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

Revisiting the concepts of de novo lipogenesis to understand the conversion of carbohydrates into fats: Stop overvaluing and extrapolating the renowned phrase "fat burns in the flame of carbohydrate"

Carbohydrates can be converted into fatty acids via de novo lipogenesis (DNL). Although DNL is considered inefficient, these endogenous fatty acids contribute substantially to the esterification pathway in adipose tissue, together with fatty acids of feeding. This article revisited the concepts of DNL and aimed to discuss the clinical magnitude of carbohydrate overfeeding and fat mass accumulation. Although fat storage resulting from fat intake is more favorable for fat mass accrual than carbohydrates due to molecule structure and metabolism (e.g., oxidation and thermic effect), carbohydrates can substantially participate in lipogenesis and esterification under excess carbohydrate intake over time. Regarding only monosaccharide overfeeding, glucose and fructose favor the subcutaneous and visceral adipose tissue, respectively. While fructose and sucrose are considered villains in nonalcoholic fatty liver disease, energy surplus from carbohydrates, regardless of sources, can be considered an underlying cause of obesity. Interestingly, some degree of DNL in adipocytes may be favorable to mitigate a high deposition of fatty acids in the liver, conferring a physiological role. Although "fat burns in the flame of carbohydrate" is a praiseworthy phrase that has helped describe basic concepts in biochemistry for many decades, it appears to be overvalued and extrapolated even nowadays. DNL cannot be neglected. It is time to consider DNL an efficient biochemical process in health and disease.

Impact of omega-3 fatty acids on hypertriglyceridemia, lipidomics, and gut microbiome in patients with type 2 diabetes

BACKGROUND

Fish oil (FO), a mixture of omega-3 fatty acids mainly comprising docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has been recommended for patients with type 2 diabetes (T2D) and hypertriglyceridemia. However, its effects on lipidomic profiles and gut microbiota and the factors influencing triglyceride (TG) reduction remain unclear.

METHODS

We conducted a 12-week, randomized, double-blind, placebo-controlled trial in 309 Chinese patients with T2D with hypertriglyceridemia (ClinicalTrials.gov: NCT03120299). Participants were randomly assigned (1:1) to receive either 4 g FO or corn oil for 12 weeks. The primary outcome was changes in serum TGs and the lipidomic profile, and the secondary outcome included changes in the gut microbiome and other metabolic variables.

FINDINGS

The FO group had significantly better TG reduction (mean [95% confidence interval (CI)]: -1.51 [-2.01, -1.01] mmol/L) compared to the corn oil group (-0.66 [-1.15, -0.16] mmol/L, p = 0.02). FO significantly altered the serum lipid profile by reducing low-unsaturated TG species and increasing those containing DHA or EPA. FO had minor effects on gut microbiota, while baseline microbial features predicted the TG response to FO better than phenotypic or lipidomic features, potentially mediated by specific lipid metabolites. A total of 9 lipid metabolites significantly mediated the link between 4 baseline microbial variables and the TG response to FO supplementation.

CONCLUSIONS

Our findings demonstrate differential impacts of omega-3 fatty acids on lipidomic and microbial profiles in T2D and highlight the importance of baseline gut microbiota characteristics in predicting the TG-lowering efficacy of FO.

FUNDING

This study was funded by the National Nature Science Foundation.

Inflammation and resolution in obesity

Inflammation is an essential physiological defence mechanism, but prolonged or excessive inflammation can cause disease. Indeed, unresolved systemic and adipose tissue inflammation drives obesity-related cardiovascular disease and type 2 diabetes mellitus. Drugs targeting pro-inflammatory cytokine pathways or inflammasome activation have been approved for clinical use for the past two decades. However, potentially serious adverse effects, such as drug-induced weight gain and increased susceptibility to infections, prevented their wider clinical implementation. Furthermore, these drugs do not modulate the resolution phase of inflammation. This phase is an active process orchestrated by specialized pro-resolving mediators, such as lipoxins, and other endogenous resolution mechanisms. Pro-resolving mediators mitigate inflammation and development of obesity-related disease, for instance, alleviating insulin resistance and atherosclerosis in experimental disease models, so mechanisms to modulate their activity are, therefore, of great therapeutic interest. Here, we review current clinical attempts to either target pro-inflammatory mediators (IL-1β, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome, tumour necrosis factor (TNF) and IL-6) or utilize endogenous resolution pathways to reduce obesity-related inflammation and improve cardiometabolic outcomes. A remaining challenge in the field is to establish more precise biomarkers that can differentiate between acute and chronic inflammation and to assess the functionality of individual leukocyte populations. Such advancements would improve the monitoring of drug effects and support personalized treatment strategies that battle obesity-related inflammation and cardiometabolic disease.

Omega-3 fatty acid regulation of lipoprotein lipase and FAT/CD36 and its impact on white adipose tissue lipid uptake

Lipid uptake by white adipose tissue (WAT) is critically important for storage of excess energy and to protect peripheral tissues from ectopic lipid deposition. When WAT becomes dysfunctional (i.e., with obesity), it is characterized by impaired lipid uptake and increased lipolysis which, together, promote whole-body dyslipidemia. Omega-3 polyunsaturated fatty acids (N-3 PUFA) are widely studied for their triacylglycerol (TAG)-lowering properties and cardiometabolic health benefits. One potential mechanism underlying these benefits is the modification of WAT lipid uptake; however, there are gaps in our understanding regarding the specific mechanisms by which N-3 PUFA function. Evidence to date suggests that N-3 PUFA promote TAG clearance by increasing lipoprotein lipase (LPL) activity and the abundance of fatty acid transporters. Specifically, N-3 PUFA have been shown to increase LPL activity through increased gene transcription and modifications of endogenously produced LPL regulators such as apolipoprotein C-II/III and angiopoietin-like proteins. This review presents and discusses the available in vitro and in vivo research to provide a comprehensive overview of N-3 PUFA regulation of WAT lipid uptake in healthy and obese contexts. Additionally, we highlight areas where more research is necessary to better understand the contribution of increased WAT lipid uptake in relation to the TAG-lowering properties associated with N-3 PUFA.

Higher docosahexaenoic acid proportions in blood are inversely associated with the prevalence of prediabetes: Evidence from the UK Biobank

Prediabetes and type 2 diabetes mellitus are growing global health concerns, predisposing individuals to various vascular complications. Lifestyle modifications, including dietary interventions, offer promising avenues for prevention and management. Using a multivariable-adjusted model, we analyzed the cross-sectional associations between plasma proportions (% of total fatty acids) of omega-3 polyunsaturated fatty acids (n3 PUFA, including total n3 PUFA, docosahexaenoic acid [DHA], non-DHA n3 PUFA), and glycated hemoglobin A1c (HbA1c) as well as the prevalence of prediabetes in a sample from the UK Biobank cohort. Our hypothesis was that proportions of n3 PUFA, especially DHA, would by inversely associated with the prediabetes prevalence. The sample (n = 92,762; 54.5% females) had an average age of 56 years and was overweight (mean body mass index = 27). The mean plasma DHA proportion in the sample was 2.03% (standard deviation [SD] = 0.67%), non-DHA n3 PUFA was 2.41% (SD = 1.02%) and total n3 PUFA was 4.43% (SD = 1.56%). Prediabetic individuals were identified by blood HbA1c proportions between 5.7% and 6.4% (39-46 mmol/mol) according to American Diabetes Association criteria. Each of the three n3 PUFA biomarkers was inversely associated with HbA1c proportions. In particular, DHA showed the strongest inverse association, with an OR of 0.62 (95% confidence intervals: 0.58, 0.67; P < .001) when comparing quintiles 5 to 1 in a fully adjusted model. These findings suggest a potential protective role of n3 PUFA, particularly DHA, in mitigating the risk of having prediabetes. Further prospective investigations are needed to clarify whether long-chain n3 PUFA could function as modifiable factors for prediabetes.

The role of dietary inflammatory index in metabolic diseases: the associations, mechanisms, and treatments

In recent years, the prevalence of metabolic diseases has increased significantly, posing a serious threat to global health. Chronic low-grade inflammation is implicated in the development of most metabolic diseases, such as type 2 diabetes mellitus (T2DM), obesity, dyslipidemia, and cardiovascular disease, serving as a link between diet and these conditions. Increasing attention has been directly toward dietary inflammatory patterns that may prevent or ameliorate metabolic diseases. The Dietary Inflammatory Index (DII) was developed to assess the inflammatory potential of dietary intake. Consequently, a growing body of research has examined the associations between the DII and the risk of several metabolic diseases. In this review, we explore the current scientific literature on the relationships between the DII, T2DM, obesity, and dyslipidemia. It summarizes recent findings and explore potential underlying mechanisms from two aspects: the interaction between diet and inflammation, and the link between inflammation and metabolic diseases. Furthermore, this review discusses the therapeutic strategies, including dietary modifications, prebiotics, and probiotics, and discusses the application of the DII in metabolic diseases, as well as future research directions.

Dietary n-3 Fatty Acids Intake and All-Cause and Cardiovascular Mortality in Patients With Prediabetes and Diabetes

CONTEXT

While the association between n-3 polyunsaturated fatty acids (PUFAs) and cardiovascular (CV) events has been thoroughly examined, there is still a scarcity of research regarding their effect on the long-term prognosis in diabetic patients.

OBJECTIVE

We aimed to explore the effects of n-3 PUFA on all-cause and cardiovascular mortality in patients with pre-diabetes and diabetes.

METHOD

Herein, a total of 16 539 eligible individuals were enrolled from the National Health and Nutrition Examination Survey (NHANES) 2003 to 2018, and categorized into T1, T2, and T3 based on the tertiles of n-3 PUFA. The Cox proportional risk regression models, Kaplan-Meier curve, and subgroup analysis were conducted to evaluate the association between n-3 PUFA and mortality. Restricted cubic spline (RCS) curves graphically demonstrated the dose-response relationship. Additionally, weighted quantile sum (WQS) models were adopted to measure the mixed and individual effects of n-3 PUFA on mortality.

RESULTS

Following a median follow-up period of 8.42 years, 3010 individuals died, with 989 deaths attributed to CV diseases. Significantly lower risk of all-cause (T2: 0.81 [0.71-0.92], T3: 0.77 [0.64-0.94]) and CV (T2: 0.75 [0.61-0.93]) mortality was observed after adjusting for multivariables compared to the reference (T1). Meanwhile, the RCS curve revealed a negative nonlinear association between n-3 PUFA and mortality. None of the interactions in any subgroup analysis were statistically significant except for BMI (P for interaction = .049). Finally, the WQS analysis demonstrated alpha-linolenic acid (ALA) and docosapentaenoic acid (DPA) as the main contributors to n-3 PUFAs' benefits against mortality.

CONCLUSION

Increased dietary intake of n-3 PUFAs, particularly ALA and DPA, was associated with a reduced risk of all-cause and CV mortality among Americans with prediabetes and diabetes.

Intermittent fasting in the management of diabetes: a review of glycemic control and safety

Intermittent fasting (IF) regimens have emerged as a dietary tool to improve the glycemic profile, but a critical appraisal of clinical studies assessing the effects of IF regimens in patients with diabetes is needed. Thus, this review encompasses clinical studies examining the impact of different IF regimens on markers of glycemic control in patients with diabetes. Furthermore, clinical nuances relative to pharmacological treatment are also addressed, mainly insulin therapy, to discuss the risk of hypoglycemic events. Only a handful of clinical studies have investigated the effects of IF on patients with diabetes. Overall, IF regimens may elicit modest benefits on glycemic parameters in patients with diabetes, but their effects are not necessarily greater than those of control diets. Last, although IF regimens may be considered safe for patients receiving insulin therapy within interventional and observational research, markers of glycemic control must be constantly monitored in clinical practice to reduce the risk of hypoglycemia and its related complications.

Influence of Type 2 Diabetes and Adipose Tissue Dysfunction on Breast Cancer and Potential Benefits from Nutraceuticals Inducible in Microalgae

Breast cancer (BC) represents the most prevalent cancer in women at any age after puberty. From a pathogenetic prospective, despite a wide array of risk factors being identified thus far, poor metabolic health is emerging as a putative risk factor for BC. In particular, type 2 diabetes mellitus (T2DM) provides a perfect example bridging the gap between poor metabolic health and BC risk. Indeed, T2DM is preceded by a status of hyperinsulinemia and is characterised by hyperglycaemia, with both factors representing potential contributors to BC onset and progression. Additionally, the aberrant secretome of the dysfunctional, hypertrophic adipocytes, typical of obesity, characterised by pro-inflammatory mediators, is a shared pathogenetic factor between T2DM and BC. In this review, we provide an overview on the effects of hyperglycaemia and hyperinsulinemia, hallmarks of type 2 diabetes mellitus, on breast cancer risk, progression, treatment and prognosis. Furthermore, we dissect the role of the adipose-tissue-secreted adipokines as additional players in the pathogenesis of BC. Finally, we focus on microalgae as a novel superfood and a source of nutraceuticals able to mitigate BC risk by improving metabolic health and targeting cellular pathways, which are disrupted in the context of T2DM and obesity.

EPA and DHA differentially improve insulin resistance by reducing adipose tissue inflammation-targeting GPR120/PPARγ pathway

Insulin resistance (IR) is a global health challenge, often initiated by dysfunctional adipose tissue. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may have different effects on IR, but the mechanisms are unknown. This study aims to evaluate the protective effect of EPA and DHA against IR in a high-fat diet (HFD) mice model and investigate whether EPA and DHA alter IR modulate the G-protein-poupled receptor 120/peroxisome proliferator-activated receptor γ (GPR120/PPARγ) pathway in macrophages and adipocytes, which may affect IR in adipocytes. The findings of this study show that 4% DHA had a better effect in improving IR and reducing inflammatory cytokines in adipose tissue of mice. Additionally, in the cell experiment, the use of AH7614 (a GPR120 antagonist) inhibited the glucose consumption increase and the increasable expression of PPARγ and insulin signaling molecules mediated by DHA in adipocytes. Furthermore, GW9662 (a PPARγ antagonist) hindered the upregulation of glucose consumption and insulin signaling molecule expression induced by EPA and DHA in adipocytes. DHA exhibited significant effects in reducing the number of migrated cells and inflammation. The compounds AH7614 and GW9662 hindered the suppressive effects of EPA and DHA on macrophage-induced IR in adipocytes. These findings suggest that DHA has a stronger potential in improving IR in adipocytes through the GPR120/PPARγ pathway in macrophages, when compared to EPA.

Exploring the causal effect of omega-3 polyunsaturated fatty acid levels on the risk of type 1 diabetes: a Mendelian randomization study

The burden of Type 1 diabetes (T1D) is vast and as of 2021, an estimated 8.4 million people were living with the disease worldwide. Predictably, this number could increase to 17.4 million people by 2040. Despite nearly a century of insulin therapy for the management of hyperglycemia in T1D, no therapies exist to treat its underlying etiopathology. Adequate dietary intake of omega-3 fatty acids (ω-3) has been reported in observational studies and Randomized Controlled Trials to be associated with reduced risk of developing T1D but results have been inconclusive. We conducted a Mendelian randomization (MR) study to explore the relationship between ω-3 intake and T1D. We performed a two-sample MR analysis using single nucleotide polymorphisms associated with ω-3 levels in a sample of 114,999 Europeans and their effects on T1D from a genome-wide association study meta-analysis of 24,840 European participants. A main MR analysis using the Inverse-variance weighted (IVW) method was conducted and validated using MR-Egger, Weighted median, and Weighted mode methods. Sensitivity analyses excluding potentially pleiotropic single nucleotide polymorphisms were also performed. Main MR analysis using the IVW method showed no evidence of a causal relationship between ω-3 levels and T1D risk (OR: 0.92, 95% CI: 0.56-1.51, p = 0.745). MR-Egger and Weighted mode methods showed similar results while Weighted median showed a marginally significant association (OR: 1.15, CI: 1.00-1.32, p = 0.048). Sensitivity analysis revealed heterogeneity in the main analysis MR estimates (IVW Q > 100, p < 0.0001) and no directional pleiotropy (Egger intercept: -0.032, p = 0.261). Our study found limited evidence of a causal association between ω-3 and T1D, with only a marginally significant association observed in one of the four MR methods. This challenges the proposition that ω-3-rich diets are of substantial benefit for the prevention and management of T1D.

The effect of curcumin and high-content eicosapentaenoic acid supplementations in type 2 diabetes mellitus patients: a double-blinded randomized clinical trial

BACKGROUND/OBJECTIVES

The present study investigated the effect of curcumin and eicosapentaenoic acid, as one the main components of omega-3 polyunsaturated fatty acids, on anthropometric, glucose homeostasis, and gene expression markers of cardio-metabolic risk in patients with type 2 diabetes mellitus.

SUBJECTS/METHODS

This clinical trial was conducted at the Endocrinology Clinic of Imam Reza Hospital in Tabriz. It aimed to determine the impact of Eicosapentaenoic Acid (EPA), Docosahexaenoic Acid (DHA), and curcumin supplements on various health indicators in patients with Type 2 Diabetes Mellitus (DM2) from 2021.02.01 to 2022.02.01. The study was a randomized double-blinded clinical trial and conducted over 12 weeks with 100 participants randomly divided into four groups. Stratified randomization was used to assign participants to two months of supplementation based on sex and Body Mass Index (BMI). The study comprised four groups: Group 1 received 2 capsules of 500 mg EPA and 200 mg DHA, along with 1 nano-curcumin placebo; Group 2 received 1 capsule of 80 mg nano-curcumin and 2 omega 3 Fatty Acids placebos; Group 3 received 2 capsules of 500 mg EPA and 200 mg DHA, and 1 capsule of 80 mg nano-curcumin; Group 4, the control, received 2 omega 3 Fatty Acids placebos and 1 nano-curcumin placebo.

RESULTS

After twelve weeks of taking EPA + Nano-curcumin supplements, the patients experienced a statistically significant reduction in insulin levels in their blood [MD: -1.44 (-2.70, -0.17)]. This decrease was significantly greater than the changes observed in the placebo group [MD: -0.63 (-1.97, 0.69)]. The EPA + Nano-curcumin group also showed a significant decrease in High-Sensitivity C-Reactive Protein (hs-CRP) levels compared to the placebo group (p < 0.05). Additionally, the EPA + Nano-curcumin group had a significant increase in Total Antioxidant Capacity (TAC) levels compared to the placebo group (p < 0.01). However, there were no significant differences in Fasting Blood Sugar (FBS), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) index, Quantitative Insulin Sensitivity Check Index (QUICKI), or Hemoglobin A1c (HbA1C) levels between the four groups (all p > 0.05). There were significant differences between the Nano-curcumin and EPA groups [MD: -17.02 (-32.99, -1.05)], and between the Nano-curcumin and control groups [MD: -20.76 (-36.73, -4.79)] in terms of lowering the serum cholesterol level. The difference in Triglycerides (TG) serum levels between the EPA + Nano-curcumin and placebo groups were not statistically significant (p = 0.093). The Nano-curcumin group showed significant decreases in Low-Density Lipoprotein (LDL) levels compared to the EPA group [MD: -20.12 (-36.90, -3.34)] and the control group [MD: -20.79 (-37.57, -4.01)]. There was a near-to-significant difference in High-Density Lipoprotein (HDL) serum levels between the EPA + Nano-curcumin and EPA groups (p = 0.056). Finally, there were significant differences in the decrease of serum Vascular Endothelial Growth Factor (VEGF) levels between the EPA and Nano-curcumin groups [MD: -127.50 (-247.91, -7.09)], the EPA and placebo groups [MD: 126.25 (5.83, 246.66)], the EPA + Nano-curcumin and Nano-curcumin groups [MD: -122.76 (-243.17, -2.35)], and the EPA + Nano- curcumin and placebo groups [MD: 121.50 (1.09, 241.92)].

CONCLUSIONS

The findings of the present study suggest that 12-week supplementation with EPA and Nano-curcumin may positively impact inflammation, oxidative stress, and metabolic parameters in patients with diabetes. The supplementation of EPA and Nano-curcumin may be a potential intervention to manage diabetes and reduce the risk of complications associated with diabetes. However, further research is needed to validate the study's findings and establish the long-term effects of EPA and Nano-curcumin supplementation in patients with diabetes.

The disparate effects of omega-3 PUFAs on intestinal microbial homeostasis in experimental rodents under physiological condition

The health benefits of omega-3 polyunsaturated fatty acids (omega-3 PUFAs), primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are linked to their regulatory effects on the composition of the gut microbiota. However, there is a lack of direct evidence on whether omega-3 PUFAs regulate the gut microbial homeostasis under physiological conditions. This study investigated the impact of equivalent doses of EPA, DHA, and fish oil (FO) with a DHA to EPA ratio of approximately 1:1 on the bacterial and fungal composition of normal young mice. This study also analyzed changes in key components of the gut microenvironment, including the colonic mucus barrier and short-chain fatty acids, to address the prebiotic potential of omega-3 PUFAs. The results showed that all three omega-3 PUFAs interventions induced significant fluctuations in the gut bacteria and fungi, leading to an increase in the abundance of some probiotics. Notably, DHA, EPA, and FO interventions significantly increased the abundance of the probiotic Lactobacillus, Bifidobacterium, and Akkermansia, respectively. Both DHA and fish oil interventions also significantly reduced the abundance of potentially pathogenic fungi, such as Aspergillus and Penicillium. Association analysis of the top 19 differential fungal and bacterial genera in abundance revealed a much more bacteria-bacteria and bacteria-fungi connections, but fewer fungi-fungi connections. This highlights the importance of bacteria in the gut microecological network. Furthermore, the levels of butyric acid and valeric acid in the colonic contents of DHA intervention group were significantly increased, and the colonic mucus layer thickness was increased in three treatment groups. In summary, DHA, EPA and FO interventions showed targeted enhancement of different probiotics and enhanced colon defense barrier (mucus barrier), showing potential prebiotic effects.

Comparison of the effects of monounsaturated fatty acids and polyunsaturated fatty acids on the lipotoxicity of islets

Background

Monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) have been reported to combat saturated fatty acid (SFA)-induced cellular damage, however, their clinical effects on patients with metabolic diseases such as diabetes and hyperlipidemia are still controversial. Since comparative studies of the effects of these two types of unsaturated fatty acids (UFAs) are still limited. In this study, we aimed to compare the protective effects of various UFAs on pancreatic islets under the stress of SFA-induced metabolic disorder and lipotoxicity.

Methods

Rat insulinoma cell line INS-1E were treated with palmitic acid (PA) with or without UFAs including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and oleic acid (OA) to determine cell viability, apoptosis, endoplasmic reticulum (ER) stress, and inflammatory. In vivo, male C57BL/6 mice were fed a 60% high-fat diet (HFD) for 12 w. Then the lard in HFD was partially replaced with fish oil (FO) and olive oil (OO) at low or high proportions of energy (5% or 20%) to observe the ameliorative effects of the UFA supplement.

Results

All UFAs significantly improved PA-induced cell viability impairment in INS-1E cells, and their alleviation on PA induced apoptosis, ER stress and inflammation were confirmed. Particularly, OA had better effects than EPA, DHA, and AA on attenuating cellular ER stress. In vivo, the diets with a low proportion of UFAs (5% of energy) had limited effects on HFD induced metabolic disorder, except for a slight improved intraperitoneal glucose tolerance in obese mice. However, when fed diets containing a high proportion of UFAs (20% of energy), both the FO and OO groups exhibited substantially improved glucose and lipid metabolism, such as decrease in total cholesterol (TC), low-density lipoprotein (LDL), fasting blood glucose (FBG), and fasting blood insulin (FBI)) and improvement of insulin sensitivity evidenced by intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test (IPITT). Unexpectedly, FO resulted in abnormal elevation of the liver function index aspartate aminotransferase (AST) in serum. Pathologically, OO attenuated HFD-induced compensatory hyperplasia of pancreatic islets, while this effect was not obvious in the FO group.

Conclusions

Both MUFAs and PUFAs can effectively protect islet β cells from SFA-induced cellular lipotoxicity. In particular, both OA in vitro and OO in vivo showed superior activities on protecting islets function and enhance insulin sensitivity, suggesting that MUFAs might have greater potential for nutritional intervention on diabetes.

New light on ω-3 polyunsaturated fatty acids and diabetes debate: a population pharmacokinetic-pharmacodynamic modelling and intake threshold study

OBJECTIVE

ω-3 polyunsaturated fatty acids (PUFA) are a key modifiable factor in the intervention of type 2 diabetes, yet recommendations for dietary consumption of ω-3 PUFA in type 2 diabetes remain ambiguous and controversial. Here, we revisit the subject in the light of population pharmacokinetic-pharmacodynamic (PPK-PD) modeling and propose a threshold for intake.

RESEARCH DESIGN AND METHODS

Plasma levels of ω-3 PUFA and glycosylated hemoglobin (HbA1c) were measured as pharmacokinetic and pharmacodynamic indicator, respectively. The nonlinear mixed effect analysis was used to construct a PPK-PD model for ω-3 PUFA and to quantify the effects of FADS gene polymorphism, age, liver and kidney function, and other covariables.

RESULTS

Data from 161 patients with type 2 diabetes in the community were modeled in a two-compartment model with primary elimination, and HDL was a statistically significant covariate. The simulation results showed that HbA1c showed a dose-dependent decrease of ω-3 PUFA plasma level. A daily intake of ω-3 PUFA at 0.4 g was sufficient to achieve an HbA1c level of 7% in more than 95% of patients.

CONCLUSIONS

PPK/PD modeling was proposed as a multilevel analytical framework to quantitatively investigate finer aspects of the complex relationship between ω-3 PUFA and type 2 diabetes on genetic and non-genetic influence factors. The results support a beneficial role for ω-3 PUFA in type 2 diabetes and suggested the intake threshold. This new approach may provide insights into the interaction of the two and an understanding of the context in which changes occur.

Omega-3 fatty acids supplementation improves early-stage diabetic nephropathy and subclinical atherosclerosis in pediatric patients with type 1 diabetes: A randomized controlled trial

BACKGROUND

Numerous studies have evaluated the beneficial effects of omega-3 fatty acids on inflammatory, autoimmune and renal diseases. However, data about the effects of omega-3 fatty acids on diabetic kidney disease in type 1 diabetes mellitus (T1DM) are lacking.

OBJECTIVES

This randomized-controlled trial assessed the effect of oral omega-3 supplementation on glycemic control, lipid profile, albuminuria level, kidney injury molecule-1 (KIM-1) and carotid intima media thickness (CIMT) in pediatric patients with T1DM and diabetic nephropathy.

METHODS

Seventy T1DM patients and diabetic nephropathy were enrolled with a mean age 15.2 ± 1.96 years and median disease duration 7 years. Patients were randomly assigned into two groups; intervention group which received oral omega-3 fatty acids capsules (1 g daily). The other group received a matching placebo and served as a control group. Both groups were followed-up for 6 months with assessment of fasting blood glucose (FBG), HbA1c, fasting lipids, urinary albumin creatinine ratio (UACR), KIM-1 and CIMT.

RESULTS

After 6 months, omega-3 fatty acids adjuvant therapy for the intervention group resulted in a significant decrease in FBG, HbA1c, triglycerides, total cholesterol, LDL-cholesterol, UACR, KIM-1 and CIMT, whereas, HDL-cholesterol was significantly higher post-therapy compared with baseline levels and compared with the control group (p < 0.05). Baseline KIM-1 levels were positively correlated to HbA1c, UACR and CIMT. Supplementation with omega-3 fatty acids was safe and well-tolerated.

CONCLUSIONS

Omega-3 fatty acids as an adjuvant therapy in pediatric T1DM patients with diabetic nephropathy improved glycemic control, dyslipidemia and delayed disease progression and subclinical atherosclerosis among those patients. This trial was registered under ClinicalTrials.gov Identifier no. NCT05980026.

Key Nutrients for Optimal Blood Glucose Control and Mental Health in Individuals with Diabetes: A Review of the Evidence

Diabetes is associated with an increased risk of mental disorders, including depression, anxiety, and cognitive decline. Mental disorders can also contribute to the development of diabetes through various mechanisms including increased stress, poor self-care behaviors, and adverse effects on glucose metabolism. Consequently, individuals suffering from either of these conditions frequently experience comorbidity with the other. Nutrition plays an important role in both diabetes and mental health disorders including depression and anxiety. Deficiencies in specific nutrients such as omega-3 fatty acids, vitamin D, B vitamins, zinc, chromium, magnesium, and selenium have been implicated in the pathogenesis of both diabetes and mental disorders. While the impact of nutrition on the progression and control of diabetes and mental disorders is broadly acknowledged, there is a notable knowledge gap concerning the implications of distinct nutrients in preventing and mitigating symptoms of both conditions when they coexist. The aim of this study was to examine the role of nutrition in improving glucose homeostasis and promoting mental well-being among individuals with diabetes. Further, we evaluated the preventive or delaying effects of key nutrients on the simultaneous manifestation of these conditions when one of them is present. Our findings indicated that the use of personalized dietary interventions and targeted nutrient supplementation can improve metabolic and mental health outcomes in patients with type 2 diabetes.

Association between dietary glycemic index and non-alcoholic fatty liver disease in patients with type 2 diabetes mellitus

Objective

Managing dietary glycemic index (GI) deserves further attention in the interplay between non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM). This study aimed to evaluate the relationship between dietary GI and the odds of NAFLD in patients with T2DM.

Methods

A cross-sectional study was carried out between April 2021 and February 2022, including 200 participants with T2DM aged 18-70 years, of which 133 had NAFLD and 67 were in the non-NAFLD group. Cardiometabolic parameters were analyzed using standard biochemical kits and dietary intake was assessed using a validated food frequency questionnaire. Binary logistic regression was applied to explore odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD according to tertiles of dietary GI.

Results

Highest vs. lowest tertile (< 57 vs. > 60.89) of energy-adjusted GI was not associated with the odds of having NAFLD (OR 1.25, 95% CI = 0.6-2.57; P-trend = 0.54) in the crude model. However, there was an OR of 3.24 (95% CI = 1.03-10.15) accompanied by a significant trend (P-trend = 0.04) after full control for potential confounders (age, gender, smoking status, duration of diabetes, physical activity, waist circumference, HbA1c, triglycerides, total cholesterol, dietary intake of total carbohydrates, simple carbohydrates, fat, and protein).

Conclusion

High dietary GI is associated with increased odds of NAFLD in subjects with T2DM. However, interventional and longitudinal cohort studies are required to confirm these findings.

Evaluating the distinct pleiotropic effects of omega-3 fatty acids on type 2 diabetes mellitus: a mendelian randomization study

BACKGROUND

Observational studies and conventional Mendelian randomization (MR) studies showed inconclusive evidence to support the association between omega-3 fatty acids and type 2 diabetes. We aim to evaluate the causal effect of omega-3 fatty acids on type 2 diabetes mellitus (T2DM), and the distinct intermediate phenotypes linking the two.

METHODS

Two-sample MR was performed using genetic instruments derived from a recent genome-wide association study (GWAS) of omega-3 fatty acids (N = 114,999) from UK Biobank and outcome data obtained from a large-scale T2DM GWAS (62,892 cases and 596,424 controls) in European ancestry. MR-Clust was applied to determine clustered genetic instruments of omega-3 fatty acids that influences T2DM. Two-step MR analysis was used to identify potential intermediate phenotypes (e.g. glycemic traits) that linking omega-3 fatty acids with T2DM.

RESULTS

Univariate MR showed heterogenous effect of omega-3 fatty acids on T2DM. At least two pleiotropic effects between omega-3 fatty acids and T2DM were identified using MR-Clust. For cluster 1 with seven instruments, increasing omega-3 fatty acids reduced T2DM risk (OR: 0.52, 95%CI 0.45-0.59), and decreased HOMA-IR (β = - 0.13, SE = 0.05, P = 0.02). On the contrary, MR analysis using 10 instruments in cluster 2 showed that increasing omega-3 fatty acids increased T2DM risk (OR:1.10; 95%CI 1.06-1.15), and decreased HOMA-B (β = - 0.04, SE = 0.01, P = 4.52 × 10^-5). Two-step MR indicated that increasing omega-3 fatty acid levels decreased T2DM risk via decreasing HOMA-IR in cluster 1, while increased T2DM risk via decreasing HOMA-B in cluster 2.

CONCLUSIONS

This study provides evidence to support two distinct pleiotropic effects of omega-3 fatty acids on T2DM risk influenced by different gene clusters, which could be partially explained by distinct effects of omega-3 fatty acids on insulin resistance and beta cell dysfunction. The pleiotropic feature of omega-3 fatty acids variants and its complex relationships with T2DM need to be carefully considered in future genetic and clinical studies.

Assessing the Highest Level of Evidence from Randomized Controlled Trials in Omega-3 Research

Over the years, there has been heightened interest in the health benefits of n-3 polyunsaturated fatty acids (PUFA) in reducing chronic diseases such as, cardiovascular disease (CVD), cancer, type 2 diabetes, and acute macular degeneration (AMD). Due to inconsistent findings in the evidence, a review to critically examine the plethora of evidence from randomized controlled trials (RCTs) in n-3 PUFA research was undertaken. The aim of this review is to study the highest level of evidence and to identify gaps in n-3 PUFA research. RCTs were originally designed for pharmaceutical research and later adopted for nutrition and food-related research. RCTs with active diseases assume that n-3 PUFA will have "drug" like effects, and this high expectation may have led to the inconsistent evidence in the literature. The inconsistency in the literature may be related to varying doses of n-3 PUFA, sources of n-3 PUFA (food vs. supplement; plant vs. marine), type of n-3 PUFA (mixture vs. purified), trial duration, population characteristics, sample size, and genetic variation. For future research, there is a need to distinguish between primary and secondary prevention, and to focus RCTs on primary prevention of chronic diseases by n-3 PUFA which is lacking in the literature.

γ-Linolenic Acid-Rich Oil- and Fish Oil-Induced Alterations of Hepatic Lipogenesis, Fatty Acid Oxidation, and Adipose Tissue mRNA Expression in Obese KK-A y Mice

The physiological activity of γ-linolenic acid (GLA)-rich evening primrose oil and eicosapentaenoic and doxosahexaenoic acids-rich fish oil, which affect hepatic fatty acid oxidation and synthesis, and adipose tissue mRNA expression were compared in diabetic obese KK-A ^y mice. The mice were fed diets containing 100 g/kg of either palm oil (saturated fat), GLA oil, or fish oil for 21 days. These oils, compared with palm oil, greatly increased the activity and mRNA levels of hepatic fatty acid oxidation enzymes. These oils also increased the carnitine concentrations and mRNA levels of carnitine transporter (solute carrier family 22, member 5) in the liver. In general, these effects were comparable between GLA and fish oils. In contrast, GLA and fish oils, compared with palm oil, reduced the activity and mRNA levels of the proteins related to hepatic lipogenesis, except for those of malic enzyme. The reducing effect was stronger for fish oil than for GLA oil. These changes were accompanied by reductions in the triacylglycerol levels in the serum and liver. The reduction in the liver was stronger for fish oil than for GLA oil. These oils also reduced epididymal adipose tissue weight accompanied by a reduction in the mRNA levels of several proteins that regulate adipocyte functions; these effects were stronger for fish oil than for GLA oil. These oils were also effective in reducing serum glucose levels. Therefore, both fish oil and GLA-rich oil were effective at ameliorating metabolic disorders related to obesity and diabetes mellitus.

Effects of omega-3 supplementation on lean body mass in cancer patients: a systematic review and meta-analysis

Omega-3 fatty acids are bioactive nutrients with the potential to preserve lean body mass in individuals with cancer. This study aimed to review the literature on randomized clinical trials that evaluated the effects of omega-3 supplementation on lean body mass in cancer patients. As secondary objectives, we evaluated the effects of omega-3 supplementation on body mass index (BMI) and body weight. We conducted a systematic review and meta-analysis in the following databases: Pubmed, LILACS, Scielo, Scopus, Web of Science, Cochrane, and Embase. It included randomized clinical trials that investigated the effects of omega-3 supplementation on lean body mass in cancer patients. Observational studies, animal experiments, studies carried out with healthy humans, and non-randomized clinical trials were excluded. We utilized the Cochrane scale to assess the quality of the studies. A meta-analysis was carried out to evaluate the effect of omega-3 on lean body mass, BMI, and body weight. Fourteen studies were included, of which four showed significant results from omega-3 supplementation for lean body mass. In the meta-analysis, omega-3 fatty acids increased lean body mass by 0.17 kg compared to placebo, but without significant differences between the groups [SMD: 0.17; CI 95%: -0.01, 0.35; I2 = 41%]. For body weight, omega-3 showed a statistically significant effect [SMD: 0.26; CI 95%: 0.06, 0.45; I2 = 46%], whereas for BMI the results were not significant. This systematic review and meta-analysis showed no statistically significant effect from omega-3 on lean body mass and BMI. On the other hand, there was a statistical significance for body weight.

Increased Plasma L-Arginine Levels and L-Arginine/ADMA Ratios after Twelve Weeks of Omega-3 Fatty Acid Supplementation in Amateur Male Endurance Runners

It is not fully understood how supplementation with omega-3 fatty acids affects the metabolism of amino acids required for the bioavailability/synthesis of NO, i.e., L-arginine (L-arg), asymmetric dimethylarginine (ADMA), their metabolites, and the L-arg/ADMA ratio and their impact on running economy (RE) in runners. Thus, 26 male amateur endurance runners completed a twelve-week study in which they were divided into two supplemented groups: the OMEGA group (n = 14; 2234 mg and 916 mg of eicosapentaenoic and docosahexaenoic acid daily) or the MCT group (n = 12; 4000 mg of medium-chain triglycerides daily). At the same time, all participants followed an endurance training program. Before and after the 12-week intervention, blood was collected from participants at two time points (at rest and immediately post-exercise) to determine EPA and DHA in red blood cells (RBCs) and plasma levels of L-arg, ADMA, and their metabolites. RBC EPA and DHA significantly increased in the OMEGA group (p < 0.001), which was related to the resting increase in L-arg (p = 0.001) and in the L-arg/ADMA ratio (p = 0.005) with no changes in the MCT group. No differences were found in post-exercise amino acid levels. A total of 12 weeks of omega-3 fatty acid supplementation at a dose of 2234 mg of EPA and 916 mg of DHA daily increased levels of L-arg and the L-arg/ADMA ratio, which indirectly indicates increased bioavailability/NO synthesis. However, these changes were not associated with improved RE in male amateur endurance runners.

Comparison of nutritional supplements for glycemic control in type 2 diabetes: A systematic review and network meta-analysis of randomized trials

AIMS

Direct and indirect evidence were combined in this systematic-review and network meta-analysis (NMA) to assess and compare the effect of nutritional supplements on glycemic control, and rank the supplements accordingly.

METHODS

PubMed, Scopus, and Web of Science were searched up to April 2021. We included randomized controlled trials that investigated the effect of vitamins D, C, and E, magnesium, zinc, calcium, selenium, and omega-3 on at least one glycemic marker, including glycated hemoglobin (HbA1c), fasting blood sugar (FBS), homeostasis model assessment-estimated insulin resistance (HOMA-IR), HOMA-B, and insulin, in adults with type 2 diabetes. To estimate effectiveness of supplements, a random-effects NMA in the Bayesian framework was applied. To assess risk of bias, Cochrane Collaboration Tool was used.

RESULTS

Analysis of 178 studies indicated that zinc, vitamin D, omega-3, vitamin C, and vitamin E were effective in reducing HbA1c with low certainty. For reduction of FBS, zinc, vitamin D, and vitamin C, and for HOMA-IR, vitamin D were effective with low certainty. None of the supplements were effective in the reduction of insulin and HOMA-B with low certainty. After excluding poor-quality studies, only vitamin D was significantly effective in reducing all of the markers. Consistently, when the analysis was restricted to studies with a duration of ≥12-weeks, vitamin D reduced HbA1c, FBS, and HOMA-IR.

CONCLUSIONS

Vitamin D supplementation was more effective compared to other supplements in improving HbA1c, FBS, and HOMA-IR, albeit with low certainty of evidence. This result was confirmed by low-risk of bias studies.

REGISTRATION

CRD42021240691.

Omega-3 fatty acids coordinate glucose and lipid metabolism in diabetic patients

Omega 3 polyunsaturated fatty acids (n-3 PUFA) are known to have beneficial effects on cardiovascular and metabolic health. However, whether different sources of n-3 PUFA, for instance fatty fish vs vegetable oils, could elicit different effects on glucose and lipid metabolism, remains to be determined. Herein we examine recent findings showing that while a plant-based n-3 PUFA supplementation for six months can reduce fasting blood glucose, marine-based n-3 PUFA can instead reduce serum levels of triglycerides. We also discuss the potential molecular mechanisms that could underlie these different effects on the regulation of glycolipid metabolism.

Effects of marine-derived and plant-derived omega-3 polyunsaturated fatty acids on erythrocyte fatty acid composition in type 2 diabetic patients

Background

Dietary fatty acids intake affects the composition of erythrocyte fatty acids, which is strongly correlated with glycolipid metabolism disorders. This study aimed at investigating the different effects of marine-derived and plant-derived omega-3 polyunsaturated fatty acid (n-3 PUFA) on the fatty acids of erythrocytes and glycolipid metabolism in patients with type 2 diabetes mellitus (T2DM).

Methods

The randomized double-blinded trial that was performed on 180 T2DM patients. The participants were randomly assigned to three groups for the six-month intervention. The participants were randomly assigned to three groups for the six-month intervention. The fish oil (FO) group was administered with FO at a dose of 3 g/day containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the perilla oil (PO) group was administered with PO at a dose of 3 g/day containing α-linolenic (ALA), the linseed and fish oil (LFO) group was administered with mixed linseed and fish oil at a dose of 3 g/day containing EPA, DHA and ALA. Demographic information were collected and anthropometric indices, glucose and lipid metabolism indexes, erythrocyte fatty acid composition were measured. Statistical analyses were performed using two-way ANOVA.

Results

A total of 150 patients finished the trial, with 52 of them in the FO group, 50 in the PO group and 48 in the LFO group. There were significant effects of time × treatment interaction on fast blood glucose (FBG), insulin, HOMA-IR and C-peptide, TC and triglyceride (TG) levels (P < 0.001). Glucose and C-peptide in PO and LFO groups decreased significantly and serum TG in FO group significantly decreased (P < 0.001) after the intervention. Erythrocyte C22: 5 n-6, ALA, DPA, n-6/n-3 PUFA, AA/EPA levels in the PO group were significantly higher than FO and LFO groups, while EPA, total n-3 PUFA and Omega-3 index were significantly higher in the FO and LFO groups compared to PO group.

Conclusion

Supplementation with perilla oil decreased FBG while fish oil supplementation decreased the TG level. Marine-based and plant-based n-3 PUFAs exhibit different effects on fatty acid compositions of erythrocytes and regulated glycolipid metabolism.

Trial registration

This trial was recorded under Chinese Clinical Trial Registry Center (NO: ChiCTR-IOR-16008435) on May 28 2016.

Sandalwood seed oil improves insulin sensitivity in high-fat/high-sucrose diet-fed rats associated with altered intestinal microbiota and its metabolites

Sandalwood seed oil (SSO), rich in ximenynic acid, is extracted from the seed kernels of Santalum spicatum. The current work aimed to clarify the potential mechanisms of SSO in preventing insulin resistance (IR) by investigating the intestinal microbiota and its metabolites. Fifty male Sprague-Dawley rats were randomly divided into a standard chow group (N), and four high-fat/high-sucrose (HFHS) diet-fed groups plus 7% of SSO, fish oil (FO), linseed oil (LO) or sunflower oil (SO), respectively. After 12 weeks, the feces were collected and subsequently the rats were sacrificed for collecting blood and tissues. The results indicated that the SSO, FO and LO groups had a lower ratio of Firmicutes to Bacteroidetes (F/B) and lower levels of Actinobacteria phylum in their feces compared to the SO group. HOMA-IR was positively correlated with F/B (r = 0.63) and Actinobacteria (r = 0.64). At the genus level, beneficial bacteria, including Oscillospira, Clostridium, Turicibacter, Ruminococcus and Coprococcus, were more abundant, while destructive bacteria, such as Collinsella, were less abundant in the SSO group than in the SO group. The concentrations of fecal short-chain fatty acids (SCFAs) were higher, and the serum LPS and trimethylamine N-oxide (TMAO) were lower in the SSO, FO and LO groups than the SO group. In addition, SCFAs were negatively (r: -0.45 to -0.82), and LPS (r: 0.12 to 0.42) and TMAO (r: 0.32 to 0.49) were positively correlated with HOMA-IR and serum IL-1β, IL-6 and TNF-α. In summary, the prevention effect of SSO on HFHS induced IR was associated with altered intestinal microbiota composition and the production of microbial metabolites.

Exploring the therapeutic potential of omega-3 fatty acids in depression

Omega-3 fatty acids have been acknowledged for their number of holdings on an individual's health. Not only in physical valuation but also in managing psychiatric disorders, omega-3 fatty acids have been found to be a powerful formula. It is proclaimed that depressive patients suffer anomaly with the levels of omega-3 polyunsaturated fatty acids in the body, coupled with insignificant EPA and DHA. Enhancement in brain functioning, neuronal functions, and paying attention in interacting with the brain cells are some of the additional tasks, being performed by the supplementation of omega-3 fatty acids. The leading and primary source via dietary supplementation involves the involvement of fish and fish products. These are hypothesized to be the best and dominant source for omega-3 fatty acids. Consumption of omega-3 fatty acid is well safe, that physician highly favors intake of these supplements, remarkably in the case of pregnant women. However, treating this serious life-threatening mental disorder leads to many adverse effects when treated with antidepressants. The dose range includes 1g/d to 10g/d, which is to be incorporated by the patient. It is also tested that the combination of EPA and DHA is found to be more efficacious for a person in treating and preventing depressive symptoms. Some studies verify the supplementation of omega-3 fatty acids in diet was coequally productive and successful with minimal side effects when analyzed with antidepressants. Despite these facts, much research is still needed and presently in process for long-term safety and studying the role of omega-3 fatty acids in human health.