Linoleic Acid In Adipose Tissue Research Articles

Linoleic acid in adipose tissue and the risk of myocardial infarction: a case-cohort study.

We investigated risk of myocardial infarction (MI) associated with the content of linoleic acid (LA) in adipose tissue, a biomarker of long-term dietary intake of LA and a marker of endogenous LA exposure. Between 1993 and 1997, 57,053 middle-aged subjects were included in the Danish Diet, Cancer and Health cohort. We performed a case-cohort study that included a random sample of the full cohort (n = 3167) and all incident MI cases appearing during 16years of follow-up (n = 2819). Information on incident MI cases was obtained by linkage with Danish nationwide registries. Adipose tissue biopsies were taken from the buttocks of the participants, and their fatty acid composition was determined using gas chromatography. HRs (hazard ratios) with 95% confidence intervals (CIs) were used to describe the associations between content of LA in adipose tissue and the risk of MI. HRs were calculated using weighted Cox proportional hazards regression with robust variance. After adjustment for established risk factors of MI, adipose tissue content of LA was not associated with the risk of MI in men and women combined (quintiles 5 versus 1, HR, 1.03 (95% CI, 0.85-1.25), P-trend = 0.970) or in men and women separately (quintiles 5 versus 1, HR, 1.05 (95% CI, 0.83-1.33), P-trend = 0.871 and quintiles 5 versus 1, HR, 0.99 (95% CI 0.72-1.37), P-trend = 0.928, respectively). Investigating the association between LA and MI with a shorter, 5- or 10-year duration of follow-up provided similar results. Content of LA in adipose tissue was not associated with the risk of MI.

Lipolysis modulates the biosynthesis of inflammatory lipid mediators derived from linoleic acid in adipose tissue of periparturient dairy cows

Oxidized linoleic acid metabolites (OXLAM) are products of adipocyte lipolysis with the potential to modulate adipose tissue (AT) lipid metabolism and inflammation. In periparturient cows, linoleic acid is preferentially mobilized from AT during lipolysis by hormone-sensitive lipase (HSL) compared with other polyunsaturated fatty acids. Enzymatic and nonenzymatic reactions generate OXLAM from linoleic acid. Among OXLAM, 9-, 10-, and 12-hydroxy-octadecadienoic acids (HODE) are associated with pro-inflammatory responses, whereas 9- and 13-oxo-octadecadienoic acids (oxoODE) and 13-HODE can facilitate inflammation resolution and promote lipogenesis. This study evaluated the effect of HSL activity on OXLAM biosynthesis using subcutaneous AT explants collected from multiparous dairy cows at 10 d before and again at 10 and 24 d after calving. Explants were treated for 3 h without or with the β-adrenergic agonist isoproterenol (ISO; 1 µM; MilliporeSigma, Burlington, MA) to induce HSL activity. The contribution of HSL to OXLAM biosynthesis was determined by inhibiting its activity with CAY10499 (2 µM; Cayman Chemical, Ann Arbor, MI). After treatments, media and explants were collected for lipidomic analysis using HPLC-tandem mass spectroscopy. Results indicated that ISO increased the biosynthesis of 9-, 12-, and 13-HODE and 9-oxoODE, and this effect was reduced at 24 d after calving. Inhibiting HSL activity partially reversed ISO effects on HODE and 9-oxoODE. Our ex vivo model demonstrated for the first time a direct effect of HSL activity on the biosynthesis of OXLAM in AT, especially at 10 d before and 10 d after calving. The biosynthesis of anti-inflammatory OXLAM is limited during the first weeks after parturition and may promote AT inflammation and lipolytic responses to negative energy balance. These results indicate that HSL activity releases linoleic acid for OXLAM biosynthesis in concentrations of a magnitude that may bypass the need for the activation of phospholipases linked with the inflammatory cascade and thus supports, in part, lipolysis-driven inflammation within AT of periparturient cows.

Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality.

Global dietary recommendations for and cardiovascular effects of linoleic acid, the major dietary omega-6 fatty acid, and its major metabolite, arachidonic acid, remain controversial. To address this uncertainty and inform international recommendations, we evaluated how in vivo circulating and tissue levels of linoleic acid (LA) and arachidonic acid (AA) relate to incident cardiovascular disease (CVD) across multiple international studies. We performed harmonized, de novo, individual-level analyses in a global consortium of 30 prospective observational studies from 13 countries. Multivariable-adjusted associations of circulating and adipose tissue LA and AA biomarkers with incident total CVD and subtypes (coronary heart disease, ischemic stroke, cardiovascular mortality) were investigated according to a prespecified analytic plan. Levels of LA and AA, measured as the percentage of total fatty acids, were evaluated linearly according to their interquintile range (ie, the range between the midpoint of the first and fifth quintiles), and categorically by quintiles. Study-specific results were pooled using inverse-variance-weighted meta-analysis. Heterogeneity was explored by age, sex, race, diabetes mellitus, statin use, aspirin use, omega-3 levels, and fatty acid desaturase 1 genotype (when available). In 30 prospective studies with medians of follow-up ranging 2.5 to 31.9 years, 15 198 incident cardiovascular events occurred among 68 659 participants. Higher levels of LA were significantly associated with lower risks of total CVD, cardiovascular mortality, and ischemic stroke, with hazard ratios per interquintile range of 0.93 (95% CI, 0.88-0.99), 0.78 (0.70-0.85), and 0.88 (0.79-0.98), respectively, and nonsignificantly with lower coronary heart disease risk (0.94; 0.88-1.00). Relationships were similar for LA evaluated across quintiles. AA levels were not associated with higher risk of cardiovascular outcomes; in a comparison of extreme quintiles, higher levels were associated with lower risk of total CVD (0.92; 0.86-0.99). No consistent heterogeneity by population subgroups was identified in the observed relationships. In pooled global analyses, higher in vivo circulating and tissue levels of LA and possibly AA were associated with lower risk of major cardiovascular events. These results support a favorable role for LA in CVD prevention.

Omega-6 vegetable oils as a driver of coronary heart disease: the oxidized linoleic acid hypothesis

The intake of omega-6 vegetable oils, particularly soybean oil, began to increase in the USA starting in the early 1900s at a time when the consumption of butter and lard...

Linoleic Acid in Adipose Tissue and Development of Ischemic Stroke: A Danish Case-Cohort Study.

BackgroundWe investigated the association between the content of linoleic acid in adipose tissue, a biomarker of long‐term intake of linoleic acid, and the risk of ischemic stroke and its subtypes.Methods and ResultsThe Danish cohort study Diet, Cancer and Health included 57 053 patients aged 50 to 65 years at enrollment. All participants had an adipose tissue biopsy performed at enrollment, while information on ischemic stroke during follow‐up was obtained from the Danish National Patient Register. Stroke diagnoses were all validated and classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification. Cases and a randomly drawn subcohort of 3500 patients had their fatty acid composition in adipose tissue determined by gas chromatography. Hazard ratios with 95% confidence intervals were calculated using weighted Cox proportional hazard regression. During 13.5 years of follow‐up, 1879 ischemic stroke cases were identified, for which 1755 adipose biopsies were available, while adipose biopsies were available for 3203 participants in the subcohort. When comparing the highest and the lowest quartiles of adipose tissue content of linoleic acid there was a negative association with the rate of total ischemic stroke (hazard ratio, 0.78; 95% confidence interval, 0.65–0.93) and large artery atherosclerosis (hazard ratio, 0.61; 95% confidence interval, 0.43–0.88), while there was an indication of a negative association with small‐vessel occlusion (hazard ratio, 0.87; 95% confidence interval, 0.69–1.11). There was no clear association with the rate of cardioembolism.ConclusionsThe content of linoleic acid in adipose tissue was inversely associated with the risk of total ischemic stroke and stroke caused by large artery atherosclerosis.

Increase in adipose tissue linoleic acid of US adults in the last half century.

Linoleic acid (LA) is a bioactive fatty acid with diverse effects on human physiology and pathophysiology. LA is a major dietary fatty acid, and also one of the most abundant fatty acids in adipose tissue, where its concentration reflects dietary intake. Over the last half century in the United States, dietary LA intake has greatly increased as dietary fat sources have shifted toward polyunsaturated seed oils such as soybean oil. We have conducted a systematic literature review of studies reporting the concentration of LA in subcutaneous adipose tissue of US cohorts. Our results indicate that adipose tissue LA has increased by 136% over the last half century and that this increase is highly correlated with an increase in dietary LA intake over the same period of time.

Serum and adipose tissue fatty acid composition as biomarkers of habitual dietary fat intake in elderly men with chronic kidney disease

Fatty acid (FA) composition in serum cholesterol esters (CE) and adipose tissue (AT) reflect the long-term FA intake in the general population. Because both dietary intake and FA biomarkers associate with renal function, our aim was to identify which CE and AT FAs are useful biomarkers of habitual FA intake in individuals with chronic kidney disease (CKD). Cross-sectional analysis was performed in 506 men (aged 70 years) with a glomerular filtration rate (GFR) of <60 mL/min per 1.73 m(2) from the Uppsala Longitudinal Study of Adult Men cohort. Dietary habits were evaluated with a 7-day dietary record. FA compositions in CE and AT were analyzed by gas-liquid chromatography in two random subsamples of 248 and 318 individuals, respectively. Both CE and AT linoleic acid and docosahexaenoic acid (DHA) were strongly associated with their corresponding intake, after adjustments for non-dietary factors. The proportions of eicosapentaenoic acid (EPA) and palmitic acid in CE and AT moderately correlated with dietary intake, whereas correlations of other FAs were weaker or absent. Proportions of EPA and DHA in CE and AT were positively associated with the total energy-adjusted fish intake. Results were confirmed in adequate reporters as identified by the Goldberg cutoff method. These relationships held constant, regardless of a GFR above or below 45 mL/min per 1.73 m(2) or the prevalence of microalbuminuria. Proportions of EPA, DHA, palmitic and linoleic acid in serum CE and AT are good indicators of their dietary intake in men with CKD. They can be considered valid biomarkers for epidemiological studies and assessment of compliance.

Cross-sectional study of conjugated linoleic acid in adipose tissue and risk of diabetes

Some experimental studies on conjugated linoleic acid (CLA) and insulin regulation suggested that CLA could be associated with risk of diabetes, but epidemiologic studies are lacking. The aim of the study was to test whether the amount of CLA in adipose tissue is associated with risk of diabetes. A cross-sectional design was used to test the study hypothesis in 232 adults with diabetes and 1512 adults without diabetes who lived in Costa Rica. The cis-9, trans-11 and trans-10, cis-12 CLA isomers in adipose tissue and 48 other fatty acids were assessed by using gas chromatography. Prevalence ratios (PRs) and 95% CIs were estimated by using Poisson regression adjusted for potential confounders. The mean (±SD) percentage of total fatty acids of CLA for the cis-9, trans-11 isomer in adipose tissue was 0.57 ± 0.18% in adults without diabetes and 0.53 ± 0.17% in adults with diabetes (P = 0.0078). The trans-10, cis-12 CLA isomer was not detected in adipose tissue. The cis-9, trans-11 CLA isomer was associated with a lower risk of diabetes. In comparison with the first quintile, the PR (95% CI) for the fifth quintile was 0.48 (0.31, 0.76) (P-trend = 0.0005) in the basic and 0.46 (0.29, 0.72) (P-trend = 0.0002) in the multivariable model. Additional adjustment for other fatty acids in adipose tissue including trans-9 16:1, which is a fatty acid that was previously associated with diabetes, did not modify the results. The observed inverse association between the cis-9, trans-11 CLA in adipose tissue and diabetes risk is consistent with the hypothesis that CLA may be involved in insulin regulation.

Conjugated linoleic acid in adipose tissue and risk of myocardial infarction

Despite the high saturated fat content of dairy products, no clear association between dairy product intake and risk of myocardial infarction (MI) has been observed. Dairy products are the main source of conjugated linoleic acid (CLA; 18:2n-7t), which is produced by the ruminal biohydrogenation of grasses eaten by cows. Pasture-grazing dairy cows have more CLA in their milk than do grain-fed cows. Some animal models have reported beneficial effects of CLA on atherosclerosis. The objective was to determine the association between the 9c,11t-CLA isomer in adipose tissue and risk of MI. The studied population consisted of 1813 incident cases of a first nonfatal acute MI and 1813 population-based controls matched for age, sex, and area of residence. All subjects lived in Costa Rica-a country that uses traditional pasture-grazing for dairy cows. Conditional logistic regression was used to estimate multivariate odds ratios and 95% CIs. Adipose tissue 9c,11t-CLA was associated with a lower risk of MI in basic and multivariate models. Compared with the lowest quintile, odds ratios and 95% CIs were 0.80 (0.61, 1.04) for the second, 0.86 (0.64, 1.14) for the third, 0.62 (0.46, 0.84) for the fourth, and 0.51 (0.36, 0.71) for the fifth quintiles (P for trend <0.0001). Dairy intake was not associated with risk of MI, despite a strong risk associated with saturated fat intake. 9c,11t-CLA, which is present in meaningful amounts in the milk of pasture-grazed cows, might offset the adverse effect of the saturated fat content of dairy products.

Cyclooxygenase‐2 Induction by trans‐10, cis‐12 Conjugated Linoleic Acid in Adipose Tissue

trans‐10, cis‐12 conjugated linoleic acid (10e12z) is the isomer linked with weight loss in animal and decreased adipose differentiation in cell culture models. The mechanism of this is still being determined. However, 10e12z induces an inflammatory response in adipose in the form of induction of interleukin (IL)‐6 and activation of NF‐κB. COX‐2 is an inflammatory mediator and is induced in response to NF‐κB. Therefore, we asked if there is a role for COX‐2 in the response of adipocytes to 10e12z. Here we show, in differentiating 3T3‐L1 cells, 10e12z reduces the ability of preadipocytes to differentiate and accumulate lipid, as measured by expression of markers such as aP2, C/EBPα and ADRP as well as oil red‐o staining. Furthermore, these effects of 10e12z are evident 5 days after induction of differentiation. Concurrently, a marked increase in the expression of COX‐2 by 10e12z treatment occurs before increases in IL‐6 expression. These results suggest that COX‐2 induction is adipocyte specific. Consistent with this, we could not induce COX‐2 in 3T3‐L1 preadipocytes. However, COX‐2 mRNA is induced rapidly in mature adipocytes reaching a maximum after 12 hours and declining to baseline after 48 hours. COX‐2 mRNA is also dose responsive, and can be significantly induced with 12.5 uM 10e12z CLA. These studies indicate that the induction of COX‐2 is an important event mediating the metabolic effects of 10e12z in adipocytes.

Alpha-Linolenic and Linoleic Acid Status of Broilers Kept on Small Holdings in Cameroon

The idea tested was that a limiting provision of alpha-linolenic acid (ALA) contributes to the poor growth performance of broilers kept on small holdings in Cameroon. The study had a cross-sectional design and involved 14 small-holder farms. The ALA and linoleic acid (LA) concentrations in the broilers' diets were determined and so were the contents of ALA and LA in adipose tissue collected from selected birds. When expressed as percentage in the whole diet, the LA content in the diets fed on the 14 farms varied between 1.64 and 3.81 % and that of ALA between 0.04 and 0.41%. There was a significant relationship between the relative percentage of ALA in the diet and that in the abdominal adipose tissue of the broilers. It wa s concluded that the LA supply was not limiting growth in the broilers. The ALA requirement of broilers is not known, but it might be in the order of 0.05 to 0.1 % of the dietary dry matter. If and when the ALA requirement is 0.05% of the diet, then the supply of ALA on at least one farm could have limited growth of the broilers. However, caution is warranted because the design of this study does not allow drawing conclusions as to cause-and-effect relations. Furthermore, on all farms growth rates were sub-optimal so that factors other than the ALA supply had limited growth. Absolute proof for a role of the ALA supply can only be obtained by controlled studies on the farms in which supplemental ALA is the only variable.

Arachidonic Acid in Adipose Tissue Is Associated with Nonfatal Acute Myocardial Infarction in the Central Valley of Costa Rica

Arachidonic acid (AA), a precursor of prothrombotic eicosanoids, is potentially atherogenic, but epidemiologic data are scarce. We evaluated the hypothesis that increased AA in adipose tissue is associated with increased risk of nonfatal acute myocardial infarction (MI), and if so, whether this association is related to dietary or adipose tissue linoleic acid. We studied the association between AA and MI in 466 cases of a first nonfatal acute MI, matched on age, gender, and residence to 466 population controls. Fatty acids (FA) were assessed by GC in adipose tissue samples collected from all subjects. Odds ratios (OR) and 95% CI were calculated from multivariate conditional logistic regression models. Subjects in the highest quintile of adipose tissue AA (0.64% of total FA) had a higher risk of nonfatal acute MI than those in the lowest quintile (0.29% of total FA), after adjusting for potential confounders including (n-3) and trans FAs (OR = 1.94, 95% CI: 1.07, 3.53, P for trend = 0.026). Adipose tissue AA was not correlated with dietary AA (r = 0.07), linoleic acid (r = 0.04), or other dietary (n-6) FAs, or with adipose tissue linoleic acid (r = -0.07). These data suggest that the association between MI and adipose tissue AA is not related to dietary intake of (n-6) FAs including linoleic acid. Better understanding of the metabolic factors that increase AA in adipose tissue is urgently needed.

Influence of dietary linseed, fish and coconut oil on growth performance of growing pigs kept on small holdings in central Vietnam.

The aim of the study was to investigate the effect on growth performance of the addition of 5% of either linseed, fish or coconut oil to the diet of growing pigs kept on small holdings in central Vietnam. The diets were fed on six different farms; there were three animals per treatment per farm. The farmers fed a base diet according to personal choice, but were instructed to use linseed, fish and coconut oil. The diets were fed to the pigs from 70 to 130 days of age. The diets with 5% linseed oil on average contained 2.4 g alpha-linolenic acid/MJ of metabolizable energy (ME) and the diets with 5% fish oil on average contained 0.06 and 0.75 g eicosapentaenoic and docosahexaenoic acid/MJ ME, respectively. The relative percentages of docosahexaenoic, eicosapentaenoic, alpha-linolenic and linoleic acid in adipose tissue were determined by the intake of the corresponding fatty acids. Dietary linseed oil vs. coconut oil significantly enhanced daily weight gain and vs. fish oil it also stimulated growth, but this effect just failed to reach statistical significance. It is concluded that extra intake of alpha-linolenic acid may stimulate growth in growing-finishing pigs, this effect being independent of the conversion of alpha-linolenic acid into eicosapentaenoic and docosahexaenoic acid.

Adipose tissue n−6 fatty acids and acute myocardial infarction in a population consuming a diet high in polyunsaturated fatty acids

The Jewish population of Israel consumes a diet rich in n-6 polyunsaturated fatty acids (PUFAs), principally linoleic acid. The consequences of this diet for ischemic heart disease (IHD) remain unclear. We assessed the association of adipose tissue n-6 fatty acids, which are derived entirely from the diet, with acute myocardial infarction (AMI). A total of 180 cases and 492 IHD-free controls aged 25-64 were included in a population-based case-control study of Jerusalem residents hospitalized with a first AMI. Diet was assessed by the use of a food-frequency questionnaire and adipose tissue fatty acids by gas chromatography of biopsy samples taken from subcutaneous gluteal tissue. The data were analyzed by multivariate logistic regression. Dietary PUFAs (: 10.1% of energy) correlated (r = 0.43, P < 0.001) with adipose tissue linoleic acid, which constituted 25.6% of storage fatty acids. High intakes of linoleic acid were not associated with excess risk of AMI (age- and sex-adjusted odds ratio for the third versus the first tertile: 0.96; 95% CI: 0.62, 1.48; NS). In contrast, arachidonic acid, the long chain n-6 derivative of linoleic acid, was positively associated with AMI (age- and sex-adjusted odds ratio: 2.12; 95% CI: 1.33, 3.36; P = 0.004). With multivariate adjustment, there was no evidence for an adverse association of linoleic acid with AMI, whereas the risk associated with arachidonic acid persisted, albeit attenuated. A very high linoleic acid intake does not appear to confer increased risk of nonfatal AMI. Nonetheless, the increased risk associated with arachidonic acid, a finding that requires confirmation, tempers an inference that diets rich in n-6 fatty acids are safe vis-à-vis coronary health.

Adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction in Costa Rica.

Alpha-linolenic acid may protect against cardiovascular disease. We examined the association between adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction (MI) in a population-based case-control study in Costa Rica. The 482 case patients with a first nonfatal acute MI and 482 population control subjects were matched by age, sex, and area of residence. Fatty acids were assessed by gas-liquid chromatography in adipose tissue samples collected from all subjects. ORs and 95% CIs were calculated from multivariate conditional logistic regression models. Subjects in the top quintiles of adipose tissue alpha-linolenic acid had a lower risk of MI than those in the lowest quintile: OR (95% CI), 1.00; 0.80 (0.52 to 1.24); 0.53 (0.34 to 0.82); 0.44 (0.28 to 0.67); and 0.37 (0.24 to 0.59); test for trend, P<0.0001. This association was strengthened after adjustment for established MI risk factors, including smoking, physical activity, income, and adipose tissue linoleic acid and trans fatty acids (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.50; test for trend, P<0.0001). Further adjustment for the intake of saturated fat, fiber, alcohol, and vitamin E did not change this association (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.55; test for trend, P<0.0001). The inverse association observed between alpha-linolenic acid and nonfatal acute MI suggests that consumption of vegetable oils rich in alpha-linolenic acid confers important protection against cardiovascular disease.

Relationships between dietary fatty acid composition and either melting point or fatty acid profile of adipose tissue in broilers

Data on the fatty acid composition of the diet and that of the adipose tissue in broilers were collected from the literature. The linear regression between the dietary and the adipose tissue unsaturated to saturated fatty acids ratio (U/S ratio) was calculated because the U/S ratio of adipose tissue fat determines its melting point, which is an indicator of the consistency of poultry fat. For 54 data points from three different experiments, the linear correlation coefficient of the relationship between dietary and adipose tissue U/S ratio was 0.77. The regression equation for linoleic acid in adipose tissue as a function of dietary linoleic acid was calculated. The linoleic acid content of adipose tissue was expressed as weight percentage of total fatty acids. Intake was expressed as either weight percentage of total fatty acids or as energy percentage of total dietary metabolizable energy. The linear correlation coefficients were 0.68 and 0.78 as based on 116 or 91 data points from 15 or 12 different experiments. Significant correlations were also found for α-linolenic acid. The linoleic acid content of adipose tissue was found to be correlated ( r=0.87) for 25 data points with that in consumable broiler meat, which may affect serum cholesterol concentrations in humans. With the help of the regression formulas presented it may be possible to formulate broiler diets in relation to consumer health and product quality.

Dietary C18:1 trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

Dietary C18:1 trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

Dietary C18:1trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

The effect of dietary C18:1 trans fatty acids on back fat composition in pigs was investigated with special emphasis on conjugated linoleic acids (CLA). A total of 12 × 4 siblings of Large White and Swiss Landrace breed were housed in groups and fattened from 22 to 103 kg live weight. Pigs were fed a control diet (barley, wheat, soybean meal) or experimental diets which consisted of the control diet with a 5% replacement of olein or stearin fractions of pork fat, or partially hydrogenated fat. The hydrogenated fat was rich in C18:1 trans fatty acids but contained only negligible amounts of CLA. In contrast olein and stearin fractions contained far less C18:1 trans fatty acids but some CLA. In the control diet no C18:1 trans fatty acids and only traces of CLA were detected. The partially hydrogenated fat led to the highest CLA content in back fat (0.44%). Intermediate amounts of CLA were measured in pigs fed the fractionated pork fat (0.22/0.23%). In pigs fed the control diet, also small amounts of CLA were detected. The results indicate that CLA may be produced by endogenous Δ9-desaturation out of dietary trans vaccenic acid in pigs.

Weight cycling-induced reduction of linoleic acid in carcass and adipose tissue in rats

Recent epidemiological studies have proposed the hypothesis that large fluctuations in body weight over time may increase the risk of cardiovascular disease. Several studies have demonstrated that there is an inverse correlation between adipose tissue linoleic acid content and the risk of coronary heart disease. This led us to consider whether several weight cyclings induced by food restriction followed by regain could affect metabolism of linoleic acid and α-linolenic acid and their longer-chain polyunsaturated fatty acids. Fifty rats were fed a semipurified diet containing 15% fat (30.5% kcal) in which linoleic acid and α-linolenic acid accounted for 7.2 and 3.5% of total fatty acids, respectively. They were randomly divided in two groups. The control (CTL) group was allowed free access to diet whereas the weight-cycled (W-CYC) rats were subjected to four cycles of partial food restriction (24% intake of ad libitum controls, about 5 g/day) for 3 or 4 days to reduce body weight followed by ad libitum refeeding until the weight reached the corresponding average of the CTL group. Four rats were killed as baseline values before weight cycle. The rest of the rats from each group were killed at the beginning ( n = 5), tge end of partial food restriction ( n = 9), and the end of ad libitum refeeding ( n = 10) in weight cycle 4. The fatty acid compositions of the liver, epididymal, and perirenal adipose tissue and carcass were determined by gas liquid chromatography. The W-CYC rats, compared with the CTL rats, increased significantly their food intake immediately after each partial food restriction but thereafter gradually reached that of the CTL. No differences in the weights of liver, epididymal, and perirenal adipose tissue were observed between the W-CYC and CTL group after four weight cycles. Contrary to ad libitum feeding, four weight cyclings decreased the content of linoleic acid in the carcass, epididymal and perirenal adipose tissue. α-linolenic acid was also lower in the W-CYC rats than in the CTL group, but a significant difference was observed only at the end of partial food restriction. Compared with those in the CTL, the liver fatty acids in the W-CYC rats were remarkably modified during the partial food restriction, showing an increase in linoleic, α-linolenic, and arachidonic acids but a decrease in oleic and palmitoleic acids. The food restriction-induced changes in liver fatty acids were reversed after the ad libitum refeeding. We conclude that weight cycling alters body fatty acid composition characterized by a selective decrease in the linoleic acid content of carcass and adipose tissues without significantly changing the total body fat content and the weight of perirenal and epididymal fat pads.

Type A behavior and adipose tissue linoleic acid: implications for stress management.

The purpose of the present study was to investigate the relation between Type A behavior and adipose tissue linoleic acid composition. The sample consisted of 73 male and female Cretan adults, 23-64 years of age. Anthropometric and arterial blood pressure measurements were taken. Adipose tissue samples were collected by aspiration and data concerning general health habits were obtained. Food intake was estimated by a 24-hour dietary recall, while Type A profile was assessed with a Greek translation of the Bortner scale. Factors associated with Type A profile are adipose tissue linoleic acid (p < 0.0004), annual income (p < 0.001), total serum cholesterol (p < 0.009), and adipose fat myristoleic acid (p < 0.02). Negative correlations were observed between adipose linoleic and myristoleic acids and the dependent variable. It appears that adipose tissue linoleic acid may be one of the etiological factors for Type A behavior in adults.