The Effect of n-3 Fatty Acids on Glucose Homeostasis and Insulin Sensitivity

Free fatty acid receptor 4 (FFA4) activation attenuates obese asthma by suppressing adiposity and resolving metaflammation

Obese asthma is recognized to have different asthma phenotypes. N-3 polyunsaturated fatty acids (PUFAs) have shown beneficial effects in obesity and metabolic syndrome. Free fatty acid receptor 4 (FFA4, also known as GPR120) is a receptor for n-3 PUFAs. In the present study, we investigated whether FFA4 activation ameliorates high-fat diet (HFD)-induced obese asthma. We investigated whether FFA4 activation ameliorates obese asthma using an FFA4 agonist, compound A (CpdA), in combination with FFA4 wild-type (WT) and knock-out (KO) mice. Administration of an FFA4 agonist, compound A (CpdA, 30 mg/kg), suppressed HFD-induced weight gain, adiposity, and airway hypersensitivity (AHR), and increased immune cell infiltration in an FFA4-dependent manner. Histological analysis revealed that CpdA treatment suppressed HFD-induced mucus hypersecretion, inflammation, and fibrosis in an FFA4-dependent manner. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) showed an HFD-induced increase in the mRNA levels of pro-inflammatory cytokines in the lungs and gonadal white adipose tissue, whereas CpdA inhibited this increase in an FFA4-dependent manner. In the fluorescence-activated cell sorting (FACS) analysis, HFD induced an increase in the lung innate lymphoid cells (ILC) ILC1, ILC2, and ILC3; however, CpdA reversed this increase. In addition, HFD induced an increase in the pro-inflammatory M1 macrophage population and a decrease in the anti-inflammatory M2 macrophage population in the lungs, whereas CpdA treatment reversed these changes. The present study suggests that FFA4 activation may have therapeutic potential in obese asthma.

Feasibility of replacing fish oil with sunflower oil on the growth, body composition, fatty acid profile, antioxidant activity, stress response, and blood biomarkers of Labeo rohita

A 90-day study was conducted to investigate the effects of substituting sunflower oil (SFO) for fish oil (FO) on various parameters in Labeo rohita (initial weight 18.21 ± 0.22 g). Five experimental diets with different levels of SFO (up to 7%) substitution for FO (0%, 25%, 50%, 75%, and 100%) were formulated, ensuring equal levels of nitrogen and lipids. The results indicated that even with 100% substitution of SFO with FO, there were no significant differences (P>0.05) were observed in growth performance. The survival rate (SR), hepato-somatic index (HSI), and viscero-somatic index (VSI) as well as whole-body composition were also nonsignificant by SFO substitution. However, the fatty acid profiles in both muscle and liver were influenced (P<0.05) by dietary substitution. Saturated fats (SFA) decreased, while monounsaturated fats (MUFA), and linoleic acid (LA) increased (P<0.05). On the other hand, the contribution of linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) decreased (P<0.05) as the amount of SFO in the diet increased. Hematology parameters, including red blood cells (RBCs), hemoglobin (Hb), and hematocrit (Hct), were not affected. Globulin (GLO) levels decreased significantly (P<0.05), while alanine transaminase (ALT) and aspartate transaminase (AST) activity showed nonsignificant increases (P>0.05). Total protein (TP) increased (P<0.05) at 100% SFO inclusion in the diet, and albumin (ALB) levels increased (P<0.05) at 75% and 100% SFO inclusion in the diet. Cholesterol (CHOL), triacylglycerol (TG), and high-density lipids (HDL) were not significantly affected (P>0.05), while low-density lipids (LDL) were significantly increased (P<0.05) compared to the control group. Cortisol (CORT) and glucose (GLU) levels showed nonsignificant (P>0.05) changes. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities in the liver and serum were not significantly (P>0.05) affected, while malondialdehyde (MDA) status was significantly (P<0.05) reduced. In conclusion, the fatty acid profile of the muscle and liver of fish was modified by the diets, and FO can be substituted with SFO up to 100% for L. rohita, which is beneficial for growth and immunity while marinating the lipid contents in fish. Our study revealed that fully replacing fish oil with SFO shows promise in fully replacing FO without compromising the growth and overall health status of the fish.

The effects of purslane (Portulaca oleracea) on glycemic indices: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Although several studies have revealed the benefits of purslane on glycemic indices, the results of some studies reject such effect. Therefore, aim of this meta-analysis of randomized controlled trials (RCTs) was to assess the effects of purslane supplementation on glycemic indices. Scientific international databases as Scopus, Web of Sciences, PubMed, Embase, and the Cochrane library were searched up to December 2022. For net changes in glycemic indices, weighted mean differences (WMDs) were calculated using random-effects models. Purslane supplementation had a statistically significant reduction in fasting blood glucose [FBG, WMD: -6.37; 95% CI: -9.34, -3.40, p < 0.001]. In addition, purslane did not significant effect on serum levels of insulin [WMD: -0.74; 95% CI: -2.58, 1.10; p = 0.430], homeostasis model assessment for insulin resistance [HOMA-IR, WMD: -0.25; 95% CI: -0.88, 0.37, p = 0.429], and QUICKI [WMD: -0.01; 95% CI: -0.01, 0.03, p = 0.317] compared with the control group. The results of our meta-analysis revealed a beneficial effect of purslane supplementation as a tool to decrease FBG levels, but not to HOMA-IR, insulin, and QUICKI levels. However, future high-quality, long-term clinical trials are needed to confirm our results.

Refined mackerel oil increases hepatic lipid accumulation and reduces choline and choline-containing metabolites in the liver tissue in mice fed a Western diet

In this study, we aimed to evaluate the impact of consuming refined mackerel oil (MO) from rest raw material on hepatic fat accumulation, glucose tolerance, and metabolomic changes in the liver from male C57BL/6N mice. The mice were fed either a Western diet (WD) or a chow diet, with 30 g or 60 g MO per kg of diet (3% or 6%) for 13 weeks. Body weight, energy intake, and feed efficiency were monitored throughout the experiment. A glucose tolerance test was conducted after 11 weeks, and metabolomic analyses of the liver were performed at termination. Inclusion of MO in the WD, but not in the chow diet, led to increased liver weight, hepatic lipid accumulation, elevated fasting blood glucose, reduced glucose tolerance, and insulin sensitivity. Hepatic levels of eicosapentaenoic and docosahexaenoic acid increased, but no changes in levels of saturated and monounsaturated fatty acids were observed. The liver metabolomic profile was different between mice fed a WD with or without MO, with a reduction in choline ether lipids, phosphatidylcholines, and sphingomyelins in mice fed MO. This study demonstrates that supplementing the WD, but not the chow diet, with refined MO accelerates accumulation of hepatic fat droplets and negatively affects blood glucose regulation. The detrimental effects of supplementing a WD with MO were accompanied by increased fat digestibility and overall energy intake, and lower levels of choline and choline-containing metabolites in liver tissue.

The Role of Organokines in Obesity and Type 2 Diabetes and Their Functions as Molecular Transducers of Nutrition and Exercise

Maintaining systemic homeostasis requires the coordination of different organs and tissues in the body. Our bodies rely on complex inter-organ communications to adapt to perturbations or changes in metabolic homeostasis. Consequently, the liver, muscle, and adipose tissues produce and secrete specific organokines such as hepatokines, myokines, and adipokines in response to nutritional and environmental stimuli. Emerging evidence suggests that dysregulation of the interplay of organokines between organs is associated with the pathophysiology of obesity and type 2 diabetes (T2D). Strategies aimed at remodeling organokines may be effective therapeutic interventions. Diet modification and exercise have been established as the first-line therapeutic intervention to prevent or treat metabolic diseases. This review summarizes the current knowledge on organokines secreted by the liver, muscle, and adipose tissues in obesity and T2D. Additionally, we highlighted the effects of diet/nutrition and exercise on the remodeling of organokines in obesity and T2D. Specifically, we investigated the ameliorative effects of caloric restriction, selective nutrients including ω3 PUFAs, selenium, vitamins, and metabolites of vitamins, and acute/chronic exercise on the dysregulation of organokines in obesity and T2D. Finally, this study dissected the underlying molecular mechanisms by which nutrition and exercise regulate the expression and secretion of organokines in specific tissues.

Short-Term Effects of Fruit Juice Enriched with Vitamin D3, n-3 PUFA, and Probiotics on Glycemic Responses: A Randomized Controlled Clinical Trial in Healthy Adults

This study aimed to determine the glycemic index (GI) of a commercial mixed fruit juice (apple, orange, grape, and pomegranate; FJ) fortified with vitamin D3 or n-3 polyunsaturated fatty acids (PUFA) or probiotics, and their combination, and their effects on glycemic responses and salivary insulin concentrations. In a randomized controlled, double-blind, crossover study, 11 healthy participants (25 ± 2 years; five women; body mass index = 23 ± 1 kg/m²) were randomly assigned to receive five types of FJs [vitD (with vitamin D3); n-3 (with n-3 PUFA); probiotics (with Lacticaseibacillus casei Shirota and Lacticaseibacillus rhamnosus GG); vitD-n-3-probiotics FJ (combination of vitD3-n-3-probiotics), control (regular FJ)], all containing 50 g available carbohydrate, and glucose as reference drink. All FJs provided low GI values (control: 54; vitD3: 52; n-3: 51; probiotics: 50; and vitD-n-3-probiotics combination: 52, on glucose scale). Compared to the FJ control, the enriched FJs produced different postprandial glycemic and insulinemic responses and affected satiety scores. All FJ types, regardless of the added biofunctional ingredients, attenuated postprandial glycemic responses, which may offer advantages to glycemic control.

Sex-specific responses in glucose-insulin homeostasis and lipoprotein-lipid components after high-dose supplementation with marine n-3 PUFAs in abdominal obesity: a randomized double-blind crossover study

Background

Clinical studies on effects of marine-derived omega-3 (n-3) polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and the plant-derived omega-6 (n-6) PUFA linoleic acid (LA) on lipoprotein-lipid components and glucose-insulin homeostasis have shown conflicting results, which may partly be explained by differential responses in females and males. However, we have lacked data on sexual dimorphism in the response of cardiometabolic risk markers following increased consumption of n-3 or n-6 PUFAs.

Objective

To explore sex-specific responses after n-3 (EPA + DHA) or n-6 (LA) PUFA supplementation on circulating lipoprotein subfractions, standard lipids, apolipoproteins, fatty acids in red blood cell membranes, and markers of glycemic control/insulin sensitivity among people with abdominal obesity.

Methods

This was a randomized double-blind crossover study with two 7-week intervention periods separated by a 9-week washout phase. Females (n = 16) were supplemented with 3 g/d of EPA + DHA (fish oil) or 15 g/d of LA (safflower oil), while males (n = 23) received a dose of 4 g/d of EPA + DHA or 20 g/d of LA. In fasting blood samples, we measured lipoprotein particle subclasses, standard lipids, apolipoproteins, fatty acid profiles, and markers of glycemic control/insulin sensitivity.

Results

The between-sex difference in relative change scores was significant after n-3 for total high-density lipoproteins (females/males: -11%*/-3.3%, p = 0.036; *: significant within-sex change), high-density lipoprotein particle size (+2.1%*/-0.1%, p = 0.045), and arachidonic acid (-8.3%*/-12%*, p = 0.012), and after n-6 for total (+37%*/+2.1%, p = 0.041) and small very-low-density lipoproteins (+97%*/+14%, p = 0.021), and lipoprotein (a) (-16%*/+0.1%, p = 0.028). Circulating markers of glucose-insulin homeostasis differed significantly after n-3 for glucose (females/males: -2.1%/+3.9%*, p = 0.029), insulin (-31%*/+16%, p < 0.001), insulin C-peptide (-12%*/+13%*, p = 0.001), homeostasis model assessment of insulin resistance index 2 (-12%*/+14%*, p = 0.001) and insulin sensitivity index 2 (+14%*/-12%*, p = 0.001), and quantitative insulin sensitivity check index (+4.9%*/-3.4%*, p < 0.001).

Conclusion

We found sex-specific responses after high-dose n-3 (but not n-6) supplementation in circulating markers of glycemic control/insulin sensitivity, which improved in females but worsened in males. This may partly be related to the sex differences we observed in several components of the lipoprotein-lipid profile following the n-3 intervention.

Clinical trial registration

https://clinicaltrials.gov/, identifier [NCT02647333].

Dietary Docosahexaenoic Acid and Glucose Systemic Metabolic Changes in the Mouse

The endocannabinoid system (ECS) participates in regulating whole body energy balance. Overactivation of the ECS has been associated with the negative consequence of obesity and type 2 diabetes. Since activators of the ECS rely on lipid-derived ligands, an investigation was conducted to determine whether dietary PUFA could influence the ECS to affect glucose clearance by measuring metabolites of macronutrient metabolism. C57/blk6 mice were fed a control or DHA-enriched semi-purified diet for a period of 112 d. Plasma, skeletal muscle, and liver were collected after 56 d and 112 d of feeding the diets for metabolomics analysis. Key findings characterized a shift in glucose metabolism and greater catabolism of fatty acids in mice fed the DHA diet. Glucose use and promotion of fatty acids as substrate were found based on levels of metabolic pathway intermediates and altered metabolic changes related to pathway flux with DHA feeding. Greater levels of DHA-derived glycerol lipids were found subsequently leading to the decrease of arachidonate-derived endocannabinoids (eCB). Levels of 1- and 2-arachidonylglcerol eCB in muscle and liver were lower in the DHA diet group compared to controls. These findings demonstrate that DHA feeding in mice alters macronutrient metabolism and may restore ECS tone by lowering arachidonic acid derived eCB.

Omega-3-Rich Fish-Oil-Influenced Mouse Gut Microbiome Shaped by Intermittent Consumption of Beef

Beef consumption can provide various amino acids, lipids, vitamins, and minerals; however, excessive intake causes metabolic disorders and increases the probability of obesity, atherosclerosis, and colorectal cancer. The intake of omega-3 fatty acids can ameliorate metabolic disorders by lowering blood glucose and triglyceride levels. In the present study, we investigated the effect of omega-3-rich fish oil on body performance and the gut microbiome in a beef-rich diet. Four-week-old C57BL/6 mice were distributed into four groups (chow diet [Chow], chow with beef diet [Beef], chow with omega-3 diet [Cw3], and chow with beef and omega-3 diet [Bw3]). We observed that body weight was unaltered between groups, and serum triglyceride levels were reduced in the omega-3 supplemented groups. The beta diversity indices, unweighted UniFrac distance (P = 0.001), and Jaccard distance (P = 0.001) showed statistically significant differences, and the principal coordinates analysis plot showed a clear separation between groups. In addition, the taxonomic comparison revealed that beef consumption increased numerous potentially pathogenic bacteria, including Escherichia-Shigella, Mucispirillum, Helicobacter, and Desulfovibrio, which were decreased following omega-3 supplementation. Metabolic comparison based on 16S rRNA revealed that energy and glucose metabolism were higher in omega-3 supplemented groups. Our findings suggest that the omega-3 supplementation under intermittent beef consumption contributes to changes in the gut microbiome and microbial metabolic pathways.

Bile acids-gut microbiota crosstalk contributes to the improvement of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) occurs that cannot effectively use the insulin. Insulin Resistance (IR) is a significant characteristic of T2DM which is also an essential treatment target in blood glucose regulation to prevent T2DM and its complications. Bile acids (BAs) are one group of bioactive metabolites synthesized from cholesterol in liver. BAs play an important role in mutualistic symbiosis between host and gut microbiota. It is shown that T2DM is associated with altered bile acid metabolism which can be regulated by gut microbiota. Simultaneously, BAs also reshape gut microbiota and improve IR and T2DM in the bidirectional communications of the gut-liver axis. This article reviewed the findings on the interaction between BAs and gut microbiota in improving T2DM, which focused on gut microbiota and its debinding function and BAs regulated gut microbiota through FXR/TGR5. Meanwhile, BAs and their derivatives that are effective for improving T2DM and other treatments based on bile acid metabolism were also summarized. This review highlighted that BAs play a critical role in the glucose metabolism and may serve as therapeutic targets in T2DM, providing a reference for discovering and screening novel therapeutic drugs.

The role of selected nutraceuticals in management of prediabetes and diabetes: An updated review of the literature

Dysglycemia is a disease state preceding the onset of diabetes and includes impaired fasting glycemia and impaired glucose tolerance. This review aimed to collect and analyze the literature reporting the results of clinical trials evaluating the effects of selected nutraceuticals on glycemia in humans. The results of the analyzed trials, generally, showed the positive effects of the nutraceuticals studied alone or in association with other supplements on fasting plasma glucose and post-prandial plasma glucose as primary outcomes, and their efficacy in improving insulin resistance as a secondary outcome. Some evidences, obtained from clinical trials, suggest a role for some nutraceuticals, and in particular Berberis, Banaba, Curcumin, and Guar gum, in the management of prediabetes and diabetes. However, contradictory results were found on the hypoglycemic effects of Morus, Ilex paraguariensis, Omega-3, Allium cepa, and Trigonella faenum graecum, whereby rigorous long-term clinical trials are needed to confirm these data. More studies are also needed for Eugenia jambolana, as well as for Ascophyllum nodosum and Fucus vesiculosus which glucose-lowering effects were observed when administered in combination, but not alone. Further trials are also needed for quercetin.

Metabolomic profiling of the Dietary Approaches to Stop Hypertension diet provides novel insights for the nutritional epidemiology of type 2 diabetes mellitus

Adherence to the Dietary Approaches to Stop Hypertension (DASH) diet is inversely associated with type 2 diabetes mellitus (T2DM) risk. Metabolic changes due to DASH adherence and their potential relationship with incident T2DM have not been described. The objective is to determine metabolite clusters associated with adherence to a DASH-like diet in the Insulin Resistance Atherosclerosis Study cohort and explore if the clusters predicted 5-year incidence of T2DM. The current study included 570 non-diabetic multi-ethnic participants aged 40–69 years. Adherence to a DASH-like diet was determined a priori through an eighty-point scale for absolute intakes of the eight DASH food groups. Quantitative measurements of eighty-seven metabolites (acylcarnitines, amino acids, bile acids, sterols and fatty acids) were obtained at baseline. Metabolite clusters related to DASH adherence were determined through partial least squares (PLS) analysis using R. Multivariable-adjusted logistic regression was used to explore the associations between metabolite clusters and incident T2DM. A group of acylcarnitines and fatty acids loaded strongly on the two components retained under PLS. Among strongly loading metabolites, a select group of acylcarnitines had over 50 % of their individual variance explained by the PLS model. Component 2 was inversely associated with incident T2DM (OR: 0·89; (95 % CI 0·80, 0·99), P-value = 0·043) after adjustment for demographic and metabolic covariates. Component 1 was not associated with T2DM risk (OR: 1·02; (95 % CI 0·88, 1·19), P-value = 0·74). Adherence to a DASH-type diet may contribute to reduced T2DM risk in part through modulations in acylcarnitine and fatty acid physiology.

The Effect of Fish Oil-Based Foods on Lipid and Oxidative Status Parameters in Police Dogs

The synthesis, degradation, and reconstruction of the cell membrane as a metabolic pathway of phospholipids is a constant and dynamic process. Fatty acids as bioactive lipid components of plasma and erythrocyte phospholipids as structural lipids have biological roles in the integrity of cell membranes. Fatty acids, depending on the chain length, the degree of saturation, and the synthesis pathways, can alleviate inflammation and oxidative stress caused by excessive exercise. Considering that changing food intake or diet can influence fatty acid phospholipid metabolism, our study aimed to determine the potential benefits of fish-based diets in working (police) dogs undergoing intensive training concerning bioactive lipids such as fatty acids, phospholipids of plasma, and erythrocytes. Fatty acid esters’ composition of plasma and erythrocyte phospholipids as a bioactive lipids, in addition to markers of oxidative stress and metabolic parameters, were analysed by GC chromatography. The food was well tolerated by all dogs, and the compliance to the diet was high throughout the study. After the treatment with fish-based food, blood glucose, total, and LDL cholesterol levels were significantly reduced, indicating positive biochemical profiles of dogs. Correlations of fatty acid phospholipid compositions between plasma and erythrocytes have shown that both plasma and erythrocytes could represent markers of omega-3 eicosapentaenoic and docosahexaenoic acid intake levels in dogs. Morover, fish-based food supplementation caused a significant reduction in lipid peroxidation markers. The enrichment of dogs’ diets with marine fish could improve oxidative status and improve roles and status of bioactive lipids, such as membrane phospholipids and fatty acids, as its components in plasma and erythrocytes in police dogs exposed to intensive exercise.

n-3 index is associated with cardiometabolic risk factors but is not improved by walnut intake in free-living elderly: a single-blind, randomised controlled trial

n-3 index, the erythrocyte proportion of the EPA + DHA fatty acids is a clinical marker of age-related disease risk. It is unclear whether regular intake of α-linolenic acid (ALA), a plant-derived n-3 polyunsaturated fatty acid, raises n-3 index in older adults. Of the 356 participants at the Loma Linda, CA centre from the original study, a randomly selected subset (n 192) was included for this secondary analysis (mostly Caucasian women, mean age 69 years). Participants were assigned to either the walnut (15 % of daily energy from walnuts) or the control group (usual diet, no walnuts) for 2 years. Erythrocyte fatty acids were determined at baseline and 1-year following intervention. No differences were observed for erythrocyte EPA, but erythrocyte DHA decreased albeit modestly in the walnut group (-0·125 %) and slightly improved in the control group (0·17 %). The change in n-3 index between the walnut and control groups was significantly different only among fish consumers (those who ate fish ≥ once/month). Longitudinal analyses combining both groups showed significant inverse association between the 1-year changes of the n-3 index and fasting plasma TAG (ß = -10), total cholesterol (ß = -5·59) and plasma glucose (ß = -0·27). Consuming ALA-rich walnuts failed to improve n-3 index in elders. A direct source of EPA/DHA may be needed to achieve desirable n-3 index, as it is inversely associated with cardiometabolic risk. Nevertheless, incorporating walnuts as part of heart healthy diets is still encouraged.

Eicosapentaenoic and docosahexaenoic acids attenuate hyperglycemia through the microbiome-gut-organs axis in db/db mice

BACKGROUND

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been suggested to prevent the development of metabolic disorders. However, their individual role in treating hyperglycemia and the mechanism of action regarding gut microbiome and metabolome in the context of diabetes remain unclear.

RESULTS

Supplementation of DHA and EPA attenuated hyperglycemia and insulin resistance without changing body weight in db/db mice while the ameliorative effect appeared to be more pronounced for EPA. DHA/EPA supplementation reduced the abundance of the lipopolysaccharide-containing Enterobacteriaceae whereas elevated the family Coriobacteriaceae negatively correlated with glutamate level, genera Barnesiella and Clostridium XlVa associated with bile acids production, beneficial Bifidobacterium and Lactobacillus, and SCFA-producing species. The gut microbiome alterations co-occurred with the shifts in the metabolome, including glutamate, bile acids, propionic/butyric acid, and lipopolysaccharide, which subsequently relieved β cell apoptosis, suppressed hepatic gluconeogenesis, and promoted GLP-1 secretion, white adipose beiging, and insulin signaling. All these changes appeared to be more evident for EPA. Furthermore, transplantation with DHA/EPA-mediated gut microbiota mimicked the ameliorative effect of DHA/EPA on glucose homeostasis in db/db mice, together with similar changes in gut metabolites. In vitro, DHA/EPA treatment directly inhibited the growth of Escherichia coli (Family Enterobacteriaceae) while promoted Coriobacterium glomerans (Family Coriobacteriaceae), demonstrating a causal effect of DHA/EPA on featured gut microbiota.

CONCLUSIONS

DHA and EPA dramatically attenuated hyperglycemia and insulin resistance in db/db mice, which was mediated by alterations in gut microbiome and metabolites linking gut to adipose, liver and pancreas. These findings shed light into the gut-organs axis as a promising target for restoring glucose homeostasis and also suggest a better therapeutic effect of EPA for treating diabetes. Video abstract.

Differential and shared effects of eicosapentaenoic acid and docosahexaenoic acid on serum metabolome in subjects with chronic inflammation

The omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affect cell function and metabolism, but the differential effects of EPA and DHA are not known. In a randomized, controlled, double-blind, crossover study, we assessed the effects of 10-week supplementation with EPA-only and DHA-only (3 g/d), relative to a 4-week lead-in phase of high oleic acid sunflower oil (3 g/day, defined as baseline), on fasting serum metabolites in 21 subjects (9 men and 12 post-menopausal women) with chronic inflammation and some characteristics of metabolic syndrome. Relative to baseline, EPA significantly lowered the tricarboxylic acid (TCA) cycle intermediates fumarate and α-ketoglutarate and increased glucuronate, UDP-glucuronate, and non-esterified DHA. DHA significantly lowered the TCA cycle intermediates pyruvate, citrate, isocitrate, fumarate, α-ketoglutarate, and malate, and increased succinate and glucuronate. Pathway analysis showed that both EPA and DHA significantly affected the TCA cycle, the interconversion of pentose and glucuronate, and alanine, and aspartate and glutamate pathways (FDR < 0.05) and that DHA had a significantly greater effect on the TCA cycle than EPA. Our results indicate that EPA and DHA exhibit both common and differential effects on cell metabolism in subjects with chronic inflammation and some key aspects of metabolic syndrome.

Maternal Supply of Fatty Acids during Late Gestation on Offspring's Growth, Metabolism, and Carcass Characteristics in Sheep

Lambs born from dams supplemented with different sources of fatty acids (FA) during late gestation have a different growth rate and plasma glucose concentration. The main objectives of this experiment were to evaluate the effect of supplementing different sources of FA during late gestation on offspring plasma metabolite concentrations, growth, and on a glucose tolerance test (GTT) during the finishing phase. Fifty-four lambs (18 pens, 3 lambs/pen) were born from ewes supplemented during late gestation with one of three treatments: (1) no FA (NF); (2) a source of monounsaturated FA (PDS, 1.01% of Ca salts); or (3) a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (EDS, 1.01% of Ca salts containing). At birth (day 0), supplementation ceased, and all ewes and lambs were placed in a common pen. On day 60, lambs were weaned, grouped by sex, blocked by body weight (BW), and placed on a common finishing diet for 54 days (FP). One lamb per pen was used for the GTT after the FP. There was a tendency for FA × Sex × Day interaction (p = 0.08) on lamb growth during the finishing period, with PDS females being heavier than PDS males, while EDS males were heavier than EDS females at day 60. There was a tendency for FA × Sex interaction (p = 0.06) for plasma insulin concentration for the GTT. Plasma insulin concentration of wethers increased as FA unsaturation degree increased during the GTT; the opposite happened with the plasma insulin concentration of female lambs. In conclusion, FA supplementation during late gestation tended to modified growth and insulin response to a GTT; these changes differed with the degree of FA unsaturation of the supplement and lamb sex.

Omega-3 Polyunsaturated Fatty Acids Prevent Nonalcoholic Steatohepatitis (NASH) and Stimulate Adipogenesis

The increasing impact of obesity on global human health intensifies the importance of studies focusing on agents interfering with the metabolism and remodeling not only of the white adipose tissue (WAT) but also of the liver. In the present study, we have addressed the impact of n-3 PUFA in adipose cells' proliferation and adipogenesis, as well as in the hepatic lipid profile and morphology. Mice were induced to obesity by the consumption of a high-fat diet (HFD) for 16 weeks. At the 9th week, the treatment with fish oil (FO) was initiated and maintained until the end of the period. The FO treatment reduced the animals' body mass, plasma lipids, glucose, plasma transaminases, liver mass, triacylglycerol, and cholesterol liver content when compared to animals consuming only HFD. FO also decreased the inguinal (ing) WAT mass, reduced adipocyte volume, increased adipose cellularity (hyperplasia), and increased the proliferation of adipose-derived stromal cells (AdSCs) which corroborates the increment in the proliferation of 3T3-L1 pre-adipocytes or AdSCs treated in vitro with n-3 PUFA. After submitting the in vitro treated (n-3 PUFA) cells, 3T3-L1 and AdSCs, to an adipogenic cocktail, there was an increase in the mRNA expression of adipogenic transcriptional factors and other late adipocyte markers, as well as an increase in lipid accumulation when compared to not treated cells. Finally, the expression of browning-related genes was also higher in the n-3 PUFA treated group. We conclude that n-3 PUFA exerts an attenuating effect on body mass, dyslipidemia, and hepatic steatosis induced by HFD. FO treatment led to decreasing adiposity and adipocyte hypertrophy in ingWAT while increasing hyperplasia. Data suggest that FO treatment might induce recruitment (by increased proliferation and differentiation) of new adipocytes (white and/or beige) to the ingWAT, which is fundamental for the healthy expansion of WAT.

No Effect of Dietary Fish Oil Supplementation on the Recruitment of Brown and Brite Adipocytes in Mice or Humans under Thermoneutral Conditions

SCOPE

Brown and brite adipocytes within the mammalian adipose organ provide non-shivering thermogenesis and thus, have an exceptional capacity to dissipate chemical energy as heat. Polyunsaturated fatty acids (PUFA) of the n3-series, abundant in fish oil, have been repeatedly demonstrated to enhance the recruitment of thermogenic capacity in these cells, consequently affecting body adiposity and glucose tolerance. These effects are scrutinized in mice housed in a thermoneutral environment and in a human dietary intervention trial.

METHODS AND RESULTS

Mice are housed in a thermoneutral environment eliminating the superimposing effect of mild cold-exposure on thermogenic adipocyte recruitment. Dietary fish oil supplementation in two different inbred mouse strains neither affects body mass trajectory nor enhances the recruitment of brown and brite adipocytes, both in the presence and absence of a β3-adrenoreceptor agonist imitating the effect of cold-exposure on adipocytes. In line with these findings, dietary fish oil supplementation of persons with overweight or obesity fails to recruit thermogenic adipocytes in subcutaneous adipose tissue.

CONCLUSION

Thus, the authors' data question the hypothesized potential of n3-PUFA as modulators of adipocyte-based thermogenesis and energy balance regulation.

Additive Effects of Omega-3 Fatty Acids and Thiazolidinediones in Mice Fed a High-Fat Diet: Triacylglycerol/Fatty Acid Cycling in Adipose Tissue

Long-chain n-3 polyunsaturated fatty acids (Omega-3) and anti-diabetic drugs thiazolidinediones (TZDs) exhibit additive effects in counteraction of dietary obesity and associated metabolic dysfunctions in mice. The underlying mechanisms need to be clarified. Here, we aimed to learn whether the futile cycle based on the hydrolysis of triacylglycerol and re-esterification of fatty acids (TAG/FA cycling) in white adipose tissue (WAT) could be involved. We compared Omega-3 (30 mg/g diet) and two different TZDs—pioglitazone (50 mg/g diet) and a second-generation TZD, MSDC-0602K (330 mg/g diet)—regarding their effects in C57BL/6N mice fed an obesogenic high-fat (HF) diet for 8 weeks. The diet was supplemented or not by the tested compound alone or with the two TZDs combined individually with Omega-3. Activity of TAG/FA cycle in WAT was suppressed by the obesogenic HF diet. Additive effects in partial rescue of TAG/FA cycling in WAT were observed with both combined interventions, with a stronger effect of Omega-3 and MSDC-0602K. Our results (i) supported the role of TAG/FA cycling in WAT in the beneficial additive effects of Omega-3 and TZDs on metabolism of diet-induced obese mice, and (ii) showed differential modulation of WAT gene expression and metabolism by the two TZDs, depending also on Omega-3.

ERK1/2 Pathway Is Involved in the Enhancement of Fatty Acids from Phaeodactylum tricornutum Extract (PTE) on Hair Follicle Cell Proliferation

Extractions from Phaeodactylum tricornutum have been widely studied and evaluated to various biological effects. The aim of this study was to investigate the promotional effect of P. tricornutum extract (PTE) on the ERK1/2 signaling pathway involved in hair follicle cell proliferation. In order to illuminate the enhancement of PTE on hair growth by promoting proliferation of hair follicle cells, the activities of human hair follicle outer root sheath cell (HFORSC), human hair follicle germinal matrix cells (HFGMC), and hair epithelial melanocytes (HEM) were observed under PET treatment. Levels of keratins, PKCζ, ERK1/2, and p38 MAPK in hair follicle cells were determined by Western blotting to illustrate the mechanisms of PTE effects on hair growth. Analyzed by GC-MS, the main polyunsaturated fatty acids which were 9.43% of total fatty acids in PTE were linolenic acid, linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid. Melanin content and tyrosinase activity in HEM were measured. The results showed that PTE exhibited remarkable enhancement on cell proliferation. Melanin production was inhibited by PTE treatment, while keratin-14, keratin-15, and keratin-17 levels on hair follicle cells were elevated at different concentrations. The promotions of ERK1/2 and p38 MAPK levels indicated that the ERK1/2 signaling pathway is involved in the proliferation of hair follicle cells. These results are the evidence that PTE potentially deserves further study as a new natural candidate for hair care applications.

The regulatory role of dietary factors in skeletal muscle development, regeneration and function

Skeletal muscle plays a crucial role in motor function, respiration, and whole-body energy homeostasis. How to regulate the development and function of skeletal muscle has become a hot research topic for improving lifestyle and extending life span. Numerous transcription factors and nutritional factors have been clarified are closely associated with the regulation of skeletal muscle development, regeneration and function. In this article, the roles of different dietary factors including green tea, quercetin, curcumin (CUR), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and resveratrol (RES) in regulating skeletal muscle development, muscle mass, muscle function, and muscle recovery have been summarized and discussed. We also reviewed the potential regulatory molecular mechanism of these factors. Based on the current findings, dietary factors may be used as a potential therapeutic agent to treat skeletal muscle dysfunction as well as its related diseases.

Dietary α-Linolenic Acid Counters Cardioprotective Dysfunction in Diabetic Mice: Unconventional PUFA Protection

Whether dietary omega-3 (n-3) polyunsaturated fatty acid (PUFA) confers cardiac benefit in cardiometabolic disorders is unclear. We test whether dietary -linolenic acid (ALA) enhances myocardial resistance to ischemia-reperfusion (I-R) and responses to ischemic preconditioning (IPC) in type 2 diabetes (T2D); and involvement of conventional PUFA-dependent mechanisms (caveolins/cavins, kinase signaling, mitochondrial function, and inflammation). Eight-week male C57Bl/6 mice received streptozotocin (75 mg/kg) and 21 weeks high-fat/high-carbohydrate feeding. Half received ALA over six weeks. Responses to I-R/IPC were assessed in perfused hearts. Localization and expression of caveolins/cavins, protein kinase B (AKT), and glycogen synthase kinase-3 β (GSK3β); mitochondrial function; and inflammatory mediators were assessed. ALA reduced circulating leptin, without affecting body weight, glycemic dysfunction, or cholesterol. While I-R tolerance was unaltered, paradoxical injury with IPC was reversed to cardioprotection with ALA. However, post-ischemic apoptosis (nucleosome content) appeared unchanged. Benefit was not associated with shifts in localization or expression of caveolins/cavins, p-AKT, p-GSK3β, or mitochondrial function. Despite mixed inflammatory mediator changes, tumor necrosis factor-a (TNF-a) was markedly reduced. Data collectively reveal a novel impact of ALA on cardioprotective dysfunction in T2D mice, unrelated to caveolins/cavins, mitochondrial, or stress kinase modulation. Although evidence suggests inflammatory involvement, the basis of this "un-conventional" protection remains to be identified.

Trace Elements and Fatty Acid Profile of Argyrosomus regius (Asso, 1801) from Mediterranean Aquaculture

Although Argyrosomus regius (Asso, 1801) counts among the most appreciated and increasingly consumed fish species in Europe, little information is available on its flesh quality. This research concerns both healthy aquatic resource diversification and good nutritional quality. It is the first study to evaluate the quality of A. regius flesh from Mediterranean aquaculture. It aims to assess the concentration of 19 trace elements and to determine the fatty acid profile of this fish farmed in the Mediterranean Sea and to discuss human exposure risks. The nutritional intake of oligoelements (selenium (Se), zinc (Zn), and chromium (Cr)) and the mean concentrations of contaminants (arsenic (As), barium (Ba), cadmium (Cd), lead (Pb), and tin (Sn)) in A. regius muscles are, respectively, above and below recommended regulatory standards set by the international legislation. Additionally, the low fat content in its muscle mass and its high level of docosahexaenoic acid (C22: 6 n-3; DHA) and, to a lesser extent, eicosapentaenoic acid (C20: 5 n-3; EPA) confers satisfying nutritional qualities. This study allowed to conclude that meager can be considered as a source of seafood with good nutritional qualities for human health.

Eicosapentaenoic and Docosahexaenoic Acids Differentially Alter Gut Microbiome and Reverse High-Fat Diet-Induced Insulin Resistance

SCOPE

To assess the individual effects of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on insulin resistance (IR), gut microbiome, and gut metabolites in high-fat-diet-induced obese (DIO) mice.

METHODS AND RESULTS

DIO mice are fed an either high-fat diet (HFD), EPA (1% w/w) enriched HFD, or DHA (1% wt/wt) enriched HFD for 15 weeks. Both EPA and DHA supplements reverse hyperglycemia and IR but do not affect body weight in DIO mice while DHA exhibits a more pronounced ameliorative effect in male mice. Both EPA- and DHA-enriched Lactobacillus and short-chain fatty acids (SCFAs)-producing species from Lachnospiraceae while reduced lipopolysaccharide (LPS)-producing Bilophila and Escherichia/Shigella. Compared with EPA, DHA-supplemented mice have more abundant propionic/butyric acid-producing bacteria, including Coprococcus, Butyricimonas synergistica, Bacteroides acidifaciens, and Intestinimonas, and less-abundant LPS-correlated species Streptococcus and p-75-a5. The shifts in gut microbiome co-occurred with the changes in levels of propionic/butyric acid, circulating LPS, and serotonin. Additionally, EPA/DHA supplementation attenuates adipose inflammation with upregulated glucose transporter 4 and Akt phosphorylation, indicating the improvement of insulin signaling.

CONCLUSION

EPA and DHA differentially reverse IR and relieve adipose inflammation while modulating gut microbiome and SCFAs/LPS production, underscoring the gut-adipose axis as a primary target of EPA/DHA.

Increased plasma levels of palmitoleic acid may contribute to beneficial effects of Krill oil on glucose homeostasis in dietary obese mice

Omega-3 polyunsatuarted fatty acids (PUFA) are associated with hypolipidemic and anti-inflammatory effects. However, omega-3 PUFA, usually administered as triacylglycerols or ethyl esters, could also compromise glucose metabolism, especially in obese type 2 diabetics. Phospholipids represent an alternative source of omega-3 PUFA, but their impact on glucose homeostasis is poorly explored. Male C57BL/6N mice were fed for 8 weeks a corn oil-based high-fat diet (cHF) alone or cHF-based diets containing eicosapentaenoic acid and docosahexaenoic acid (~3%; wt/wt), admixed either as a concentrate of re-esterified triacylglycerols (ω3TG) or Krill oil containing mainly phospholipids (ω3PL). Lean controls were fed a low-fat diet. Insulin sensitivity (hyperinsulinemic-euglycemic clamps), parameters of glucose homeostasis, adipose tissue function, and plasma levels of N-acylethanolamines, monoacylglycerols and fatty acids were determined. Feeding cHF induced obesity and worsened (~4.3-fold) insulin sensitivity as determined by clamp. Insulin sensitivity was almost preserved in ω3PL but not ω3TG mice. Compared with cHF mice, endogenous glucose production was reduced to 47%, whereas whole-body and muscle glycogen synthesis increased ~3-fold in ω3PL mice that showed improved adipose tissue function and elevated plasma adiponectin levels. Besides eicosapentaenoic and docosapentaenoic acids, principal component analysis of plasma fatty acids identified palmitoleic acid (C16:1n-7) as the most discriminating analyte whose levels were increased in ω3PL mice and correlated negatively with the degree of cHF-induced glucose intolerance. While palmitoleic acid from Krill oil may help improve glucose homeostasis, our findings provide a general rationale for using omega-3 PUFA-containing phospholipids as nutritional supplements with potent insulin-sensitizing effects.

The Changes of Serum Metabolites in Diabetic GK Rats after Ileal Transposition Surgery

BACKGROUND

Ileal transposition (IT) surgery could improve metabolism. Metabolomics has been applied comprehensively in analyzing the global dynamic alterations of metabolites. In the present study, we aimed to investigate serum metabolite alterations in diabetic Goto-Kakizaki (GK) rats after IT surgery.

METHODS

Male GK rats were subjected to IT and Sham-IT surgery. Six weeks later, body weight, food intake, fat mass, and serum biochemical parameters were measured. The serum metabolomic fingerprint was analyzed using ultra-performance liquid chromatography-mass spectrometry (LC-MS)-based, non-targeted metabolomic approach. The differential metabolites were identified using principal component analysis and orthogonal partial least squares discriminant analysis. Metabolic pathway analysis was performed using HMDB and KEGG databases.

RESULTS

The body weight, food intake, fat mass, serum levels of glucose and insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) of IT rats were significantly decreased when compared with Sham-IT rats (all P < 0.05). In the metabolomics analysis, ten serum differential metabolites were identified. Compared with Sham-IT rats, serum LysoPC(O-18:0) and PG(20:4/20:0) of IT rats were decreased, while genistein 4'-O-glucuronide, 5,6:8,9-Diepoxyergost-22-ene-3,7beta-diol, PI(16:0/18:2(9Z,12Z)), docosapentaenoic acid, 3-Oxo-4,6-choladienoic acid, 3-Oxocholic acid, and TG were increased. Pathway analysis highlighted the following pathways: ether lipid metabolism, alpha linolenic acid and linolenic acid metabolism, incretin synthesis and secretion, free fatty acid receptors, and biosynthesis of unsaturated fatty acids.

CONCLUSIONS

IT surgery could significantly decrease body weight and fat mass and improve glucose metabolism in diabetic GK rats. These beneficial effects might be related to the changes of serum metabolites which involved in lipid metabolism, bile acids, and incretin.

The effect of omega-3 and vitamin D co-supplementation on glycemic control and lipid profiles in reproductive-aged women with pre-diabetes and hypovitaminosis D: a randomized controlled trial

BACKGROUND

Prediabetes can predispose the individual to type 2 diabetes in the long-term. The present study was conducted to determine the effectiveness of vitamin D and omega-3 co-supplementation on glycemic control and serum lipid profiles in women of reproductive age with prediabetes and hypovitaminosis D.

METHODS

The present factorial, triple-blind, clinical trial was conducted on 168 women of reproductive age with prediabetes and hypovitaminosis D. The participants were assigned to four groups based on block randomization method: the placebo group received omega-3 and vitamin D placebos; the omega-3 group took omega-3 supplements and vitamin D placebos; the vitamin D group received omega-3 placebos and vitamin D supplements and the co-supplementation group. The groups received every 2 weeks 50,000 IU pearls of vitamin D and twice-daily doses of 1000-mg omega-3 tablets or placebos for 8 weeks. Dietary intake, physical activity, anthropometric indices and blood biochemical tests were measured at the beginning and end of the study. Analysis was performed using two-way mixed ANOVA.

RESULTS

A significant reduction was observed in fasting glucose, insulin, homeostasis model assessment-beta cell function, weight and waist circumference in the co-supplementation group compared to the other three groups (P < 0.05). Moreover, high-density lipoprotein-cholesterol levels increased significantly in the co-supplementation group compared to the other three groups (P < 0.05). Despite the fact that homeostasis model assessment-insulin resistance, total cholesterol, triglyceride and low-density lipoprotein-cholesterol levels decreased after intervention in the co-supplementation group, there was no significant difference between the groups in these outcomes.

CONCLUSION

Vitamin D and omega-3 co-supplementation improved fasting serum glucose, insulin, high-density lipoprotein-cholesterol level, homeostasis model assessment-beta cell function, weight and waist circumference in women of reproductive age with prediabetes and hypovitaminosis D. This co-supplementation can therefore be recommended for glycemic control in these women.Trial registration Iranian Registry of Clinical Trials Code: IRCT20100130003226N17. Registered on 9 Feb. 2019.

The effect of co supplementation of omega-3 and vitamin D on cardio metabolic risk factors and psychological distress in reproductive-aged women with prediabetes and hypovitaminosis D: a study protocol for a randomized controlled trial

BACKGROUND

A prediabetic state is a risk factor for type 2 diabetes. There are no approved drugs to manage prediabetes. Among the supplements routinely used by individuals, vitamin D and omega-3 have been studied to reduce fasting blood sugar. However, their co-supplementation has not been studied in individuals with prediabetes. This randomized controlled trial is designed to determine the effects of these two supplements on fasting blood sugar, other cardio metabolic risk factors, and psychological distress in reproductive-aged women with prediabetes and hypovitaminosis D.

METHODS/DESIGN

This 2 × 2 factorial, triple-blind, randomized, placebo-controlled, clinical trial will be done on 168 women of reproductive age diagnosed with prediabetes and hypovitaminosis D. Participants will be randomly assigned equally to four groups: (1) 1000 mg omega-3 fatty acid twice a day + vitamin D placebo every two weeks; (2) omega-3 fatty acid placebo twice a day + 50,000 IU vitamin D every two weeks; (3) 1000 mg omega-3 fatty acid twice a day + 50,000 IU vitamin D every two weeks; (4) omega-3 fatty acid placebo twice a day + vitamin D placebo every two weeks for eight weeks. At the beginning, participants will provide a self-reported questionnaire on the sociodemographic characteristics. At baseline and post-intervention visits, physical activity, Depression Anxiety Stress Scale 21 and Pittsburgh Sleep Quality Index, and a three-day food record will be collected for each individual. Blood pressure, weight, height, and waist circumference will also be measured. At the beginning and at the end, a blood sample will be used for estimating serum glucose indices (fasting blood sugar and insulin, homeostasis model assessment-insulin resistance, homeostasis model assessment-beta cell function), lipids (triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol), and vitamin D status. Data analysis using Kolmogorov-Smirnov test, paired t-test, one-way analysis of variance, and repeated measures analysis of variance will be conducted through SPSS-24 software.

DISCUSSION

The primary aim of the present trial is to determine the effect of vitamin D and/or omega-3 on glycemic indices, lipid profiles, psychological distress, blood pressure, and anthropometric indices in prediabetic women with hypovitaminosis D. The results from this trial will provide evidence on the efficacy of these two supplements for preventing or delaying the onset of type 2 diabetes in high-risk individuals.

TRIAL REGISTRATION

Iran Clinical Trials Registry, IRCT20100130003226N17. Registered on 9 February 2019.

Blood biomarkers of various dietary patterns correlated with metabolic indicators in Taiwanese type 2 diabetes

Background

Metabolic alterations correlate with adverse outcomes in type 2 diabetes. Dietary modification serves as an integral part in its treatment.

Objective

We examined the relationships among dietary patterns, dietary biomarkers, and metabolic indicators in type 2 diabetes (n = 871).

Design

Diabetic patients (n = 871) who provided complete clinical and dietary data in both 2008 and 2009 were selected from a cohort participating in a diabetic control study in Taiwan. Dietary data were obtained using a short, semiquantitative food frequency questionnaires, and dietary pattern identified by factor analysis. Multiple linear regressions were used to analyze the association between dietary biomarkers (ferritin, folate, and erythrocyte n-3 polyunsaturated fatty acids [n-3 PUFAs]) and metabolic control upon adjusting for confounders.

Results

Three dietary patterns (high-fat meat, traditional Chinese food–snack, and fish–vegetable) were identified. Ferritin correlated positively with high-fat meat factor scores (P for trend <0.001). Erythrocyte n-3 PUFAs (eicosapentaenoic acid [EPA] + docosahexaenoic acid [DHA], n-3/n-6 PUFA ratio) correlated positively with fish–vegetable factor scores (all P for trends <0.001). Multiple linear regressions revealed a positive relationship between ferritin concentrations and fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), and triglycerides, but a negative relationship with high-density lipoprotein cholesterol (HDL-C). Erythrocyte n-3 PUFA, EPA+DHA, and n-3/n-6 PUFA ratio were negatively linked to FPG, HbA1c, and triglycerides (all P < 0.05) and positively with HDL-C (though n-3/n-6 ratio marginally correlated).

Conclusions

Ferritin and n-3 PUFA can serve as valid biomarkers for high-fat meat and fish–vegetable dietary patterns. Unlike ferritin, erythrocyte n-3 PUFA status was related to better glycemic and blood lipid profiles. Our results suggest that habitual consumption of diet pattern rich in fish and vegetables may contribute in part to a healthier metabolic profile in type 2 diabetes.

Natural CLA-Enriched Lamb Meat Fat Modifies Tissue Fatty Acid Profile and Increases n-3 HUFA Score in Obese Zucker Rats

Ruminant fats are characterized by different levels of conjugated linoleic acid (CLA) and α-linolenic acid (18:3n-3, ALA), according to animal diet. Tissue fatty acids and their N-acylethanolamides were analyzed in male obese Zucker rats fed diets containing lamb meat fat with different fatty acid profiles: (A) enriched in CLA; (B) enriched in ALA and low in CLA; (C) low in ALA and CLA; and one containing a mixture of olive and corn oils: (D) high in linoleic acid (18:2n-6, LA) and ALA, in order to evaluate early lipid metabolism markers. No changes in body and liver weights were observed. CLA and ALA were incorporated into most tissues, mirroring the dietary content; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased according to dietary ALA, which was strongly influenced by CLA. The n-3 highly-unsaturated fatty acid (HUFA) score, biomarker of the n-3/n-6 fatty acid ratio, was increased in tissues of rats fed animal fats high in CLA and/or ALA compared to those fed vegetable fat. DHA and CLA were associated with a significant increase in oleoylethanolamide and decrease in anandamide in subcutaneous fat. The results showed that meat fat nutritional values are strongly influenced by their CLA and ALA contents, modulating the tissue n-3 HUFA score.

Changes in Plasma Free Fatty Acids Associated with Type-2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with increased total plasma free fatty acid (FFA) concentrations and an elevated risk of cardiovascular disease. The exact mechanisms by which the plasma FFA profile of subjects with T2DM changes is unclear, but it is thought that dietary fats and changes to lipid metabolism are likely to contribute. Therefore, establishing the changes in concentrations of specific FFAs in an individual’s plasma is important. Each type of FFA has different effects on physiological processes, including the regulation of lipolysis and lipogenesis in adipose tissue, inflammation, endocrine signalling and the composition and properties of cellular membranes. Alterations in such processes due to altered plasma FFA concentrations/profiles can potentially result in the development of insulin resistance and coagulatory defects. Finally, fibrates and statins, lipid-regulating drugs prescribed to subjects with T2DM, are also thought to exert part of their beneficial effects by impacting on plasma FFA concentrations. Thus, it is also interesting to consider their effects on the concentration of FFAs in plasma. Collectively, we review how FFAs are altered in T2DM and explore the likely downstream physiological and pathological implications of such changes.

Synergistic Effects of DHA and Sucrose on Body Weight Gain in PUFA-Deficient Elovl2 -/- Mice

The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is implicated in the regulation of both lipid and carbohydrate metabolism. Thus, we questioned whether dietary DHA and low or high content of sucrose impact on metabolism in mice deficient for elongation of very long-chain fatty acids 2 (ELOVL2), an enzyme involved in the endogenous DHA synthesis. We found that Elovl2 -/- mice fed a high-sucrose DHA-enriched diet followed by the high sucrose, high fat challenge significantly increased body weight. This diet affected the triglyceride rich lipoprotein fraction of plasma lipoproteins and changed the expression of several genes involved in lipid metabolism in a white adipose tissue. Our findings suggest that lipogenesis in mammals is synergistically influenced by DHA dietary and sucrose content.

A Lipophilic Fucoxanthin-Rich Phaeodactylum tricornutum Extract Ameliorates Effects of Diet-Induced Obesity in C57BL/6J Mice

Phaeodactylum tricornutum (P. tricornutum) comprise several lipophilic constituents with proposed anti-obesity and anti-diabetic properties. We investigated the effect of an ethanolic P. tricornutum extract (PTE) on energy metabolism in obesity-prone mice fed a high fat diet (HFD). Six- to eight-week-old male C57BL/6J mice were switched to HFD and, at the same time, received orally placebo or PTE (100 mg or 300 mg/kg body weight/day). Body weight, body composition, and food intake were monitored. After 26 days, blood and tissue samples were collected for biochemical, morphological, and gene expression analyses. PTE-supplemented mice accumulated fucoxanthin metabolites in adipose tissues and attained lower body weight gain, body fat content, weight of white adipose tissue (WAT) depots, and inguinal WAT adipocyte size than controls, independent of decreased food intake. PTE supplementation was associated with lower expression of Mest (a marker of fat tissue expandability) in WAT depots, lower gene expression related to lipid uptake and turnover in visceral WAT, increased expression of genes key to fatty acid oxidation and thermogenesis (Cpt1, Ucp1) in subcutaneous WAT, and signs of thermogenic activation including enhanced UCP1 protein in interscapular brown adipose tissue. In conclusion, these data show the potential of PTE to ameliorate HFD-induced obesity in vivo.

Fatty acids: a role for Africa?

Health effects of fatty acids have been very controversial. Total mortality is inversely associated with the amount of total fat consumed. In contrast,transfatty acids or SFA intake is positively related to mortality while the inverse is observed with consumption of MUFA or PUFA. Among PUFA, long-chain (LC)n-3 PUFA have many beneficial effects. Dietary intake of some types of fatty acids is specific to Africa. Energy from saturated fat does not exceed 14% and energy fromn-6 PUFA does not exceed 8% of total energy intake. Dietary intake of LCn-3 PUFA is less than 100 mg/d whereas international recommendations promote 250–500 mg/d. Consumption of plantn-3 PUFA mainly α-linolenic acid (ALA) is highly variable depending on the country. Both fish and ALA availability are low in several African countries. The prevalence of diabetes and cardiovascular events remain very low in Africa, partly explained by the fact that the whole dietary pattern is globally the best of all continents. One objective of ‘fat for Africa’ could be to increase, as much as possible, the dietary intake of LCn-3 PUFA by promoting sustainable aquaculture and to maintain as much as possible traditional dietary pattern by preventing a tendency to westernisation, provided that the amount of energy and protein is sufficient to fight against wasting and stunting where it still exists.

Future perspectives of the pharmacological management of diabetic dyslipidemia

INTRODUCTION

Diabetic dyslipidemia is frequent among patients with type 2 diabetes mellitus (T2DM) and is characterized by an increase in triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), and small-dense (atherogenic) particles, and by a decrease in low high-density lipoprotein cholesterol (HDL-C) and apolipoprotein (Apo) A1 that are strongly related to insulin resistance. The increased flux of free fatty acids from adipose tissue to the liver aggravates hepatic insulin resistance and promotes all of aspects of the dyslipidemic state. Areas covered: Statins are the first-line agents for treatment while other lipid-lowering drugs (ezetimibe, fibrate and proprotein convertase subtilisin/kexin type 9) or novel anti-diabetic agents (dipeptidyl peptidase-4 inhibitors (DPP-4is), glucagon like peptide-1 receptor agonist (GLP-1RA), sodium/glucose cotransporter 2 inhibitors (SGLT2is)) or nutraceuticals (berberine, omega 3 fatty acid, red yeast rice) can be used alone or in combination. Expert commentary: In patients with T2DM, lipid abnormalities should be identified and treated as part of the overall diabetic treatment, in order to prevent cardiovascular disease. The choice of drugs to be used is mainly based on the lipid profile and on the characteristic lipoprotein abnormalities; the use of new drugs for the treatment of hyperglycemia and lipids alteration in these patients can improve diabetic dyslipidemia.

Cod-Liver Oil Improves Metabolic Indices and hs-CRP Levels in Gestational Diabetes Mellitus Patients: A Double-Blind Randomized Controlled Trial

OBJECTIVE

To investigate the effects of cod-liver oil on metabolic status and high-sensitivity C-reactive protein (hs-CRP) in patients with gestational diabetes mellitus (GDM).

METHODS

This study was a randomized, double-blinded, placebo-controlled trial with the allocation ratio of 1 : 1. The contents of EPA and DHA in cod-liver oil were measured using a gas chromatograph. A total of 550 GDM patients were randomly divided into the intervention group (cod-liver oil) and the control group (placebo, mineral oil), and both groups were given regular dietary care. Glycosylated hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG), lipid profiles, homeostatic model assessment insulin resistance (HOMA-IR), and hs-CRP were measured. Primary outcomes were different in HbA1c, FPG, 2hPG, and HOMA-IR between the two groups after 4-week randomization. Secondary outcomes were the blood glucose levels and perinatal complications (pregnancy-induced hypertension, polyhydramnios, premature delivery, postpartum hemorrhage, postpartum infection, premature rupture of membranes, and cesarean section) between the two groups before and after 12-16 weeks of cod-liver oil intervention from middle pregnancy to late pregnancy.

RESULTS

EPA and DHA were the main components of cod-liver oil with 76 mg/mL and 150 mg/mL, respectively. There was no significant difference for primary outcomes in the levels of HbA1c, FPG, 2hPG, HOMA-IR, and lipid profiles between the two groups (P > 0.05). For the secondary outcomes, the levels of HbA1c, FPG, 2hPG, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol ratio (LDL-C), HOMA-IR, and hs-CRP in the intervention group were significantly lower than those in the control group (P < 0.05). The incidence of perinatal complications in the intervention group was lower than that in the control group too (P < 0.05).

CONCLUSIONS

Cod-liver oil consumption effectively reduced the levels of blood glucose, lipid levels, hs-CRP, and HOMA-IR and the incidence of perinatal complications.

Effect of combined use of a low-carbohydrate, high-protein diet with omega-3 polyunsaturated fatty acid supplementation on glycemic control in newly diagnosed type 2 diabetes: a randomized, double-blind, parallel-controlled trial

Background

The combined effect of a low-carbohydrate, high-protein (LCHP) diet and omega-3 (n-3) polyunsaturated fatty acid (PUFA) supplementation on patients with type 2 diabetes (T2D) is not known.

Objective

The aim of this study was to evaluate the effect of an LCHP diet combined with ω-3 (LCHP+ω-3) on glycemic control in patients with T2D.

Design

In this randomized, double-blind, parallel-controlled trial, 122 newly diagnosed participants with T2D were randomly assigned to receive a high-carbohydrate, low-protein diet with low ω-3 PUFAs [control (CON)], an LCHP, ω-3, or LCHP+ω-3 diet for 12 wk. The ratio of carbohydrate to protein was 42:28 in the LCHP and LCHP+ω-3 diet and 54:17 in the CON and ω-3 diet. The participants were given 6 g fish oil/d (containing 3.65 g docosahexaenoic acid, eicosapentaenoic acid, and docosapentaenoic acid/d) in the ω-3 and LCHP+ω-3 diet groups or 6 g corn oil/d (placebo) in the CON and LCHP diet groups.

Results

Compared with the CON diet group, greater decreases in glycated hemoglobin (HbA1c) and fasting glucose were observed in all of the other 3 diet groups at 12 wk. Of note, HbA1c reduction in the LCHP+ω-3 diet group (-0.51%; 95% CI: -0.64%, -0.37%) was greater than that in the LCHP (P = 0.03) and ω-3 (P = 0.01) diet groups at 12 wk. In terms of fasting glucose, only the LCHP+ω-3 diet group showed a significant decrease at 4 wk (P = 0.03 compared with CON). Moreover, the reduction in fasting glucose in the LCHP+ω-3 diet group (-1.32 mmol/L; 95% CI: -1.72, -0.93 mmol/L) was greater than that in the LCHP (P = 0.04) and ω-3 (P = 0.03) diet groups at 12 wk.

Conclusions

The LCHP+ω-3 diet provided greater effects on HbA1c and fasting glucose and faster effects on fasting glucose than both the LCHP and ω-3 diets, indicating the potential necessity of combining an LCHP diet with ω-3 PUFAs in T2D control. This trial was registered at chictr.org.cn/ as ChiCTR-TRC-14004704.

Fish oil and wheat-germ oil supplementation restores ovarian function in streptozotocin-diabetic rats

Diabetes is a chronic metabolic disorder and has a profound impact on women's reproductive health. This study aimed to investigate the protective effect of a mixture of fish oil (FO) and wheat-germ oil (WGO) on ovarian dysfunction in diabetic rats. Female Albino rats were divided into control, diabetic and FO-WGO-diabetic groups. Diabetes was induced by intraperitoneal injection of 65mgkg^-1 streptozotocin (STZ). Three weeks later, rats were given oral supplement of 0.4gkg^-1 oil mix (1000mg FO+100mg WGO) daily for 3 weeks. Antioxidant activity was assessed by measuring malondialdehyde (MDA) and reduced glutathione (GSH) levels, the GSH:oxidised glutathione (GSSG) ratio and superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities. Ovary function was indicated by serum concentrations of FSH, oestradiol (E₂), LH, anti-Müllerian hormone (AMH), ovary histopathology and follicle counts. Anti-inflammatory properties were detected by measuring nuclear factor (NF)-κB in follicular cells by immunohistochemistry. FO-WGO supplementation enhanced CAT, SOD and GPx activities and raised GSH levels and the GSH:GSSG ratio. Supplementation also increased FSH, E₂, LH and AMH levels and follicle counts. Moreover, NF-kB expression and MDA were reduced. These findings indicate that FO-WGO supplementation preserved ovarian function in STZ-induced diabetic rats.

Functionality of cow milk naturally enriched with polyunsaturated fatty acids and polyphenols in diets for diabetic rats

The increasing incidence of diabetes mellitus is becoming a serious threat to human health in various parts of the world. Studies with dairy products have shown a potential beneficial effect against diabetes. This experiment evaluated the supplementation of milk naturally enriched with polyunsaturated fatty acids (PUFA) and polyphenols in rats with streptozotocin-induced diabetes. Forty male 28-day-old Wistar rats were distributed in four experimental treatments of diabetic animals (streptozotocin induction) and a normal group (non-induced). Experimental treatments were: control (water), whole common milk (COM-M), milk enriched with PUFA (PUFA-M), milk enriched with PUFA and polyphenols (PUFA/P-M) through a special diet offered to dairy cows. Milk supplementation at a dose 5 mL/kg body weight was performed for 77 days, 42 days before and 35 days after diabetes induction. The COM-M supplementation increased brown fat deposits, reduced post-induction glucose levels, reduced blood fructosamine levels, and improved glucose tolerance. Milk enriched with PUFA reduced final fasting glucose, LDL levels, and improved blood antioxidant capacity. Milk enriched with PUFA and polyphenols promoted an increase in gastrocnemius muscle mass, and a reduction in mesenteric fat and LDL levels. Milk intake, with an emphasis on milk enriched with PUFA and polyphenols, attenuated the metabolic disorders of streptozotocin-induced diabetes in rats.

Omega-3 Fatty Acids and Fatty Liver Disease in Children

Nonalcoholic fatty liver disease (NAFLD) represents the most common cause of chronic liver disease in Industrialized Countries in adults and children. It is estimated that NAFLD will become the main indication for liver transplantation in the next decade. NAFLD is also considered the hepatic feature of metabolic syndrome and therefore it is generally associated to the risk of developing some metabolic complications, with negative impact on patient's survival. Today, no pharmacological treatment has been identified for NAFLD, and behavioral approach, based on diet and regular physical exercise, represent the current recommended treatment, even if with disappointing results. For these reasons, several pharmacological trials have been conducted, in order to identify possible alternative therapy direct against pathogenetic targets of NAFLD. Several data have suggested the potential beneficial role of omega-3 fatty acids in NAFLD and its related metabolic disarray. In this chapter, we try to elucidate the molecular and clinical available evidence for the omega-3 supplementation in pediatric NAFLD patients.

Differential modulation of white adipose tissue endocannabinoid levels by n-3 fatty acids in obese mice and type 2 diabetic patients

n-3 polyunsaturated fatty acids (n-3 PUFA) might regulate metabolism by lowering endocannabinoid levels. We examined time-dependent changes in adipose tissue levels of endocannabinoids as well as in parameters of glucose homeostasis induced by n-3 PUFA in dietary-obese mice, and compared these results with the effect of n-3 PUFA intervention in type 2 diabetic (T2DM) subjects. Male C57BL/6J mice were fed for 8, 16 or 24 weeks a high-fat diet alone (cHF) or supplemented with n-3 PUFA (cHF + F). Overweight/obese, T2DM patients on metformin therapy were given for 24 weeks corn oil (Placebo; 5 g/day) or n-3 PUFA concentrate as above (Omega-3; 5 g/day). Endocannabinoids were measured by liquid chromatography-tandem mass-spectrometry. Compared to cHF-fed controls, the cHF + F mice consistently reduced 2-arachidonoylglycerol (up to ~2-fold at week 24) and anandamide (~2-fold) in adipose tissue, while the levels of endocannabinoid-related anti-inflammatory molecules N-eicosapentaenoyl ethanolamine (EPEA) and N-docosahexaenoyl ethanolamine (DHEA) increased more than ~10-fold and ~8-fold, respectively. At week 24, the cHF + F mice improved glucose tolerance and fasting blood glucose, the latter being positively correlated with adipose 2-arachidonoylglycerol levels only in obese cHF-fed controls, like fasting insulin and HOMA-IR. In the patients, n-3 PUFA failed to reduce 2-arachidonoylglycerol and anandamide levels in adipose tissue and serum, but they increased both adipose tissue and serum levels of EPEA and DHEA. In conclusion, the inability of n-3 PUFA to reduce adipose tissue and serum levels of classical endocannabinoids might contribute to a lack of beneficial effects of these lipids on glucose homeostasis in T2DM patients.

Diabetes and lipid metabolism

The authors review the association between diabetes mellitus (DM) and aberrations of lipid metabolism related to DM, diabetic dyslipidemia (DD). DM is considered as a major health burden worldwide and one of the most important modifiable cardiovascular disease (CVD) risk factors. This applies to both the developed and the developing countries, especially the latter. While patients with type 1 DM, 10% of all DM cases, usually do not have dyslipidemia, DD is frequent among patients with type 2 DM (T2DM) (prevalence > 75%) and is mainly a mixed dyslipidemia [increase in triglycerides (TGs), low high-density lipoprotein cholesterol (HDL-C), and small-dense (atherogenic), low-density lipoprotein cholesterol (LDL-C) particles]. The components of DD, which is characterized by quantitative (mentioned above), qualitative, and kinetic abnormalities all contributing to CVD risk, are mostly related to insulin resistance. Statins, ezetimibe, and PCSK9 inhibitors can be used in monotherapy or consecutively in combinations if needed. Statins compose the main drug. For the residual CVD risk after statin treatment, the use of statin-fibrate combinations is indicated only in patients with mixed dyslipidemia. In conclusion, DD is a major health problem worldwide. It is a significant CVD risk factor and should be treated according to current guidelines. The means today exist to normalize all quantitative, qualitative, and kinetic aberrations of DD, thereby reducing CVD risk.