Individual Non-esterified Fatty Acids Research Articles

Abstract P175: Total Fasting and Post-Load and Individual Fasting Non-Esterified Fatty Acids and Total and Cause-Specific Mortality: The Cardiovascular Health Study

Background: Total fasting non-esterified fatty acid (NEFA) levels have been associated with total and cause-specific mortality in older adults, but the corresponding associations with NEFA levels following the metabolic challenge of an oral glucose tolerance test (OGTT) and with individual fasting NEFA species have not been quantified Methods: We studied 1996 participants from the Cardiovascular Health Study with a mean age of 78 years who had total serum NEFA measured enzymatically before and two hours after an OGTT and fasting individual NEFA measured using gas chromatography in samples collected in 1996-1997. 1678 participants died over a median follow-up of 11 years. Multivariable Cox proportional hazard models were used to evaluate adjusted hazard ratios (aHR) for mortality associated with standard deviation increments of fasting and post-load total NEFA and fasting individual and subclasses (saturated, monounsaturated, n-3 and n-6 polyunsaturated, and trans) Results: Fasting NEFA were associated with an increased risk of all-cause mortality (aHR 1.17, 95% CI 1.10 - 1.23). In contrast, levels of post-load NEFA were not associated with mortality (aHR 0.98, 95% CI 0.93 - 1.03). Among NEFA subclasses, only monounsaturated fatty acid (MUFA) were associated with total mortality (aHR 1.24, 95% CI 1.09 - 1.41). In cause-specific analyses, MUFA were associated with higher risk of death from dementia, cardiovascular, respiratory, infectious and kidney disease. For individual NEFAs, nervonic acid (aHR 1.06, 95% CI 1.01 - 1.12) and petroselaidic acid (aHR 1.21, 95% CI 1.03 - 1.42) were associated with higher risk of all-cause mortality whereas eicosapentaenoic acid (aHR 0.90, 95% CI 0.82 - 0.99) was associated with lower risk Conclusion: Among community-dwelling older adults, total fasting but not post-load NEFA were associated with higher risk of death. Among subclasses and individual species, MUFA, nervonic, and petroselaidic acids were associated with higher risk, and eicosapentanoic acid with lower risk, of mortality.

The Associations of Individual and Subclasses of Nonesterified Fatty Acids With Disability, and Mobility Limitation in Older Adults: The Cardiovascular Health Study.

We sought to determine the associations between individual nonesterified fatty acids (NEFAs) and disability and mobility limitation. We studied 1734 participants in the Cardiovascular Health Study (CHS), an ongoing population-based cohort study of community-living older American adults. We measured 35 individual NEFA species in fasting serum samples obtained at the 1996-1997 clinic visit. Using yearly assessments of activities of daily living and self-reported mobility, we identified participants with incident disability or mobility limitation during 15years of follow-up. Cox proportional hazards regression models were used to determine the associations between per SD increment in the individual NEFAs and incident disability and mobility limitations with adjustment for potential confounding factors. Higher concentrations of total and a broad range of individual NEFA species were associated with risk of disability and mobility limitation (disability: HR per SD of total NEFA [SD=174.70]=1.11, 95% CI=1.04-1.18, p=.001; mobility limitation: HR per SD of total NEFA=1.09, 95% CI=1.02-1.16, p=.01). Among individual saturated NEFAs (SFAs), myristic (14:0) and palmitic (16:0) acids were significantly associated with higher risk of both disability and mobility limitations, but longer-chain FAs were not. Most individual monounsaturated (MUFA), n-6 polyunsaturated fatty acids (PUFAs), and trans FAs were positively significantly associated with higher risks of both disability and mobility limitation. In contrast, most n-3 PUFA species were not associated with disability or mobility limitation. Higher risks of disability and mobility limitation were observed for proinflammatory intermediate-chain SFAs, MUFAs, n-6 PUFAs, and trans FAs. Our findings indicated no significant association for anti-inflammatory n-3 PUFAs.

Serum Nonesterified Fatty Acids and Incident Stroke: The CHS.

BackgroundSignificant associations between total nonesterified fatty acid (NEFA) concentrations and incident stroke have been reported in some prospective cohort studies. We evaluated the associations between incident stroke and serum concentrations of nonesterified saturated, monounsaturated, polyunsaturated, and trans fatty acids.Methods and ResultsCHS (Cardiovascular Health Study) participants (N=2028) who were free of stroke at baseline (1996–1997) and had an archived fasting serum sample were included in this study. A total of 35 NEFAs were quantified using gas chromatography. Cox proportional hazards regression models were used to evaluate associations of 5 subclasses (nonesterified saturated, monounsaturated, omega (n)‐6 polyunsaturated, n‐3 polyunsaturated, and trans fatty acids) of NEFAs and individual NEFAs with incident stroke. Sensitivity analysis was conducted by excluding cases with hemorrhagic stroke (n=45). A total of 338 cases of incident stroke occurred during the median 10.5‐year follow‐up period. Total n‐3 (hazard ratio [HR], 0.77 [95% CI, 0.61–0.97]) and n‐6 (HR, 1.32 [95% CI, 1.01–1.73]) subclasses of NEFA were negatively and positively associated with incident stroke, respectively. Among individual NEFAs, dihomo‐γ‐linolenic acid (20:3n‐6) was associated with higher risk (HR, 1.29 [95% CI, 1.02–1.63]), whereas cis‐7‐hexadecenoic acid (16:1n‐9c) and arachidonic acid (20:4n‐6) were associated with a lower risk (HR, 0.67 [95% CI, 0.47–0.97]; HR, 0.81 [95% CI. 0.65–1.00], respectively) of incident stroke per standard deviation increment. After the exclusion of cases with hemorrhagic stroke, these associations did not remain significant.ConclusionsA total of 2 NEFA subclasses and 3 individual NEFAs were associated with incident stroke. Of these, the NEFA n‐3 subclass and dihomo‐γ‐linolenic acid are diet derived and may be potential biomarkers for total stroke risk.

Serum Non-Esterified Fatty Acids, Carotid Artery Intima-Media Thickness and Flow-Mediated Dilation in Older Adults: The Cardiovascular Health Study (CHS)

Backgrounds and aims: Elevated common carotid artery intima-media thickness (carotid IMT) and diminished flow-mediated dilation (FMD) are early subclinical indicators of atherosclerosis. Serum total non-esterified fatty acid (NEFA) concentrations have been positively associated with subclinical atherosclerosis. The relations between individual NEFA, carotid IMT and FMD have as yet to be assessed. Methods: We investigated the associations between fasting serum individual NEFA, carotid IMT and FMD among Cardiovascular Health Study (CHS) participants with (n = 255 for carotid IMT, 301 for FMD) or without (n = 1314 for carotid IMT, 1462 for FMD) known atherosclerotic cardiovascular disease (ASCVD). Using archived samples (fasting) collected from 1996–1997 (baseline), 35 individual NEFAs were measured using gas chromatography. Carotid IMT and estimated plaque thickness (mean of maximum internal carotid IMT) were determined in 1998–1999. FMD was measured in 1997–1998. Linear regression adjusted by the Holm-Bonferroni method was used to assess relations between individual NEFA, carotid IMT and FMD. Results: In multivariable adjusted linear regression models per SD increment, the non-esterified trans fatty acid conjugated linoleic acid (trans-18:2 CLA) was positively associated with carotid IMT [β (95% CI): 44.8 (19.2, 70.4), p = 0.025] among participants with, but not without, ASCVD [2.16 (−6.74, 11.5), p = 1.000]. Non-esterified cis-palmitoleic acid (16:1n-7c) was positively associated with FMD [19.7 (8.34, 31.0), p = 0.024] among participants without, but not with ASCVD. No significant associations between NEFAs and estimated plaque thickness were observed. Conclusions: In older adults, serum non-esterified CLA and palmitoleic acid were positively associated with carotid IMT and FMD, respectively, suggesting potential modifiable biomarkers for arteriopathy.

Associations of maternal and infant metabolite profiles with foetal growth and the odds of adverse birth outcomes.

SummaryBackgroundAdaptations in maternal and foetal metabolic pathways may predispose to altered foetal growth and adverse birth outcomes.ObjectiveTo assess the associations of maternal early‐pregnancy metabolite profiles and infant metabolite profiles at birth with foetal growth from first trimester onwards and the odds of adverse birth outcomes.MethodsIn a prospective population‐based cohort among 976 Dutch pregnant women and their children, serum concentrations of amino acids, non‐esterified fatty acids (NEFA), phospholipids (PL) and carnitines in maternal early‐pregnancy blood and in cord blood were obtained by liquid‐chromatography tandem mass spectrometry. Information on foetal growth was available from first trimester onwards.ResultsAfter false discovery rate correction for multiple testing, higher infant total and individual NEFA concentrations were associated with a lower weight, length, and head circumference at birth. Higher infant total and individual acyl‐lysophosphatidylcholine (lyso.PC.a) and alkyl‐lysophosphatidylcholine concentrations were associated with higher weight and head circumference (lyso.PC.a only) at birth, higher odds of LGA and lower odds of SGA. Few individual maternal metabolites were associated with foetal growth measures in third trimester and at birth, but not with the odds of adverse birth outcomes.ConclusionsOur results suggest that infant metabolite profiles, particularly total and individual lyso.PC.a and NEFA concentrations, were strongly related to growth measures at birth and the odds of adverse birth outcomes. Few individual maternal early‐pregnancy metabolites, but not total metabolite concentrations, are associated with foetal growth measures in third trimester and at birth.

Serum Fasting Non-esterified Fatty Acids and Carotid Artery Intima-Media Thickness in Older Adults: The Cardiovascular Health Study

ObjectivesCarotid artery intima-media thickness (CIMT) has been used as an early indicator of subclinical atherosclerosis. Multiple studies have identified significant associations between plasma total non-esterified fatty acid (NEFA) concentrations and risk factors associated with subclinical atherosclerosis. However, the relationship between CIMT and serum NEFA is less clear. We hypothesized fasting serum total, individual saturated, and trans NEFA are positively associated with, and individual monounsaturated, n-6 polyunsaturated (PUFA) and n-3 PUFA NEFA are inversely associated with, CIMT. MethodsWe investigated the associations between fasting serum NEFA, and CIMT assessed in 1998–1999 among Cardiovascular Health Study (CHS) participants (N = 1,569) not taking anti-diabetic medication. A total of 35 individual NEFAs were measured in stored specimens from 1996–1997 using gas chromatography. CIMT was determined using ultrasound images, and was defined as the sum of the maximum common CIMT at the far wall divided by its standard deviation (SD) and the maximum internal CIMT at the far wall divided by its SD. At baseline, mean age was 77.3 ± 4.2, body mass index (BMI) was 26.8 ± 4.3 and 64% were female. Associations were assessed by linear regression, with adjustments for other individual NEFAs, age, sex, race, field center, education, smoking, BMI, physical activity, alcohol consumption, eGFR, serum albumin, hyperglycemia, hypertension, use of anti-hypertensive, statin, and other lipid-lowering drugs. ResultsIn adjusted models per SD increment, linoelaidic acid (trans18:2) was positively associated with CIMT [β (95% confidence interval): 10.4 (0.99, 19.8), P = 0.03], and α-linolenic acid (18:3n-3) was marginally associated with lower CIMT [–21.2 (–42.6, 0.2), P = 0.05]. No significant associations were observed between total NEFAs or any other individual NEFAs (SFA, MUFA, and n-6 PUFA) and CIMT. ConclusionsIn this large community-based cohort of older adults, higher concentration of linoelaidic acid was positively associated with CIMT, suggesting the importance of partially hydrogenated fat in the development of subclinical atherosclerosis in older adults. Overall, however, serum fasting NEFAs were largely unrelated to subclinical atherosclerosis in CHS participants. Funding SourcesNIH, NHLBI, USDA.

Associations of Serum Nonesterified Fatty Acids With Coronary Heart Disease Mortality and Nonfatal Myocardial Infarction: The CHS (Cardiovascular Health Study) Cohort.

BackgroundSignificant associations have been reported between serum total nonesterified fatty acid (NEFA) concentrations and coronary heart disease (CHD) mortality and incident nonfatal myocardial infarction (MI) in some prospective cohort studies. Little is known about whether individual or subclasses (saturated, polyunsaturated [n‐6 and n‐3], and trans fatty acids) of serum NEFAs relate to CHD mortality and nonfatal MI.Methods and ResultsCHS (Cardiovascular Health Study) participants (N=1681) who had no history of MI, angina, or revascularization or were free of MI at baseline (1996–1997) were included. NEFAs were quantified using gas chromatography. Cox regression analysis was used to evaluate associations of 5 subclasses and individual NEFAs with CHD composite (CHD mortality and nonfatal MI), CHD mortality, and incident nonfatal MI. During a median follow‐up of 11.7 years, 266 cases of CHD death and 271 cases of nonfatal MI occurred. In the fully adjusted model, no significant associations were identified between individual NEFA and CHD composite. Exploratory analyses indicated that lauric acid (12:0) was negatively associated (hazard ratio [HR], 0.76; 95% CI, 0.59–0.98; P=0.0328) and dihomo‐γ‐linolenic acid (20:3n‐6) was positively associated with CHD mortality (HR, 1.34; 95% CI, 1.02–1.76; P=0.0351). Elaidic acid (18:1n‐7t) was positively associated with incident nonfatal MI (HR, 1.46; 95% CI, 1.01–2.12; P=0.0445). No significant associations were observed for NEFA subclass and any outcomes.ConclusionsIn CHS participants, 2 NEFAs, dihomo‐γ‐linolenic and elaidic acids, were positively associated with CHD mortality and nonfatal MI, respectively, suggesting potential susceptibility biomarkers for risks of CHD mortality and nonfatal MI.

Serum non-esterified fatty acid levels and hip fracture risk: The Cardiovascular Health Study

Serum non-esterified fatty acids (NEFAs) are bioactive metabolic intermediates that can be taken up by bone tissue. Their associations with hip fracture risk have not been previously examined. Thirty-five individual NEFAs in five classes (saturated [SFA], mono-un-saturated [MUFA], poly-unsaturated n-6 and n-3 [PUFA], and trans-FA) were measured in Cardiovascular Health Study participants (n = 2139, mean age 77.8 years) without known diabetes. The multivariable associations of NEFA levels with hip fracture risk were evaluated in Cox hazards models. We documented 303 incident hip fractures during 11.1 years of follow-up. Among the five NEFA classes, total trans FA levels were positively associated with higher hip fracture risk (HR 1.17 [95% CI, 1.04, 1.31; p = 0.01] per one standard deviation higher level). The SFA lignoceric acid (24:0) was positively associated with higher risk (HR 1.09 [1.04, 1.1]; p < 0.001), while behenic (22:0) and docosatetraenoic (22:4 n6) acids were associated with lower risk (HR 0.76 [0.61, 0.94]; p = 0.01; 0.84 [0.70, 1.00]; p = 0.05, respectively). Total plasma trans NEFA levels are related to hip fracture risk, suggesting an unrecognized benefit of their systematic removal from food. Novel associations of individual NEFAs with hip fracture risk require confirmation in other cohort studies.

Serum Individual Nonesterified Fatty Acids and Risk of Heart Failure in Older Adults

Background: Heart failure (HF) is highly prevalent among older adults and is associated with high costs. Although serum total nonesterified fatty acids (NEFAs) have been positively associated with HF risk, the contribution of each individual NEFA to HF risk has not been examined. Objective: The aim of this study was to examine the association of individual fasting NEFAs with HF risk in older adults. Methods: In this prospective cohort study of older adults, we measured 35 individual NEFAs in 2,140 participants of the Cardiovascular Health Study using gas chromatography. HF was ascertained using review of medical records by an endpoint committee. Results: The mean age was 77.7 ± 4.4 years, and 38.8% were male. During a median follow-up of 9.7 (maximum 19.0) years, 655 new cases of HF occurred. In a multivariable Cox regression model controlling for demographic and anthropometric variables, field center, education, serum albumin, glomerular filtration rate, physical activity, alcohol consumption, smoking, hormone replacement therapy, unintentional weight loss, and all other measured NEFAs, we observed inverse associations (HR [95% CI] per standard deviation) of nonesterified pentadecanoic (15:0) (0.73 [0.57–0.94]), γ-linolenic acid (GLA) (0.87 [0.75–1.00]), and docosahexaenoic acid (DHA) (0.73 [0.61–0.88]) acids with HF, and positive associations of nonesterified stearic (18:0) (1.30 [1.04–1.63]) and nervonic (24:1n-9) (1.17 [1.06–1.29]) acids with HF. Conclusion: Our data are consistent with a higher risk of HF with nonesterified stearic and nervonic acids and a lower risk with nonesterified 15:0, GLA, and DHA in older adults. If confirmed in other studies, specific NEFAs may provide new targets for HF prevention.

Nonesterified Fatty Acids and Kidney Function Decline in Older Adults: Findings From the Cardiovascular Health Study

Circulating nonesterified fatty acids (NEFAs) make up a small portion of circulating lipids but are a metabolically important energy source. Excessive circulating NEFAs may contribute to lipotoxicity in many tissues, including the kidneys. We investigated the relationship between total circulating NEFA concentration and kidney outcomes in older, community-dwelling adults. Prospective cohort study. 4,698 participants≥65 years of age in the Cardiovascular Health Study who underwent total fasting serum NEFA concentration measurements in 1992-1993. Fasting serum NEFA concentration at one time point. Three primary outcomes: estimated glomerular filtration rate (eGFR) decline of≥30%, the composite of eGFR decline≥30% or kidney failure with replacement therapy, and change in eGFR. These outcomes were assessed over 4- and 13-year periods. Logistic regression for the dichotomous outcomes and mixed effects models for the continuous outcome, with sequential adjustment for baseline covariates. Inverse probability of attrition weighting was implemented to account for informative attrition during the follow-up periods. Serum NEFA concentrations were not independently associated with kidney outcomes. In unadjusted and partially adjusted analyses, the highest quartile of serum NEFA concentration (compared with lowest) was associated with a higher risk of≥30% eGFR decline at 4 years and faster rate of decline of eGFR. No associations were evident after adjustment for comorbidities, lipid levels, insulin sensitivity, medications, and vital signs: the odds ratio for the eGFR decline outcome was 1.33 (95% CI, 0.83-2.13), and the difference in eGFR slope in the highest versus lowest quartile of serum NEFA concentration was-0.15 (95% CI,-0.36 to 0.06) mL/min/1.73m2 per year. Single NEFA measurements, no measurements of post-glucose load NEFA concentrations or individual NEFA species, no measurement of baseline urine albumin. A single fasting serum NEFA concentration was not independently associated with long-term adverse kidney outcomes in a cohort of older community-living adults.

Individual non-esterified fatty acids and incident atrial fibrillation late in life

ObjectiveObesity and dysmetabolism are major risk factors for atrial fibrillation (AF). Expansion of fat depots is associated with increased circulating total non-esterified fatty acids (NEFAs), elevated levels of which are...

Serum Non-esterified Fatty Acids and Risk of Incident Stroke in Older Adults: The Cardiovascular Health Study

Abstract Objectives Significant associations between plasma total non-esterified fatty acid (NEFA) concentrations and incident ischemic stroke have been reported in some but not all prospective cohort studies. Given the functional and structural diversity among circulating NEFA, the association of individual or sub-groups of circulating NEFAs may provide additional insight into their relationship with incident stroke. We hypothesized fasting serum monounsaturated, n-6 polyunsaturated (PUFA) and n-3 PUFA NEFA are inversely associated, and saturated and trans NEFA are positively associated with incident stroke. Methods We analyzed the incidence of stroke among Cardiovascular Health Study (CHS) participants who were free of stroke in 1996–1997 (baseline) and had an archived fasting serum sample (N = 2028). At baseline, mean age was 77.8 ± 4.5, body mass index (BMI) was 26.7 ± 4.4 and 61% were female. A total of 38 individual NEFAs were measured using gas chromatography. Cox regression was used to evaluate the association of individual and 5 sub-group (saturated, monounsaturated, n-6 PUFA, n-3 PUFA and trans) NEFAs with incident stroke, adjusting for age, sex, race and field center (model 1); model 1 covariates plus serum albumin, smoking, education, physical activity, alcohol consumption, eGFR, BMI, aspirin use, waist circumference, hypertension, prevalent diabetes and total serum cholesterol concentration (model 2). Results A total of 338 cases of incident stroke occurred during median follow-up of 10.5 years. In the fully adjusted model 2, individuals in the highest quartile of serum 16:1n-7 had a 56% higher risk of stroke (quartiles 4 versus 1, hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.08–2.25; P-trend = 0.02); highest quartile of total n-6 PUFA NEFA had a 40% higher risk (HR, 1.40; 95% CI, 0.99–1.98; P-trend = 0.03); and highest quartile of 20:3n-6 had a 53% higher risk (HR, 1.53; 95% CI, 1.09–2.14; P-trend = 0.01). No significant associations were observed between saturated, n-3 PUFA, and trans NEFAs with incident stroke. Conclusions These data suggest a positive association between fasting serum 16:1n-7, 20:3n-6 and total n-6 PUFA NEFAs with incident stroke in CHS participants. No significant associations were observed for the other individual or sub-groups of NEFAs. Funding Sources NIH and USDA.

Calorie Restriction Improves Physical Performance and Modulates the Antioxidant and Inflammatory Responses to Acute Exercise.

Our aim was to characterize the effects of calorie restriction on the anthropometric characteristics and physical performance of sportsmen and to evaluate the effects of calorie restriction and acute exercise on mitochondria energetics, oxidative stress, and inflammation. Twenty volunteer taekwondo practitioners undertook a calorie restriction of 30–40% on three alternate days a week for one month. Eleven volunteer sportsmen participated as controls. Both groups performed an energy efficiency test to evaluate physical performance, and samples were taken before and after exercise. The total weight of participants significantly decreased (5.9%) after calorie restriction, while the efficiency of work and the contributions of fat to obtain energy were enhanced by calorie restriction. No significant differences induced by acute exercise were observed in individual non-esterified fatty acid percentage or oxidative stress markers. Calorie restriction downregulated the basal gene expression of nitric oxide synthase, antioxidant enzymes, mitochondrial uncoupling proteins, and repairing stress proteins, but it enhanced the expression of sirtuins in peripheral blood mononuclear cells. In conclusion, one month of calorie restriction decreases body weight and increases physical performance, enhancing energy efficiency, moderating the antioxidant and inflammatory basal gene expression, and influencing its response to acute exercise.

Abstract P560: Serum Non-esterified Fatty Acids and Risk of Incident Stroke in Older Adults: The Cardiovascular Health Study

Introduction: Serum non-esterified fatty acids (NEFAs) have been linked to both local and systemic inflammation and are higher in individuals with obesity, diabetes, cardiovascular disease, and ischemic stroke risk. Significant associations between total plasma NEFA concentrations and incident ischemic stroke have been reported in some but not all prospective studies. Given the functional and structural diversity among circulating NEFA, the associations of individual or clusters of circulating NEFAs may provide additional insight into their relationship with incident stroke. Hypothesis: Fasting serum n-3 NEFAs are inversely associated, and saturated and trans NEFAs are positively associated with incident stroke. Methods: We analyzed the incidence of stroke among Cardiovascular Health Study (CHS) participants who were free of stroke in 1996-1997 and underwent fasting NEFA profile measurement. At baseline, mean age was 77.8±4.5, body mass index was 26.7±4.4 and 61% were female. A total of 38 individual NEFAs in 5 classes (saturated, monounsaturated, polyunsaturated n-6, polyunsaturated n-3 and trans NEFAs) were measured using gas chromatography. Cox regression was used to evaluate the association of individual NEFA species with incident stroke, adjusting for: age, sex, race, and field center (model 1); model 1 covariates plus smoking, education, physical activity, alcohol consumption, eGFR, BMI, aspirin use, waist circumference, hypertension, prevalent diabetes, and cholesterol (model 2). Results: A total of 338 cases of incident stroke occurred during median follow-up of 10.5 years. In the fully adjusted model, trans -palmitoleic acid was inversely associated with incident stroke (HR per 1 mol% of NEFA composition: 0.03 [95% CI: 0.00 to 0.77], P &lt;0.03). Serum docosahexaenoic acid levels were associated with lower risk of incident stroke (HR: 0.63 [95% CI: 0.40 to 1.00], P &lt;0.05). Total n-3 fatty acids (HR: 0.78 [95% CI: 0.63 to 0.97]) and docosapentaenoic acid (HR: 0.12 [95% CI: 0.02 to 0.88]) were each associated with lower risk of incident stroke only in model 1. No significant association of saturated NEFAs with incidence of stroke was observed. Conclusion: Among fasting serum NEFA, docosahexaenoic acid and trans -palmitoleic acid were inversely associated with incident stroke, suggesting that these fatty acids may protect older adults from stroke.

Trafficking of nonesterified fatty acids in insulin resistance and relationship to dysglycemia.

In adipose, insulin functions to suppress intracellular lipolysis and secretion of nonesterified fatty acid (NEFA) into plasma. We applied glucose and NEFA minimal models (MM) following a frequently sampled intravenous glucose tolerance test (FSIVGTT) to assess glucose-specific and NEFA-specific insulin resistance. We used total NEFA and individual fatty acids in the NEFA MM, comparing the model parameters in metabolic syndrome (MetSyn) subjects (n = 52) with optimally healthy controls (OptHC; n = 14). Results are reported as mean difference (95% confidence interval). Using the glucose MM, MetSyn subjects had lower [-73% (-82, -57)] sensitivity to insulin (Si) and higher [138% (44, 293)] acute insulin response to glucose (AIRg). Using the NEFA MM, MetSyn subjects had lower [-24% (-35, -13)] percent suppression, higher [32% (15, 52)] threshold glucose (gs), and a higher [81% (12, 192)] affinity constant altering NEFA secretion (ϕ). Comparing fatty acids, percent suppression was lower in myristic acid (MA) than in all other fatty acids, and the stearic acid (SA) response was so unique that it did not fit the NEFA MM. MA and SA percent of total were increased at 50 min after glucose injection, whereas oleic acid (OA) and palmitic acid (PA) were decreased (P < 0.05). We conclude that the NEFA MM, as well as the response of individual NEFA fatty acids after a FSIVGTT, differ between OptHC and MetSyn subjects and that the NEFA MM parameters differ between individual fatty acids.

Prolonged monitoring of postprandial lipid metabolism after a western meal rich in linoleic acid and carbohydrates.

Today, awareness has been raised regarding high consumption of n-6 polyunsaturated fatty acids (PUFA) in western diets. A comprehensive analysis of total and individual postprandial fatty acids profiles would provide insights into metabolic turnover and related health effects. After an overnight fast, 9 healthy adults consumed a mixed meal comprising 97 g carbohydrate and 45 g fat, of which 26.4 g was linoleic acid (LA). Nonesterified fatty acids (NEFA), phospholipid fatty acids (PL-FA) and triacylglycerol fatty acids (TG-FA) were monitored in plasma samples, at baseline and hourly over a 7-h postprandial period. Total TG-FA concentration peaked at 2 h after the meal and steadily decreased thereafter. LA from TG18:2n-6 and behenic acid from TG22:0 showed the highest response among TG-FA, with a biphasic response detected for the former. PL-FA exhibited no change. Total NEFA initially decreased to nadir at 1 h, then increased to peak at 7 h. The individual NEFA showed the same response curve except LA and some very-long-chain saturated fatty acids (VLCSFA, ≥20 carbon chain length) that markedly increased shortly after the meal intake. The similarities and dissimilarities in lipid profiles between study subjects at different time points were visualized using nonmetric multi-dimensional scaling. Overall, the results indicate that postprandial levels of LA and VLCSFA, either as NEFA or TG, were most affected by the test meal, which might provide an explanation for the health effects of this dietary lifestyle characterized by high intake of mixed meals rich in n-6 PUFA.

Acute Changes in Non-esterified Fatty Acids in Patients with Type 2 Diabetes Receiving Bariatric Surgery

The purpose of this study was to compare acute changes of non-esterified fatty acids (NEFA) in relation to beta cell function (BCF) and insulin resistance in obese patients with type 2 diabetes (T2D) who underwent laparoscopic gastric bypass (GBP), laparoscopic sleeve gastrectomy (SG) or very low calorie diet (VLCD). In a non-randomised study, fasting plasma samples were collected from 38 obese patients with T2D, matched for age, body mass index (BMI) and glycaemic control, who underwent GBP (11) or SG (14) or VLCD (13). Samples were collected the day before and 3days after the intervention, during a 75-g oral glucose tolerance test. Glucose, insulin, c-peptide, glucagon like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) were measured, and individual NEFAs were measured using a triple-quadrupole liquid chromatography-mass spectrometry (LC-MS/MS). BCF by mathematical modelling and insulin resistance were estimated. Palmitic acid significantly decreased after each intervention. Monounsaturated/polyunsaturated ratio (MUFA/PUFA) and unsaturated/saturated fat ratios increased after each intervention. BCF was improved only after VLCD. Linoleic acid was positively correlated with total insulin secretion (p=0.03). Glucose sensitivity correlated with palmitic acid (p=0.01), unsaturated/saturated ratio (p=0.0008) and MUFA/PUFA (p=0.009). HOMA-IR correlated with stearic acid (p=0.03), unsaturated/saturated ratio (p=0.005) and MUFA/PUFA (p=0.009). GIP AUC0-120 correlated with stearic acid (p=0.04), but not GLP-1. GBP, SG and VLCD have similar acute effects on decreasing palmitic acid. Several NEFAs correlated with BCF parameters and HOMA-IR.

Differential intracellular calcium influx, nitric oxide production, ICAM-1 and IL8 expression in primary bovine endothelial cells exposed to nonesterified fatty acids

BackgroundNonesterified fatty acids (NEFAs) are involved in proinflammatory processes in cattle, including in the increased expression of adhesion molecules in endothelial cells. However, the mechanisms underlying these effects are still unknown. The aim of this study was to assess the effects of NEFAs on the intracellular calcium (Ca2+i) influx, nitric oxide production, and ICAM-1 and IL-8 expression in primary bovine umbilical vein endothelial cells (BUVECs).ResultsMyristic (MA), palmitic (PA), stearic (SA), oleic (OA) and linoleic acid (LA) rapidly increased Ca2+i. The calcium response to all tested NEFAs showed an extracellular calcium dependence and only the LA response was significantly inhibited until the intracellular calcium was chelated. The EC50 values for MA and LA were 125 μM and 37 μM, respectively, and the MA and LA effects were dependent on calcium release from the endoplasmic reticulum stores and on the L-type calcium channels. Only the calcium response to MA was significantly reduced by GW1100, a selective G-protein-coupled free fatty acid receptor (GPR40) antagonist. We also detected a functional FFAR1/GPR40 protein in BUVECs by using western blotting and the FFAR1/GPR40 agonist TAK-875. Only LA increased the cellular nitric oxide levels in a calcium-dependent manner. LA stimulation but not MA stimulation increased ICAM-1 and IL-8-expression in BUVECs. This effect was inhibited by GW1100, an antagonist of FFAR1/GPR40, but not by U-73122, a phospholipase C inhibitor.ConclusionsThese findings strongly suggest that each individual NEFA stimulates endothelial cells in a different way, with clearly different effects on intracellular calcium mobilization, NO production, and IL-8 and ICAM-1 expression in primary BUVECs. These findings not only extend our understanding of NEFA-mediated diseases in ruminants, but also provide new insight into the different molecular mechanisms involved during endothelial cell activation by NEFAs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0654-3) contains supplementary material, which is available to authorized users.

Contribution of glycerophospholipids and sphingomyelin to the circulating NEFA

BackgroundSerum nonesterified fatty acids (NEFA) are known to be associated with the development of insulin resistance. Recently, differences in the NEFA profile were found in subjects with history of gestational diabetes (postGDM) and healthy controls. Little is known about the NEFA sources in the postprandial state, which prevails most of the day in humans in modern societies. In the present study, we aimed to explore the potential contributions of glycerophospholipid (GPL) and sphingomyelin (SM) fatty acids to the circulating NEFA. MethodsSerum-samples of 19 postGDM women and 20 controls were obtained in fasting state (t0) and 90 minutes (t90) after an oral glucose tolerance test. Fatty acid composition of NEFA and SM were analyzed with liquid chromatography coupled to triple quadrupole mass spectrometry and GPL by gas chromatography. ResultsThe ratio of individual NEFA at t90 vs. t0 (t90/0-ratio) showed no difference between the two groups but increased with chain-length (7% for C16:1, 82% for C26:3). Only NEFA 10:0 was found with lower concentration at t0 and t90 in postGDM. At t90, long-chain polyunsaturated fatty acid correlated closely between NEFA and GPL in postGDM (20:5, 22:4, 22:5 and 22:6) and controls (20:3, 20:4 and 20:5). Very long-chain fatty acid 24:0 correlated significantly between NEFA and SM in postGDM and controls. Saturated and monounsaturated fatty acids correlated less between NEFA and GPL or SM. ConclusionsThe NEFA composition varied highly between fasting and fed state in both groups. GPL appeared to contribute long-chain polyunsaturated fatty acid, while SM appeared to contribute very long-chain fatty acids to the NEFA pool.

Fasting Nonesterified Fatty Acid Profiles in Childhood and Their Relationship With Adiposity, Insulin Sensitivity, and Lipid Levels

The objective of this study was to examine the major constituent of nonesterified fatty acids in children with respect to auxologic parameters, insulin sensitivity, and lipid levels, because nonesterified fatty acid levels are elevated in obesity and are important in the development of comorbidities. Fasting blood samples were obtained from 73 children (43 girls; 49 obese; median [range] age: 11.4 [0.9-17.6] years). Concentrations of the major circulating nonesterified fatty acids (myristate, palmitate, oleate, stearate, and arachidate) were determined by gas chromatography mass spectrometry, alongside measurement of insulin, adiponectin, and lipid profiles. The sum of all nonesterified fatty acids was significantly higher in obese versus normal-weight children, although gender (but not age or puberty) was an important determinant, with the difference remaining significant only in boys. Overall, obese children had higher concentrations of myristate, palmitate, and oleate but not stearate or arachidate. Age was an important determinant of myristate and arachidate, whereas gender proved more important for palmitate and stearate. Fasting insulin concentrations were not associated with either total nonesterified fatty acid concentrations or any of the individual nonesterified fatty acids, although a positive correlation was found between adiponectin and total nonesterified fatty acid concentrations that was independent of obesity status and that seemed mediated by changes in palmitate and stearate. Serum total cholesterol and low-density lipoprotein (but not high-density lipoprotein) levels seemed to correlate positively with circulating concentrations of palmitate, oleate, and stearate, whereas serum triacylglycerols correlated with myristate, palmitate, and oleate concentrations. Nonesterified fatty acid concentrations are elevated in obese children, primarily as a result of increases in myristate, palmitate, and oleate. Independent effects of nonesterified fatty acids on circulating adiponectin levels and lipid parameters were observed, although we found no relationship between nonesterified fatty acid concentrations and the insulin resistance identified with obesity.