Fatty acids in multiple circulating lipid fractions reflects the composition of liver triglycerides in humans

1. Male, female and castrated rats treated with oestradiol (30mug./week) or testosterone (2mg./week) were given an essential fatty acid-deficient diet containing 10% of hydrogenated coconut oil for 9 weeks. The concentrations and fatty acid composition of plasma phospholipids, cholesteryl esters and triglycerides were determined. 2. Between the second and third weeks of the deficiency, concentrations of plasma cholesteryl esters, phospholipids and triglycerides decreased, then remained relatively constant. There were no significant differences between males and females, but oestradiol caused a significant rise in plasma phospholipids and triglycerides as compared with testosterone-treated animals. 3. During the first 2 weeks of the deficiency, linoleic acid in the plasma lipids of all groups decreased to low concentrations and changed very little thereafter. 4. Female rats maintained higher percentages and concentrations of arachidonic acid and stearic acid in plasma phospholipids and arachidonic acid in cholesteryl esters than did males. Males had higher proportions of eicosatrienoic acid and oleic acid. There was no sex difference in the fatty acid composition of plasma triglycerides. 5. Oestradiol-treated rats had concentrations of cholesteryl and phospholipid arachidonate comparable with those of female rats and higher than the testosterone-treated group. Eicosatrienoic acid in the oestradiol-treated rats was high and resembled that of the male rats, apparently because of the higher concentration of plasma phospho lipids in this group. 6. Supplementation of the essential fatty acid-deficient rats with linoleate restored plasma cholesteryl and phospholipid linoleate and arachidonate nearly to normal concentrations in a single day. The increase in arachidonic acid in these fractions was accompanied by a similar quantitative decrease in eicosatrienoic acid. 7. These sex differences appear to be related to the smaller size of the female rat and to a more direct influence of oestradiol on the formation or maintenance of phospholipids rich in arachidonic acid.

Platelet aggregation and its relation to fatty acid composition of platelets, plasma and adipose tissue was determined in 196 randomly selected, free-living, 40-49-year-old men in two regions of Finland (east and southwest) with a nearly twofold difference in the IHD rate. There were no significant east-southwest differences in platelet aggregation induced with ADP, thrombin or epinephrine. ADP-induced platelet secondary aggregation showed significant negative associations with all C20-C22 omega 3-fatty acids in platelets (r = -0.26- -0.40) and with the platelet 20: 5 omega 3/20: 4 omega 6 and omega 3/omega 6 ratios, but significant positive correlations with the contents of 18:2 in adipose tissue (r = 0.20) and plasma triglycerides (TG) (r = 0.29). Epinephrine-induced aggregation correlated negatively with 20: 5 omega 3 in plasma cholesteryl esters (CE) (r = -0.23) and TG (r = -0.29), and positively with the total percentage of saturated fatty acids in platelets (r = 0.33), but had no significant correlations with any of the omega 6-fatty acids. Thrombin-induced aggregation correlated negatively with the omega 3/6 omega ratio in adipose tissue (r = -0.25) and the 20: 3 omega 6/20: 4 omega 6 ratio in plasma CE (r = -0.27) and free fatty acids (FFA) (r = -0.23), and positively with adipose tissue 18:2 (r = 0.23) and 20:4 omega 6 (r = 0.22) in plasma phospholipids (PL). The percentages of prostanoid precursors in platelet lipids, i.e. 20:3 omega 6, 20:4 omega 6 and 20:5 omega 3, correlated best with the same fatty acids in plasma CE (r = 0.32 - 0.77) and PL (r = 0.28 - 0.74). Platelet 20:5 omega 3 had highly significant negative correlations with the percentage of 18:2 in adipose tissue and all plasma lipid fractions (r = -0.35 - -0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

Liquid crystal monomers (LCMs) are new pollutants derived from emissions from liquid crystal displays (LCDs). In recent years, environmental and health concerns on LCMs have mainly focused on nematic and smectic LCMs. However, information regarding cholesteric LCMs in the environment remains lacking. Herein, we made the first comprehensive screening of cholesteric LCMs in e-waste dust. Target analysis uncovered the presence of 28 cholesteric LCMs in dust samples, including 14 fatty acid cholesteryl esters (FACEs), 9 alkyl carbonate cholesteryl esters (ACCEs), and 5 other-type cholesteryl esters. According to the analogous characteristics of FACEs, a suspect screening framework identified an additional 43 long-chain FACEs. Overall, 71 cholesteric LCMs were identified, with 30 detected in >50% of samples. The median and highest values of their sum concentrations were 94.3 and 1880 ng/g, respectively. FACEs emerged as the dominant group, with long-chain FACEs, particularly FACEs (18:0), exhibiting significantly more abundance than short-chain and medium-chain FACEs. In silico predictive modeling revealed that most of these newly identified cholesteric LCMs exhibited medium-to-high estrogenic/androgenic activities. Our findings confirm cholesteric LCMs as another abundant class of LCD-derived new pollutants in the environment and highlight the need to include these new chemicals in the future risk assessment of LCMs.

Cholesteryl esters prepared from the fatty acid methyl esters of linseed oil, pig liver lipids, and Japanese anchory oil have been separated on the basis of their chain lengths and number of double bonds by gas liquid chromatography on a cyanosiloxane SILAR 10C column. The equivalent chain lengths of cholesteryl esters having acyl groups with 14-22 carbons and 0-6 double bonds are presented. A significant influence of the column temperature on the equivalent chain lengths of the polyenoic fatty acid cholesteryl esters has been found. Separation of the cholestanyl and epicholestanyl esters of linseed oil fatty acids, respectively, under the same conditions is also described.

Our aim was to investigate the fasting proportions of fatty acids and estimated desaturase and elongase activities in three different lipid fractions in plasma, phospholipids (PLs), cholesteryl esters (CEs) and triacylglycerols (TGs), as predictors for the worsening of glycaemia (area under the glucose curve in an OGTT [glucose AUC]) and incident type 2 diabetes in a 5.9 year follow-up of the Metabolic Syndrome in Men population-based cohort. Fatty acid proportions were measured in plasma PL, CE and TG fractions in 1,364 Finnish men aged 45-68 years at baseline. The prospective follow-up study included only men who were non-diabetic at baseline and had data available at follow-up (n = 1,302). A total of 71 participants developed new type 2 diabetes during follow-up. After adjusting for confounding factors, total saturated fatty acids, palmitoleic acid (16:1n-7), dihomo-γ-linolenic acid (20:3n-6) and estimated stearoyl-CoA desaturase 1 and Δ(6)-desaturase (D6D) enzyme activities significantly predicted the worsening of glycaemia whereas total polyunsaturated fatty acid, linoleic acid (18:2n-6) and elongase activity predicted a decrease in the glucose AUC. Estimated D6D activity and dihomo-γ-linolenic acid (20:3n-6) were associated with an increased risk of incident type 2 diabetes. Results were consistent across the three different lipid fractions. However, fatty acid proportions in the PL and CE fractions were stronger predictors for glycaemia and incident type 2 diabetes compared with fatty acid proportions in the TG fraction. Selected fatty acid proportions of plasma lipid fractions and their ratios, which reflect desaturase and elongase enzyme activities, may be good biomarkers for the worsening of glycaemia and incident type 2 diabetes.

Research on possible physiological changes as a consequence of a specific lifestyle and long-term strenuous exercise in boxing has been sparse. We determined plasma and erythrocyte phospholipid (PL) fatty acids (FA) profile of 16 elite amateur male boxers (22.4±3.3 years of age), and compared them with a control group composed of 19 sedentary (24.4±3.4) year-old men. The percentages of total saturated fatty acids (SFA) and monosaturated FA in plasma phospholipids were significantly higher (P <0.001) in boxers compared to the control group. On the other hand, all studied polyunsaturated fatty acids (PUFA) in plasma PL with the exception of eicosapentaenoic acid (EPA, 20:5, n–3) and docosatetraenoic acid (DTA, 22:4, n–6) were significantly lower in boxers than in sedentary men. Total PUFA, n–6 PUFA and n–3 PUFA were also significantly lower in boxers (P <0.001), whereas the n–6/n–3 ratio was higher in boxers than in control group (P <0.01). Boxers had significantly higher proportion of all SFA in erythrocyte PL compared to the control group (P <0.05). In addition, the percentage of linoleic acid was lower in boxers' erythrocyte PL than in the control group (P <0.05). The results show two potentially unfavourable main features of the FA profile of boxers, that is, a higher n–6/n–3 ratio in plasma PL and a higher percentage of SFA in both plasma and erythrocyte phospholipids compared to controls. As SFA correlates directly with the incidence of cardiovascular disease and high n–6/n–3 ratio has been shown to stimulate carcinogenesis and modulate inflammation and autoimmunity, this profile could be detrimental to the health of boxers. The mechanism underlying these differences requires further investigation; however the results suggest benefits of nutritional intervention.

We aimed to investigate the effects of fish oil (FO) supplementation to pregnant women on the maternal and fetal fatty acid profile in plasma and erythrocyte phospholipids (PL) and to identify the best compartment for the assessment of fatty acid status. A multi-centre, double-blind, controlled trial was conducted. Healthy pregnant women from three European centres were randomly assigned to receive from week 20 of gestation until delivery a daily dietary supplement with either FO (500 mg DHA+150 mg EPA), 400 μg 5-methyltetrahydrofolate, both or placebo. Fatty acids in plasma and erythrocyte PL were determined in maternal blood (week 20, week 30 of pregnancy and delivery) and in cord blood (delivery). FO supplementation increased DHA levels in maternal and cord plasma and erythrocyte PL. Higher percentage changes were observed in erythrocyte PL than in plasma PL. There were significant correlations between plasma and erythrocyte fatty acid levels in maternal and cord blood. Significant correlations between maternal and cord fatty acid levels at delivery in plasma and erythrocytes were also observed; however, correlation coefficients were higher for erythrocyte phophatidylethanolamine. FO supplementation increases maternal and fetal DHA status. Both plasma and erythrocytes appear to be suitable to evaluate the fatty acid status of mothers but erythrocytes seem to be a more reliable marker in neonates.

BackgroundCirculating odd-chain fatty acids pentadecanoic (15:0) and heptadecanoic acid (17:0) are considered to reflect dairy intake. In cohort studies, higher circulating 15:0 and 17:0 were associated with lower type 2 diabetes risk. A recent randomized controlled trial in humans suggested that fiber intake also increased circulating 15:0 and 17:0, potentially resulting from fermentation by gut microbes. We examined the associations of dairy and fiber intake with circulating 15:0 and 17:0 in patients with a history of myocardial infarction (MI).MethodsWe performed cross-sectional analyses in a subsample of 869 Dutch post-MI patients of the Alpha Omega Cohort who had data on dietary intake and circulating fatty acids. Dietary intakes (g/d) were assessed using a 203-item food frequency questionnaire. Circulating 15:0 and 17:0 (as % of total fatty acids) were measured in plasma phospholipids (PL) and cholesteryl esters (CE). Spearman correlations (rs) were computed between intakes of total dairy, dairy fat, fiber, and circulating 15:0 and 17:0.ResultsPatients were on average 69 years old, 78% was male and 21% had diabetes. Total dairy intake comprised predominantly milk and yogurt (69%). Dairy fat was mainly derived from cheese (47%) and milk (15%), and fiber was mainly from grains (43%). Circulating 15:0 in PL was significantly correlated with total dairy and dairy fat intake (both rs = 0.19, p < 0.001), but not with dietary fiber intake (rs = 0.05, p = 0.11). Circulating 17:0 in PL was correlated both with dairy intake (rs = 0.14 for total dairy and 0.11 for dairy fat, p < 0.001), and fiber intake (rs = 0.19, p < 0.001). Results in CE were roughly similar, except for a weaker correlation of CE 17:0 with fiber (rs = 0.11, p = 0.001). Circulating 15:0 was highest in those with high dairy intake irrespective of fiber intake, while circulating 17:0 was highest in those with high dairy and fiber intake.ConclusionsIn our cohort of post-MI patients, circulating 15:0 was associated with dairy intake but not fiber intake, whereas circulating 17:0 was associated with both dairy and fiber intake. These data suggest that cardiometabolic health benefits previously attributed to 17:0 as a biomarker of dairy intake may partly be explained by fiber intake.

Background: Odd-chain fatty acids (OCFA) pentadecanoic (15:0) and heptadecanoic acid (17:0) are considered to reflect dairy intakes in studies on cardiometabolic outcomes. A recent randomized controlled trial on dietary fiber showed that circulating proportions of these OCFA may also be related to fiber intake, which may result from fermentation by gut microbes. Objective: To examine the associations between circulating OCFA and dairy and fiber intake in patients with a history of myocardial infarction. Methods: We performed cross-sectional analyses in a subsample of 896 Dutch post-MI patients of the Alpha Omega Cohort. Proportions of OCFA (as % of total fatty acids) were measured in plasma phospholipids (PL) and cholesterol esters (CE). Dietary intakes (g/d) were assessed using a 203-item validated food frequency questionnaire. Spearman correlations ( r ) were computed between circulating OCFA in PL and CE and intakes of total dairy, types of dairy products, dietary fiber and total meat. Results: Patients were on average 69 years old, 78% was male and 89% used statins. Dairy intake was predominantly from milk and yogurt. PL 15:0 was positively correlated with total dairy intake ( r =0.16, p&lt;0.001; Table 1), especially yogurt. PL 15:0 was not correlated with dietary fiber ( r =0.01, p=0.75). For CE 15:0, correlations were similar. PL 17:0 was positively correlated with total dairy ( r =0.15, p&lt;0.001), but also with dietary fiber ( r =0.13, p&lt;0.001). For CE 17:0 similar correlations were observed, although somewhat weaker (dairy: r =0.10, p=0.003; fiber: r =0.09, p=0.009). OCFA were not significantly correlated with meat intake. Conclusions: Plasma PL 15:0 and CE 15:0 were related to dairy and not to fiber intake. PL 17:0 and CE 17:0 were equally related to dairy and fiber intake. Cardiometabolic health benefits attributed to biomarkers of dairy intake, especially 17:0, may be (partly) attributable to fiber intake. Further research is needed into endogenous OCFA synthesis as a result of fermentation of dietary fiber by gut microbes.

Polyunsaturated fatty acids (PUFA), which comprise 25-30% of the fatty acids in the human brain, are necessary for normal brain development and function. PUFA cannot be synthesized de novo and must be supplied to the brain by the plasma. It is necessary to know the PUFA content and composition of the various plasma lipids and lipoproteins in order to understand how these fatty acids are taken up and metabolized by the brain. Human plasma free fatty acid (FFA) ordinarily contains about 15% linoleic acid (18:2n-6) and 1% arachidonic acid (AA) (20:4n-6). Plasma triglycerides, phospholipids, and cholesterol esters also are rich in linoleic acid, and the phospholipids and cholesterol esters contain about 10% AA. These findings suggest that the brain probably can obtain an adequate supply of n-6 PUFA from either the plasma FFA or lipoproteins. By contrast, the plasma ordinarily contains only one-tenth as much n-3 PUFA, and the amounts range from 1% alpha-linolenic acid (18:3n-3) in the plasma FFA to 2% docosahexaenoic acid (22:6n-3, DHA) in the plasma phospholipids. The main n-3 PUFA in the brain is DHA. Therefore, if the plasma FFA is the primary source of fatty acid for the brain, much of the DHA must be synthesized in the brain from n-3 PUFA precursors. Alternatively, if the brain requires large amounts of preformed DHA, the phospholipids contained in plasma lipoproteins are the most likely source.

We have studied the fatty acids of red cell phospholipids, plasma phospholipids, cholesteryl esters and high density lipoproteins in 19 violent offenders and in 25 age-matched controls. There were highly significant increases in oleic acid (18:ln9) in plasma phospholipids, cholesteryl esters and high density lipoproteins, and there were decreases in arachidonic acid (20:4n6) in the same lipids in the offenders. There were also decreased concentrations of other n6 and n3 long chain polyunsaturated fatty acids in the offenders. The reductions in n6 fatty acids were evident without an increase in linoleic acid (18:2n6), therefore it is unlikely that the findings can be explained by altered activity of the delta-6 desaturase enzyme.

Methionine-choline-deficient (MCD) diets that cause steatohepatitis in rodents are typically enriched in polyunsaturated fat. To determine whether the fat composition of the MCD formula influences the development of liver disease, we manufactured custom MCD formulas with fats ranging in PUFA content from 2% to 59% and tested them for their ability to induce steatohepatitis. All modified-fat MCD formulas caused identical degrees of hepatic steatosis and resulted in a similar distribution of fat within individual hepatic lipid compartments. The fatty acid composition of hepatic lipids, however, reflected the fat composition of the diet. Mice fed a PUFA-rich MCD formula showed extensive hepatic lipid peroxidation, induction of proinflammatory genes, and histologic inflammation. When PUFAs were substituted with more saturated fats, lipid peroxidation, proinflammatory gene induction, and hepatic inflammation all declined significantly. Despite the close relationship between PUFAs and hepatic inflammation in mice fed MCD formulas, dietary fat had no impact on MCD-mediated damage to hepatocytes. Indeed, histologic apoptosis and serum alanine aminotransferase levels were comparable in all MCD-fed mice regardless of dietary fat content. Together, these results indicate that dietary PUFAs promote hepatic inflammation but not hepatotoxicity in the MCD model of liver disease. These findings emphasize that individual dietary nutrients can make specific contributions to steatohepatitis.

Different metabolism of EPA, DPA and DHA in humans: A double-blind cross-over study

Estrogens may affect the essential n-6 and n-3 fatty acids arachidonic acid (AA; C20:4n-6) and docosahexaenoic acid (DHA; C22:6n-3). Therefore, we investigated the long-term effects of hormone replacement therapy and raloxifene, a selective estrogen-receptor modulator, in two randomized, double-blind, placebo-controlled studies. In study I, 95 healthy, non-hysterectomized, early postmenopausal women (age range 47-59 years) received one of the following treatments: daily raloxifene 60 mg (n=24), daily raloxifene 150 mg (n=23), 0.625 mg conjugated equine estrogens (CEE) plus 2.5 mg medroxyprogesterone acetate (MPA; n=24), or placebo (n=24). In study II, 30 men (age range 60-69 years) received daily 120 mg raloxifene (n=15) or placebo (n=15). In study I, plasma cholesteryl ester fatty acids were measured at baseline and after 6, 12, and 24 months in 83 (drop out rate 13%), 73 (23%), and 70 (25%) women respectively. In study II, fatty acids were measured at baseline and after 3 months in 29 men (drop out rate 3%). In postmenopausal women, administration of 150 mg raloxifene increased AA by a mean of +6.1% (P=0.055, not significant). Administration of CEE plus MPA increased AA by +14.1% (P<0.0005). Mean changes in DHA were +22.1% (P=0.003) and +14.9% (P=0.047) respectively, as compared with placebo. In men, 120 mg raloxifene for 3 months did not significantly affect AA (-5.2%; P=0.342) or DHA (+4.0%; P=0.755), but it increased testosterone levels by +19.8% (P=0.006). Administration of raloxifene 150 mg/day as well as CEE plus MPA to postmenopausal women increases the proportion of AA and DHA in plasma cholesteryl esters during a follow-up of 2 years. Short term administration of raloxifene in elderly men did not affect AA or DHA. The synthesis of AA and DHA from precursors may be enhanced through an estrogen receptor-dependent pathway.

In human as well as animal atherosclerosis, the bulk of lipids accumulates in lesions in the form of small spheres. We have studied these particulate lipids in human fatty streak and fibrous plaque lesions, and determined their average diameter as 1.9μ and defined their liquid crystalline nature as lyotropic smectic mesophase. We have designated these lipid bodies in atherosclerosis as lipid inclusions.In this study we isolated these lipid inclusions from fatty streak and fibrous plaque lesions of aortic atherosclerosis of each 21 subjects, with an average age of 40.9 and 51.2, respectively, who died sudden and unexpected death. Lipids were analysed by quantitative thin-layer chromatography and cholesteryl ester fatty acids by gas-liquid chromatography for comparison between inclusions and inclusion-free tissue residues, and also between the inclusions of fatty streak and fibrous plaque lesions.The compositions of lipids of the inclusions were remarkably uniform and strikingly different from those of inclusion-free residues, respectively: cholesteryl esters 82.3 vs 34.6% free cholesterol 4.9 vs 20.4%, triglycerides 4.3 vs 4.8%, and total phospholipids 8.7 vs 40.1% in fatty streaks, and cholesteryl esters 60.8 vs 42.0%, free cholesterol 13.0 vs 28.9%, triglycerides 10.4 vs 6.3% and total phospholipids 15.8 vs 22.9% in fibrous plaques. The proportions of individual phospholipids were also different in lecithin and sphingomyelin between the inclusions and the residues in fatty streaks. The compositions of inclusions of fatty streaks were significantly different from those of fibrous plaque inclusions with the exception of triglycerides and lysolecithin. Major fatty acid of cholesteryl esters in both fatty streak and fibrous plaque inclusions was oleate.These results indicate that (i) the lipid inclusions from both fatty streaks and fibrous plaques are quite unique in the chemical compositions when compared with those of any other blood lipids or serum lipoproteins such as chylomicron, VLDL, LDL, and HDL. (ii) that the metabolic origin of the lipid inclusions, therefore, cannot be explained by a simple deposition of blood lipid constituents or serum lipoproteins in the lesion tissues, and (iii) that the liquid crystalline nature of the inclusions largly due to physical properties of cholesteryl ester molecules seems to be playing a crucial role in the pathogenesis and development of fatty streak and fibrous plaque lesions.