Effects of dietary eicosapentaenoic acid and docosahexaenoic acid supplementation on metabolic syndrome: A systematic review and meta-analysis of data from 33 randomized controlled trials

Comparison of the efficacy of fish oil and probiotic supplementation on glucose and lipid metabolism in patients with type 2 diabetes: a systematic review and network meta-analysis

BACKGROUND

Abnormalities in glucose and lipid metabolism contribute to the progression and exacerbation of type 2 diabetes mellitus (T2DM). Fish oil and probiotics are dietary supplements that have the potential to improve glucose and lipid metabolism. However, their efficacy remains unclear in T2DM patients.

METHODS

PubMed, Embase, and the Cochrane Library were retrieved to collect randomized controlled trials (RCTs) on the efficacy of fish oil or probiotic supplementation in T2DM patients from the database inception to December 13, 2023. Primary outcome indicators encompassed glycated hemoglobin (HbA1c), homeostatic model assessment for insulin resistance (HOMA-IR) and blood lipid profile (triglyceride (TG) and total cholesterol (TC). Secondary outcome indicators included inflammatory markers such as tumor necrosis factor -α (TNF-α) and adipocytokine (including leptin and adiponectin). The R software was used for statistical analysis, and GraphPad Prism was used for figure rendering.

RESULTS

A total of 60 RCTs involving 3845 T2DM patients were included in the analysis. The results showed that the probiotics (Bifidobacterium, Lactobacillus, Lactococcus, Propionibacterium, etc.) were more effective in reducing HOMA-IR than fish oil (Surca = 0.935). Bifidobacterium demonstrated the highest efficacy in reducing HbA1c levels (Surca = 0.963). Regarding lipid metabolism, fish oil was superior to probiotics in lowering TG and TC levels (Surca values of 0.978 and 0.902, respectively). Furthermore, fish oil outperformed probiotics in reducing TNF-α (Surca = 0.839) and leptin (Surca = 0.712), and increasing adiponectin levels (Surca = 0.742). Node-splitting analysis showed good consistency (P > 0.05 for direct, indirect, and network comparison across various interventions).

CONCLUSIONS

In T2DM patients, fish oil was more effective than probiotics in regulating lipid metabolism. Probiotics outperformed fish oil in regulating glucose metabolism particularly; specifically, Bifidobacterium showed higher efficacy in reducing blood glucose.

Common clinical laboratory features among women with polycystic ovary syndrome and metabolic syndrome

Women with polycystic ovary syndrome (PCOS) have a high prevalence of metabolic syndrome (MS), with rates up to 33%. This is associated with long-term consequences such as cardiovascular diseases, type 2 diabetes mellitus (T2DM), cancer, sleep apnea, and psychological issues. The prevalence of MS worldwide is often associated with obesity and T2DM, yet regional variations are reported. In this study, 122 women consulting general practice and family medicine physicians were evaluated, revealing a BMI exceeding 30 kg/m2. Among MS criteria, the most common diagnoses were T2DM in 29 patients, insulin resistance (IR) in 36, arterial hypertension (AH) in 51, reduced HDL levels in 53, and elevated triglycerides in 39. Further analysis revealed 16 unique combinations of MS components in these patients, with 75% of PCOS cases exhibiting three MS components and 25% having four. Additionally, research indicated that most women with PCOS face persistent, treatment-resistant obesity, with a notably higher BMI (ρ=0.87; r=0.76). These findings highlight the multifactorial nature of PCOS and MS etiology.

Lipid-Lowering Nutraceuticals for an Integrative Approach to Dyslipidemia

Dyslipidemia is a treatable risk factor for atherosclerotic cardiovascular disease that can be addressed through lifestyle changes and/or lipid-lowering therapies. Adherence to statins can be a clinical challenge in some patients due to statin-associated muscle symptoms and other side effects. There is a growing interest in integrative cardiology and nutraceuticals in the management of dyslipidemia, as some patients desire or are actively seeking a more natural approach. These agents have been used in patients with and without established atherosclerotic cardiovascular disease. We provide an updated review of the evidence on many new and emerging nutraceuticals. We describe the mechanism of action, lipid-lowering effects, and side effects of many nutraceuticals, including red yeast rice, bergamot and others.

Effects of Microalgae on Metabolic Syndrome

Metabolic syndrome (MetS) is a cluster of metabolic disturbances, including abdominal obesity, hypertension, hypertriglyceridemia, reduced high-density lipoprotein cholesterol (HDL-C) and hyperglycemia. Adopting a healthier lifestyle and multiple drug-based therapies are current ways to manage MetS, but they have limited efficacy, albeit the prevalence of MetS is rising. Microalgae is a part of the human diet and has also been consumed as a health supplement to improve insulin sensitivity, inflammation, and several components of MetS. These therapeutic effects of microalgae are attributed to the bioactive compounds present in them that exhibit antioxidant, anti-inflammatory, anti-obesity, antihypertensive, hepatoprotective and immunomodulatory effects. Therefore, studies investigating the potential of microalgae in alleviating MetS are becoming more popular, but a review on this topic remains scarce. In this review, we discuss the effects of microalgae, specifically on MetS, by reviewing the evidence from scientific literature covering in vitro and in vivo studies. In addition, we also discuss the underlying mechanisms that modulate the effects of microalgae on MetS, and the limitations and future perspectives of developing microalgae as a health supplement for MetS. Microalgae supplementation is becoming a viable approach in alleviating metabolic disturbances and as a unique addition to the management of MetS.

Effects of Omega-3 Fatty Acids Supplementation on Serum Lipid Profile and Blood Pressure in Patients with Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The purpose of this study was to explore the effect of omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation on serum lipid profile and blood pressure in patients with metabolic syndrome. We searched PubMed, Web of Science, Embase, and the Cochrane library from database inception to 30 April 2022. This meta-analysis included eight trials with 387 participants. We found that supplementation of n-3 PUFAs has no significant reduction in TC level (SMD = -0.02; 95% CI: -0.22 ~ 0.18, I² = 23.7%) and LDL-c level in serum (SMD = 0.18; 95% CI: -0.18 ~ 0.53, I² = 54.9%) of patients with metabolic syndrome. Moreover, we found no significant increase in serum high-density lipoprotein cholesterol level (SMD = 0.02; 95% CI: -0.21 ~ 0.25, I² = 0%) in patients with metabolic syndrome after consuming n-3 PUFAs. In addition, we found that n-3 PUFAs can significantly decrease serum triglyceride levels (SMD= -0.39; 95% CI: -0.59 ~ -0.18, I² = 17.2%), systolic blood pressure (SMD = -0.54; 95% CI: -0.86 ~ -0.22, I² = 48.6%), and diastolic blood pressure (SMD = -0.56; 95% CI: -0.79 ~ 0.33, I² = 14.0%) in patients with metabolic syndrome. The results from the sensitivity analysis confirmed that our results were robust. These findings suggest that n-3 PUFA supplementation may serve as a potential dietary supplement for improving lipids and blood pressure in metabolic syndrome. Given the quality of the included studies, further studies are still needed to verify our findings.

The plasma phospholipidome of the bottlenose dolphin (Tursiops truncatus) is modulated by both sex and developmental stage

Lipidomics represent a valid complementary tool to the biochemical analysis of plasma in humans. However, in cetaceans, these tools have been unexplored. Here, we evaluated how the plasma lipid composition of Tursiops truncatus is modulated by developmental stage and sex, aiming at a potential use of lipidomics in integrated strategies to monitor cetacean health. We characterized the fatty acid profile and detected a total of 26 fatty acids in T. truncatus plasma. The most abundant fatty acids were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1n-9). Interestingly, there are consistent differences between the fatty acid profile of mature female and mature male specimens. Phospholipidome analysis identified 320 different lipid species belonging to phosphatidylcholine (PC, 105 lipid species), lysophosphatidylcholine (42), phosphatidylethanolamine (PE, 67), lysophosphatidylethanolamine (18), phosphatidylglycerol (14), lysophosphatidylglycerol (8), phosphatidylinositol (14), lysophosphatidylinositol (2), phosphatidylserine (3), sphingomyelin (45) and ceramides (2) classes. The statistical analysis of the phospholipidome showed that its composition allows discriminating mature animals between sexes and mature males from immature males. Notably, discrimination between sexes is mainly determined by the contents of PE plasmalogens and lysophospholipids (LPC and LPE), while the differences between mature and immature male animals were mainly determined by the levels of PC lipids. This is the first time that a correlation between developmental stage and sex and the lipid composition of the plasma has been established in cetaceans. Being able to discern between age and sex-related changes is an encouraging step towards using these tools to also detect differences related to disease/dysfunction processes.

Obesity-Associated Dyslipidemia Is Moderated by Habitual Intake of Marine-Derived n-3 Polyunsaturated Fatty Acids in Yup'ik Alaska Native People: A Cross-Sectional Mediation-Moderation Analysis

BACKGROUND

Obesity leads to insulin resistance, altered lipoprotein metabolism, dyslipidemia, and cardiovascular disease. The relationship between long-term intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) and prevention of cardiometabolic disease remains unresolved.

OBJECTIVES

The aim of this study was to explore direct and indirect pathways between adiposity and dyslipidemia, and the degree to which n-3 PUFAs moderate adiposity-induced dyslipidemia in a population with highly variable n-3 PUFA intake from marine foods.

METHODS

In total, 571 Yup'ik Alaska Native adults (18-87 y) were enrolled in this cross-sectional study. The red blood cell (RBC) nitrogen isotope ratio (15N/14N, or NIR) was used as a validated objective measure of n-3 PUFA intake. EPA and DHA were measured in RBCs. Insulin sensitivity and resistance were estimated by the HOMA2 method. Mediation analysis was conducted to evaluate the contribution of the indirect causal path between adiposity and dyslipidemia mediated through insulin resistance. Moderation analysis was used to assess the influence of dietary n-3 PUFAs on the direct and indirect paths between adiposity and dyslipidemia. Outcomes of primary interest included plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), non-HDL-C, and triglycerides (TG).

RESULTS

In this Yup'ik study population, we found that up to 21.6% of the total effects of adiposity on plasma TG, HDL-C, and non-HDL-C are mediated through measures of insulin resistance or sensitivity. Moreover, RBC DHA and EPA moderated the positive association between waist circumference (WC) and TC or non-HDL-C, whereas only DHA moderated the positive association between WC and TG. However, the indirect path between WC and plasma lipids was not significantly moderated by dietary n-3 PUFAs.

CONCLUSIONS

Intake of n-3 PUFAs may independently reduce dyslipidemia through the direct path resulting from excess adiposity in Yup'ik adults. NIR moderation effects suggest that additional nutrients contained in n-3 PUFA-rich foods may also reduce dyslipidemia.

The beneficial effects of omega-3 polyunsaturated fatty acids on controlling blood pressure: An umbrella meta-analysis

Several meta-analyses have revealed that n-3 PUFAs can lower blood pressure, but the findings are conflicting. In this regard, the present umbrella meta-analysis aimed was performed to clarify whether n-3 PUFAs have effects on blood pressure. PubMed, Scopus, Embase, Web of Science, and Google Scholar were used as international databases from inception to May 2022. To examine the effects of n-3 PUFA supplementation on blood pressure, a random-effects model was applied. The leave-one-out method was performed for the sensitivity analysis. The pooled estimate of 10 meta-analyses with 20 effect sizes revealed significant reductions in both systolic (ES = −1.19 mmHg; 95% CI: −1.76, −0.62, p < 0.001) and diastolic blood pressure (ES = −0.91 mmHg, 95% CI: −1.35, −0.47; p < 0.001) following n-3 PUFAs supplementation. In studies with a sample size of ≤ 400 participants and a mean age over 45, SBP and DBP were found to be substantially reduced. Overall, this umbrella meta-analysis indicates that n-3 PUFAs supplementation might play a role in improving DBP and SBP.

N-3 PUFAs and their specialized pro-resolving lipid mediators on airway inflammatory response: beneficial effects in the prevention and treatment of respiratory diseases

Respiratory diseases include a wide range of pathologies with different clinical manifestations, affecting the normal airways and lung function. An increase in the inflammatory response is considered a characteristic hallmark of these diseases, being also a critical factor for their progression. The n-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic acid (C20:4n-3, EPA), docosahexaenoic acid (C22:6n-3, DHA) and their lipid mediators are known to have an inflammation pro-resolution effect. The effects of these n-3 PUFAs in the prevention and treatment of respiratory diseases are beginning to be understood. Consequently, this article aims to analyze the influence of n-3 PUFAs and their lipid mediators on the inflammatory response in respiratory health, emphasizing recent data concerning their beneficial effects in the prevention and possible treatment of different respiratory diseases, particularly asthma, airway allergic syndromes and chronic obstructive pulmonary disease. The review includes studies regarding the effects of EPA, DHA, and their specialized pro-resolving lipid mediators (SPMs) on in vivo and in vitro models of respiratory disease, concluding that EPA and DHA have a positive impact in attenuating the pro-inflammatory response in respiratory diseases, reducing symptoms like nasal congestion, fever and difficulty in breathing. Controversial data reported are probably due to differences in several factors, including the dosages, administration vehicles, and the supplementation times employed, which are aspects that remain to be addressed in future studies.

Flazin as a Lipid Droplet Regulator against Lipid Disorders

Lipid disorders are closely related to numerous metabolic diseases, and lipid droplets (LDs) have been considered as a new target for regulating lipid metabolism. Dietary intervention and nutraceuticals provide safe and long-term beneficial effects for treating metabolic diseases. Flazin is a diet-derived bioactive constituent mainly existing in fermented foods, of which the lipid metabolism improvement function has not been studied. In this study, the effect of flazin on lipid regulation at both cell level and organelle level was investigated. Lipidomic profiling showed that flazin significantly decreased cellular triglyceride (TG) by 12.0–22.4% compared with modeling groups and improved the TG and free fatty acid profile. LD staining revealed that flazin efficiently reduced both cellular neutral lipid content by 17.4–53.9% and LD size by 10.0–35.3%. Furthermore, nanoelectrospray ionization mass spectrometry analysis proved that flazin exhibited a preferential suppression of LD TG and regulated LD morphology, including a size decrease and surface property improvement. An evaluation of related gene expression suggested the mechanism to be lipolysis promotion and lipogenesis inhibition. These findings indicated that flazin might be an LD regulator for reversing lipid metabolism disturbance. Moreover, the strategy proposed in this study may contribute to developing other nutraceuticals for treating lipid disorder-related metabolic diseases.

The effects of dietary supplements and natural products targeting glucose levels: an overview

Identifying effective dietary supplements and medicinal herbs has attracted the attention of clinicians and researchers to complement the standard treatment in controlling diabetes mellitus. In the present overview, we aimed to collect studies with the highest level of evidence to shed light on detecting the most effective dietary supplements and medicinal herbs for controlling glycemic status. For the current overview, four electronic databases, including PubMed, Scopus, Web of Science, and Cochrane Library, were systematically searched from inception to 31 December 2020 and then updated until 1 October 2021 to obtain eligible meta-analyses on either dietary supplements or medicinal herbs and their effects on glycemic status. Fasting blood sugar (FBS) and Hemoglobin A1C (HbA1C) were considered as primary outcomes. Finally, ninety-one meta-analyses on dietary supplements (n = 55) and herbs (n = 36) were included. Evidence showed positive effects of chromium, zinc, propolis, aloe vera, milk thistle, fenugreek, cinnamon, ginger, and nettle on FBS and/or HbA1C. However, mostly the heterogeneity (I2) was high. Other supplements and herbs also showed no reduction in glucose levels or their effects were small. Although some dietary supplements and medicinal herbs showed a significant reduction in FBS and/or HbA1C, mostly their effects from the clinical point of view were not remarkable. In addition, due to high heterogeneity, publication bias, and a limited number of included studies in most cases further clinical trials are needed for making decision on anti-diabetic supplement efficacy.

Specialized pro-resolving mediators as modulators of immune responses

Specialized pro-resolving mediators (SPMs) are endogenous small molecules produced mainly from dietary omega-3 polyunsaturated fatty acids by both structural cells and cells of the active and innate immune systems. Specialized pro-resolving mediators have been shown to both limit acute inflammation and promote resolution and return to homeostasis following infection or injury. There is growing evidence that chronic immune disorders are characterized by deficiencies in resolution and SPMs have significant potential as novel therapeutics to prevent and treat chronic inflammation and immune system disorders. This review focuses on important breakthroughs in understanding how SPMs are produced by, and act on, cells of the adaptive immune system, specifically macrophages, B cells and T cells. We also highlight recent evidence demonstrating the potential of SPMs as novel therapeutic agents in topics including immunization, autoimmune disease and transplantation.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

Omega-3 index and type 2 diabetes: Systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

The relationship between omega-3 index and type 2 diabetes (T2D) is not well established. It is unclear if the change of omega-3 index will affect T2D. Aiming of the present systematic review was to elucidate the correlation between omega-3 index and T2D.

METHODS AND STUDY DESIGN

A comprehensive search on PubMed, EMBASE and Web of Science (from 1948 to May 2021) was conducted. The overall effect size (standard mean difference) was combined using a random-effect model.

RESULTS

Eight eligible case-control studies were identified, and there were 1,357 patients with T2D and 1,616 non-diabetic controls. The result showed that the omega-3 index was significantly lower in diabetic cases than that in controls (SMD= -1.31; 95% confidence interval (CI): -1.40, -1.22), but with significant heterogeneity (I² = 99.0%). In subgroup analysis based on race, a negative correlation was found in Asians (SMD = -1.71; 95% CI: -1.82, -1.60), and heterogeneity was substantially decreased (I²=0).

CONCLUSIONS

omega-3 index is negatively correlated with T2D, which indicated that increased dietary intake of omega-3 fatty acids might have beneficial on T2D prevention.

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.