Major Trans Fatty Acid Research Articles

Quantitative Analysis of Trans‐Fatty Acids in Human Plasma

Trans‐fatty acids (TFA) intake has been associated with risk factors for cardiovascular disease. However, little is known about the TFA levels in humans or about how these levels relate to other fatty acids (FA).In order to assess TFA levels in humans we have developed and validated an isotope dilution‐gas chromatography‐negative chemical ionization‐mass spectrometry method for the quantitation of 28 FA in human plasma, including 4 major TFA. We analyzed 73 convenience samples from adults. All samples contained TFA, with average levels ± standard deviation of 2.66 ± 1.29 μM for palmitelaidic acid 12.70 ± 8.31 μM for elaidic acid, 16.59 ± 11.10 μM for vaccenic acid, and 1.15 ± 0.52 μM for linoelaidic acid. The sum of all FA was 9647 ± 2913 μM. The sum of the 4 TFA accounted for 0.34 ± 0.20 % of total FA. FA values expressed as percent of total FA showed negative association between monounsaturated FA and polyunsaturated fatty acids (PUFAs), ω‐6 PUFAs, and ω‐3 PUFAs. Negative trends were also seen between certain TFA and the summed PUFAs. We have developed an analytical method that enables the assessment of major TFA and other FA in 100 μL of plasma, which allows the investigation of FA concentrations as well as differences in the composition of these FA in plasma. This method is being used to analyze samples from the National Health and Nutrition Examination Survey (NHANES).

The effect of pasteurisation temperature on the CLA content and fatty acid composition of white pickled cheese

In this study, the effect of pasteurisation temperature on fatty acid composition of cheese was investigated. The fatty acid composition of raw and different heat-treated milk, salt and salt-free cheese were determined using cheese made from raw milk at temperatures varying between 70 and 90°C for 5 min. Generally, C 16:0 palmitic acid was the major fatty acid present in all milk and cheese samples. C 18:1 t11 vaccenic acid was the major trans fatty acid (TFA) in all samples. C 18:2 cis-9, trans-11 (Rumenic acid) was the major CLA isomer in these samples. Pasteurisation temperatures had no effect on TFA, CLA and fatty acid composition of the milk and cheese samples.

Soybean (Glycine max L. Merr.) hexane extracts inhibit cellular fatty acid uptake by reducing the expression of fatty acid transporters

Intake of saturated and trans-fatty acids is a strong risk factor for coronary heart disease. We investigated the inhibitory effects of 2 hexane extracts from white (WBE) and black soybeans (BBE) on cellular fatty acid uptake in vitro. Transcellular uptake of elaidic acid (t18:1), a major trans-fatty acid present in processed foods, in Caco-2 monolayers was significantly reduced by 28.3 and 16.7% 60 min after WBE and BBE treatment, respectively. Results of flow cytometry (FACS) analysis showed significant reductions in boron-dipyrromethene (BODIPY) fluorescence-labeled fatty acid uptake by 35.4 and 40.2% with WBE and BBE treatment, respectively. BBE treatment significantly reduced the expression of fatty acid transport protein-4 and CD36 in Caco-2 cells, as determined by quantitative real time-polymerase chain reaction (qRT-PCR). Similar trends were found in WBE treatment, although to a lesser degree. These observations suggest that soybean extract may reduce fatty acid uptake and cellular fat accumulation by altering fatty acid transporter expression.

Diet and plasma evaluation of the main isomers of conjugated linoleic acid and trans-fatty acids in a population sample from Mediterranean north-east Spain

The aim of the present study was to describe the dietary pattern of a representative sample of 516 adult participants (203 men and 313 women) from Catalonia, a Spanish Mediterranean region, to assess their current dietary and plasma levels of trans C18:1, the major trans-fatty acid (TFA), and cis-9, trans-11 CLA, and trans-10, cis-12 CLA, the two major conjugated linoleic acid (CLA) isomers, and to evaluate their correlation with several cardiovascular disease risk factors. The population was a random sample derived from the Catalan Nutrition Survey. Plasma levels of the CLA isomers were determined in a subsample of 100 volunteers. The Catalan diet seemed to maintain some traits of the ‘traditional’ Mediterranean diet, although other components were lost. The dietary intakes of saturated fatty acids (SFA), TFA, cis-9, trans-11 CLA, and trans-10, cis-12 CLA were 12.3%, 0.84% (2.0 g/d), 0.030% (71.5 mg/d), and 0.0015% (3.4 mg/d) of the energy intake, respectively. Trans C18:1 accounted for 0.19% of the total plasma fatty acids, while the sum of cis-9, trans-11and trans-10, cis-12 CLA isomers represented about 0.09% of the plasma fatty acids. Trans C18:1 isomers correlated significantly with the intake of French fries and pastries, while cis-9, trans-11 CLA significantly correlated with the intake of dairy products and ruminant meat. None of the cardiovascular disease risk factors were found to be associated with the plasma levels of TFA or CLA. The results of this study suggest that monounsaturated fatty acids (MUFA) are the main dietary fat source in the Catalan population, due to their regular olive oil consumption. Moreover, plasma levels of the main TFA and CLA suggest that the Catalan diet is not at present strongly influenced by the occidental dietary patterns. However, a reduction of the intake of SFA in the Catalan population should be recommended.

FATTY ACID COMPOSITIONS OF TURKISH SHORTENINGS WITH EMPHASIS ON TRANS FATTY ACIDS

ABSTRACT The fatty acid (FA ) composition and the trans FA (TFA) content of Turkish shortenings were determined by capillary gas–liquid chromatography. The saturated FA, monounsaturated FA and polyunsaturated FA contents were within the ranges of 27.4–48.8, 33.8–56.7 and 8.4–35.3% of total FA, respectively. The total TFA ranged from 2.7 to 23.9% of total FA. The total trans C18:1 acid was the major TFA in all the analyzed brands, representing 82.3–94.5% of total TFA. The total trans C18:2 acid varied from 0.2 to 2.9% of total FA, while the total trans C18:3 acid was only found at very low levels (0.1% of total FA) in the samples of two brands. It is clear from the results that partially hydrogenated vegetable oils with high TFA content are still the major raw materials used in the production of Turkish shortenings.PRACTICAL APPLICATIONSThe fatty acid (FA) composition of the shortenings, with emphasis on trans FA (TFA), was studied. It is important to reduce the amounts of dietary TFA because of their deleterious effects on human health, mainly on the cardiovascular system. As demonstrated in the present investigation, nevertheless, partially hydrogenated vegetable oils with high TFA content are still the major raw materials used for shortening production. On the other hand, reducing the total TFA content in the shortenings leads to an increase in saturated FA content. It is important to consider the data obtained in the industrial applications in order to improve the FA profile of the shortenings.

The Diversity of Health Effects of Individual trans Fatty Acid Isomers

There are multiple adverse effects of trans fatty acids (TFA) that are produced by partial hydrogenation (i.e., manufactured TFA), on CVD, blood lipids, inflammation, oxidative stress, endothelial health, body weight, insulin sensitivity, and cancer. It is not yet clear how specific TFA isomers vary in their biological activity and mechanisms of action. There is evidence of health benefits on some of the endpoints that have been studied for some animal TFA isomers, such as conjugated linoleic acid; however, these are not a major TFA source in the diet. Future research will bring clarity to our understanding of the biological effects of the individual TFA isomers. At this point, it is not possible to plan diets that emphasize individual TFA from animal sources at levels that would be expected to have significant health effects. Due to the multiple adverse effects of manufactured TFA, numerous agencies and governing bodies recommend limiting TFA in the diet and reducing TFA in the food supply. These initiatives and regulations, along with potential TFA alternatives, are presented herein.

Trans-fatty acids and sudden cardiac death

Sudden cardiac death (SCD) is usually due to ventricular fibrillation and can occur as a first manifestation of heart disease. Prevention of ventricular fibrillation and SCD with n − 3 polyunsaturated fatty acids is well documented. Trans-fatty acids (TFA) in the diet and cell membranes might affect the risk of SCD as well. We review evidence from an observational study that high levels of trans-18:2 (9 cis-, 12 trans- and 9 trans-, 12 cis-isomers of linoleic acid) in red blood cell membranes are associated with markedly higher risk of SCD. In contrast, cell membrane levels of trans-18:1 ( trans-isomers of oleic acid), the major TFA in foods, do not appear associated with higher risk of SCD. While further studies are needed to investigate possible effects of trans-18:2 on arrhythmia, it would be prudent to limit dietary intake of trans-18:2.

Sequentially combined estradiol valerate plus levonorgestrel therapy decreases 18:1 trans-fatty acid content of plasma lipids in healthy postmenopausal women

Trans-fatty acids (TFA) have been classified as atherogenic dietary constituents but the effect of hormone replacement therapy (HRT) on their concentrations is not known. We used a washout protocol to study the effect of long-term estrogen and combined estrogen–progestin HRT on plasma elaidate (18:1t), which is the trans isomer of oleate and the major TFA in the diet. The study group comprised 15 women receiving estradiol valerate HRT and 15 women receiving combined HRT with estradiol valerate and levonorgestrel. The concentrations of elaidate in plasma phospholipids, cholesteryl esters and triglycerides were determined by gas chromatography. At baseline, the total plasma elaidate concentration was lower in the combined HRT group than in the estradiol valerate HRT group (p < 0.01). In the combined HRT group, the concentration of elaidate increased significantly after withdrawal of HRT (p < 0.001) and decreased again to the baseline level after restart of therapy (p < 0.001). These changes were due to decreases in the concentrations of phospholipids and triglycerides; in phospholipids there was also a proportional decrease of elaidate. There were no changes in elaidate in women receiving estradiol valerate alone. Our results suggest that long-term combined HRT treatment decreases plasma TFA, which is not achieved by estrogen alone.

Bioconversion of vaccenic acid to conjugated linoleic acid in humans

Vaccenic acid (11-trans octadecenoic acid; VA), a major trans fatty acid in the fat of ruminants, is produced in the rumen and converted in tissues to rumenic acid (9-cis, 11-trans octadecenoic acid; RA), an isomer of conjugated linoleic acid, by Delta(9)-desaturase. There are indications that this conversion also occurs in humans. The aim of this controlled intervention was to study the conversion of VA to RA in humans after consumption of diets with increasing amounts of VA. Thirty healthy subjects consumed a baseline diet rich in oleic acid for 2 wk. The subjects were then divided into 3 groups (n = 10 per group) and provided a diet containing 1.5, 3.0, or 4.5 g VA/d for 9 d. All diets contained equal amounts of macronutrients and differed only in their fatty acid compositions. The fats were mixed into conventional foods, and nearly all food was provided during the study. The proportion of VA in serum total fatty acids increased 94%, 307%, and 620% above baseline with the 1.5-, 3.0-, and 4.5-g diets, respectively. This was associated with a linear increase in the proportion of RA. The conversion rate was 19% on average, with significant interindividual differences with all 3 intakes of VA. The urinary excretion of 8-iso-prostaglandin F(2alpha) increased in all groups (P < 0.001). The results quantify the desaturation of VA to RA in humans. Conversion is likely to contribute significantly to the amount of RA available to the body, and dietary intakes of VA should thus be taken into account when predicting RA status.

Fish and cardiovascular disease

Recent epidemiological studies have showed that excessive intake of trans fatty acids (TFA) can be a residual risk for the development of coronary artery disease (CAD) even under medical management, including statins. This study aimed at investigating the association between lipid profile, including serum TFA concentration, and plaque vulnerability using optical coherence tomography (OCT).The level of serum elaidic acid, a major TFA component, was measured using gas chromatography in 161 consecutively enrolled patients with CAD under guideline-directed risk factor management. OCT was performed to evaluate morphological features of angiographic intermediate stenosis (30% < diameter of stenosis <70%). OCT data were also used to measure lipid index (LI), defined as mean lipid arc multiplied by lipid length, and determine the presence of thin-cap fibroatheroma (TCFA), defined as a lipid-rich plaque with the smallest fibrous cap thickness <65 μm and the maximal arc >90°.Among 190 lesions assessed using OCT, 49 TCFAs were detected. In patients with at least one TCFA lesion, levels of elaidic acid (12.9 ± 4.9 vs. 10.3 ± 4.3 μmol/L, p = 0.001), triglycerides (169 ± 81 vs. 130 ± 60 mg/dL, p = 0.005), and remnant-like particle cholesterol (10.4 ± 6.5 vs. 7.7 ± 4.7 mg/dL, p = 0.005) were higher than in those without TCFAs. Generalized estimating equations identified elaidic acid level as the independent risk factor of TCFA. LI had a positive correlation with elaidic acid level (r = 0.173, p = 0.025).TFA may affect plaque vulnerability in patients with CAD. Serum TFA concentration may represent another cardiovascular risk factor during conventional risk factor management.

The identity of the cholesteryl esters in human milk

AbstractMilk samples were collected from 11 mothers who were at least 4 weeks postpartum. The amounts of fat and the fatty acid compositions of cholesteryl esters (CE) and triacylglycerols (TG) in the milk were determined. The mean concentration of total milk lipid was 3.01 gm/100 ml of milk±.42 SD. The major fatty acids esterified with CE and TG were 16∶0,cis 18∶1 and 18∶2. The patterns were similar except for a greater proportion ofcis 18∶1 in the CE. The majortrans fatty acid detected was the 18∶1 isomer which accounted for 4.48% of the TG fatty acids and 2.96% of the CE fatty acids.