particularly high D6D was detected in high quartile groups of FBS and insulin (p = 0.016 and p = 0.042). In linear regression analysis, D9D and/or C14:0 + C16:0 were significant contributors to serum TG and blood pressures. D6D was a contributing factor to FBS.

CONCLUSIONS

The indices of D9D and D6D from erythrocyte membrane phospholipids and the proportion of saturated fatty acids were increased as the cardiovascular risk factors, including serum TG, blood pressures, and FBS increased their levels (IRB number C2014199 (1396)).

Salvia libanotica improves glycemia and serum lipid profile in rats fed a high fat diet

BACKGROUND

Salvia libanotica (S. Libanotica) is a commonly used herb in folk medicine in Lebanon and the Middle East. The present study aimed to assess the scientific basis for the therapeutic use of S. libanotica in glycemia and to evaluate its effects on lipemia and abdominal fat.

METHODS

Animals were fed a high-fat diet and allocated into a control and three experimental groups (GI, GII and GIII) receiving incremental doses of the plant water extract in drinking water (50, 150 and 450 mg/Kg body weight respectively) for six weeks.

RESULTS

The intake of S. libanotica extract was associated with a significant decrease in fasting serum glucose (102.9 ± 10.8 in GII and 87.5 ± 6.4 in GIII vs. 152.1 ± 7.9 mg/dl in controls) and a two fold increase in fasting serum insulin (GIII) and liver glycogen content (GII and GIII). Group III also had better glucose tolerance following intraperitoneal glucose challenges. Additionally, the plant extract intake produced a significant improvement in serum HDL (34.4 ± 2.4 in GIII vs. 27.2 ± 1.9 mg/dl in controls) and HDL/LDL cholesterol ratio (2.79 ± 0.32 in GII and 3.02 ± 0.31 in GIII vs. 1.74 ± 0.18 in controls), as well as a decrease in abdominal fat.

CONCLUSION

The current study is the first to demonstrate that the chronic intake of S. libanotica infusion helps in the prevention of high fat-induced hyperglycemia and dyslipidemia. This supports the plant use as a remedy for the prevention of type 2 diabetes and cardiovascular diseases.

N-3PUFA differentially modulate palmitate-induced lipotoxicity through alterations of its metabolism in C2C12 muscle cells

Excessive energy intake leads to fat overload and the formation of lipotoxic compounds mainly derived from the saturated fatty acid palmitate (PAL), thus promoting insulin resistance (IR) in skeletal muscle. N-3 polyunsaturated fatty acids (n-3PUFA) may prevent lipotoxicity and IR. The purpose of this study was to examine the differential effects of n-3PUFA on fatty acid metabolism and insulin sensitivity in muscle cells. C2C12 myotubes were treated with 500 μM of PAL without or with 50 μM of alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) for 16 h. PAL decreased insulin-dependent AKT activation and glucose uptake and increased the synthesis of ceramides and diglycerides (DG) derivatives, leading to protein kinase Cθ activation. EPA and DHA, but not ALA, prevented PAL-decreased AKT activation but glucose uptake was restored to control values by all n-3PUFA vs. PAL. Total DG and ceramide contents were decreased by all n-3PUFA, but only EPA and DHA increased PAL β-oxidation, decreased PAL incorporation into DG and reduced protein kinase Cθ activation. EPA and DHA emerge as better candidates than ALA to improve fatty acid metabolism in skeletal muscle cells, notably via their ability to increase mitochondrial β-oxidation.

Excess of free fatty acids as a cause of metabolic dysfunction in skeletal muscle

Obesity is often associated with metabolic impairments in peripheral tissues. Evidence suggests an excess of free fatty acids (FFA) as one factor linking obesity and related pathological conditions and the impact of FFA overload on skeletal muscle metabolism is described herein. Obesity is associated with dysfunctional adipose tissue unable to buffer the flux of dietary lipids. Resulting increased levels and fluxes of plasma FFA lead to ectopic lipid deposition and lipotoxicity. FFA accumulated in skeletal muscle are associated with insulin resistance and overall cellular dysfunction. Mechanisms supposed to be involved in these conditions include the Randle cycle, intracellular accumulation of lipid metabolites, inflammation and mitochondrial dysfunction or mitochondrial stress. These mechanisms are described and discussed in the view of current experimental evidence with an emphasis on conflicting theories of decreased vs. increased mitochondrial fat oxidation associated with lipid overload. Since different types of FFA may induce diverse metabolic responses in skeletal muscle cells, this review also focuses on cellular mechanisms underlying the different action of saturated and unsaturated FFA.

Dietary Fat Intake and the Risk of Metabolic Syndrome in Korean Adults

Background

The effect of dietary fat intake on the risk of cardiovascular disease remains unclear. We investigated the association between dietary fat and specific types of fat intake and the risk of metabolic syndrome.

Methods

The study population included 1,662 healthy adults who were 50.2 years of age and had no known hypertension, diabetes, hyperlipidemia, or metabolic syndrome at the initial visit. Dietary intake was obtained from a 1-day food record. During 20.7 months of follow-up, we documented 147 cases of metabolic syndrome confirmed by self-report, anthropometric data, and blood test results. The intakes of total fat, vegetable fat, animal fat, saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA), monounsaturated fatty acid (MUFA), and cholesterol level divided by quintile. Multivariate analyses included age, sex, body mass index, smoking status, alcohol intake, physical activity, total calorie, and protein intake.

Results

Vegetable fat intake was inversely associated with metabolic syndrome risk (odds ratio for the highest vs. the lowest quintile, 0.33; 95% confidence interval, 0.14 to 0.76). Total fat, animal fat, SFA, PUFA, MUFA, and cholesterol intakes showed no association with metabolic syndrome. Vegetable fat intake was inversely associated with the risk of hypertriglyceridemia among the components of metabolic syndrome.

Conclusion

These data support an inverse association between vegetable fat and the risk of metabolic syndrome.

Maternal saturated-fat-rich diet promotes leptin resistance in fetal liver lipid catabolism and programs lipid homeostasis impairments in the liver of rat offspring

We aimed to analyze if an overload of saturated fat in maternal diet induced lipid metabolic impairments in livers from rat fetuses that persist in the offspring and to identify potential mechanisms involving fetal leptin resistance. Female rats were fed either a diet enriched in 25% of saturated fat (SFD rats) or a regular diet (controls). Fetuses of 21days of gestation and offspring of 21 and 140days of age were obtained and plasma and liver were kept for further analysis. Livers from a group of control and SFD fetuses were cultured in the presence or absence of leptin. Leptin or vehicle was administered to control fetuses during the last days of gestation and, on day 21, fetal livers and plasma were obtained. Lipid levels were assessed by thin-layer chromatography and mRNA gene expression of CPT1, ACO and PPARα by RT-PCR. Liver lipid levels were increased and CPT1 and ACO were down-regulated in fetuses and offspring from SFD rats compared to controls. After the culture with leptin, control fetal livers showed increased ACO and CPT1 expression and decreased lipid levels, while fetal livers from SFD rats showed no changes. Fetal administration of leptin induced a decrease in ACO and no changes in CPT1 expression. In summary, our results suggest that a saturated fat overload in maternal diet induces fetal leptin resistance in liver lipid catabolism, which might be contributing to liver lipid alterations that are sustained in the offspring.

Modelling the Interplay between Lifestyle Factors and Genetic Predisposition on Markers of Type 2 Diabetes Mellitus Risk

The risk of developing type 2 diabetes mellitus (T2DM) is determined by a complex interplay involving lifestyle factors and genetic predisposition. Despite this, many studies do not consider the relative contributions of this complex array of factors to identify relationships which are important in progression or prevention of complex diseases. We aimed to describe the integrated effect of a number of lifestyle changes (weight, diet and physical activity) in the context of genetic susceptibility, on changes in glycaemic traits in overweight or obese participants following 12-months of a weight management programme. A sample of 353 participants from a behavioural weight management intervention were included in this study. A graphical Markov model was used to describe the impact of the intervention, by dividing the effects into various pathways comprising changes in proportion of dietary saturated fat, physical activity and weight loss, and a genetic predisposition score (T2DM-GPS), on changes in insulin sensitivity (HOMA-IR), insulin secretion (HOMA-B) and short and long term glycaemia (glucose and HbA1c). We demonstrated the use of graphical Markov modelling to identify the importance and interrelationships of a number of possible variables changed as a result of a lifestyle intervention, whilst considering fixed factors such as genetic predisposition, on changes in traits. Paths which led to weight loss and change in dietary saturated fat were important factors in the change of all glycaemic traits, whereas the T2DM-GPS only made a significant direct contribution to changes in HOMA-IR and plasma glucose after considering the effects of lifestyle factors. This analysis shows that modifiable factors relating to body weight, diet, and physical activity are more likely to impact on glycaemic traits than genetic predisposition during a behavioural intervention.

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.