Omega-3 polyunsaturated fatty acid and insulin sensitivity: a meta-analysis of randomized controlled trials

Type 2 Diabetes Mellitus and Sarcopenia as Comorbid Chronic Diseases in Older Adults: Established and Emerging Treatments and Therapies

Type 2 diabetes mellitus (T2DM) and sarcopenia (low skeletal muscle mass and function) share a bidirectional relationship. The prevalence of these diseases increases with age and they share common risk factors. Skeletal muscle fat infiltration, commonly referred to as myosteatosis, may be a major contributor to both T2DM and sarcopenia in older adults via independent effects on insulin resistance and muscle health. Many strategies to manage T2DM result in energy restriction and subsequent weight loss, and this can lead to significant declines in muscle mass in the absence of resistance exercise, which is also a first-line treatment for sarcopenia. In this review, we highlight recent evidence on established treatments and emerging therapies targeting weight loss and muscle mass and function improvements in older adults with, or at risk of, T2DM and/or sarcopenia. This includes dietary, physical activity and exercise interventions, new generation incretin-based agonists and myostatin-based antagonists, and endoscopic bariatric therapies. We also highlight how digital health technologies and health literacy interventions can increase uptake of, and adherence to, established and emerging treatments and therapies in older adults with T2DM and/or sarcopenia.

Impact of saturated compared with unsaturated dietary fat on insulin sensitivity, pancreatic β-cell function and glucose tolerance: a systematic review and meta-analysis of randomized, controlled trials

BACKGROUND

The impact of the dietary fat type on type 2 diabetes (T2D) remains unclear.

OBJECTIVES

We aimed to evaluate the effects of replacing dietary saturated fatty acids (SFA) with mono- or poly-unsaturated fatty acids (MUFA and PUFA, respectively) on insulin sensitivity, pancreatic β-cell function, and glucose tolerance, as surrogate endpoints for T2D.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials that replaced ≥5% of total energy intake provided by SFA with MUFA or PUFA and reported indexes of insulin sensitivity, β-cell function, and/or glucose tolerance. We searched MEDLINE, Scopus, and the Cochrane Library (CENTRAL) up to 9 January, 2023. Eligible interventions had to be isocaloric, with no significant difference in other macronutrients. Data were synthesized using random-effects model meta-analysis.

RESULTS

Of 6355 records identified, 10 parallel and 20 crossover trials with 1586 participants were included. The mean age of the participants was 42 years, 47% were male, mean body mass index (BMI; in kg/m2) was 26.8, median baseline fasting glucose was 5.13 mmol/L, and the median duration of interventions was 5 weeks. Replacing SFA with MUFA or PUFA had no significant effects on insulin sensitivity [standardized mean difference (SMD) SFA compared with MUFA: 0.01, 95% confidence interval (CI): -0.06 to 0.09, I2 = 0% and SMD SFA compared with PUFA: 0, 95% CI: -0.15 to 0.14, I2 = 0%]. Replacing SFA with MUFA did not significantly impact the β-cell function, evaluated by the disposition index (mean difference: -12, 95% CI: -158 to 133, I2=0%). Evidence on glucose tolerance (SFA compared with MUFA or PUFA) and on β-cell function when SFA were replaced with PUFA was scant.

CONCLUSIONS

Short-term substitution of saturated with unsaturated fat does not significantly affect insulin sensitivity nor β-cell function (the latter in the SFA compared with MUFA comparison). Future studies are needed to elucidate longer term effects of dietary fat saturation on glucose homeostasis. This trial was registered at PROSPERO as CRD42020178382.

Changes in serum brain-derived neurotrophic factor following supplementation of omega 3 fatty acids: A systematic review and Meta-Regression analysis

BACKGROUND & AIMS

This study aimed to comprehensively investigate the effects of omega 3 supplementation on BDNF.

METHODS

Original databases were searched using standard keywords to identify all controlled trials that investigating the BDNF effects of omega 3 supplementation. Pooled weighted mean difference and 95% confidence intervals were achieved by random-effects model analysis for the best estimation of outcomes.

RESULTS

According to the results of a random-effects meta-analysis, omega 3 supplementation significantly raised BDNF levels compared to the control group (pooled WMD of 1.01 μmol/L; 95% confidence interval [CI] 0.35 to 1.67; P = 0.003) and this increase was even more pronounced for interventions >10 weeks and doses ≤1500 mg/day. Additionally, in individuals under 50 years of age, a greater increase in the effects of omega-3 supplements on this brain factor was observed.

CONCLUSIONS

The present comprehensive review and meta-regression analysis generally showed that omega-3 supplementation can statistically significantly increase BDNF levels.

Omega-3 polyunsaturated fatty acids in the treatment of non-alcoholic fatty liver disease: An umbrella systematic review and meta-analysis

There has been conflicting evidence from meta-analyses on the effect of polyunsaturated fatty acids (PUFA) on non-alcoholic fatty liver disease (NAFLD). Therefore, in this umbrella meta-analysis, we are evaluating whether omega-3 PUFA supplementation has any benefit in treating NAFLD. Electronic databases such as PubMed, Web of Science, Scopus, Embase and Google Scholar were assessed to October 2022. This meta-analysis included all meta-analyses that examined the effect of PUFAs on liver fat and liver function tests [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT)]. Meta-analysis was conducted using a random effects model. Subgroup analyses and sensitivity analyses were also performed. In total, eight articles involving 6,561 participants met the eligibility criteria. Advantageous impacts PUFA supplementation were observed on ALT (ES_WMD  = -6.72 IU/L; 95% CI: -8.61, -4.84; p < 0.001, and ES_SMD  = -0.52 IU/L; 95% CI: -0.84, -0.20, p < 0.001), AST (ES_WMD  = -3.73 IU/L, 95% CI: -5.93, -1.53, p < 0.001, and ES_SMD  = -0.65 IU/L; 95% CI: -1.08, -0.22, p = 0.003), GGT levels (ES_WMD  = -4.20 IU/L, 95% CI: -6.85, -1.55, p = 0.002), and liver fat (ES_WMD  = -5.16; 95% CI: -8.49, -1.82, p < 0.001). Intervention with omega-3 PUFAs improves ALT, AST, GGT, and liver fat in patients with NAFLD. Thus, omega-3 PUFAs could be considered as a therapeutic option in the treatment of NAFLD.

The effects of camelina sativa oil and high-intensity interval training on liver function and metabolic outcomes in male type 2 diabetic rats

Objectives

The purpose of this study was to evaluate the independent and combined effects of camelina sativa oil and high-intensity interval training (HIIT) on liver function, and metabolic outcomes in streptozotocin-induced diabetic rats.

Methods

Forty male Wistar rats were randomly assigned to five equal groups (8 per group): Normal control (NC), diabetic control (DC), diabetic + camelina sativa oil (300 mg/kg by oral gavage per day; D + CSO), diabetic + HIIT (running on a treadmill 5 days/week for 8 weeks; D + HIIT), diabetic + camelina sativa oil + HIIT (D + CSO +  HIIT).

Results

In all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) compared to the DC, hepatic TNF-α, MDA, and histopathology markers, decreased and hepatic PGC-1α, and PPAR-γ increased (p < 0.05). However, the effect of D + CSO was greater than D + HIIT alone. Hepatic TG decreased significantly in D + HIIT and D + CSO + HIIT compared to other groups (p < 0.001). Fasting plasma glucose in all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) and HOMA-IR in D + CSO and D + CSO + HIIT were decreased compared to DC (p < 0.001). Only hepatic TAC and fasting plasma insulin remained unaffected in the three diabetic groups (p < 0.001). Overall, D + CSO + HIIT had the largest effect on all outcomes.

Conclusions

At the doses and treatment duration used in the current study, combination of CSO and HIIT was beneficial for reducing liver function and metabolic outcomes other than CSO and HIIT alone.

Dietary Patterns Derived from Reduced Rank Regression Are Associated with the 5-Year Occurrence of Metabolic Syndrome: Aichi Workers' Cohort Study

The aim of the present study was to derive dietary patterns to explain variation in a set of nutrient intakes or in the measurements of waist circumference (WC) and fasting blood glucose (FBG) using reduced rank regression (RRR) and to prospectively investigate these patterns in relation to the risk of developing metabolic syndrome (MetS) and its components during the follow-up. The study participants were comprised of 2944 government employees aged 30−59 years without MetS. RRR was applied with 38 food groups as predictors and with two sets of response variables. The first set included intake of putatively beneficial nutrients, and the first factor retained was named the Healthy Dietary Pattern (HDP). The second one included baseline WC and FBG, and the first factor was named the Unhealthy Dietary Pattern (UHDP). Multivariable Cox proportional hazard model was used to estimate hazard ratio and 95% confidence intervals with adjustments for age, sex, total energy consumption and other potential confounders. During the 5-year median follow-up, we ascertained 374 cases of MetS. The HDP score was inversely associated with the incidence of MetS (p-trend = 0.009) and hypertension (p-trend = 0.002) and marginally significantly associated with elevated triglyceride and decreased high-density lipoprotein cholesterol (p-trend = 0.08). The UHDP score was linearly positively associated with the incidence of MetS and all its components (all p-trend < 0.05). Both the HDP and UHDP predicted the development of MetS and its components.

Habitual Intake of Marine-Derived n-3 PUFAs is Inversely Associated with a Cardiometabolic Inflammatory Profile in Yup'ik Alaska Native People

BACKGROUND

The relationship between dietary n-3 PUFAs and the prevention of cardiometabolic diseases, including type 2 diabetes, is unresolved. Examination of the association between n-3 PUFAs and chronic low-grade inflammation in a population where many individuals have had an extremely high intake of marine mammals and fish throughout their lifespan may provide important clues regarding the impact of n-3 PUFAs on health.

OBJECTIVES

The aim of this study was to explore associations between concentrations of n-3 PUFAs resulting from habitual intake of natural food sources high in fish and marine mammals with immune biomarkers of metabolic inflammation and parameters of glucose regulation.

METHODS

A total of 569 Yup'ik Alaska Native adults (18-87 years old) were enrolled in this cross-sectional study between December 2016 and November 2019. The RBC nitrogen isotope ratio (NIR; 15N/14N) was used as a validated measure of n-3 PUFA intake to select 165 participant samples from the first and fourth quartiles of n-3 PUFA intakes. Outcomes included 38 pro- and anti-inflammatory cytokines and 8 measures of glucose homeostasis associated with type 2 diabetes risks. These outcomes were evaluated for their associations with direct measurements of EPA, DHA, and arachidonic acid in RBCs.

ANALYSIS

Linear regression was used to detect significant relationships with cytokines and n-3 PUFAs, adiposity, and glucose-related variables.

RESULTS

The DHA concentration in RBC membranes was inversely associated with IL-6 (β = -0.0066; P < 0.001); EPA was inversely associated with TNFα (β = -0.4925; P < 0.001); and the NIR was inversely associated with Monocyte chemoattractant protein-1 (MCP-1) (β = -0.8345; P < 0.001) and IL-10 (β = -1.2868; P < 0.001).

CONCLUSIONS

Habitual intake of marine mammals and fish rich in n-3 PUFAs in this study population of Yup'ik Alaska Native adults is associated with reduced systemic inflammation, which may contribute to the low prevalence of diseases in which inflammation plays an important role.

A plasma fatty acid profile associated to type 2 diabetes development: from the CORDIOPREV study

PURPOSE

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. For this reason, it is essential to identify biomarkers for the early detection of T2DM risk and/or for a better prognosis of T2DM. We aimed to identify a plasma fatty acid (FA) profile associated with T2DM development.

METHODS

We included 462 coronary heart disease patients from the CORDIOPREV study without T2DM at baseline. Of these, 107 patients developed T2DM according to the American Diabetes Association (ADA) diagnosis criteria after a median follow-up of 60 months. We performed a random classification of patients in a training set, used to build a FA Score, and a Validation set, in which we tested the FA Score.

RESULTS

FA selection with the highest prediction power was performed by random survival forest in the Training set, which yielded 4 out of the 24 FA: myristic, petroselinic, α-linolenic and arachidonic acids. We built a FA Score with the selected FA and observed that patients with a higher score presented a greater risk of T2DM development, with an HR of 3.15 (95% CI 2.04-3.37) in the Training set, and an HR of 2.14 (95% CI 1.50-2.84) in the Validation set, per standard deviation (SD) increase. Moreover, patients with a higher FA Score presented lower insulin sensitivity and higher hepatic insulin resistance (p < 0.05).

CONCLUSION

Our results suggest that a detrimental FA plasma profile precedes the development of T2DM in patients with coronary heart disease, and that this FA profile can, therefore, be used as a predictive biomarker. CLINICAL TRIALS.GOV.

IDENTIFIER

NCT00924937.

Effects of eicosapentaenoic acid on serum levels of selenoprotein P and organ-specific insulin sensitivity in humans with dyslipidemia and type 2 diabetes

AIM

Selenoprotein P (SeP, encoded by SELENOP in humans) is a hepatokine that causes insulin resistance in the liver and skeletal muscle. It was found that polyunsaturated fatty acid eicosapentaenoic acid (EPA) downregulates Selenop expression by inactivating SREBP-1c. The present study aimed to examine the effect of EPA for 12 weeks on circulating SeP levels and insulin sensitivity in humans with type 2 diabetes.

METHODS

A total of 20 participants with dyslipidemia and type 2 diabetes were randomly assigned to an EPA (900 mg, twice daily) group and a control group. The primary endpoint was a change in serum SeP levels. Organ-specific insulin sensitivity in the liver (HGP and %HGP), skeletal muscle (Rd), and adipose tissue (FFA and %FFA) were assessed using a hyperinsulinemic-euglycemic clamp study with stable isotope-labeled glucose infusion.

RESULTS

Serum SeP levels were not changed in either group at the end of the study. In the EPA group, the changes in SeP levels were positively correlated with the change in serum EPA levels (r = 0.709, P = 0.022). Treatment with EPA significantly enhanced %FFA but not %HGP and Rd. The change in serum EPA levels was significantly positively correlated with the change in %HGP, and negatively correlated with changes in Rd.

CONCLUSIONS

The change in serum EPA levels was positively correlated with serum SeP levels, hepatic insulin sensitivity, and negatively with skeletal muscle insulin sensitivity in humans with type 2 diabetes. The EPA-induced enhancement of hepatic insulin sensitivity might be associated with a mechanism independent of serum SeP levels.

Marine Oil from C. finmarchicus Enhances Glucose Homeostasis and Liver Insulin Resistance in Obese Prediabetic Individuals

The intermediate state between normal glucose tolerance and overt type 2 diabetes mellitus is associated with micro- and macrovascular diseases, requiring safe and cost-effective treatment measures interventions. A novel source of LC n-3 FAs is Calanus finmarchicus Oil, which showed promising effects on glucose homeostasis in preclinical studies due to anti-obesity effects and/or anti-inflammatory properties. In total, 43 obese patients (BMI: 31.7 ± 5.2 kg/m²) were allocated in the following two groups: (1) Calanus oil group (2 g CO/day) and (2) placebo group (2 g paraffin oil/day). Markers of glucose metabolism, body composition and energy intake were measured at the beginning (t0), after 12 weeks (t₁₂) and 16 weeks (t₁₆). Overall, parameters reflecting abnormal glucose homeostasis and insulin resistance in the liver, including fasting insulin (−2.9 mU/L ± 4.10, p < 0.05), HOMA-IR (−0.9 ± 1.28, p < 0.05) and hepatic insulin resistance index (−1.06 ± 1.72 × 10⁶, p < 0.05) significantly enhanced after a 12-week CO-intervention, while no differences were observed in HbA1c, AUC_0–2h Glucose, AUC_0–2h Insulin, 2 h plasma glucose and muscle insulin sensitivity index. Our results indicate that Calanus oil causes beneficial effects on glucose metabolism and insulin resistance in obese patients, with clinical relevance to be verified in further studies. In addition, the possible active compounds and their mechanisms of action should be elucidated.

Altered RBC membrane lipidome: A possible etiopathogenic link for the microvascular impairment in Type 2 diabetes

AIMS

Disturbances in red blood cells' (RBCs) membrane structure, that result in altered rheological properties, have been implicated in the pathogenesis of microvascular complications of diabetes mellitus(T2DM). However, the compositional alterations in RBCs membranes of T2DM patients have not been characterized in detail.

METHODS

NMR-based lipidomic approach used for the global investigation of the lipidome of RBCs membrane in 20 newly diagnosed T2DM patients. Twenty healthy individuals served as controls.

RESULTS

In the lipidomic analysis, the discrimination power among the two groups was of high significance. T2DM patients characterized by an increased content of cholesterol, total sphingolipids, sphingomyelin and glycolipids, and decreased total phospholipids, mainly due to phosphatidylethanolamine, total ether glycerolipids and plasmalogen-phospholipids, and higher cholesterol-to-phospholipids molecular ratio compared to controls. In T2DM, lipids were esterified with saturated rather than unsaturated fatty acids, an atherogenic pattern that may be involved in the impairment of membrane fluidity and rigidity.

CONCLUSIONS

NMR-based lipidomic analysis of RBCs can provide insights into molecular lipid features of membrane microenvironment that influence their vital function and rheological behavior in microvascular network in T2DM.Early identification of these disturbances, even before the onset of diabetes, could critically help to the development of novel preventative and curative therapies for reducing the risk of microvascular dysfunction.

A Deeper Assessment of ω3-Poly-Unsaturated Fatty Acids in Polycystic Ovary Syndrome Management. Comment on Regidor et al. Chronic Inflammation in PCOS: The Potential Benefits of Specialized Pro-Resolving Lipid Mediators (SPMs) in the Improvement of the Resolutive Response. Int. J. Mol. Sci. 2021, 22, 384

I have read with great interest the article recently published by Regidor et al. [...].

Omega-3 fatty acid blood levels are inversely associated with cardiometabolic risk factors in HFpEF patients: the Aldo-DHF randomized controlled trial

Objectives

To evaluate associations of omega-3 fatty acid (O3-FA) blood levels with cardiometabolic risk markers, functional capacity and cardiac function/morphology in patients with heart failure with preserved ejection fraction (HFpEF).

Background

O3-FA have been linked to reduced risk for HF and associated phenotypic traits in experimental/clinical studies.

Methods

This is a cross-sectional analysis of data from the Aldo-DHF-RCT. From 422 patients, the omega-3-index (O3I = EPA + DHA) was analyzed at baseline in n = 404 using the HS-Omega-3-Index^® methodology. Patient characteristics were; 67 ± 8 years, 53% female, NYHA II/III (87/13%), ejection fraction ≥ 50%, E/e′ 7.1 ± 1.5; median NT-proBNP 158 ng/L (IQR 82–298). Pearson’s correlation coefficient and multiple linear regression analyses, using sex and age as covariates, were used to describe associations of the O3I with metabolic phenotype, functional capacity, echocardiographic markers for LVDF, and neurohumoral activation at baseline/12 months.

Results

The O3I was below (< 8%), within (8–11%), and higher (> 11%) than the target range in 374 (93%), 29 (7%), and 1 (0.2%) patients, respectively. Mean O3I was 5.7 ± 1.7%. The O3I was inversely associated with HbA1c (r = − 0.139, p = 0.006), triglycerides-to-HDL-C ratio (r = − 0.12, p = 0.017), triglycerides (r = − 0.117, p = 0.02), non-HDL-C (r = − 0.101, p = 0.044), body-mass-index (r = − 0.149, p = 0.003), waist circumference (r = − 0.121, p = 0.015), waist-to-height ratio (r = − 0.141, p = 0.005), and positively associated with submaximal aerobic capacity (r = 0.113, p = 0.023) and LVEF (r = 0.211, p < 0.001) at baseline. Higher O3I at baseline was predictive of submaximal aerobic capacity (β = 15.614, p < 0,001), maximal aerobic capacity (β = 0.399, p = 0.005) and LVEF (β = 0.698, p = 0.007) at 12 months.

Conclusions

Higher O3I was associated with a more favorable cardiometabolic risk profile and predictive of higher submaximal/maximal aerobic capacity and lower BMI/truncal adiposity in HFpEF patients.

Graphic abstract

Omega-3 fatty acid blood levels are inversely associated with cardiometabolic risk factors in HFpEF patients. Higher O3I was associated with a more favorable cardiometabolic risk profile and aerobic capacity (left) but did not correlate with echocardiographic markers for left ventricular diastolic function or neurohumoral activation (right). An O3I-driven intervention trial might be warranted to answer the question whether O3-FA in therapeutic doses (with the target O3I 8–11%) impact on echocardiographic markers for left ventricular diastolic function and neurohumoral activation in patients with HFpEF. This figure contains modified images from Servier Medical Art (https://smart.servier.com) licensed by a Creative Commons Attribution 3.0 Unported License.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-021-01925-9.

Effects of DHA-Rich n-3 Fatty Acid Supplementation and/or Resistance Training on Body Composition and Cardiometabolic Biomarkers in Overweight and Obese Post-Menopausal Women

Resistance training (RT) and n-3 polyunsaturated fatty acids (n-3 PUFA) supplementation have emerged as strategies to improve muscle function in older adults. Overweight/obese postmenopausal women (55–70 years) were randomly allocated to one of four experimental groups, receiving placebo (olive oil) or docosahexaenoic acid (DHA)-rich n-3 PUFA supplementation alone or in combination with a supervised RT-program for 16 weeks. At baseline and at end of the trial, body composition, anthropometrical measures, blood pressure and serum glucose and lipid biomarkers were analyzed. Oral glucose tolerance tests (OGTT) and strength tests were also performed. All groups exhibit a similar moderate reduction in body weight and fat mass, but the RT-groups maintained bone mineral content, increased upper limbs lean mass, decreased lower limbs fat mass, and increased muscle strength and quality compared to untrained-groups. The RT-program also improved glucose tolerance (lowering the OGTT incremental area under the curve). The DHA-rich supplementation lowered diastolic blood pressure and circulating triglycerides and increased muscle quality in lower limbs. In conclusion, 16-week RT-program improved segmented body composition, bone mineral content, and glucose tolerance, while the DHA-rich supplement had beneficial effects on cardiovascular health markers in overweight/obese postmenopausal women. No synergistic effects were observed for DHA supplementation and RT-program combination.

Associations Between Erythrocyte Membrane Fatty Acid Compositions and Biomarkers of Vascular Health in Adults With Type 1 Diabetes With and Without Insulin Resistance: A Cross-Sectional Analysis

OBJECTIVES

The aim of this study was to assess the relationship between specific erythrocyte fatty acid levels and vascular health in type 1 diabetes (T1D) with and without insulin resistance (IR).

METHODS

We analyzed baseline pretreatment data in a subset of 23 patients with T1D from a previously published randomized controlled trial consisting of comprehensive erythrocyte-derived fatty acid profiles and a panel of inflammation-associated endothelial markers. Estimated glucose disposal rate was used to identify and categorize patients with IR. We utilized principal component analysis (PCA) to cluster vascular biomarkers to compute a single "vascular signal" and utilized univariate linear regression models to investigate the association with IR and fatty acid profiles.

RESULTS

Subjects with IR displayed significantly higher levels of linoleic acid (p=0.001), lower levels of eicosapentaenoic acid (EPA) (p<0.001), lower levels of omega-3 polyunsaturated fatty acid (n-3PUFA) (p<0.006) and an increased omega-6 (n-6)PUFA:n-3PUFA ratio (p=0.001). IR was associated with significantly higher linoleic acid levels, total n-6PUFA and an increased ratio of n-6PUFA:n-3PUFA, and negatively associated with arachidonic acid and EPA levels, total saturated fatty acid and total n-3PUFA. The PCA-derived vascular biomarker cluster was positively associated with linoleic acid and n-6PUFA:n-3PUFA ratio, and inversely associated with EPA.

CONCLUSIONS

Specific erythrocyte membrane fatty acid compositions are associated with impaired vascular health and IR in adults with T1D. These findings suggest that IR and risk of associated complications may be influenced by specific fatty acid profiles, and thus potentially modified by the selective targeting of dietary fatty acids.

Polyunsaturated fatty acids as modulators of fat mass and lean mass in human body composition regulation and cardiometabolic health

It is now recognized that the amount and type of dietary fat consumed play an important role in metabolic health. In humans, high intake of polyunsaturated fatty acids (PUFAs) has been associated with reductions in cardiovascular disease risk, improvements in glucose homeostasis, and changes in body composition that involve reductions in central adiposity and, more recently, increases in lean body mass. There is also emerging evidence, which suggests that high intakes of the plant-based essential fatty acids (ePUFAs)-n-6 linoleic acid (LA) and n-3 α-linolenic acid (ALA)-have a greater impact on body composition (fat mass and lean mass) and on glucose homeostasis than the marine-derived long-chain n-3 PUFA-eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In addition, high intake of both ePUFAs (LA and ALA) may also have anti-inflammatory effects in humans. The purpose of this review is to highlight the emerging evidence, from both epidemiological prospective studies and clinical intervention trials, of a role for PUFA, in particular ePUFA, in the long-term regulation of body weight and body composition, and their impact on cardiometabolic health. It also discusses current notions about the mechanisms by which PUFAs modulate fat mass and lean mass through altered control of energy intake, thermogenesis, or lean-fat partitioning.

Omega-3 supplementation and diabetes: A systematic review and meta-analysis

This study aimed to review the literature on studies that evaluated the effects of omega-3 supplementation on parameters of diabetes in humans. An online search was conducted in the following databases: Pubmed, LILACS, Scielo, Scopus, and Web of Science. It included experimental studies that investigated the effects of omega-3 supplementation for diabetes treatment or prevention and its relationship with fasting blood glucose, insulin resistance, and glycated hemoglobin. Observational, non-human studies and non-randomized clinical trials were excluded. The Cochrane scale assessed the quality of the studies. A meta-analysis was carried out to evaluate the effect of omega-3 on fasting blood glucose, insulin resistance, and glycated hemoglobin. Thirty studies were included in the review. Almost 70% (n = 20) demonstrated at least one significant effect of the omega-3 supplementation related to diabetes. In the meta-analysis, there was a significant effect on the reduction of fasting blood glucose [SMD: -0.48; CI95%: -0.76, -0.19; p = 0.01; I2 = 88%] and insulin resistance [SMD: -0.61; CI95%: -0.98, -0.24; p = 0.01; I2 = 90%]. For glycated hemoglobin, there was no significant effect in the meta-analysis. This systematic review with meta-analysis demonstrated that supplementation with omega-3 has protective effects on diabetes parameters.

Experience in Nutrition Management of Diabetes-Affected COVID-19 Patients

When diabetic patients are ill, their bodies react by releasing hormones to combat the illness. These hormones can be triggered by some states, such as infections. Some illnesses that most likely have an influence on blood glucose levels include common cold or flu, COVID-19, bronchitis, or chest infections. So, it is important for diabetic patients affected by COVID-19 to eat a healthy balanced diet to maintain stable blood glucose levels and enhance their immune functions. The immune response has often been demonstrated to be attenuated by insufficient nutrition in many model systems as well as in human studies. We summarize and propose potential nutritional therapeutic options available for the treatment of this novel coronavirus in diabetic patients.

Chronic Inflammation in PCOS: The Potential Benefits of Specialized Pro-Resolving Lipid Mediators (SPMs) in the Improvement of the Resolutive Response

PCOS as the most common endocrine disorder of women in their reproductive age affects between 5–15% of the female population. Apart from its cardinal symptoms, like irregular and anovulatory cycles, hyperandrogenemia and a typical ultrasound feature of the ovary, obesity, and insulin resistance are often associated with the disease. Furthermore, PCOS represents a status of chronic inflammation with permanently elevated levels of inflammatory markers including IL-6 and IL-18, TNF-α, and CRP. Inflammation, as discovered only recently, consists of two processes occurring concomitantly: active initiation, involving “classical” mediators including prostaglandins and leukotrienes, and active resolution processes based on the action of so-called specialized pro-resolving mediators (SPMs). These novel lipid mediator molecules derive from the essential ω3-poly-unsaturated fatty acids (PUFAs) DHA and EPA and are synthesized via specific intermediates. The role and benefits of SPMs in chronic inflammatory diseases like obesity, atherosclerosis, and Diabetes mellitus has become a subject of intense research during the last years and since PCOS features several of these pathologies, this review aims at summarizing potential roles of SPMs in this disease and their putative use as novel therapeutics.

Effect of omega-3 fatty acids on glucose homeostasis: role of free fatty acid receptor 1

Insulin resistance is a worldwide health problem. This study investigated the acute effects of eicosapentanoic acid (EPA) on glucose homeostasis focusing on the role of free fatty acid receptor 1 (FFAR1) and the chronic effects of fish oil omega-3 fatty acids on insulin resistance. Insulin resistance was induced by feeding mice high-fructose, high-fat diet (HFrHFD) for 16 weeks. In the first part, the acute effects of EPA alone and in combination with GW1100 and DC260126 (FFAR1 blockers) on glucose homeostasis and hepatic phosphatidyl-inositol 4,5-bisphosphate (PIP2) and diacylglycerol (DAG) were investigated in standard chow diet (SCD)- and HFrHFD-fed mice. In the second part, mice were treated with fish oil omega-3 fatty acids for 4 weeks starting at the week 13 of feeding HFrHFD. Changes in the blood- and liver tissue-insulin resistance markers and FFAR1 downstream signals were recorded at the end of experiment. Results showed that EPA increased 0 and 30 min blood glucose levels after glucose load in SCD-fed mice but improved glucose tolerance in HFrHFD-fed mice. Moreover, FFAR1 blockers reduced EPA effects on glucose tolerance and hepatic PIP2 and DAG levels. On the other hand, chronic use of fish oil omega-3 fatty acids increased FBG levels and decreased serum insulin and triglycerides levels without improving the index of insulin resistance. Also, they increased hepatic β-arrestin-2, PIP2, and pS473 Akt levels but decreased DAG levels. In conclusion, EPA acutely improved glucose homeostasis in HFrHFD-fed mice by modulating the activity of FFAR1. However, the chronic use of fish oil omega-3 fatty acids did not improve the insulin resistance.

Overview of dietary supplements on patients with type 2 diabetes

BACKGROUND AND AIMS

The primary approach for managing type 2 diabetes mellitus (T2DM) involves lifestyle modification and diet therapy along with pharmacologic interventions. Many patients are interested to identify nutritional supplements that may provide benefit in prevention and management of diabetes. However, the efficacy and safety of nutritional supplements such as chromium, n-3 polyunsaturated fatty acids (PUFAs), vitamin D, zinc and magnesium in disease treatment is a worrying and controversial matter. In this narrative review, patients and health care providers are introduced to the effects of mentioned dietary supplements that may help in choosing or not choosing these supplements in treatment of diabetes.

METHODS

This review was carried out using comprehensive and systematic literature reports on the dietary supplements in the management of diabetes. Empirical searches were conducted using Google Scholar, Science Direct and PubMed databases. Searches were also undertaken using keywords, in English, such as "chromium" OR "vitamin D" OR "omega-3 fatty acids" OR "zinc" OR "magnesium" in combination with "type 2 diabetes".

RESULTS

The available evidence is insufficient to create a definite conclusion that nutritional supplements including chromium, n-3 PUFAs, vitamin D, zinc and magnesium might be beneficial for the prevention and treatment of T2DM and therefore, the general recommendation to use these supplements in the management of diabetes cannot be justified. The results of most studies lack uniformity across multiple aspects, including different dose and formation of supplements, duration, and subjects under intervention.

CONCLUSIONS

There is a need for well-designed, high quality, large and long-term studies to strengthen the available evidence and ensure the safety and efficacy of products.

Docosahexaenoic Acid-Rich Fish Oil Supplementation Reduces Kinase Associated with Insulin Resistance in Overweight and Obese Midlife Adults

Targeting kinases linked to insulin resistance (IR) and inflammation may help in reducing the risk of type 2 diabetes (T2D) and Alzheimer’s disease (AD) in its early stages. This study aimed to determine whether DHA-rich fish oil supplementation reduces glycogen synthase kinase (GSK-3), which is linked to both IR and AD. Baseline and post-intervention plasma samples from 58 adults with abdominal obesity (Age: 51.7 ± 1.7 years, BMI: 31.9 ± 0.8 kg/m²) were analysed for outcome measures. Participants were allocated to 2 g DHA-rich fish oil capsules (860 mg DHA + 120 mg EPA) (n = 31) or placebo capsules (n = 27) per day for 12 weeks. Compared to placebo, DHA-rich fish oil significantly reduced GSK-3β by −2.3 ± 0.3 ng/mL. An inverse correlation (p < 0.05) was found between baseline insulin and IR and their changes following intervention only in participants with C-reactive protein levels higher than 2.4 mg/L. DHA-rich fish oil reduces GSK-3 and IR, suggesting a potential role of long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) in ameliorating AD risk.

Nutritional Strategies to Offset Disuse-Induced Skeletal Muscle Atrophy and Anabolic Resistance in Older Adults: From Whole-Foods to Isolated Ingredients

Preserving skeletal muscle mass and functional capacity is essential for healthy ageing. Transient periods of disuse and/or inactivity in combination with sub-optimal dietary intake have been shown to accelerate the age-related loss of muscle mass and strength, predisposing to disability and metabolic disease. Mechanisms underlying disuse and/or inactivity-related muscle deterioration in the older adults, whilst multifaceted, ultimately manifest in an imbalance between rates of muscle protein synthesis and breakdown, resulting in net muscle loss. To date, the most potent intervention to mitigate disuse-induced muscle deterioration is mechanical loading in the form of resistance exercise. However, the feasibility of older individuals performing resistance exercise during disuse and inactivity has been questioned, particularly as illness and injury may affect adherence and safety, as well as accessibility to appropriate equipment and physical therapists. Therefore, optimising nutritional intake during disuse events, through the introduction of protein-rich whole-foods, isolated proteins and nutrient compounds with purported pro-anabolic and anti-catabolic properties could offset impairments in muscle protein turnover and, ultimately, the degree of muscle atrophy and recovery upon re-ambulation. The current review therefore aims to provide an overview of nutritional countermeasures to disuse atrophy and anabolic resistance in older individuals.

Are marine n-3 fatty acids protective towards insulin resistance? From cell to human

Marine n-3 fatty acids improve most of the biochemical alterations associated with insulin resistance (IR). Experimental models of dietary-induced IR in rodents have shown their ability (often at a very high dose) to prevent IR, but with sometimes a tissue specific effect. However, in a high sucrose diet-induced IR rat model, they are unable to reverse IR once installed; in other rodent models (dexamethasone, Zucker rats), they are inefficacious perhaps because of the severity of IR. The very low incidence of type-2 diabetes (T2D) in Inuits in the 1960s, which largely increased over the following decades in parallel to the replacement of their traditional marine food for a western diet strongly suggests a protective effect of marine n-3 towards the risk of T2D; this was confirmed by reversal of its incidence in intervention studies reintroducing their traditional food. In healthy subjects and insulin-resistant non-diabetic patients, most trials and meta-analyses conclude to an insulin-sensitising effect and to a very probable preventive or alleviating effect towards IR. Concerning the risk of T2D, concordant data allow us to conclude the protective effect of marine n-3 in Asians while suspicion exists of an aggravation of risk in Westerners, but with the possibility that it could be explained by a high heterogeneity of studies performed in this population. Some longitudinal cohorts in US/European people showed no association or a decreased risk. Further studies using more homogeneous doses, sources of n-3 and assessment of insulin sensitivity methods are required to better delineate their effects in Westerners.

Dietary fats and cardiometabolic disease: mechanisms and effects on risk factors and outcomes

The effect of dietary fats on cardiometabolic diseases, including cardiovascular diseases and type 2 diabetes mellitus, has generated tremendous interest. Many earlier investigations focused on total fat and conventional fat classes (such as saturated and unsaturated fats) and their influence on a limited number of risk factors. However, dietary fats comprise heterogeneous molecules with diverse structures, and growing research in the past two decades supports correspondingly complex health effects of individual dietary fats. Moreover, health effects of dietary fats might be modified by additional factors, such as accompanying nutrients and food-processing methods, emphasizing the importance of the food sources. Accordingly, the rapidly increasing scientific findings on dietary fats and cardiometabolic diseases have generated debate among scientists, caused confusion for the general public and present challenges for translation into dietary advice and policies. This Review summarizes the evidence on the effects of different dietary fats and their food sources on cell function and on risk factors and clinical events of cardiometabolic diseases. The aim is not to provide an exhaustive review but rather to focus on the most important evidence from randomized controlled trials and prospective cohort studies and to highlight current areas of controversy and the most relevant future research directions for understanding how to improve the prevention and management of cardiometabolic diseases through optimization of dietary fat intake.

Evaluation of Anti-Hyperlipidemic Activity of Extracted Alpha-linlenic Acid from Natural Linum Usitatissimum Compared with Atorvastatin in High Fat Diet Induced Rats

Linum Usitatissimum (LU) has a lipid-lowering action in both normal and diabetic animals. Because OS leaves are rich in oil, the present study was conducted to explain the anti-hyperlipidemic and organ-protective effect of LU fixed oil in rats fed with a high fat (HF) diet. LU fixed oil was extracted by hexane and the fatty acids composition identified by GC-MS. Four groups of male Wister rats included a normal control group, a high fat fed-diet (HF) group, a HF group treated with LU fixed oil, and a HF group treated with a reference drug Atorvastatin. The results show that LU fixed oil contains five kinds of fatty acids, of which alpha-linolenic acid was the major fatty acid. LU fixed oil depressed high serum levels of total cholesterol, triglyceride, LDL-C, and AI, whereas no significant effect on HDL-C was observed. LU fixed oil also suppressed high levels of liver cholesterol and triglyceride with no significant effect on both lipids in feces. In addition, LU fixed oil normalized the high serum levels of LDH and CK-MB but no significant effect on high serum levels of ALT, AST, and ALP was obtained. We conclude that treatment with LU fixed oil during the last three weeks of HF diet feeding decreased the high serum lipid profile and expressed anti artherogenic and cardio protective actions against hyperlipidemia. The anti-hyperlipidemic action of OS fixed oil was mainly resulted from the suppression of liver lipid synthesis. Linolenic acid and linoleic acid contained in LU fixed oil were possibly responsible for both lipid-lowering and cardiac protective action against hyperlipidemia.

An overview of phytochemicals and potential health-promoting properties of black walnut

Black walnut contains a diverse mixture of bioactive compounds, including phenolics, phytosterols, unsaturated fatty acids, and tocopherols potentially important to human health.

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.

Immuno-Resolving Ability of Resolvins, Protectins, and Maresins Derived from Omega-3 Fatty Acids in Metabolic Syndrome

Omega-3 fatty acid consumption has been suggested to be beneficial for the prevention of type 2 diabetes mellitus (T2DM). Its effects have been attributed to anti-inflammatory activity, with the inhibition of arachidonic acid metabolism playing a central role. However, a more recent view is that omega-3 fatty acids play an active role as the precursors of potent, specialized pro-resolving mediators (SPMs), such as resolvins, protectins, and maresins. Docosahexaenoic acid (DHA)- and eicosapentaenoic-acid-derived SPMs are identified in the adipose tissue but the levels of certain SPMs (e.g., protectin D1) are markedly reduced with obesity, suggesting adipose SPM deficiency, potentially resulting in unresolved inflammation. Supplementation of the biosynthetic intermediates of SPM (e.g., 17-hydroxy-DHA) or omega-3 fatty acids increases the level of adipose SPMs, reduces adipose inflammation (decrease in macrophage accumulation and change to less inflammatory macrophages), and enhances insulin sensitivity. The findings from studies using rodent obesity models must be translated to humans. It will be important to further elucidate the underlying mechanisms by which obesity reduces the levels of and the sensitivity to SPM in adipose tissues. This will enable the development of nutrition therapy to enhance the effects of omega-3 fatty acids in the prevention and/or treatment of T2DM.

A Dietary Pattern Derived from Reduced Rank Regression and Fatty Acid Biomarkers Is Associated with Lower Risk of Type 2 Diabetes and Coronary Artery Disease in Chinese Adults

BACKGROUND

Combinations of circulating fatty acids may affect the risk of type 2 diabetes (T2D) and coronary artery disease (CAD). No previous studies have identified a dietary pattern predicting fatty acid profiles using reduced rank regression (RRR) and evaluated its associations with the risk of T2D and CAD.

OBJECTIVE

The aim of this study was to derive a dietary pattern to explain variation in plasma fatty acid concentrations using RRR and evaluate these in relation to risk of T2D and CAD.

METHODS

We derived a dietary pattern using fatty acid concentrations from 711 controls of a nested case-control study in the Singapore Chinese Health Study using RRR with 36 food and beverages as predictors and 19 fatty acid biomarkers as responses. Dietary pattern scores were then calculated for the full cohort of men and women (mean age: 56 y). We followed up 45,411 and 58,065 participants for incident T2D and CAD mortality, respectively. Multivariable Cox regression models were used to estimate HRs and 95% CIs.

RESULTS

We identified a dietary pattern high in soy, vegetables, fruits, tea, tomato products, bread, fish, margarine and dairy, and low in rice, red meat, coffee, alcohol, sugar-sweetened beverages, and eggs. This pattern predicted higher circulating n-3 (ω-3) PUFAs (18:3n-3, 20:3n-3, 20:5n-3), odd-chain fatty acids (15:0, 17:0), 18:2n-6 and 20:1, and lower 20:4n-6 and 16:1. During a mean follow-up of 11 y and 19 y, 5207 T2D and 3016 CAD mortality events, respectively, were identified. Higher dietary pattern scores were associated with a lower risk of T2D [multivariable-adjusted HR comparing extreme quintiles, 0.86 (95% CI: 0.79, 0.95); P-trend <0.001] and CAD mortality [HR, 0.76 (95% CI: 0.68, 0.86); P-trend <0.001].

CONCLUSIONS

Dietary patterns reflecting higher circulating n-3 PUFAs, odd-chain fatty acids, and linoleic acid may be associated with lower T2D and CAD risk in Chinese adults. This trial was registered at www.clinicaltrials.gov as NCT03356340.

Improving Metabolic Control Through Functional Foods

Background:

Functional foods are designed to have physiological benefits and reduce the risk of chronic disease beyond basic nutritional functions. Conditions related to overnutrition such as Metabolic Syndrome and Type 2 diabetes are increasingly serious concerns in Western societies. Several nutrient classes are considered to protect against these conditions and this review focuses on the latest clinical and preclinical evidence supporting their efficacy and the molecular mechanisms by which they act.

Methods:

The review searched the literature for information and data on the following functional food components and their protective effects against Metabolic Syndrome and Type 2 Diabetes: Dietary fiber; Medium-chain triglycerides and Ketone esters; ω3 Polyunsaturated fatty acids and Antioxidants.

Results:

Data from a hundred and four studies were reviewed and summarized. They indicate that dietary fiber results in the production of beneficial short chain fatty acids via intestinal microbiota, as well as increasing intestinal secretion of incretins and satiety peptides. Medium chain triglycerides and ketone esters promote thermogenesis, inhibit lipolysis and reduce inflammation. They also decrease endogenous synthesis of triglycerides and fatty acids. ω3-PUFA’s act to soften inflammation through an increase in adiponectin secretion. Antioxidants are involved in the protection of insulin sensitivity by PTP1B suppression and SIRT1 activation.

Conclusion:

Functional foods have actions that complement and/or potentiate other lifestyle interventions for reversing Metabolic Syndrome and Type 2 Diabetes. Functional foods contribute to reduced food intake by promoting satiety, less weight gain via metabolic uncoupling and improved insulin sensitivity via several distinct mechanisms.

Plasma phospholipid n-3 and n-6 polyunsaturated fatty acids in relation to cardiometabolic markers and gestational diabetes: A longitudinal study within the prospective NICHD Fetal Growth Studies

BACKGROUND

Despite dietary recommendations of polyunsaturated fatty acids (PUFAs) for cardiometabolic health, n-3 and n-6 PUFAs and their interplay in relation to diabetes risk remain debated. Importantly, data among pregnant women are scarce. We investigated individual plasma phospholipid n-3 and n-6 PUFAs in early to midpregnancy in relation to subsequent risk of gestational diabetes mellitus (GDM).

METHODS AND FINDINGS

Within the National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies-Singleton Cohort (n = 2,802), individual plasma phospholipid n-3 and n-6 PUFAs levels were measured at gestational weeks (GWs) 10-14, 15-26, 23-31, and 33-39 among 107 GDM cases (ascertained on average at GW 27) and 214 non-GDM controls. Conditional logistic regression was used, adjusting for major risk factors for GDM. After adjusting for covariates, individual n-3 eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) were inversely correlated with insulin-resistance markers, whereas individual n-6 dihomo-gamma-linolenic acid (DGLA) was positively correlated with insulin-resistance markers. At GW 15-26, a standard deviation (SD) increase in total n-3 PUFAs and individual n-3 DPA was associated with a 36% (adjusted odds ratio 0.64; 95% CI 0.42-0.96; P = 0.042) and 33% (0.67; 95% CI 0.45-0.99; P = 0.047) lower risk of GDM, respectively; however, the significance did not persist after post hoc false-discovery rate (FDR) correction (FDR-corrected P values > 0.05). Associations between total n-6 PUFAs and GDM were null, whereas associations with individual n-6 PUFAs were differential. Per SD increase, gamma-linolenic acid (GLA) at GWs 10-14 and DGLA at GWs 10-14 and 15-26 were significantly associated with a 1.40- to 1.95-fold higher risk of GDM, whereas docosatetraenoic acid (DTA) at GW 15-26 was associated with a 45% (0.55; 95% CI 0.37-0.83) lower risk of GDM (all FDR-corrected P values < 0.05). Null associations were observed for linoleic acid (LA) in either gestational window in relation to risk of GDM. Women with high (≥median) n-3 PUFAs and low (<median) n-6 PUFAs levels had a 64% (95% CI 0.14-0.95; P value = 0.039) lower risk of GDM versus women with low n-3 and high n-6 PUFAs. Limitations include the inability to distinguish between exogenous and endogenous influences on circulating PUFA levels and the lack of causality inherent in observational studies.

CONCLUSIONS

Our findings may suggest a potential role of primarily endogenously metabolized plasma phospholipid n-6 PUFAs including GLA, DGLA, and DTA in early to midpregnancy in the development of GDM. Null findings on primarily diet-derived n-3 EPA and DHA and n-6 LA do not provide strong evidence to suggest a beneficial role in prevention of GDM, although not excluding the potential benefit of EPA and DHA on glucose-insulin homeostasis given the inverse associations with insulin-resistance markers. Our findings highlight the importance of assessing individual circulating PUFAs to investigate their distinct pathophysiologic roles in glucose homeostasis in pregnancy.

Omega-3 Fatty Acids for the Management of Hypertriglyceridemia: A Science Advisory From the American Heart Association

Hypertriglyceridemia (triglycerides 200-499 mg/dL) is relatively common in the United States, whereas more severe triglyceride elevations (very high triglycerides, ≥500 mg/dL) are far less frequently observed. Both are becoming increasingly prevalent in the United States and elsewhere, likely driven in large part by growing rates of obesity and diabetes mellitus. In a 2002 American Heart Association scientific statement, the omega-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were recommended (at a dose of 2-4 g/d) for reducing triglycerides in patients with elevated triglycerides. Since 2002, prescription agents containing EPA+DHA or EPA alone have been approved by the US Food and Drug Administration for treating very high triglycerides; these agents are also widely used for hypertriglyceridemia. The purpose of this advisory is to summarize the lipid and lipoprotein effects resulting from pharmacological doses of n-3 FAs (>3 g/d total EPA+DHA) on the basis of new scientific data and availability of n-3 FA agents. In treatment of very high triglycerides with 4 g/d, EPA+DHA agents reduce triglycerides by ≥30% with concurrent increases in low-density lipoprotein cholesterol, whereas EPA-only did not raise low-density lipoprotein cholesterol in very high triglycerides. When used to treat hypertriglyceridemia, n-3 FAs with EPA+DHA or with EPA-only appear roughly comparable for triglyceride lowering and do not increase low-density lipoprotein cholesterol when used as monotherapy or in combination with a statin. In the largest trials of 4 g/d prescription n-3 FA, non-high-density lipoprotein cholesterol and apolipoprotein B were modestly decreased, indicating reductions in total atherogenic lipoproteins. The use of n-3 FA (4 g/d) for improving atherosclerotic cardiovascular disease risk in patients with hypertriglyceridemia is supported by a 25% reduction in major adverse cardiovascular events in REDUCE-IT (Reduction of Cardiovascular Events With EPA Intervention Trial), a randomized placebo-controlled trial of EPA-only in high-risk patients treated with a statin. The results of a trial of 4 g/d prescription EPA+DHA in hypertriglyceridemia are anticipated in 2020. We conclude that prescription n-3 FAs (EPA+DHA or EPA-only) at a dose of 4 g/d (>3 g/d total EPA+DHA) are an effective and safe option for reducing triglycerides as monotherapy or as an adjunct to other lipid-lowering agents.

Effect of low-ratio n-6/n-3 PUFA on blood glucose: a meta-analysis

OBJECTIVE

The aim of this meta-analysis was to investigate the effect of increasing dietary low-ratio n-6/n-3 polyunsaturated fatty acid (PUFA) intake on blood glucose and other related indicators.

METHODS

We systematically searched randomized controlled trials of low-ratio n-6/n-3 PUFA intervention on PubMed, Embase, Cochrane library and related references up to August 2018. The change values were calculated as the weighted mean difference (WMD) by using a random-effect model.

RESULTS

Eleven randomized controlled trials were included. No significant effect of dietary low-ratio n-6/n-3 PUFA supplementation was observed on fasting blood glucose (WMD: 0.057 mmol L^-1; 95% CI: -0.090 to 0.204 mmol L^-1), insulin (WMD: -0.757 mIU L^-1; 95% CI: -2.419 to 0.904 mIU L^-1), insulin resistance index (WMD: -0.201; 95% CI: -0.566 to 0.165), and glycosylated hemoglobin (WMD: -0.063%; 95% CI: -0.061 to 0.186%). Subgroup analysis showed that the effect of low-ratio n-6/n-3 PUFA on the reduction of the plasma insulin level in North America (WMD: -3.473 mIU L^-1; 95% CI: -5.760 to -1.185 mIU L^-1) was more obvious than that in Asian countries (WMD: -0.797 mIU L^-1; 95% CI: -2.497 to 0.902 mIU L^-1) and European countries (WMD: -0.063 mIU L^-1; 95% CI: -0.061 to 0.186 mIU L^-1). In the subgroup of diabetic subjects, low-ratio n-6/n-3 PUFA supplementation can decrease the plasma insulin level (WMD: -3.010 mIU L^-1; 95% CI: -5.371 to -0.648 mIU L^-1) and insulin resistance index (WMD: -0.460; 95% CI: -0.908 to -0.012). When the intervention period was longer than 8 weeks, low-ratio n-6/n-3 PUFA supplementation could also decrease the plasma insulin level (WMD: -2.782 mIU L^-1; 95% CI: -4.946 to -0.618 mIU L^-1). No significant publication bias was observed for all blood glucose and other related indicators as suggested by Begg's test and Egger's test.

CONCLUSION

Our meta-analysis found that low-ratio n-6/n-3 PUFA supplementation could improve the glucose metabolism by reducing the insulin and insulin resistance in the diabetic patients. Low-ratio n-6/n-3 PUFA supplementation could reduce the plasma insulin level when the supplementation duration was longer than 8 weeks.

Mediterranean Diet Pyramid: A Proposal for Italian People. A Systematic Review of Prospective Studies to Derive Serving Sizes

In the last decade, a number of meta-analyses of mostly observational studies evaluated the relation between the intake of food groups and the risk of noncommunicable diseases (NCDs). In this study, we systematically reviewed dose-response meta-analyses of prospective studies with the aim to derive the quantities of food to consume to attain a protective (Mediterranean food) or a non-adverse (non-Mediterranean food) effect toward selected NCDs such as cardiovascular disease (CVD) including coronary heart disease (CHD) and stroke, type 2 diabetes (T2DM), colorectal (CRC) and breast cancer. These derived quantities, wherever possible, were suggested for a quantification of food servings of the Mediterranean Diet Pyramid proposed for Italian People (MDPPI). This pyramid came from the Modern Mediterranean Diet Pyramid developed in 2009 for Italian people. A weekly menu plan was built on the advice about frequency of intakes and serving sizes of such pyramid and the nutritional composition of this diet was compared with the Reference Italian Mediterranean Diet followed in 1960 in Nicotera. The diet built according the advice of MDPPI was very similar to that of Nicotera in the late 1950s that has been chosen as Italian Reference Mediterranean Diet with the exception of percentage of energy provided by cereals that was lower and of fruits and vegetables that was higher. Saturated fatty acids were only the 6% of daily energy intake. Also the Mediterranean Adequacy Index (MAI) was very similar to that of the aforementioned diet.

Effects of abomasal infusions of fatty acids and one-carbon donors on hepatic ceramide and phosphatidylcholine in lactating Holstein dairy cows

Our objectives were to (1) determine whether the abomasal infusion of behenic acid (C22:0) elevated hepatic ceramide relative to palmitic acid (C16:0) or docosahexaenoic acid (C22:6n-3) infusion; (2) assess whether the abomasal infusion of choline chloride or l-serine elevated hepatic phosphatidylcholine (PC) in cows abomasally infused with C16:0; and (3) characterize the PC lipidome in cows abomasally infused with C22:6n-3, relative to C16:0 or C22:0 infusion. In a 5 × 5 Latin square design, 5 rumen-cannulated Holstein cows (214 ± 4.9 DIM; 3.2 ± 1.1 parity) were enrolled in a study with 6-d periods. Abomasal infusates consisted of (1) palmitic acid (PA; 98% C16:0); (2) PA + choline chloride (PA+C; 50 g/d choline chloride); (3) PA + l-serine (PA+S; 170 g/d l-serine); (4) behenic acid (BA; 92% C22:0); and (5) an algal oil rich in docosahexaenoic acid (DHA; 44% C22:6n-3). Emulsion infusates provided 301 g/d of total fatty acids containing a minimum of 40 g/d of C16:0. Cows were fed a corn silage-based diet. Milk was collected on d -2, -1, 5, and 6. Blood was collected and liver biopsied on d 6 of each period. Although we did not detect differences in milk yield, milk fat yield and content were lower in cows infused with DHA relative to PA. Plasma triacylglycerol concentrations were lower with DHA treatment relative to PA or BA. Cows infused with DHA had lower plasma insulin concentrations relative to cows infused with PA only. For objective 1, hepatic ceramide-d18:2/22:0 was highest in cows infused with BA relative to other treatments. For objective 2, plasma free choline concentrations were greater in PA+C cows relative to PA; however, we did not observe this effect with PA+S. Plasma total PC concentrations were similar for all treatments. Regarding the hepatic lipidome, a total of 18 hepatic PC were higher (e.g., PC-16:1/18:2) and 25 PC were lower (e.g., PC-16:0/22:6) with PA+C infusion relative to PA. In addition, 17 PC were higher (e.g., PC-20:3/22:5) and 21 PC were lower (e.g., PC-18:0/22:6) with PA+S infusion relative to PA. For objective 3, hepatic concentrations of many individual saturated PC (e.g., PC-18:0/15:0) were lower with DHA relative to other treatments. Hepatic concentrations of highly unsaturated PC with very-long-chain fatty acids (e.g., PC-14:0/22:6) were higher in DHA-infused cows relative to PA, PA+C, PA+S, or BA. The abomasal infusion of emulsions containing palmitic acid, palmitic acid with choline chloride or serine, behenic acid, or docosahexaenoic acid influence the hepatic ceramide and PC profiles of lactating cows.

Polyunsaturated Fatty Acids and Glycemic Control in Type 2 Diabetes

The impact of dietary fat on the risk of cardiovascular disease (CVD) has been extensively studied in recent decades. Solid evidence indicates that replacing saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFAs) decreases blood cholesterol levels and prevents CVD and CVD mortality. Studies indicate that fat quality also may affect insulin sensitivity and hence, the risk of type 2 diabetes (T2D). A high intake of SFAs has shown to increase the risk of T2D in prospective studies, while a high intake of PUFAs reduces the risk. Whether PUFAs from marine or vegetable sources affect glycemic regulation differently in T2D remains to be elucidated. The aim of the present review was therefore to summarize research on human randomized, controlled intervention studies investigating the effect of dietary PUFAs on glycemic regulation in T2D. About half of the studies investigating the effect of fish, fish oils, vegetable oils, or nuts found changes related to glycemic control in people with T2D, while the other half found no effects. Even though some of the studies used SFA as controls, the majority of the included studies compared PUFAs of different quality. Considering that both marine and vegetable oils are high in PUFAs and hence both oils may affect glycemic regulation, the lack of effect in several of the included studies may be explained by the use of an inappropriate control group. It is therefore not possible to draw a firm conclusion, and more studies are needed.

Pathobiological mechanisms underlying metabolic syndrome (MetS) in chronic obstructive pulmonary disease (COPD): clinical significance and therapeutic strategies

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and is currently the 4th largest cause of death in the world. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities (e.g. skeletal muscle wasting, ischemic heart disease, cognitive dysfunction) and infective viral and bacterial acute exacerbations (AECOPD). Current pharmacological treatments for COPD are relatively ineffective and the development of effective therapies has been severely hampered by the lack of understanding of the mechanisms and mediators underlying COPD. Since comorbidities have a tremendous impact on the prognosis and severity of COPD, the 2015 American Thoracic Society/European Respiratory Society (ATS/ERS) Research Statement on COPD urgently called for studies to elucidate the pathobiological mechanisms linking COPD to its comorbidities. It is now emerging that up to 50% of COPD patients have metabolic syndrome (MetS) as a comorbidity. It is currently not clear whether metabolic syndrome is an independent co-existing condition or a direct consequence of the progressive lung pathology in COPD patients. As MetS has important clinical implications on COPD outcomes, identification of disease mechanisms linking COPD to MetS is the key to effective therapy. In this comprehensive review, we discuss the potential mechanisms linking MetS to COPD and hence plausible therapeutic strategies to treat this debilitating comorbidity of COPD.

Curcumin and/or omega-3 polyunsaturated fatty acids supplementation reduces insulin resistance and blood lipids in individuals with high risk of type 2 diabetes: a randomised controlled trial

Background

Lowering insulin resistance and dyslipidaemia may not only enhance glycaemic control but also preserve the β-cell function, reducing the overall risk of developing type 2 diabetes (T2D). The current study was aimed to evaluate the effects of curcumin and/or long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) supplementation on glycaemic control and blood lipid levels in individuals at high risk of developing T2D.

Methods

This was a 2 × 2 factorial, randomised, double-blinded, placebo-controlled study. Participants were allocated to either double placebo (PL) or curcumin plus placebo matching for LCn-3PUFA (CC), or LCn-3PUFA plus placebo matching for curcumin (FO), or curcumin plus LCn-3PUFA (CC-FO) for twelve weeks. Primary outcome of the trial was glycaemic indices (HbA1C, fasting glucose and insulin). Insulin resistance and sensitivity is measured using homeostatic model assessment model.

Results

A total of sixty-four participants (PL, n = 16; CC, n = 15; FO, n = 17, CC-FO, n = 16) were included in the final analysis. Post-intervention, HbA1c and fasting glucose remained unchanged across all the groups. Insulin sensitivity was significantly improved in the CC supplemented group (32.7 ± 10.3%) compared to PL (P = 0.009). FO and CC-FO tended to improve insulin sensitivity by 14.6 ± 8.5% and 8.8 ± 7.7% respectively, but the difference did not reach significance. Triglyceride levels were further increased in the PL (26.9 ± 7.4%), however, CC and CC-FO supplementation reduced the triglycerides, FO resulted in the greatest reduction in triglycerides (− 16.4 ± 4.5%, P < 0.001).

Conclusion

Reduction in insulin resistance and triglycerides by curcumin and LCn-3PUFA appears to be attractive strategies for lowering the risk of developing T2D. However, this study failed to demonstrate complimentary benefits of curcumin and LCn-3PUFA on glycaemic control.

Trail registration

ACTRN12615000559516.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-0967-x) contains supplementary material, which is available to authorized users.

Effects of n-3 fatty acid supplements on cardiometabolic profiles in hypertensive patients with abdominal obesity in Inner Mongolia: a randomized controlled trial

Daily supplementation with n-3 fatty acid (FA) has been believed to be an adjunct or alternative to drug treatments to reduce blood pressure (BP) and triglyceride (TG) levels in western patients with high risk of cardiovascular disease.

Science behind the cardio-metabolic benefits of omega-3 polyunsaturated fatty acids: biochemical effects vs. clinical outcomes

Lower incidence of cardiovascular disease (CVD) in the Greenland Inuit, Northern Canada and Japan has been attributed to their consumption of seafood rich in long chain omega-3 polyunsaturated fatty acids (LCn-3PUFA). While a large majority of pre-clinical and intervention trials have demonstrated heart health benefits of LCn-3PUFA, some studies have shown no effects or even negative effects. LCn-3PUFA have been shown to favourably modulate blood lipid levels, particularly a reduction in circulating levels of triglycerides. High density lipoprotein-cholesterol (HDL-C) levels are elevated following dietary supplementation with LCn-3PUFA. Although LCn-3PUFA have been shown to increase low-density lipoprotein-cholesterol (LDL-C) levels, the increase is primarily in the large-buoyant particles that are less atherogenic than small-dense LDL particles. The anti-inflammatory effects of LCn-3PUFA have been clearly outlined with inhibition of NFkB mediated cytokine production being the main mechanism. In addition, reduction in adhesion molecules (intercellular adhesion molecule, ICAM and vascular cell adhesion molecule 1, VCAM-1) and leukotriene production have also been demonstrated following LCn-3PUFA supplementation. Anti-aggregatory effects of LCn-3PUFA have been a subject of controversy, however, recent studies showing sex-specific effects on platelet aggregation have helped resolve the effects on hyperactive platelets. Improvements in endothelium function, blood flow and blood pressure after LCn-3PUFA supplementation add to the mechanistic explanation on their cardio-protective effects. Modulation of adipose tissue secretions including pro-inflammatory mediators and adipokines by LCn-3PUFA has re-ignited interest in their cardiovascular health benefits. The aim of this narrative review is to filter out the reasons for possible disparity between cohort, mechanistic, pre-clinical and clinical studies. The focus of the article is to provide possible explanation for the observed controversies surrounding heart health benefits of LCn-3PUFA.

The effect of nutrient supplementation in the management of polycystic ovary syndrome-associated metabolic dysfunctions: A critical review

Polycystic ovary syndrome (PCOS) is complex heterogeneous disorder that has several aspects in terms of pathology such as metabolic, endocrine, reproductive, and psychological. However, the etiology of PCOS remains poorly understood. Several studies suggest that insulin resistance and hyperandrogenism play a central role in the progression of PCOS pathophysiology. Therefore, common treatment strategies of PCOS are based on lifestyle modification, which include exercise, diet, and nutrient supplementation therapy. Recent studies have recommended some nutrients such as vitamins, minerals, and vitamin-like nutrients for the therapy of PCOS because each has at least one functional property in PCOS-induced pathways. Therefore, it is claimed that the cause of PCOS could be vitamin or mineral deficiency. This review aims to provide a critical literature survey on nutritional supplementation for the treatment of PCOS-associated endocrine and metabolic dysfunctions and discuss the role of nutrients in the management of PCOS in view of the clinical trials and experimental studies.

Lipid remodeling and an altered membrane-associated proteome may drive the differential effects of EPA and DHA treatment on skeletal muscle glucose uptake and protein accretion

In striated muscle, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have differential effects on the metabolism of glucose and differential effects on the metabolism of protein. We have shown that, despite similar incorporation, treatment of C₂C₁₂ myotubes (CM) with EPA but not DHA improves glucose uptake and protein accretion. We hypothesized that these differential effects of EPA and DHA may be due to divergent shifts in lipidomic profiles leading to altered proteomic profiles. We therefore carried out an assessment of the impact of treating CM with EPA and DHA on lipidomic and proteomic profiles. Fatty acid methyl esters (FAME) analysis revealed that both EPA and DHA led to similar but substantials changes in fatty acid profiles with the exception of arachidonic acid, which was decreased only by DHA, and docosapentanoic acid (DPA), which was increased only by EPA treatment. Global lipidomic analysis showed that EPA and DHA induced large alterations in the cellular lipid profiles and in particular, the phospholipid classes. Subsequent targeted analysis confirmed that the most differentially regulated species were phosphatidylcholines and phosphatidylethanolamines containing long-chain fatty acids with five (EPA treatment) or six (DHA treatment) double bonds. As these are typically membrane-associated lipid species we hypothesized that these treatments differentially altered the membrane-associated proteome. Stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics of the membrane fraction revealed significant divergence in the effects of EPA and DHA on the membrane-associated proteome. We conclude that the EPA-specific increase in polyunsaturated long-chain fatty acids in the phospholipid fraction is associated with an altered membrane-associated proteome and these may be critical events in the metabolic remodeling induced by EPA treatment.

Linoleic acid, glycemic control and Type 2 diabetes

Dietary fat quality, especially the intake of specific types of fatty acids, impacts the risk of many chronic diseases, including cardiovascular diseases, certain cancers and type 2 diabetes (T2DM). A recent pooled analysis involving 20 studies from around the world revealed that higher linoleic acid (18:2n-6 LA) biomarker is associated with dose-dependent decreases in the incidence of T2DM. This latest study corroborates earlier cross-sectional studies and intervention trials showing that biomarkers of LA intake are associated with reduced risk of T2DM and better glycemic control and/or insulin sensitivity. This review highlights key clinical trials that have evaluated the role of LA in glycemia and the related condition, insulin sensitivity.

Reprint of: Marine OMEGA-3 fatty acids in the prevention of cardiovascular disease

Omega-6 (ω6) and omega-3 (ω3) fatty acids are two classes of dietary polyunsaturated fatty acids derived from linoleic acid (18:2ω6) and α-linolenic acid (18:3ω3), respectively. Enzymatic metabolism of linoleic and α-linolenic acids generates arachidonic acid (20:4ω6) and eicosapentaenoic acid (20:5ω3; EPA), respectively, both of which are substrates for enzymes that yield eicosanoids with multiple and varying physiological functions. Further elongation and desaturation of EPA yields the 22-carbon fatty acid docosahexaenoic acid (22:6ω3; DHA). The main dietary source of EPA and DHA for human consumption is fish, especially oily fish. There is considerable evidence that EPA and DHA are protective against cardiovascular disease (heart disease and stroke), particularly in individuals with pre-existing disease. ω3 Fatty acids benefit multiple risk factors including blood pressure, blood vessel function, heart function and blood lipids, and they have antithrombotic, anti-inflammatory and anti-oxidative actions. ω3 Fatty acids do not adversely interact with medications. Supplementation with ω3 fatty acids is recommended in individuals with elevated blood triglyceride levels and patients with coronary heart disease. A practical recommendation for the general population is to increase ω3 fatty acid intake by incorporating fish as part of a healthy diet that includes increased fruits and vegetables, and moderation of salt intake. Health authorities recommend the general population should consume at least two oily fish meals per week.

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.