Clustering effects on postprandial insulin secretion and sensitivity in response to meals with different fatty acid compositions

Serum lipidomic profiling of dairy calves fed milk replacers containing animal or vegetable fats

Vegetable fat blends are commonly used as fat sources in milk replacers (MR) for calves, but their composition differs considerably from that of bovine milk fat. The aim of this study was to investigate the serum lipid profile of pre-weaned calves fed twice-daily MR containing 30% fat (% DM). Upon arrival, 30 male Holstein-Friesian calves (BW = 45.6 ± 4.0 kg, age = 2.29 ± 0.8 d) were randomly assigned to 2 experimental diets (n = 15 per treatment): one MR was derived from either vegetable fats (VG; 80% rapeseed and 20% coconut fats) or animal fats (AN; 65% Packer's lard and 35% dairy cream). The 2 MR formulas contained 30% fat, 24% CP, and 36% lactose. Calves were housed indoors in individual pens with ad libitum access to chopped straw and water. Daily milk allowances were 6.0 L from d 1 to 5, 7.0 L from d 6 to 9, and 8.0 L from d 10 to 35, divided into 2 equal meals and prepared at 13.5% solids. An untargeted liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) method was employed to analyze the lipid profiles in the serum of calves sampled from the jugular vein at 35 d of age. In total, 594 lipids were characterized, comprising 25 different lipid classes. Principal component analysis (PCA) showed significant separation between VG and AN, indicating different lipid profiles in the serum. An orthogonal partial least squares discriminant analysis (OPLS-DA) classification model was used to further validate the distinction between the 2 treatment groups. The model exhibited a robust class separation and high predictive accuracy. Using a Volcano plot (fold change threshold ≥1.5 and false discovery rate ≤0.05), it was observed that calves fed AN had higher levels of 39 lipid species in serum than calves fed VG, whereas 171 lipid species were lower in the AN group. Lipid classes, such as phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), triglycerides (TG), lysophosphatidylcholine (LPC), and lysophosphatidylethanolamine (LPE), were different. In particular, PC and PE were observed at lower levels in calves fed AN, possibly indicating shifts in cell membrane characteristics, intracellular signaling, and liver functions. In addition, a decrease in certain triglyceride (TG) species was observed in calves fed AN, including a decrease in TG species such as TG 36:0 and TG 38:0, possibly related to variations in the content of certain fatty acids (FA) within the AN MR, such as C10:0, C12:0, C14:0, and C18:0 compared with the VG MR. Calves fed AN had lower levels of LPC and LPE, and lyso-phosphatidylinositol (LPI), SM, and phosphatidylinositol (PI) species than calves fed VG, suggesting shifts in lipoprotein and lipid metabolic pathways. In conclusion, these results deepen the understanding of how lipid sources in MR can modulate the serum lipidome profiles of dairy calves.

Palm oil as part of a high-fat diet: advances and challenges, or possible risks of pathology?

Nutritional status disorders have the most significant impact on the development of cardiovascular and oncologic diseases; therefore, the interest in the study of palm oil as among the leading components of nutrition has been increasing. The data examined in this review were sourced from the Scopus, SCIE (Web of Science), PubMed and PubMed Central, MEDLINE, CAPlus/SciFinder, and Embase databases; experts in the field; bibliographies; and abstracts from review analyses from the past 15 years. This review summarizes recent research data focusing on the quantitative and qualitative composition of nutrition of modern humans; concepts of the relationship between high-fat diets and disorders of insulin functioning and transport and metabolism of fatty acids; analyses of data regarding the palmitic acid (16:0) to oleic acid (18:1) ratio; and the effect of diet based on palm oil consumption on cardiovascular risk factors and lipid and lipoprotein levels. Several studies suggest a potential vector contributing to the transmission of maternal, high-fat-diet-induced, addictive-like behaviors and obesogenic phenotypes across generations. The relationship between cholesterol accumulation in lysosomes that may lead to lysosome dysfunction and inhibition of the autophagy process is analyzed, as is the progression of inflammatory diseases, atherosclerosis, nonalcoholic liver inflammation, and obesity with associated complications. Data are discussed from analyses of differences between rodent models and human population studies in the investigated different effects of palm oil consumption as a high-fat diet component. A conclusion is reached that the results cannot be generalized in human population studies because no similar effects were observed. Although there are numerous published reports, more studies are necessary to elucidate the complex regulatory mechanisms in digestive and nutrition processes, because there are great differences in lipoprotein profiles between rodents and humans, which makes it difficult to reproduce the pathology of many diseases caused by different types of the high-fat diet.

Fat composition of milk replacer influences postprandial and oxidative metabolisms in dairy calves fed twice daily

Milk replacers (MR) for calves contain alternative fat sources as substitute for milk fat. This substitution leads to differences in fat properties, such as the fatty acid profile and the triglyceride structure. This study evaluated how fat composition in MR affects gastrointestinal health, blood redox parameters, and postprandial metabolism in calves fed twice daily. Forty-five individually housed male Holstein-Friesian calves (2.3 ± 0.85 d of age) were assigned to 1 of 15 blocks based on the age and the day of arrival. Within each block, calves were randomly assigned to 1 of 3 experimental diets and received their respective diet from arrival until 35 d after arrival. The 3 experimental diets (n = 15 per treatment group) consisted of an MR with a blend of vegetable fats containing rapeseed and coconut (VG), an MR with only animal fats from lard and dairy cream (AN), and an MR containing a mixture of animal and vegetable fats including lard and coconut (MX). The fatty acid profile of each MR was formulated to resemble that of bovine milk fat while using only 2 fat sources. All MR were isoenergetic, with 30% fat (% DM), 24% crude protein, and 36% lactose. Chopped straw and water were available ad libitum from arrival onward but no starter feed was provided. Daily milk allowances were 6.0 L from d 1 to 5, 7.0 L from d 6 to 9, and 8.0 L from d 10 to 35, divided into 2 equal meals and prepared at 135 g/L (13.5% solids). Fecal appearance was scored daily; calves were weighed and blood was drawn on arrival and weekly thereafter. Urine and feces were collected over a 24-h period at wk 3 and 5 to determine apparent total-tract digestibility and assess gastrointestinal permeability using indigestible markers. Postprandial metabolism was evaluated at wk 4 by sequential blood sampling over 7.5 h, and the abomasal emptying rate was determined by acetaminophen appearance in blood. Fat composition in MR did not affect growth, MR intake, gastrointestinal permeability, nor nutrient digestibility. The percentage of calves with abnormal fecal scores was lower at wk 2 after arrival in calves fed VG than MX, whereas AN did not differ from the other treatments. Calves fed AN and MX had higher thiobarbituric acid reactive substances measured in serum than VG, whereas plasma ferric-reducing ability was greater in calves fed MX than VG. Postprandial acetaminophen concentrations did not differ across treatment groups, but the area under the curve was smaller in calves fed VG than in the other 2 treatments, which is indicative of a slower abomasal emptying. Postprandial serum triglyceride concentration was greater in calves fed AN than VG, whereas MX did not differ from the other treatments. Based on these outcomes, all 3 fat blends can be considered suitable for inclusion in MR for calves.

Saturated fatty acids inhibit unsaturated fatty acid induced glucose uptake involving GLUT10 and aerobic glycolysis in bovine granulosa cells

Fatty acids have been shown to modulate glucose metabolism in vitro and in vivo. However, there is still a need for substantial evidence and mechanistic understanding in many cell types whether both saturated and unsaturated fatty acids (SFAs and UFAs) pose a similar effect and, if not, what determines the net effect of fatty acid mixes on glucose metabolism. In the present study, we asked these questions by treating granulosa cells (GCs) with the most abundant non-esterified fatty acid species in bovine follicular fluid. Results revealed that oleic and alpha-linolenic acids (UFAs) significantly increased glucose consumption compared to palmitic and stearic acids (SFAs). A significant increase in lactate production, extracellular acidification rate, and decreased mitochondrial activity indicate glucose channeling through aerobic glycolysis in UFA treated GCs. We show that insulin independent glucose transporter GLUT10 is essential for UFA driven glucose consumption, and the induction of AKT and ERK signaling pathways necessary for GLUT10 expression. To mimic the physiological conditions, we co-treated GCs with mixes of SFAs and UFAs. Interestingly, co-treatments abolished the UFA induced glucose uptake and metabolism by inhibiting AKT and ERK phosphorylation and GLUT10 expression. These data suggest that the net effect of fatty acid induced glucose uptake in GCs is determined by SFAs under physiological conditions.

Circulating palmitoyl sphingomyelin levels predict the 10-year increased risk of cardiovascular disease death in Chinese adults: findings from the Da Qing Diabetes Study

BACKGROUND

Higher levels of palmitoyl sphingomyelin (PSM, synonymous with sphingomyelin 16:0) are associated with an increased risk of cardiovascular disease (CVD) in people with diabetes. Whether circulating PSM levels can practically predict the long-term risk of CVD and all-cause death remains unclear. This study aimed to investigate whether circulating PSM is a real predictor of CVD death in Chinese adults with or without diabetes.

METHODS

A total of 286 and 219 individuals with and without diabetes, respectively, from the original Da Qing Diabetes Study were enrolled. Blood samples collected in 2009 were used as a baseline to assess circulating PSM levels. The outcomes of CVD and all-cause death were followed up from 2009 to 2020, and 178 participants died, including 87 deaths due to CVD. Cox proportional hazards regression was used to estimate HRs and their 95% CIs for the outcomes.

RESULTS

Fractional polynomial regression analysis showed a linear association between baseline circulating PSM concentration (log-2 transformed) and the risk of all-cause and CVD death (p < 0.001), but not non-CVD death (p > 0.05), in all participants after adjustment for confounders. When the participants were stratified by PSM-tertile, the highest tertile, regardless of diabetes, had a higher incidence of CVD death (41.5 vs. 14.7 and 22.2 vs. 2.9 per 1000 person-years in patients with and without diabetes, respectively, all log-rank p < 0.01). Individuals with diabetes in the highest tertile group had a higher risk of CVD death than those in the lowest tertile (HR = 2.73; 95%CI, 1.20-6.22).

CONCLUSIONS

Elevated PSM levels are significantly associated with a higher 10-year risk of CVD death, but not non-CVD death, in Chinese adults with diabetes. These findings suggest that PSM is a potentially useful long-term predictor of CVD death in individuals with diabetes.

GPCR-mediated effects of fatty acids and bile acids on glucose homeostasis

Fatty acids and glucose are key biomolecules that share several commonalities including serving as energy substrates and as signaling molecules. Fatty acids can be synthesized endogenously from intermediates of glucose catabolism via de-novo lipogenesis. Bile acids are synthesized endogenously in the liver from the biologically important lipid molecule, cholesterol. Evidence abounds that fatty acids and bile acids play direct and indirect roles in systemic glucose homeostasis. The tight control of plasma glucose levels during postprandial and fasted states is principally mediated by two pancreatic hormones, insulin and glucagon. Here, we summarize experimental studies on the endocrine effects of fatty acids and bile acids, with emphasis on their ability to regulate the release of key hormones that regulate glucose metabolism. We categorize the heterogenous family of fatty acids into short chain fatty acids (SCFAs), unsaturated, and saturated fatty acids, and highlight that along with bile acids, these biomolecules regulate glucose homeostasis by serving as endogenous ligands for specific G-protein coupled receptors (GPCRs). Activation of these GPCRs affects the release of incretin hormones by enteroendocrine cells and/or the secretion of insulin, glucagon, and somatostatin by pancreatic islets, all of which regulate systemic glucose homeostasis. We deduce that signaling induced by fatty acids and bile acids is necessary to maintain euglycemia to prevent metabolic diseases such as type-2 diabetes and related metabolic disorders.

Effect of guanylin peptides on pancreas steatosis and function in experimental diet-induced obesity and after bariatric surgery

Introduction

Obesity contributes to ectopic fat deposition in non-adipose organs, including the pancreas. Pancreas steatosis associates with inflammation and β-cell dysfunction, contributing to the onset of insulin resistance and type 2 diabetes. An improvement of pancreatic steatosis and indices of insulin resistance is observed following bariatric surgery, but the underlying mechanisms remain unknown. We sought to analyze whether guanylin (GUCA2A) and uroguanylin (GUCA2B), two gut hormones involved in the regulation of satiety, food preference and adiposity, are involved in the amelioration of pancreas fat accumulation after bariatric surgery.

Methods

Pancreas steatosis, inflammation, islet number and area were measured in male Wistar rats with diet-induced obesity (n=125) subjected to surgical (sham operation and sleeve gastrectomy) or dietary (pair-fed to the amount of food eaten by gastrectomized animals) interventions. The tissue distribution of guanylate cyclase C (GUCY2C) and the expression of the guanylin system were evaluated in rat pancreata by real-time PCR, Western-blot and immunohistochemistry. The effect of guanylin and uroguanylin on factors involved in insulin secretion and lipogenesis was determined in vitro in RIN-m5F β-cells exposed to lipotoxic conditions.

Results

Sleeve gastrectomy reduced pancreas steatosis and inflammation and improved insulin sensitivity and synthesis. An upregulation of GUCA2A and GUCY2C, but not GUCA2B, was observed in pancreata from rats with diet-induced obesity one month after sleeve gastrectomy. Interestingly, both guanylin and uroguanylin diminished the lipotoxicity in palmitate-treated RIN-m5F β-cells, evidenced by lower steatosis and downregulated lipogenic factors Srebf1, Mogat2 and Dgat1. Both guanylin peptides reduced insulin synthesis (Ins1 and Ins2) and release from RIN-m5F β-cells, but only guanylin upregulated Wnt4, a factor that controls β-cell proliferation and function.

Discussion

Together, sleeve gastrectomy reduced pancreatic steatosis and improved β-cell function. Several mechanisms, including the modulation of inflammation and lipogenesis as well as the upregulation of GUCA2A in the pancreas, might explain this beneficial effect of bariatric surgery.

Beneficial effects of monounsaturated fatty acid-rich blended oils with an appropriate polyunsaturated/saturated fatty acid ratio and a low n-6/n-3 fatty acid ratio on the health of rats

BACKGROUND

The effects of dietary fat on health are influenced by its fatty acid profile. We aimed to determine the effects of monounsaturated fatty acid (MUFA)-rich blended oils (BO) containing a balance of polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs) and with a low n-6/n-3 PUFA ratio on the health of rats fed normal or high-fat diets. The BO was obtained by mixing red palm oil, rice bran oil (RO), tea seed oil and flaxseed oil in appropriate proportions.

RESULTS

BO consumption reduced the serum low-density lipoprotein cholesterol (LDL-C), non-esterified fatty acid (NEFA), insulin (INS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1 (IL-1), high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), lipid peroxide (LPO) and oxidized LDL (ox-LDL) concentrations and the homeostasis model assessment of insulin resistance (HOMA-IR); it increased the high-density lipoprotein cholesterol (HDL-C), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) concentrations, and the bone mineral density (BMD) versus control oil-containing normal and high-fat diets. BO also reduced the triglyceride (TG), hs-CRP, MDA, ox-LDL and reactive oxygen species (ROS) concentrations; and increased the serum HDL-C and SOD, and BMD versus RO-containing high-fat diets. Finally, BO reduced the glucose (GLU) and INS, and HOMA-IR; it increased HDL-C, SOD, femoral weight and BMD versus RO-containing normal diets.

CONCLUSION

BOs with an appropriate fatty acid profile have beneficial effects on the glucolipid metabolism, inflammation, oxidative stress and bone quality of rats when included in both normal and high-fat diets. © 2022 Society of Chemical Industry.

Analysis of Hepatic Lipid Metabolism Model: Simulation and Non-Stationary Global Sensitivity Analysis

Lipid metabolism is a complex process and it is extremely helpful to simulate its performance with different models that explain all the biological processes that comprise it, which then enables its better understanding as well as understanding the kinetics of the process itself. Typically, kinetic parameters are obtained from a number of sources under specific experimental conditions, and they are a source of uncertainty. Sensitivity analysis is a useful technique for controlling the uncertainty of model parameters. It evaluates a model's dependence on its input variables. In this work, hepatic lipid metabolism was mathematically simulated and analyzed. Simulations of the model were performed using different initial plasma glucose (G_B) and plasma triacylglyceride (TAG) concentrations according to proposed menus for different meals (breakfast, lunch, snack and dinner). A non-stationary Fourier amplitude sensitivity test (FAST) was applied to analyze the effect of 78 kinetic parameters on 24 metabolite concentrations and 45 reaction rates of the biological part of the hepatic lipid metabolism model at five time points (t_f = 10, 50, 100, 250 and 500 min). This study examined the total influence of input parameter uncertainty on the variance of metabolic model predictions. The majority of the propagated uncertainty is due to the interactions of numerous factors rather than being linear from one parameter to one result. Obtained results showed differences in the model control regarding the different initial concentrations and also the changes in the model control over time. The aforementioned knowledge enables dietitians and physicians, working with patients who need to regulate fat metabolism due to illness and/or excessive body mass, to better understand the problem.

Dietary fat quantity and quality in early pregnancy and risk of gestational diabetes mellitus in Chinese women: a prospective cohort study

We aimed to examine the association between the quantity and quality of dietary fat in early pregnancy and gestational diabetes mellitus (GDM) risk. In total, 1477 singleton pregnant women were included from Sichuan Provincial Hospital for Women and Children, Southwest China. Dietary information was collected by a 3-d 24-h dietary recall. GDM was diagnosed based on the results of a 75-g, 2-h oral glucose tolerance test at 24-28 gestational weeks. Log-binomial models were used to estimate relative risks (RR) and 95% CI. The results showed that total fat intake was positively associated with GDM risk (Q4 v. Q1: RR = 1·40; 95 % CI 1·11, 1·76; Ptrend = 0·001). This association was also observed for the intakes of animal fat and vegetable fat. After stratified by total fat intake (< 30 %E v. ≥ 30 %E), the higher animal fat intake was associated with higher GDM risk in the high-fat group, but the moderate animal fat intake was associated with reduced risk of GDM (T2 v. T1: RR = 0·65; 95 % CI 0·45, 0·96) in the normal-fat group. Vegetable fat intake was positively associated with GDM risk in the high-fat group but not in the normal-fat group. No association between fatty acids intakes and GDM risk was found. In conclusion, total fat, animal and vegetable fat intakes were positively associated with GDM risk, respectively. Whereas when total fat intake was not excessive, higher intakes of animal and vegetable fat were likely irrelevant with increased GDM risk, even the moderate animal fat intake could be linked to lower GDM risk.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

Lipotoxicity and β-Cell Failure in Type 2 Diabetes: Oxidative Stress Linked to NADPH Oxidase and ER Stress

A high caloric intake, rich in saturated fats, greatly contributes to the development of obesity, which is the leading risk factor for type 2 diabetes (T2D). A persistent caloric surplus increases plasma levels of fatty acids (FAs), especially saturated ones, which were shown to negatively impact pancreatic β-cell function and survival in a process called lipotoxicity. Lipotoxicity in β-cells activates different stress pathways, culminating in β-cells dysfunction and death. Among all stresses, endoplasmic reticulum (ER) stress and oxidative stress have been shown to be strongly correlated. One main source of oxidative stress in pancreatic β-cells appears to be the reactive oxygen species producer NADPH oxidase (NOX) enzyme, which has a role in the glucose-stimulated insulin secretion and in the β-cell demise during both T1 and T2D. In this review, we focus on the acute and chronic effects of FAs and the lipotoxicity-induced β-cell failure during T2D development, with special emphasis on the oxidative stress induced by NOX, the ER stress, and the crosstalk between NOX and ER stress.

Impact of Meal Fatty Acid Composition on Postprandial Lipemia in Metabolically Healthy Adults and Individuals with Cardiovascular Disease Risk Factors: A Systematic Review

Consuming fat results in postprandial lipemia, which is defined as an increase in blood triglyceride (TG) concentration. According to current knowledge, an excessively elevated postprandial TG concentration increases the risk of cardiovascular disease (CVD). It is well known that meal-dependent (e.g., nutrient composition) as well as meal-independent factors (e.g., age) determine the magnitude of the lipemic response. However, there is conflicting evidence concerning the influence of fatty acid (FA) composition on postprandial TG concentration. The FA composition of a meal depends on the fat source used; for example, butter and coconut oil are rich in SFAs, while olive oil and canola oil have a high content of unsaturated FAs. To investigate the influence of meals prepared with fat sources rich in either SFAs or unsaturated FAs on postprandial lipemia, we carried out a systematic literature search in PubMed, Scopus, and the Cochrane Library. Randomized crossover studies were analyzed and the AUC of postprandial TG concentration served as the primary outcome measure. To examine the influence of health status, we differentiated between metabolically healthy individuals and those with CVD risk factors. In total, 23 studies were included. The results show that, in metabolically healthy adults, the FA composition of a meal is not a relevant determinant of postprandial lipemia. However, in individuals with CVD risk factors, SFA-rich meals (>32 g SFA/meal) often elicited a stronger lipemic response than meals rich in unsaturated FAs. The results suggest that adults with hypertriglyceridemia, an elevated BMI (≥30 kg/m2), and/or who are older (>40 y) may benefit from replacing SFA sources with unsaturated FAs. These hypotheses need to be verified by further studies in people with CVD risk factors using standardized postprandial protocols. This review was registered in PROSPERO as CRD42021214508 (https://www.crd.york.ac.uk/prospero/).

Complete CSN1S2 Characterization, Novel Allele Identification and Association With Milk Fatty Acid Composition in River Buffalo

The αs2-casein is one of the phosphoproteins secreted in all ruminants' milk, and it is the most hydrophilic of all caseins. However, this important gene (CSN1S2) has not been characterized in detail in buffaloes with only two alleles detected (reported as alleles A and B), and no association studies with milk traits have been carried out unlike what has been achieved for other species of ruminants. In this study, we sequenced the whole gene of two Mediterranean river buffalo homozygotes for the presence/absence of the nucleotide C (g.7539G>C) realized at the donor splice site of exon 7 and, therefore, responsible for the skipping of the same exon at mRNA level (allele B). A high genetic variability was found all over the two sequenced CSN1S2 alleles. In particular, 74 polymorphic sites were found in introns, six in the promoter, and three SNPs in the coding region (g.11072C>T, g.12803A>T, and g.14067A>G) with two of them responsible for amino acid replacements. Considering this genetic diversity, those found in the database and the SNP at the donor splice site of exon 7, it is possible to deduce at least eight different alleles (CSN1S2 A, B, B1, B2, C, D, E, and F) responsible for seven different possible translations of the buffalo αs2-casein. Haplotype data analysis suggests an evolutionary pathway of buffalo CSN1S2 gene consistent with our proposal that the published allele CSN1S2 A is the ancestral αs2-CN form, and the B2 probably arises from interallelic recombination (single crossing) between the alleles D and B (or B1). The allele CSN1S2 C is of new identification, while CSN1S2 B, B1, and B2 are deleted alleles because all are characterized by the mutation g.7539G>C. Two SNPs (g.7539G>C and g.14067A>G) were genotyped in 747 Italian buffaloes, and major alleles had a relative frequency of 0.83 and 0.51, respectively. An association study between these SNPs and milk traits including fatty acid composition was carried out. The SNP g.14067A>G showed a significant association (P < 0.05) on the content of palmitic acid in buffalo milk, thus suggesting its use in marker-assisted selection programs aiming for the improvement of buffalo milk fatty acid composition.

Acute effects of an isocaloric macronutrient-matched breakfast meal containing almonds on glycemic, hormonal, and appetite responses in men with type 2 diabetes: a randomized crossover study

This randomized crossover study assessed the acute effects of almonds on postprandial glycemic, hormonal, and appetite responses in a sample of 7 men with type 2 diabetes (T2D). Participants completed 2 experimental visits during which a control (white bread, butter, cheese) and a test (white bread, almonds) meal were ingested. Energy, available carbohydrate, total lipid, and protein content were the same in both meals. Blood samples were collected in fasting state as well as 15, 30, 60, 90, 120, and 240 min postprandially for quantifying blood glucose, as well as insulin and glucagon-like peptide-1 (GLP-1) serum concentrations. Subjective appetite sensations were assessed using visual analog scales at the same time-points. Within this sample of participants, the test meal was found to be associated with lower postprandial glycemia and insulinemia, higher GLP-1 serum concentrations, decreased hunger and desire to eat, and increased fullness. The test meal was also associated with an increased estimated glucose metabolic clearance rate, indicating higher postprandial insulin sensitivity. Overall, results suggest that almonds' macronutrient subtype profile could have a beneficial impact on postprandial glycemic, hormonal, and appetite responses in men with T2D. Studies with larger sample sizes are warranted to confirm these findings. Novelty A meal containing almonds (vs. isocaloric macronutrient-matched control) induced lower glycemic and insulinemic responses. A meal containing almonds (vs. isocaloric macronutrient-matched control) induced a greater elevation in postprandial GLP-1 serum concentrations. A meal containing almonds (vs. isocaloric macronutrient-matched control) induced more favourable postprandial appetite responses.

Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes

Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.

Determination of glycemic index of enteral formulas used in clinical practice

Glycemic Index (GI) is a measure of carbohydrate quality and is recognised as a valid and reproducible method of classifying carbohydrate foods according to its effects on postprandial glycaemia. In this randomised crossover trial (RBR-7rjx3k) we determined the GI of nine enteral formulas, following the Food and Agriculture Organisation/World Health Organisation method. Forty healthy participants were included in the study (85% female mean age 27.1 ± 6.7 years). GI of the enteral formulas ranged from 40.5 to 85.2; four formulas had high GI (Nutrienteral 1.5^®, Novasource GI Control^®, Diamax^®, Isosource Soya^®), two intermediate GI (Fresubin 1.2 HP Fibre^®, Nutrison Energy Multifiber 1.5^®) and three low GI (Trophic 1.5^®, Glucerna^®, Novasource GC HP^®). The GI coefficient of variation ranged from 22.9% to 83.6%. The effect of the enteral formulas with low GI in glycemic control of patients with enteral nutrition prescription needs to be test in future studies.

Negative Effects of Cyclic Palmitate Treatment on Glucose Responsiveness and Insulin Production in Mouse Insulinoma Min6 Cells Are Reversible

Pancreatic β-cell failure is characterized by compromised insulin secretion in response to glucose, which ultimately results in hyperglycemia, the clinical hallmark of type 2 diabetes mellitus (T2DM). Acute exposure to plasma free fatty acids (FFAs) potentiates glucose stimulated insulin secretion (GSIS), while chronic exposure impairs GSIS, and the latter has been associated with the mechanism of β cell failure in obesity linked T2DM. By contrast, growth hormone (GH) signaling has been linked positively to GSIS in β cells. Numerous studies have examined chronic exposure of β cells to elevated FFAs both with in vivo cohorts and in vitro models. Little attention, however, has been given to the fluctuation of plasma FFA levels due to rhythmic effects that are affected by daily diet and fat intake. Mouse insulinoma Min6 cells were exposed to cyclic/daily palmitate treatment over 2 and 3 days to assess effects on GSIS. Cyclic/daily palmitate treatment with a period of recovery negatively affected GSIS in a dose-dependent manner. Removal of palmitate after two cycles/day resulted in reversal of the effect on GSIS, which was also reflected by relative gene expression involved in insulin biosynthesis (Ins1, Ins2, Pdx1, and MafA) and GSIS (glucose 2 transporter and glucokinase). Modest positive effects on GSIS and glucokinase transcript levels were also observed when Min6 cells were cotreated with human GH and palmitate. These observations indicate that like continuous palmitate treatment, cyclic exposure to palmitate can acutely impair GSIS over 48 and 72 h. However, they also suggest that the negative effects of short periods of exposure to FFAs on β cell function remain reversible.

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

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

Fatty Acid-Stimulated Insulin Secretion vs. Lipotoxicity

Fatty acid (FA)-stimulated insulin secretion (FASIS) is reviewed here in contrast to type 2 diabetes etiology, resulting from FA overload, oxidative stress, intermediate hyperinsulinemia, and inflammation, all converging into insulin resistance. Focusing on pancreatic islet β-cells, we compare the physiological FA roles with the pathological ones. Considering FAs not as mere amplifiers of glucose-stimulated insulin secretion (GSIS), but as parallel insulin granule exocytosis inductors, partly independent of the K_ATP channel closure, we describe the FA initiating roles in the prediabetic state that is induced by retardations in the glycerol-3-phosphate (glucose)-promoted glycerol/FA cycle and by the impaired GPR40/FFA1 (free FA1) receptor pathway, specifically in its amplification by the redox-activated mitochondrial phospholipase, iPLA2γ. Also, excessive dietary FAs stimulate intestine enterocyte incretin secretion, further elevating GSIS, even at low glucose levels, thus contributing to diabetic hyperinsulinemia. With overnutrition and obesity, the FA overload causes impaired GSIS by metabolic dysbalance, paralleled by oxidative and metabolic stress, endoplasmic reticulum stress and numerous pro-apoptotic signaling, all leading to decreased β-cell survival. Lipotoxicity is exerted by saturated FAs, whereas ω-3 polyunsaturated FAs frequently exert antilipotoxic effects. FA-facilitated inflammation upon the recruitment of excess M1 macrophages into islets (over resolving M2 type), amplified by cytokine and chemokine secretion by β-cells, leads to an inevitable failure of pancreatic β-cells.

Effects of immediate-release niacin and dietary fatty acids on acute insulin and lipid status in individuals with metabolic syndrome

BACKGROUND

The nature of dietary fats profoundly affects postprandial hypertriglyceridemia and glucose homeostasis. Niacin is a potent lipid-lowering agent. However, limited data exist on postprandial triglycerides and glycemic control following co-administration of high-fat meals with a single dose of niacin in subjects with metabolic syndrome (MetS). The aim of the study was to explore whether a fat challenge containing predominantly saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) or MUFAs plus omega-3 long-chain polyunsaturated (LCPUFAs) fatty acids together with a single dose of immediate-release niacin have a relevant role in postprandial insulin and lipid status in subjects with MetS.

RESULTS

In a randomized crossover within-subject design, 16 men with MetS were given a single dose of immediate-release niacin (2 g) and ∼15 cal kg^-1 body weight meals containing either SFAs, MUFAs, MUFAs plus omega-3 LCPUFAs or no fat. At baseline and hourly over 6 h, plasma glucose, insulin, C-peptide, triglycerides, free fatty acids (FFAs), total cholesterol, and both high- and low-density lipoprotein cholesterol were assessed. Co-administered with niacin, high-fat meals significantly increased the postprandial concentrations of glucose, insulin, C-peptide, triglycerides, FFAs and postprandial indices of β-cell function. However, postprandial indices of insulin sensitivity were significantly decreased. These effects were significantly attenuated with MUFAs or MUFAs plus omega-3 LCPUFAs when compared with SFAs.

CONCLUSION

In the setting of niacin co-administration and compared to dietary SFAs, MUFAs limit the postprandial insulin, triglyceride and FFA excursions, and improve postprandial glucose homeostasis in MetS. © 2017 Society of Chemical Industry.

Individual fatty acids in erythrocyte membranes are associated with several features of the metabolic syndrome in obese children

PURPOSE

Obesity leads to the clustering of cardiovascular (CV) risk factors and the metabolic syndrome (MetS) also in children and is often accompanied by non-alcoholic fatty liver disease. Quality of dietary fat, beyond the quantity, can influence CV risk profile and, in particular, omega-3 fatty acids (FA) have been proposed as beneficial in this setting. The aim of the study was to evaluate the associations of individual CV risk factors, characterizing the MetS, with erythrocyte membrane FA, markers of average intake, in a group of 70 overweight/obese children.

METHODS

We conducted an observational study. Erythrocyte membrane FA were measured by gas chromatography. Spearman correlation coefficients (r_S) were calculated to evaluate associations between FA and features of the MetS.

RESULTS

Mean content of Omega-3 FA was low (Omega-3 Index = 4.7 ± 0.8%). Not omega-3 FA but some omega-6 FA, especially arachidonic acid (AA), were inversely associated with several features of the MetS: AA resulted inversely correlated with waist circumference (r_S = - 0.352), triglycerides (r_S = - 0.379), fasting insulin (r_S = - 0.337) and 24-h SBP (r_S = - 0.313). Total amount of saturated FA (SFA) and specifically palmitic acid, correlated positively with waist circumference (r_S = 0.354), triglycerides (r_S = 0.400) and fasting insulin (r_S = 0.287). Fatty Liver Index (FLI), a predictive score of steatosis based on GGT, triglycerides and anthropometric indexes, was positively correlated to palmitic acid (r_S = 0.515) and inversely to AA (r_S = - 0.472).

CONCLUSIONS

Our data suggest that omega-6 FA, and especially AA, could be protective toward CV risk factors featuring the MetS and also to indexes of hepatic steatosis in obese children, whereas SFA seems to exert opposite effects.

Carbohydrate metabolism and gene expression of sirtuin 1 in healthy subjects after Sacha inchi oil supplementation: a randomized trial

The addition of Sacha inchi oil improved insulin sensitivity in people with higher glycemic response after a fat load.

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

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

Initial hyperinsulinemia and subsequent β-cell dysfunction is associated with elevated palmitate levels

BACKGROUND

The prevalence of obesity-related diabetes in childhood is increasing and circulating levels of nonesterified fatty acids may constitute a link. Here, the association between palmitate and insulin secretion was investigated in vivo and in vitro.

METHODS

Obese and lean children and adolescents (n = 80) were included. Palmitate was measured at fasting; insulin and glucose during an oral glucose tolerance test (OGTT). Human islets were cultured for 0 to 7 d in presence of 0.5 mmol/l palmitate. Glucose-stimulated insulin secretion (GSIS), insulin content and apoptosis were measured.

RESULTS

Obese subjects had fasting palmitate levels between 0.10 and 0.33 mmol/l, with higher average levels compared to lean subjects. While obese children with elevated palmitate (>0.20 mmol/l) had accentuated insulin levels during OGTT, obese adolescents with high palmitate had delayed first-phase insulin response. In human islets exposed to palmitate for 2 d GSIS was twofold enhanced, but after 7 d attenuated. Intracellular insulin content decreased time-dependently in islets cultured in the presence of palmitate and cleaved caspase 3 increased.

CONCLUSION

The rapid accentuated and delayed insulin secretory responses observed in obese children and adolescents, respectively, with high palmitate levels may reflect changes in islet secretory activity and integrity induced by extended exposure to the fatty acid.

Effect of fat type in baked bread on amylose-lipid complex formation and glycaemic response

The formation of amylose-lipid complexes (ALC) had been associated with reduced starch digestibility. A few studies have directly characterised the extent of ALC formation with glycaemic response. The objectives of this study were to investigate the effect of using fats with varying degree of saturation and chain length on ALC formation as well as glycaemic and insulinaemic responses after consumption of bread. Healthy men consumed five test breads in a random order: control bread without any added fats (CTR) and breads baked with butter (BTR), coconut oil (COC), grapeseed oil (GRP) or olive oil (OLV). There was a significant difference in glycaemic response between the different test breads (P=0·002), primarily due to COC having a lower response than CTR (P=0·016), but no significant differences between fat types were observed. Insulinaemic response was not altered by the addition of fats/oils. Although BTR was more insulinotropic than GRP (P<0·05), postprandial β-cell function did not differ significantly. The complexing index (CI), a measure of ALC formation, was significantly higher for COC and OLV compared with BTR and GRP (P<0·05). CI was significantly negatively correlated with incremental AUC (IAUC) of change in blood glucose concentrations over time (IAUCglucose) (r -0·365, P=0·001). Linear regression analysis showed that CI explained 13·3 % of the variance and was a significant predictor of IAUCglucose (β=-1·265, P=0·001), but IAUCinsulin did not predict IAUCglucose. Our study indicated that a simple way to modulate glycaemic response in bread could lie in the choice of fats/oils, with coconut oil showing the greatest attenuation of glycaemic response.

Addition of a dairy fraction rich in milk fat globule membrane to a high-saturated fat meal reduces the postprandial insulinaemic and inflammatory response in overweight and obese adults

Meals high in SFA, particularly palmitate, are associated with postprandial inflammation and insulin resistance. Milk fat globule membrane (MFGM) has anti-inflammatory properties that may attenuate the negative effects of SFA-rich meals. Our objective was to examine the postprandial metabolic and inflammatory response to a high-fat meal composed of palm oil (PO) compared with PO with an added dairy fraction rich in MFGM (PO+MFGM) in overweight and obese men and women (n 36) in a randomised, double-blinded, cross-over trial. Participants consumed two isoenergetic high-fat meals composed of a smoothie enriched with PO with v. without a cream-derived complex milk lipid fraction ( dairy fraction rich in MFGM) separated by a washout of 1-2 weeks. Serum cytokines, adhesion molecules, cortisol and markers of inflammation were measured at fasting, and at 1, 3 and 6 h postprandially. Glucose, insulin and lipid profiles were analysed in plasma. Consumption of the PO + MFGM v. PO meal resulted in lower total cholesterol (P = 0·021), LDL-cholesterol (P = 0·046), soluble intracellular adhesion molecule (P = 0·005) and insulin (P = 0·005) incremental AUC, and increased IL-10 (P = 0·013). Individuals with high baseline C-reactive protein (CRP) concentrations (≥3 mg/l, n 17) had higher (P = 0·030) insulin at 1 h after the PO meal than individuals with CRP concentrations <3 mg/l (n 19). The addition of MFGM attenuated this difference between CRP groups. The addition of a dairy fraction rich in MFGM attenuated the negative effects of a high-SFA meal by reducing postprandial cholesterol, inflammatory markers and insulin response in overweight and obese individuals, particularly in those with elevated CRP.

Content and Composition of Branched-Chain Fatty Acids in Bovine Milk Are Affected by Lactation Stage and Breed of Dairy Cow

Dairy products contain bioactive fatty acids (FA) and are a unique dietary source of an emerging class of bioactive FA, branched-chain fatty acids (BCFA). The objective of this study was to compare the content and profile of bioactive FA in milk, with emphasis on BCFA, among Holstein (HO), Jersey (JE), and first generation HO x JE crossbreeds (CB) across a lactation to better understand the impact of these factors on FA of interest to human health. Twenty-two primiparous cows (n = 7 HO, n = 7 CB, n = 8 JE) were followed across a lactation. All cows were fed a consistent total mixed ration (TMR) at a 70:30 forage to concentrate ratio. Time points were defined as 5 days in milk (DIM), 95 DIM, 185 DIM, and 275 DIM. HO and CB had a higher content of n-3 FA at 5 DIM than JE and a lower n-6:n-3 ratio. Time point had an effect on the n-6:n-3 ratio, with the lowest value observed at 5 DIM and the highest at 185 DIM. The content of vaccenic acid was highest at 5 DIM, yet rumenic acid was unaffected by time point or breed. Total odd and BCFA (OBCFA) were higher in JE than HO and CB at 185 and 275 DIM. Breed affected the content of individual BCFA. The content of iso-14:0 and iso-16:0 in milk was higher in JE than HO and CB from 95 to 275 DIM. Total OBCFA were affected by time point, with the highest content in milk at 275 DIM. In conclusion, HO and CB exhibited a higher content of several bioactive FA in milk than JE. Across a lactation the greatest content of bioactive FA in milk occurred at 5 DIM and OBCFA were highest at 275 DIM.

Indices of dietary fat quality during midpregnancy is associated with gestational diabetes

OBJECTIVE

To investigate the relationship between gestational diabetes mellitus (GDM) and the usual intake of fatty acids and indices of dietary fat quality [the atherogenicity (AI) and thrombogenicity indices (TI), and the ratios of hypo-and hypercholesterolemic (hH), ∑n-3/∑n-6, and polyunsaturated/saturated fatty acids (P:S)], during mid-pregnancy.

METHODS

799 adult pregnant women living in Ribeirão Preto, SP, Brazil were screened and accepted for this cross-sectional GDM study. The Multiple Source Method was used to estimate participants' usual diet, using two 24-hour dietary recalls during mid-pregnancy. Diagnosis of GDM was defined by the American Diabetes Association criteria of 2015. Logistic regression analysis were used to assess the association between GDM and dietary fat, adjusted for age, education, parity, gestational age at the time of the interview, pre-pregnancy and current BMI, prior GDM, family history of diabetes, smoking, physical activity, energy, fiber, and fatty acids.

RESULTS

The mean (standard deviation) age of the women was 28 (5) years, and 19% had GDM. After multiple adjustments, inverse associations between the highest tertile of ∑n-3 fatty acids intake [0.21 (0.08-0.56)], α-linolenic intake [0.15 (0.05-0.42)], and GDM were found. A positive association between GDM and the highest tertile of TI [2.66 (1.34-5.29)], and a negative association with the highest tertile of hH ratio [0.41 (0.22-0.77)], were observed. No association between GDM and other indices of dietary fat quality were found.

CONCLUSION

The quality of dietary fat during pregnancy is strongly associated with GDM. Randomized clinical trial are needed to confirm these findings.