Serum n-6 fatty acids and lipoprotein subclasses in middle-aged men: the population-based cross-sectional ERA-JUMP study

An overview on lipids in nuts and oily fruits: oil content, lipid composition, health effects, lipidomic fingerprinting and new biotechnological applications of their by-products

Tree nuts and oily fruits are used as a diet complement and are highly consumed worldwide. The production and consumption of these foods have been increasing, and an enormous global market value is forecasted for 2023. Besides their high nutritional value and lipid content, they provide health benefits to fat metabolism, heart, skin, and brain. The industrial by-products of these oily foods represent promising raw materials for many industries. However, the lipidomic analysis of nuts and oily fruits is still in its early stages. State-of-the-art analytical approaches for the lipid profiling and fingerprinting of nuts and oily fruits have been developed using high-performance liquid chromatography and high-resolution mass spectrometry for the accurate identification and structural characterization at the molecular species level. It is expected to bring a new understanding of these everyday foods' nutritional and functional value. This review comprises the oil content and lipid composition of various nuts and oily fruits, particularly those mostly consumed worldwide and having recognized beneficial health effects, biological activities associated with the lipids from different oily foodstuffs, analytical methodologies to analyze lipids in nuts and oily fruits, and the potential biotechnological applications of their industrial by-products for a lipid-based commercial valorization.

Lipidomics in gestational diabetes mellitus

PURPOSE OF REVIEW

Epidemiological and mechanistic studies have reported relationships between blood lipids, mostly measured by traditional method in clinical settings, and gestational diabetes mellitus (GDM). Recent advances of high-throughput lipidomics techniques have made available more comprehensive lipid profiling in biological samples. This review aims to summarize evidence from prospective studies in assessing relations between blood lipids and GDM, and discuss potential underlying mechanisms.

RECENT FINDINGS

Mass spectrometry and nuclear magnetic resonance spectroscopy-based analytical platforms are extensively used in lipidomics research. Epidemiological studies have identified multiple novel lipidomic biomarkers that are associated with risk of GDM, such as certain types of fatty acids, glycerolipids, glycerophospholipids, sphingolipids, cholesterol, and lipoproteins. However, the findings are inconclusive mainly due to the heterogeneities in study populations, sample sizes, and analytical platforms. Mechanistic evidence indicates that abnormal lipid metabolism may be involved in the pathogenesis of GDM by impairing pancreatic β-cells and inducing insulin resistance through several etiologic pathways, such as inflammation and oxidative stress.

SUMMARY

Lipidomics is a powerful tool to study pathogenesis and biomarkers for GDM. Lipidomic biomarkers and pathways could help to identify women at high risk for GDM and could be potential targets for early prevention and intervention of GDM.

Effect of n-3 (Omega-3) Polyunsaturated Fatty Acid Supplementation on Metabolic and Inflammatory Biomarkers and Body Weight in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of RCTs

Beneficial effects of n-3 fatty acids on metabolic biomarkers in patients with type 2 diabetes (T2DM) has been reported. The objectives of this current research were to investigate the effects of n-3 supplementation on metabolic factors, weight, and body mass index (BMI) in patients with type 2 diabetes mellitus (T2DM), using a meta-analysis of randomized, controlled trials (RCTs). Online databases PubMed, Embase, Web of Science, and Science Direct were searched until 2021 to identify eligible articles. Thirty trials were included. The results showed that n-3 consumption can significantly reduce glycemic factors including fasting blood sugar (FBS) (−0.36 (−0.71 to −0.01)), glycated hemoglobulin (HbA1c) (−0.74 (−1.13 to −0.35)), and homeostatic model assessment of insulin resistance (HOMA.IR) (−0.58 (−1.13 to −0.03)). Furthermore, significant improvement in lipid profile including triglycerides (TG) (−0.27 (−0.37 to −0.18)), total cholesterol (−0.60 (−0.88 to −0.32)), low density lipoprotein (LDL) (−0.54 (−0.85 to −0.23)), and high-density lipoprotein (HDL) (0.60 (0.23 to 0.96)) levels were found in the present meta-analysis. The reduction in the inflammatory marker’s tumor necrosis factor-alpha (TNF-α) (−0.13 (−0.75 to 0.48)) and c-reactive protein (CRP) (−0.72 (−1.70 to 0.27)), as well as weight (−0.09 (−0.24 to 0.07)) and BMI (−0.13 (−0.29 to 0.02)) were not statistically significant. Furthermore, the findings revealed that the optimal dose and duration of n-3 consumption for patients with T2DM is 1000–2000 mg/d for more than 8 weeks. The present meta-analysis and review reveals that n-3 supplementation can improve glycemic factors and lipid profile in patients with T2DM. Furthermore, n-3 supplementation may provide beneficial effects on inflammatory markers and body weight if used at the appropriate dose and duration.

The effects of fat consumption on low-density lipoprotein particle size in healthy individuals: a narrative review

Cardiovascular disease (CVD) is the number one contributor to death in the United States and worldwide. A risk factor for CVD is high serum low-density lipoprotein cholesterol (LDL-C) concentrations; however, LDL particles exist in a variety of sizes that may differentially affect the progression of CVD. The small, dense LDL particles, compared to the large, buoyant LDL subclass, are considered to be more atherogenic. It has been suggested that replacing saturated fatty acids with monounsaturated and polyunsaturated fatty acids decreases the risk for CVD. However, certain studies are not in agreement with this recommendation, as saturated fatty acid intake did not increase the risk for CVD, cardiovascular events, and/or mortality. Furthermore, consumption of saturated fat has been demonstrated to increase large, buoyant LDL particles, which may explain, in part, for the differing outcomes regarding fat consumption on CVD risk. Therefore, the objective was to review intervention trials that explored the effects of fat consumption on LDL particle size in healthy individuals. PubMed and Web of Science were utilized during the search process for journal articles. The results of this review provided evidence that fat consumption increases large, buoyant LDL and/or decreases small, dense LDL particles, and therefore, influences CVD risk.

Associations of Arachidonic Acid Synthesis with Cardiovascular Risk Factors and Relation to Ischemic Heart Disease and Stroke: A Univariable and Multivariable Mendelian Randomization Study

Arachidonic acid (AA), a major long-chain omega-6 polyunsaturated fatty acid, is associated with ischemic heart disease (IHD) and stroke. We assessed bi-directional associations of AA synthesis reflected by plasma phospholipid AA with CVD risk factors, and identified mediators of associations of AA with IHD and stroke using Mendelian randomization (MR). We used two-sample MR to assess bi-directional associations of AA synthesis with lipids, blood pressure, adiposity, and markers of inflammation and coagulation. We used multivariable MR to assess mediators of associations of AA with IHD and stroke. Genetically predicted AA (% of total fatty acids increase) was positively associated with apolipoprotein B (ApoB, 0.022 standard deviations (SD), 95% confidence interval (CI) 0.010, 0.034), high-density (0.030 SD, 95% CI 0.012, 0.049) and low-density lipoprotein cholesterol (LDL-C, 0.016 SD, 95% CI 0.004, 0.027) and lower triglycerides (-0.031 SD, 95% CI -0.049, -0.012) but not with other traits. Genetically predicted these traits gave no association with AA. The association of AA with IHD was attenuated adjusting for ApoB or LDL-C. Genetically predicted AA was associated with lipids but not other traits. Given ApoB is thought to be the key lipid in IHD, the association of AA with IHD is likely mediated by ApoB.

Do polyunsaturated fatty acids protect against bone loss in our aging and osteoporotic population?

Age-related bone loss is inevitable in both men and women and there will soon be more people of extreme old age than ever before. Osteoporosis is a common chronic disease and as the proportion of older people, rate of obesity and the length of life increases, a rise in age-related degenerating bone diseases, disability, and prolonged dependency is projected. Fragility fractures are one of the most severe complications associated with both primary and secondary osteoporosis and current treatment strategies target weight-bearing exercise and pharmacological intervention, both with limited long-term success. Obesity and osteoporosis are intimately interrelated, and diet is a variable that plays a significant role in bone regeneration and repair. The Western Diet is characterized by its unhealthy components, specifically excess amounts of saturated fat intake. This review examines the impact of saturated and polyunsaturated fatty acid consumption on chronic inflammation, osteogenesis, bone architecture, and strength and explores the hypothesis that dietary polyunsaturated fats have a beneficial effect on osteogenesis, reducing bone loss by decreasing chronic inflammation, and activating bone resorption through key cellular and molecular mechanisms in our aging population. We conclude that aging, obesity and a diet high in saturated fatty acids significantly impairs bone regeneration and repair and that consumption of ω-3 polyunsaturated fatty acids is associated with significantly increased bone regeneration, improved microarchitecture and structural strength. However, ω-6 polyunsaturated fatty acids were typically pro-inflammatory and have been associated with an increased fracture risk. This review suggests a potential role for ω-3 fatty acids as a non-pharmacological dietary method of reducing bone loss in our aging population. We also conclude that contemporary amendments to the formal nutritional recommendations made by the Food and Nutrition Board may be necessary such that our aging population is directly considered.

Liver Metabolomics Reveals the Effect of Lactobacillus reuteri on Alcoholic Liver Disease

Alcoholic liver disease (ALD), a type of chronic liver disease that is prevalent worldwide, is still identified to have a poor prognosis despite many medical treatment protocols. Thus, it is urgent to develop and test new treatment protocols for ALD. Lactobacillus reuteri (L. reuteri) has been widely used in the clinical treatment of digestive system diseases, but studies on the protective effect of L. reuteri on ALD are considered to be rare. Therefore, in the present study, we examined the effect of L. reuteri on ALD and provide data that are significant in the development of new treatment protocols for ALD. An ALD model has been established in C57BL/6J mice treated according to the Gao-binge modeling method. Mice in the treatment group were administered with L. reuteri. Hematoxylin and eosin (H&E) staining, oil red O staining, immunohistochemistry, and biochemical analyses were performed to detect the phenotypic changes in the liver among mice in the different treatment groups. L. reuteri treatment reversed inflammatory cell infiltration and lipid accumulation. Moreover, AST, ALT, TG, and TCH levels were also reduced in the probiotics-treatment group. Five candidate biomarkers were found in the liver metabolites of different treatment groups by UPLC/QTOF-MS and a multivariate analysis. Several fatty acid metabolic pathways such as linoleic acid metabolism and glycerolipid metabolism were involved. All these findings suggested that L. reuteri treatment reversed the phenotype of ethanol-induced hepatitis and metabolic disorders. These findings provide evidence that L. reuteri might serve as a new therapeutic strategy for ALD.

The Short Overview on the Relevance of Fatty Acids for Human Cardiovascular Disorders

This review presents existing evidence of the influence of saturated and unsaturated fatty acids on cardiovascular diseases (CVD). Data are discussed regarding the roles of the most relevant fatty acids, such as myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), α-linolenic (C18:3, ω-3), γ-linolenic (C18:3, ω-6), arachidonic (C20:4), eicosapentaenoic (C20:5), docosahexaenoic (C22:6), and docosapentaenoic (C22:5) acid. The accumulated knowledge has expanded the understanding of the involvement of fatty acids in metabolic processes, thereby enabling the transition from basic exploratory studies to practical issues of application of these biomolecules to CVD treatment. In the future, these findings are expected to facilitate the interpretation and prognosis of changes in metabolic lipid aberrations in CVD.

Roles of endogenous ether lipids and associated PUFAs in the regulation of ion channels and their relevance for disease

Ether lipids (ELs) are lipids characterized by the presence of either an ether linkage (alkyl lipids) or a vinyl ether linkage [i.e., plasmalogens (Pls)] at the sn1 position of the glycerol backbone, and they are enriched in PUFAs at the sn2 position. In this review, we highlight that ELs have various biological functions, act as a reservoir for second messengers (such as PUFAs) and have roles in many diseases. Some of the biological effects of ELs may be associated with their ability to regulate ion channels that control excitation-contraction/secretion/mobility coupling and therefore cell physiology. These channels are embedded in lipid membranes, and lipids can regulate their activities directly or indirectly as second messengers or by incorporating into membranes. Interestingly, ELs and EL-derived PUFAs have been reported to play a key role in several pathologies, including neurological disorders, cardiovascular diseases, and cancers. Investigations leading to a better understanding of their mechanisms of action in pathologies have opened a new field in cancer research. In summary, newly identified lipid regulators of ion channels, such as ELs and PUFAs, may represent valuable targets to improve disease diagnosis and advance the development of new therapeutic strategies for managing a range of diseases and conditions.

Dietary fatty acids and CD36-mediated cholesterol homeostasis: potential mechanisms

Currently, the prevention and treatment of CVD have been a global focus since CVD is the number one cause of mortality and morbidity. In the pathogenesis of CVD, it was generally thought that impaired cholesterol homeostasis might be a risk factor. Cholesterol homeostasis is affected by exogenous factors (i.e. diet) and endogenous factors (i.e. certain receptors, enzymes and transcription factors). In this context, the number of studies investigating the potential mechanisms of dietary fatty acids on cholesterol homeostasis have increased in recent years. As well, the cluster of differentiation 36 (CD36) receptor is a multifunctional membrane receptor involved in fatty acid uptake, lipid metabolism, atherothrombosis and inflammation. CD36 is proposed to be a crucial molecule for cholesterol homeostasis in various mechanisms including absorption/reabsorption, synthesis, and transport of cholesterol and bile acids. Moreover, it has been reported that the amount of fatty acids and fatty acid pattern of the diet influence the CD36 level and CD36-mediated cholesterol metabolism principally in the liver, intestine and macrophages. In these processes, CD36-mediated cholesterol and lipoprotein homeostasis might be impaired by dietary SFA and trans-fatty acids, whereas ameliorated by MUFA in the diet. The effects of PUFA on CD36-mediated cholesterol homeostasis are controversial depending on the amount of n-3 PUFA and n-6 PUFA, and the n-3:n-6 PUFA ratio. Thus, since the CD36 receptor is suggested to be a novel nutrient-sensitive biomarker, the role of CD36 and dietary fatty acids in cholesterol metabolism might be considered in medical nutrition therapy in the near future. Therefore, the novel nutritional target of CD36 and interventions that focus on dietary fatty acids and potential mechanisms underlying cholesterol homeostasis are discussed in this review.

Serum long-chain n-3 polyunsaturated fatty acids and aortic calcification in middle-aged men: The population-based cross-sectional ERA-JUMP study

BACKGROUND AND AIM

Few studies have examined the association of long-chain n-3 polyunsaturated fatty acids (LCn-3PUFAs) with the measures of atherosclerosis in the general population. This study aimed to examine the relationship of total LCn-3PUFAs, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) with aortic calcification.

METHODS AND RESULTS

In a multiethnic population-based cross-sectional study of 998 asymptomatic men aged 40-49 years (300 US-White, 101 US-Black, 287 Japanese American, and 310 Japanese in Japan), we examined the relationship of serum LCn-3PUFAs to aortic calcification (measured by electron-beam computed tomography and quantified using the Agatston method) using Tobit regression and ordinal logistic regression after adjusting for potential confounders. Overall 56.5% participants had an aortic calcification score (AoCaS) > 0. The means (SD) of total LCn-3PUFAs, EPA, and DHA were 5.8% (3.3%), 1.4% (1.3%), and 3.7% (2.1%), respectively. In multivariable-adjusted Tobit regression, a 1-SD increase in total LCn-3PUFAs, EPA, and DHA was associated with 29% (95% CI = 0.51, 1.00), 9% (95% CI = 0.68, 1.23), and 35% (95% CI = 0.46, 0.91) lower AoCaS, respectively. Results were similar in ordinal logistic regression analysis. There was no significant interaction between race/ethnicity and total LCn-3PUFAs, EPA or DHA on aortic calcification.

CONCLUSIONS

This study showed the significant inverse association of LCn-3PUFAs with aortic calcification independent of conventional cardiovascular risk factors among men in the general population. This association appeared to be driven by DHA but not EPA.

Comparison of carotid plaque burden among healthy middle-aged men living in the US, Japan, and South Korea

BACKGROUND

Carotid plaque has emerged as a marker of coronary heart disease (CHD) risk. Comparison of carotid plaque burden between different race/ethnic groups may provide a relative estimate of their future CHD risk.

METHODS

We conducted a population-based study among apparently healthy middle-aged men aged 40-49 years (ERA JUMP study (n = 924)) and recruited 310 Whites in Pittsburgh, US, 313 Japanese in Otsu, Japan, and 301 Koreans in Ansan, South Korea. The number of carotid plaque and CHD risk factors was assessed using a standardized protocol across all centers. The burden of carotid plaque was compared between race/ethnic groups after adjustment for age and BMI, and after multivariable adjustment for other CHD risk factors using marginalized zero-inflated Poisson regression models. Cross-sectional associations of risk factors with plaque were examined.

RESULTS

Whites (22.8%) had more than four-fold higher prevalence (p < 0.01) of carotid plaque than Japanese men (4.8%) while the prevalence among Koreans was 10.6%. These differences remained significant after adjustment for age, BMI as well as other risk factors - incidence density ratio (95% confidence interval) for plaque was 0.13 (0.07, 0.24) for Japanese and 0.32 (0.18, 0.58) for Koreans as compared to Whites. Age, hypertension and diabetes were the only risk factors significantly associated with presence of carotid plaque in the overall population.

CONCLUSION

Whites have significantly higher carotid plaque burden than men in Japan and Korea. Lower carotid plaque burden among Japanese and Koreans is independent of traditional CVD risk factors.

Differentiating the biological effects of linoleic acid from arachidonic acid in health and disease

Dietary fatty acids are associated with the development of many chronic diseases, such as obesity, diabetes, cardiovascular disease, metabolic syndrome, and several cancers. This review explores the literature surrounding the combined and individual roles of n-6 PUFAs linoleic acid (LA) and arachidonic acid (AA) as they relate to immune and inflammatory response, cardiovascular health, liver health, and cancer. The evidence suggests that a pro-inflammatory view of LA and AA may be over simplified. Overall, this review highlights gaps in our understanding of the biological roles of LA, AA and their complex relationship with n-3 PUFA and the need for future studies that examine the roles of individual fatty acids, rather than groups.

Improvement of the omega 3 index of healthy subjects does not alter the effects of dietary saturated fats or n-6PUFA on LDL profiles

BACKGROUND AND AIMS

Dietary fat composition is known to modulate circulating lipid and lipoprotein levels. Although supplementation with long chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) has been shown to reduce plasma triglyceride levels, the effect of the interactions between LCn-3PUFA and the major dietary fats consumed has not been previously investigated.

METHODS

In a randomized controlled parallel design clinical intervention, we examined the effect of diets rich in either saturated fatty acids (SFA) or omega-6 polyunsaturated fatty acids (n-6PUFA) on plasma lipid levels and lipoprotein profiles (lipoprotein size, concentration and distribution in subclasses) in subjects with an adequate omega 3 index. Twenty six healthy subjects went through a four-week pre-supplementation period with LCn-3PUFA and were then randomized to diets rich in either n-6PUFA or SFA both supplemented with LCn-3PUFA.

RESULTS

The diet rich in n-6PUFA decreased low density lipoprotein (LDL) particle concentration (-8%, p=0.013) and LDL cholesterol (LDL-C) level (-8%, p=0.021), while the saturated fat rich diet did not affect LDL particle concentration or LDL-C levels significantly. Nevertheless, dietary saturated fatty acids increased LCn-3PUFA in plasma and tissue lipids compared with n-6PUFA, potentially reducing other cardiovascular risk factors such as inflammation and clotting tendency.

CONCLUSION

Improvement on the omega 3 index of healthy subjects did not alter the known effects of dietary saturated fats and n-6PUFA on LDL profiles.

Impact of methods used to express levels of circulating fatty acids on the degree and direction of associations with blood lipids in humans

Numerous studies have examined relationships between disease biomarkers (such as blood lipids) and levels of circulating or cellular fatty acids. In such association studies, fatty acids have typically been expressed as the percentage of a particular fatty acid relative to the total fatty acids in a sample. Using two human cohorts, this study examined relationships between blood lipids (TAG, and LDL, HDL or total cholesterol) and circulating fatty acids expressed either as a percentage of total or as concentration in serum. The direction of the correlation between stearic acid, linoleic acid, dihomo-γ-linolenic acid, arachidonic acid and DHA and circulating TAG reversed when fatty acids were expressed as concentrations v. a percentage of total. Similar reversals were observed for these fatty acids when examining their associations with the ratio of total cholesterol:HDL-cholesterol. This reversal pattern was replicated in serum samples from both human cohorts. The correlations between blood lipids and fatty acids expressed as a percentage of total could be mathematically modelled from the concentration data. These data reveal that the different methods of expressing fatty acids lead to dissimilar correlations between blood lipids and certain fatty acids. This study raises important questions about how such reversals in association patterns impact the interpretation of numerous association studies evaluating fatty acids and their relationships with disease biomarkers or risk.

Brachial-ankle pulse wave velocity is associated with coronary calcification among 1131 healthy middle-aged men

BACKGROUND

Brachial-ankle pulse wave velocity (baPWV) is a simple and reproducible measure of arterial stiffness and is extensively used to assess cardiovascular disease (CVD) risk in eastern Asia. We examined whether baPWV is associated with coronary atherosclerosis in an international study of healthy middle-aged men.

METHODS

A population-based sample of 1131 men aged 40-49 years was recruited - 257 Whites and 75 Blacks in Pittsburgh, US, 228 Japanese-Americans in Honolulu, US, 292 Japanese in Otsu, Japan, and 279 Koreans in Ansan, Korea. baPWV was measured with an automated waveform analyzer (VP2000, Omron) and atherosclerosis was examined as coronary artery calcification (CAC) by computed-tomography (GE-Imatron EBT scanner). Association of the presence of CAC (defined as ≥ 10 Agatston unit) was examined with continuous measure as well as with increasing quartiles of baPWV.

RESULTS

As compared to the lowest quartile of baPWV, the multivariable-adjusted odds ratio (95% Confidence Interval [CI]) for the presence of CAC in the combined sample was 1.70 (0.98, 2.94) for 2nd quartile, 1.88 (1.08, 3.28) for 3rd quartile, and 2.16 (1.19, 3.94) for 4th quartile (p-trend = 0.01). The odds for CAC increased by 19% per 100 cm/s increase (p < 0.01), or by 36% per standard-deviation increase (p < 0.01) in baPWV. Similar effect-sizes were observed in individual races, and were significant among Whites, Blacks and Koreans.

CONCLUSION

baPWV is cross-sectionally associated with CAC among healthy middle-aged men. The association was significant in Whites and Blacks in the US, and among Koreans. Longitudinal studies are needed to determine its CVD predictive ability.

The role of n - 6 and n - 3 polyunsaturated fatty acids in the manifestation of the metabolic syndrome in cardiovascular disease and non-alcoholic fatty liver disease

Cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD) are manifestations of the metabolic syndrome. CVD remains the number one cause of mortality in the West, while NAFLD is the most common liver disease. Growing evidence suggests that polyunsaturated fatty acids (PUFA) influence risk factors including circulating lipids and inflammation on the development of CVD and NAFLD. N - 6 and n - 3 PUFA are comprised of distinct family members, which are increasingly recognized for their individual effects. Therefore, this review examines what is currently known about the specific effects of the major n - 3 and n - 6 PUFA on CVD and NAFLD. Overall, this review supports a beneficial effect of n - 3 PUFA and highlights distinctive effects between alpha-linolenic acid found in plant oils relative to marine derived eicosapentaenoic acid and docosahexaenoic acid. This review also highlights contrasting health effects between the n - 6 PUFA, linoleic and arachidonic acid.

Lipoprotein particle profiles compared with standard lipids in association with coronary artery calcification in the general Japanese population

OBJECTIVE

The utility of lipoprotein particle profiles measured by nuclear magnetic resonance (NMR) spectroscopy beyond standard serum lipids remains inconclusive. Furthermore, few studies have compared NMR measurements with standard lipids in association with coronary artery calcification (CAC) in Japanese, where the coronary atherosclerotic burden is low. We examined whether NMR-based lipoprotein particle profiles are associated with CAC, and compared them with standard lipid and lipid ratios in the Japanese general population.

METHODS AND RESULTS

We conducted a cross-sectional study in 851 men aged 40-79 years without cardiovascular diseases and lipid-lowering therapies. Adjusted odds ratios (ORs) (95% confidence intervals) for the top versus the bottom quartile of NMR-measured particle concentrations were 2.01 (1.24-3.23) for low-density lipoprotein (LDL-P), 1.04 (0.62-1.75) for high-density lipoprotein (HDL-P), 1.82 (1.13-2.95) for very-low-density lipoprotein (VLDL-P), and 1.92 (1.18-3.17) for LDL-P/HDL-P ratio. Similarly adjusted ORs of NMR-measured particle sizes were 0.59 (0.36-0.97) for LDL-P, 0.66 (0.40-1.10) for HDL-P, and 0.67 (0.40-1.12) for VLDL-P. The corresponding ORs were 1.82 (1.14-2.90) for total cholesterol (TC), 2.06 (1.28-3.30) for low-density lipoprotein cholesterol (LDL-C), 0.56 (0.34-0.91) for high-density lipoprotein cholesterol (HDL-C), 2.02 (1.24-3.29) for triglycerides, 2.08 (1.29-3.36) for non-high-density lipoprotein cholesterol (non-HDL-C), 2.27 (1.37-3.78) for TC/HDL-C ratio, and 1.73 (1.06-2.85) for LDL-C/HDL-C ratio. After mutual adjustment for total LDL-P concentration and TC/HDL-C ratio or non-HDL-C, LDL-P was no longer associated, whereas TC/HDL-C ratio remained significantly associated with CAC.

CONCLUSIONS

In community-based Japanese men, the overall association of CAC with NMR-measured lipoprotein indices is comparable, but not superior, to that with standard lipids.

Evening primrose oil ameliorates platelet aggregation and improves cardiac recovery in myocardial-infarct hypercholesterolemic rats

Omega-6 polyunsaturated fatty acids (n-6 PUFA) are well known for their role in cardiovascular disease (CVD). We proposed that Evening prime rose oil (EPO) can improve the outcome of a heart with myocardial infarction (MI) in the presence of diet-induced hyperaggregability. This study was designed to examine its cholesterol lowering, antithrombotic and anti-inflammatory effects. High fat diet was administered for 4 weeks then MI was induced by isoproterenol (85 mg/kg/s.c./24 h). Treatment with EPO (5 or 10 gm/kg/day) for 6 weeks improved the electrocardiographic pattern, serum lipid profile, cardiac biomarkers as well as Platelet aggregation percent. We reported decreased serum level of TNF-α, IL-6 and COX-2 with attenuation of TNF-α and TGF-β in the cardiac homogenate. Moreover, histopathology revealed marked amelioration. Finally, we provide evidence that EPO improve cardiac recovery in hypercholesterolemic myocardial infarct rats. These effects are attributed to direct hypocholesterolemic effect and indirect effect on the synthesis of eicosanoids (prostaglandins, cytokines).

Effect of PUFA-rich plant oil on risk factors of STZ-induced diabetes in Wistar rats

OBJECTIVE

This study has been focused on the effect of an n-6 polyunsaturated fatty acid (PUFA) rich plant oil on oxidation and glycooxidation stress markers as well as on antioxidant enzyme activities in male Wistar rats with streptozotocin-induced diabetes.

METHODS

The non-diabetic and diabetic groups of Wistar rats were administered plant oil at concentrations of 100 and 500 mg/kg body weight and controls without plant oil. The parameters of glycaemic control, lipid profile, total antioxidant status, antioxidant enzyme activities, together with oxidative and glycooxidative stress markers were measured in the blood.

RESULTS

The intake of the plant oil did not significantly influence the parameters of glycaemic control and significantly increased the levels of all lipid profile parameters in the diabetic rats. Plant oil administration significantly decreased the total antioxidant status and glutathione peroxidase activity and the activity of Cu/Zn superoxide dismutase was significantly increased. The plant oil also increased the levels of lipoperoxides and advanced the glycation end products.

DISCUSSION

These results suggest that the plant oil with high concentrations of n-6 PUFA - linoleic acid, acts prooxidatively when administered to the rats.

Cross-sectional and longitudinal associations of circulating omega-3 and omega-6 fatty acids with lipoprotein particle concentrations and sizes: population-based cohort study with 6-year follow-up

BACKGROUND

Cross-sectional studies have suggested that serum omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) are related to favorable lipoprotein particle concentrations. We explored the associations of serum n-3 and n-6 PUFAs with lipoprotein particle concentrations and sizes in a general population cohort at baseline and after 6 years.

FINDINGS

The cohort included 665 adults (274 men) with a 6-year follow-up. Nutritional counseling was given at baseline. Serum n-3 and n-6 PUFAs and lipoprotein particle concentrations and the mean particle sizes of VLDL, LDL, and HDL were quantified by nuclear magnetic resonance (NMR) spectroscopy for all baseline and follow-up samples at the same time. Concentrations of n-3 and n-6 PUFAs were expressed relative to total fatty acids. At baseline, n-3 PUFAs were not associated with lipoprotein particle concentrations. A weak negative association was observed for VLDL (P = 0.021) and positive for HDL (P = 0.011) particle size. n-6 PUFA was negatively associated with VLDL particle concentration and positively with LDL (P < 0.001) and HDL particle size (P < 0.001). The 6-year change in n-3 PUFA correlated positively with the change in particle size for HDL and LDL lipoproteins but negatively with VLDL particle size. An increase in 6-year levels of n-6 PUFAs was negatively correlated with the change in VLDL particle concentration and size, and positively with LDL particle size.

CONCLUSION

Change in circulating levels of both n-3 and n-6 PUFAs, relative to total fatty acids, during 6 years of follow-up are associated with changes in lipoprotein particle size and concentrations at the population level.

Association between serum fatty acids and lipoprotein subclass profile in healthy young adults: exploring common genetic and environmental factors

OBJECTIVE

Little is known about the associations of serum fatty acids with lipoprotein profile and the underlying genetic and environmental etiology of these relationships. We aimed to analyze the phenotypic association of serum n-6 and n-3 polyunsaturated (PUFAs), monounsaturated (MUFAs) and saturated (SFAs) fatty acids (relative proportion to total fatty acids) with lipids and lipoproteins, and to quantify common genetic and environmental factors determining their covariation.

METHODS

Two cohorts of healthy Finnish twins were assessed in young adulthood. Data were available for 1269 individual twins including 561 complete pairs. Serum metabolites were measured by nuclear magnetic resonance spectroscopy. Bivariate quantitative genetic models were used to decompose the phenotypic covariance between the pairs of traits into genetic and environmental components.

RESULTS

Among the strongest correlations observed, serum total n-6 PUFAs and linoleic acid were inversely (max. r=-0.65) and MUFAs positively (max. r=0.63) correlated with triglycerides and very low-density lipoprotein (VLDL) particle concentration, particularly with large VLDL (for n-6 PUFAs) and medium VLDL (for MUFAs). Genetic factors significantly contributed to their covariance with bivariate heritability estimates ranging from 44% to 56% for n-6 PUFAs and 58% to 66% for MUFAs. Genetic correlations with lipid traits were moderate to high (max. rA=-0.59 and 0.70 for n-6 PUFAs and MUFAs, respectively). Statistically significant, but substantially weaker phenotypic correlations of total n-3 PUFAs, docosahexaenoic acid (DHA) and SFAs with lipoprotein profile were not decomposed into their genetic and environmental components.

CONCLUSION

Shared genetic factors are important in explaining why higher concentrations of serum n-6 PUFAs and lower concentrations of serum MUFAs strongly associate with lower triglyceride and VLDL particle concentrations.

A cross-sectional association of obesity with coronary calcium among Japanese, Koreans, Japanese Americans, and U.S. whites

AIMS

Conflicting evidence exists regarding whether obesity is independently associated with coronary artery calcium (CAC), a measure of coronary atherosclerosis. We examined an independent association of obesity with prevalent CAC among samples of multi-ethnic groups whose background populations have varying levels of obesity and coronary heart disease (CHD).

METHODS AND RESULTS

We analysed a population-based sample of 1212 men, aged 40-49 years free of clinical cardiovascular disease recruited in 2002-06; 310 Japanese in Japan (JJ), 294 Koreans in South Korea (KN), 300 Japanese Americans (JA), and 308 Whites in the USA (UW). We defined prevalent CAC as an Agatston score of ≥10. Prevalent CAC was calculated by tertile of the body mass index (BMI) in each ethnic group and was plotted against the corresponding median of tertile BMI. Additionally, logistic regression was conducted to examine whether an association of the BMI was independent of conventional risk factors. The median BMI and crude prevalence of CAC for JJ, KN, JA, and UW were 23.4, 24.4, 27.4, and 27.1 (kg/m2); 12, 11, 32, and 26 (%), respectively. Despite the absolute difference in levels of BMI and CAC across groups, higher BMI was generally associated with higher prevalent CAC in each group. After adjusting for age, smoking, alcohol, hypertension, lipids, and diabetes mellitus, the BMI was positively and independently associated with prevalent CAC in JJ, KN, UW, but not in JA.

CONCLUSION

In this multi-ethnic study, obesity was independently associated with subclinical stage of coronary atherosclerosis among men aged 40-49 years regardless of the BMI level.

The omega-6 arachidonic fatty acid, but not the omega-3 fatty acids, inhibits osteoblastogenesis and induces adipogenesis of human mesenchymal stem cells: potential implication in osteoporosis

Arachidonic fatty acid (AA) induces adipogenesis in human mesenchymal stem cells cultures, and high concentrations inhibit osteoblastogenesis; whereas eicosapentaenoic and docosahexaenoic fatty acids do not induce adipogenesis and do not inhibit osteoblastogenesis. In mesenchymal stem cells, omega-6 arachidonic polyunsaturated fatty acid promotes the differentiation of adipocytes and inhibits the osteoblast differentiation. While omega-3 fatty acids do not affect the adipogenic differentiation their effects on osteoblastogenesis are less relevant. An increased ratio of omega-3/omega-6 fatty acid consumption can prevent bone mass loss.

INTRODUCTION

Consumption of omega-3 may protect against osteoporosis since they may inhibit osteoclastogenesis. However, with aging, MSC in bone marrow are increasingly differentiated into adipocytes, reducing the number of osteoblasts. Products derived from omega-6 and omega-3 metabolism may affect MSC differentiation into osteoblasts and adipocytes.

METHODS

Human MSC have been differentiated into osteoblasts or adipocytes in the presence of omega-6 (AA), or omega-3 (DHA and EPA), and osteoblastic and adipocytic markers have been analyzed.

RESULTS

AA decreases the expression of osteogenic markers and the osteoprotegerin/receptor activator of nuclear factor kappa β ligand gene expression ratio (opg/rankl). High concentrations of AA inhibit the mineralization and cause the appearance of adipocytes in MSC differentiating into osteoblasts to a higher extent than DHA or EPA. In MSC differentiated into adipocytes, AA increases adipogenesis, while DHA and EPA do not affect it. AA caused the appearance of adipocytes in undifferentiated MSC. The lipoxygenase gene (alox15b) is induced by omega-3 in MSC induced to osteoblasts, and by omega-6 in MSC induced to adipocytes.

CONCLUSIONS

An increase in the intake of omega-3 respect to omega-6 may provide protection against the loss of bone mass, since omega-6 favors the osteoclastic activity by diminishing the opg/rankl gene expression in osteoblasts and promotes MSC differentiation into adipocytes, thus diminishing the production of osteoblasts.

Impact of omega-6 fatty acids on cardiovascular outcomes: A review

Poly unsaturated fatty acids (PUFAs) have usually been associated with beneficial health effects on early life and later life disease such as cardiovascular diseases (CVD). Emerging evidence, however, suggests that PUFA species (n-3, n-6) have differential health effects. N-6 PUFAs, in particular, have sparked a scientific debate regarding their role in human physiological processes. Current dietary recommendations for n-6 fatty acids have been based on animal studies, insufficient epidemiological evidence and mixed PUFA interventions, therefore, require reconsideration. This review has analyzed human epidemiological and interventional studies, published in the last five years, focusing on n-6 fatty acids' impact on CVD outcomes (CVD events, blood lipids, blood pressure, inflammation, oxidative stress/atherosclerosis). The evidence is mixed, with differential effects within the n-6 fatty acid series. These outcomes are also dependent on ethnicity and background health status. Further, data from developing countries are sparse, thus, well designed intervention trials and population based studies in developing country settings on specific n-6 fatty acid intake and health effects are desired.

Fatty acids in cardiovascular health and disease: a comprehensive update

Research dating back to the 1950s reported an association between the consumption of saturated fatty acids (SFAs) and risk of coronary heart disease. Recent epidemiological evidence, however, challenges these findings. It is well accepted that the consumption of SFAs increases low-density lipoprotein cholesterol (LDL-C), whereas carbohydrates, monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) do not. High-density lipoprotein (HDL)-C increases with SFA intake. Among individuals who are insulin resistant, a low-fat, high-carbohydrate diet typically has an adverse effect on lipid profiles (in addition to decreasing HDL-C, it also increases triglyceride and LDL particle concentrations). Consequently, a moderate fat diet in which unsaturated fatty acids replace SFAs and carbohydrates are not augmented is advised to lower LDL-C; compared with a low-fat diet, a moderate-fat diet will lower triglycerides and increase HDL-C. Now, there is some new evidence that is questioning the health benefits of even MUFAs and PUFAs. In addition, in a few recent studies investigators have also failed to demonstrate expected cardiovascular benefits of marine-derived omega-3 fatty acids. To clarify the clinical pros and cons of dietary fats, the National Lipid Association held a fatty acid symposium at the 2011 National Lipid Association Scientific Sessions. During these sessions, the science regarding the effects of different fatty acid classes on coronary heart disease risk was reviewed.

Coronary artery calcification by computed tomography in epidemiologic research and cardiovascular disease prevention

Both American and European guidelines recommend coronary artery calcification (CAC) as a tool for screening asymptomatic individuals at intermediate risk for coronary heart disease (CHD). These recommendations are based on epidemiologic studies mostly in the United States. We review (1) the use of CAC in primary prevention of CHD in the United States, (2) epidemiologic studies of CAC in asymptomatic adults outside of the United States, and (3) international epidemiologic studies of CAC. This review will not consider clinical studies of CAC among patients or symptomatic individuals. US studies have shown that CAC is a strong independent predictor of CHD in both sexes among middle-aged and old age groups, various ethnic groups, and individuals with and without diabetes and that CAC plays an important role in reclassifying individuals from intermediate to high risk. Studies in Europe support these conclusions. The Electron-Beam Tomography, Risk Factor Assessment Among Japanese and US Men in the Post-World-War-II birth cohort (ERA JUMP) Study is the first international study to compare subclinical atherosclerosis, including CAC among Japanese, Japanese Americans, Koreans, and whites. It showed that as compared with whites, Japanese had lower levels of atherosclerosis, whereas Japanese Americans had similar or higher levels. CAC is being increasingly used as a screening tool for asymptomatic individuals in Europe and the United States. CAC is a powerful research tool, because it enables us to describe differences in atherosclerotic burden across populations. Such research could identify factors responsible for differences among populations, which may improve CHD prevention.

Significant inverse associations of serum n-6 fatty acids with plasma plasminogen activator inhibitor-1

Epidemiological studies suggested that n-6 fatty acids, especially linoleic acid (LA), have beneficial effects on CHD, whereas some in vitro studies have suggested that n-6 fatty acids, specifically arachidonic acid (AA), may have harmful effects. We examined the association of serum n-6 fatty acids with plasminogen activator inhibitor-1 (PAI-1). A population-based cross-sectional study recruited 926 randomly selected men aged 40-49 years without CVD during 2002-2006 (310 Caucasian, 313 Japanese and 303 Japanese-American men). Plasma PAI-1 was analysed in free form, both active and latent. Serum fatty acids were measured with gas-capillary liquid chromatography. To examine the association between total n-6 fatty acids (including LA and AA) and PAI-1, multivariate regression models were used. After adjusting for confounders, total n-6 fatty acids, LA and AA, were inversely and significantly associated with PAI-1 levels. These associations were consistent across three populations. Among 915 middle-aged men, serum n-6 fatty acids had significant inverse associations with PAI-1.