Hydrogenated Marine Oil Research Articles

Dietary macronutrients modulate the fatty acyl composition of rat liver mitochondrial cardiolipins

The interaction of dietary fats and carbohydrates on liver mitochondria were examined in male FBNF1 rats fed 20 different low-fat isocaloric diets. Animal growth rates and mitochondrial respiratory parameters were essentially unaffected, but mass spectrometry-based mitochondrial lipidomics profiling revealed increased levels of cardiolipins (CLs), a family of phospholipids essential for mitochondrial structure and function, in rats fed saturated or trans fat-based diets with a high glycemic index. These mitochondria showed elevated monolysocardiolipins (a CL precursor/product of CL degradation), elevated ratio of trans-phosphocholine (PC) (18:1/18:1) to cis-PC (18:1/18:1) (a marker of thiyl radical stress), and decreased ubiquinone Q9; the latter two of which imply a low-grade mitochondrial redox abnormality. Extended analysis demonstrated: i) dietary fats and, to a lesser extent, carbohydrates induce changes in the relative abundance of specific CL species; ii) fatty acid (FA) incorporation into mature CLs undergoes both positive (>400-fold) and negative (2.5-fold) regulation; and iii) dietary lipid abundance and incorporation of FAs into both the CL pool and specific mature tetra-acyl CLs are inversely related, suggesting previously unobserved compensatory regulation. This study reveals previously unobserved complexity/regulation of the central lipid in mitochondrial metabolism.

Quantitative analysis of long-chain trans-monoenes originating from hydrogenated marine oil.

Gas chromatography (GC) is used for the analysis of trans-fatty acids in partially hydrogenated vegetable oils. Although trans-isomers of C18 carbon length predominate in partially hydrogenated vegetable oils, trans-isomers of C20 and C22 carbon length occur in partially hydrogenated fish oil. We report a simple silver ion chromatographic combined with capillary GC technique for quantitative analysis of trans-monoenes derived from partially hydrogenated fish oil. Silver nitrate thin-layer chromatographic (TLC) plates are developed in toluene/hexane (50:50, vol/vol). Fatty acid methyl esters are separated into saturates (Rf 0.79), trans-monoenes (Rf 0.49), cis-monoenes (Rf 0.27), dienes (Rf 0.10), and polyunsaturated fatty acids with three or more double bonds remaining at the origin. The isolated trans-monoenes are quantitatively analyzed by capillary GC. The technique of argentation TLC with GC analysis of isolated methyl esters is highly reproducible with 4.8% variation (i.e., coefficient of variation, CV%) in R. values and 4.3 and 6.9% CV% in quantification within batch and between batch, respectively. Furthermore, the combined technique revealed that direct GC analysis underestimated the trans-content of margarines by at least 30%. In this study, C20 and C22 trans-monoenes were found in relatively large quantities; 13.9% (range 10.3-19.6%) and 7.5% (range 5.3-11.5%), respectively, in margarine purchased in 1995, but these C20 and C22 trans-monoenes were much reduced (0.1%) in a fresh selection of margarine purchased in 1998. Compositional data from labels underestimated the trans-content of margarines, especially those derived from hydrogenated marine oil. Low levels of C20 transmonoenes (range 0.1-0.3%) and C22 trans-monoenes (range 0.0-0.1%) were identified in adipose tissue obtained from healthy volunteers in 1995, presumably indicating consumption of partially hydrogenated fish oil.

TransFatty Acids in Bakery Products from 14 European Countries: the TRANSFAIR Study

The fatty acid composition of bakery products from 14 European countries was analyzed with particular emphasis ontransfatty acids. The proportion oftransfatty acids in cookies and biscuits ranged from <1 to 28%.Transfatty acids content in sweet pastry ranged from practically 0 to 33%. Croissants and doughnuts had varying amounts oftransfatty acids, with the highest value of 15% in croissants and 32% in doughnuts. The totaltransfatty acid content in pizzas was mostly in the same order and varied from <1% to 5%. Most hydrogenated marine oil-based bakery products were found in Iceland and in Norway. In Finland, Portugal, Italy, Netherlands, and United Kingdom no bakery products based on hydrogenated marine oils could be identified. Bakery products based on hydrogenated vegetable fats were present in almost every country. It can be concluded that in bakery products it is difficult to identify the presence oftransfatty acids.

Ischaemic heart disease and consumption of hydrogenated marine oils in England and Wales.

The aim was to examine the hypothesis that hydrogenated fats, particularly those obtained from marine oils, may present a health hazard. Storage fat specimens obtained at necropsy were collected from several areas in England and Wales during 1975-1978. Cases (n = 136 samples) consisted of males dying of ischaemic heart disease, male deaths from unrelated causes acting as controls (n = 95 samples). The fatty acid compositions of the specimens were determined, and analysis included those acids--16:1 trans and "higher" C-20 plus C-22 (H)--highly characteristic of partially hydrogenated marine oils. The case samples, which had been shown to be the richer in 16:1 trans (p less than 0.005), were now found to have a significantly higher value of the ratio 16:1 trans to H (p less than 0.002), arising from consumption of differing hydrogenated marine oil types. It is concluded that the cases had consumed a greater amount (p less than 0.001) of hydrogenated marine oils of a certain type, ie, that manufactured from certain highly unsaturated raw oils. The process of partial hydrogenation results in conversion to a product containing large amounts of polyunsaturated acids (PUFA) which are no longer in the natural all-cis methylene interrupted configuration. Such isomeric PUFA may obstruct or compete with utilisation of natural PUFA. It is further concluded that the case excess did not rise from medical advice favouring margarine or from any difference in social class status, but rather from fortuitous selection of margarine brand.

Differential induction of peroxisomal oxidation of palmitic acid and 3α,7α,12α-trihydroxy-5β-cholestanoic acid in rat liver

The effect of feeding rats 20% partially hydrogenated marine oil (PHMO), 20% soybean oil, or clofibrate on the conversion of 3α,7α,12α-trihydroxy-5β-cholestanoic acid to cholic acid was studied in light mitochondrial (L) fractions prepared from liver. 20% PHMO gave a doubling both of the specific and of the total activity of the cholic acid formation compared to those found in the L-fraction from animals given standard pellets. 20% soybean oil induced the specific and the total activity to a lesser extent, 1.4- and 1.2-fold, respectively. The specific and total activity of the peroxisomal β-oxidation of palmitic acid were induced 2.4- and 2.7-fold, respectively, by PHMO feeding. Soybean oil gave a smaller increase, 2-fold, in both specific and total activity. Clofibrate, a known peroxisomal proliferator, induced the specific and total activity of the peroxisomal fatty acid β-oxidation 5.2- and 5.7-fold, respectively, whereas the specific activity of the cholic acid formation remained unchanged compared to standard pellet feeding. The same pattern was found in the postnuclear supernatants (E-fractions), excluding the possibility that different treatments caused different distributions of organelles between the fractions. This differential induction of two similar peroxisomal reaction sequences suggests that at least two mechanisms for peroxisomal induction exist.

Influence of dietary linoleic acid andtrans fatty acids on the fatty acid profile of cardiolipins in rats

Cardiolipins (CL) have unique fatty acid profiles with generally high levels of polyunsaturated fatty acids, primarily 18:2n-6, and low levels of saturated fatty acids. In order to study the effect of dietary fatty acid isomers on the fatty acid composition of cardiolipins, rats were fed partially hydrogenated marine oils (HMO), rich in 16:1, 18:1, 20:1, and 22:1 isomeric fatty acids, supplemented with linoleic acid at levels ranging from 1.9% to 14.5% of total fat. Although the dietary fats contained 33% trans fatty acids, the levels of trans fatty acids in CL were below 2.5% in all organs. The fatty acid profiles of cardiolipins of liver, heart, kidney and testes showed different responses to dietary linoleic acid level. In liver, the contents of 18:2 reflected the dietary levels. In heart and kidney, the levels of 18:2 also paralleled increasing dietary levels, but in all groups fed HMO, levels of 18:2 were considerably higher than in the reference group fed palm oil. In testes, the 18:2 levels were unaffected by the dietary level of 18:2 and HMO.

Changes in the activities of dihydroxyacetone phosphate and glycerol-3-phosphate acyltransferases in rat liver under various conditions

Activities of enzymes relating to the acyl dihydroxyacetone phosphate (acyl DHAP) pathway were determined in rat liver under conditions known to elevate the peroxisomal β-oxidation activity. In fasted and streptozotocin-induced diabetic rats, DHAP acyltransferase activity showed a small but significant increase, though the activities of glycerol-3-phosphate (GP) acyltransferase and alkyl DHAP synthase were not changed. After 2 weeks, feeding of 20% partially hydrogenated marine oil, the activity of DHAP acyltransferase also increased to 140% of the control. The feeding of 0.25% clofibrate and 2% di(2-ethylhexyl)phthalate (DEHP) increased the activities of both DHAP and GP acyltransferases by 2- to 3-fold, whereas alkyl DHAP synthase activity decreased under the same conditions. A fractionation study showed that the increases in the activities of DHAP acyltransferase and acyl /alkyl DHAP reductase in the liver of rats treated with DEHP occurred mainly in peroxisomes and microsomes, respectively. The phospholipid contents per mg protein of the isolated hepatic peroxisomes from rats were as follows (percent of the control): fasting, 62%; diabetic, 69%; high fat-diet, 89%; clofibrate-treated, 126%; DEHP-treated, 119%. These results suggest that glycerophospholipid metabolism might also be controlled by peroxisomal enzymes under physiological and pathological conditions.

Different regulation of hepatic peroxisomal β-oxidation activity in rats treated with clofibrate and partially hydrogenated marine oil

Total RNAs from the livers of rats treated with clofibrate and partially hydrogenated marine oil (PHMO) wer translated in a reticulocyte-lysate cell-free protein-synthesizing system. In clofibrate-treated rats, mRNA activity for acyl-CoA oxidase (AO), the rate-limiting enzyme of the peroxisomal β-oxidation system, was increased markedly compared with the control, whereas the increase was less than 2-fold in PHMO-treated rats. When rats were treated with both clofibrate and PHMO in vivo , an additional increase in the hepatic AO activity was observed compared with either treatment alone, suggesting that increases in the activities of peroxisomal β-oxidation in the rats treated with clofibrate and PHMO are based on two distinct mechanisms.

Turnover of fatty acyl‐CoA oxidase in the liver of rats fed on a partially hydrogenated marine oil

The change in turnover of fatty acyl-CoA oxidase (FAO), the rate-limiting enzyme of the peroxisomal beta-oxidation system, was investigated in rats fed a 30% (w/w) partially hydrogenated marine oil (PHMO) diet. The FAO activity increased five-fold after two weeks of PHMO feeding, and decreased after withdrawal of the diet. Based on in vivo experiments using L-[4,5-3H]leucine and an immunoprecipitation technique, the increase in the activity of FAO could be accounted for by a 1.6-fold higher rate of FAO synthesis and a 3.4-fold slower rate of FAO degradation as compared to controls. In the same PHMO-fed rats, the rates of synthesis and degradation of carnitine palmitoyltransferase were 1.8-fold higher and 2.0-fold slower, respectively, as compared to controls. The results indicate that the observed increase in the activity of the enzymes of peroxisomal beta-oxidation is mainly due to a reduced rate of FAO degradation in the liver of rats fed the PHMO diet.

Dietary linoleic acid and the fatty acid profiles in rats fed partially hydrogenated marine oils.

The influence of the linoleic acid levels of diets containing partially hydrogenated marine oils (HMO) rich in isomeric 16:1, 18:1, 20:1 and 22:1 fatty acids on the fatty acid profiles of lipids from rat liver, heart and adipose tissue was examined. Five groups of rats were fed diets containing 20 wt % fat--16% HMO + 4% vegetable oils. In these diets, the linoleic acid contents varied between 1.9% and 14.5% of the dietary fatty acids, whereas the contents of trans fatty acids were 33% in all groups. A sixth group was fed a partially hydrogenated soybean oil (HSOY) diet containing 8% linoleic acid plus 32% trans fatty acids, mainly 18:1, and a seventh group, 20% palm oil (PALM), with 10% linoleic acid and no trans fatty acids. As the level of linoleic acid in the HMO diets increased from 1.9% to 8.2%, the contents of (n-6) polyunsaturated fatty acids (PUFA) in the phospholipids increased correspondingly. At this dietary level of linoleic acid, a plateau in (n-6) PUFA was reached that was not affected by further increase in dietary 18:2 (n-6) up to 14.5%. Compared with the HSOY- or PALM-fed rats, the plateau values of 20:4(n-6) were considerably lower and the contents of 18:2(n-6) higher in liver phosphatidylcholines (PC) and heart PC. Heart phosphatidylethanolamines (PE) on the contrary, had elevated contents of 20:4(n-6), but decreased 22:5(n-6) compared with the PALM group.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischaemic Heart Disease and Consumption of Hydrogenated Marine Oils

Ischaemic Heart Disease and Consumption of Hydrogenated Marine Oils

Influence of dietary fat on metabolism of (14-14C)erucic acid in the perfused rat liver. Distribution of metabolites in lipid classes.

Two groups of rats were fed diets containing 20% by weight of either partially hydrogenated marine oil supplemented with sunflower seed oil (PHMO) or palm oil (PO) for 8 wk. Using a liver perfusion system, the effect of dietary long chain monoenoic fatty acids on the uptake and metabolism of [14-14C]erucic acid was studied. The perfusion times were 15 and 60 min, respectively. The two groups showed equal ability for erucic acid uptake in the liver but differed in the channeling of the fatty acids into various metabolic pathways. A higher metabolic turnover of 22:1 in the PHMO livers relative to the PO livers was demonstrated by an increased recovery of total [14C]labeling in the triglyceride (TG) and phospholipid (PL) fractions, already evident after 15 min of perfusion. The chain-shortening capacity was highest in the PHMO group, reflected by a higher [14C]18:1 incorporation in both TG and PL, and increasing from 15 to 60 min of perfusion. The amount of [14C]18:1 found in PL and TG after 60 min of perfusion of livers from rats fed PO corresponded to that shown for the PHMO group after 15 min. The PL demonstrated a discrimination against 22:1 compared to TG, and, when available, 18:1 was highly preferred for PL-synthesis. The total fatty acid distribution in the TG, as determined by gas liquid chromatography (GLC), reflected the composition of the dietary fats. In the total liver PL, 22:1 and 20:1 were present in negligible amounts, although the PHMO diet contained 12-13% of both 22:1 and 20:1. In the free fatty acid fraction (FFA), the major part of the radioactivity (approximately 80%) was [14-14C]erucic acid, and only small amounts of [14C]18:1 (less than 2%) were present, even after 60 min of perfusion. The shortened-chain 18:1 was readily removed from the FFA pool and preferentially used for lipid esterification.

Effects of feeding high-fat diets to rats: metabolism of erucic acid (C 22:1 n-9) in the perfused liver and secretion of metabolites to the perfusate.

The liver metabolism of erucic acid, 22:1 n-9, was studied in rat livers perfused with 14-14C-labelled erucic acid for 15 and 60 min, determining the distribution of radioactivity in the perfusate and in the lipids of the liver cell organelles. The rats were adapted to a high-fat diet containing either partially hydrogenated marine oil (PHMO) or palm oil (PO), both adjusted to a 10% content of linoleic acid. The results showed an efficient uptake and metabolism of erucic acid with the secretion to the perfusate medium of labelled free fatty acids other than erucic acid, labelled phospholipids as well as water soluble oxidation products. Only minor amounts of secreted labelled triglycerides were found within 60 min of perfusion. In the liver, labelled lipids accumulated in the endoplasmic reticulum, after 15 min mainly as free fatty acids, after 60 min as triglycerides. The esterification pathway, including the erucic acid given as well as chain-shortened fatty acids, seemed to be preferred under the experimental conditions and with adequate linoleic acid in the diet. A chain shortening of erucic acid probably took place in both peroxisomes and mitochondria shown by the presence of labelled 18:1 and 20:1 in the organelle-bound phospholipids. A chain shortening was found in both dietary groups, and is assumed to be an affect of the adaptation to a high-fat diet rather than an effect of dietary very long chain monoenoic fatty acids. Somewhat higher levels were found in the PHMO group, but the difference in the dietary fat was not a major factor in the liver lipid adaptation.

Stimulation of hepatic polyamine metabolism following intraperitoneal injection of some dietary oils.

Intraperitoneal injection of partially hydrogenated marine oil into rats is shown to cause marked stimulation of hepatic polyamine metabolism, as characterized by increased activity of ornithine decarboxylase (EC 4.1.1.17), and corresponding increase in tissue levels of putrescine. A maximal effect was observed about 5 hours after injection. An effect on the hepatic activity of S-adenosyl-methionine decarboxylase (EC 4.1.1.50) was also observed. Of the various dietary oils examined only partially hydrogenated marine oil gave significant stimulation of polyamine metabolism. A single oral dose of partially hydrogenated marine oil gave a small increase in hepatic ornithine decarboxylase activity.

Chain-shortening of erucic acid and microperoxisomal beta-oxidation in rat small intestine.

The ability of rat small intestine to chain-shorten C22:1 fatty acids was investigated. Radioactive chain-shortened products, mainly C18:1, were demonstrated in intestinal-lymph lipids after intraluminal injection of [14-14C]erucic acid. Chain-elongation to C24:1 was also observed. Adaptation to a diet containing C22:1 fatty acids (partially hydrogenated-marine-oil diet) slightly increased the percentage of chain-shortened products. Microperoxisomal beta-oxidation activity, measured as CN(-)-insensitive palmitoyl-CoA-dependent NAD+ reduction, was detected in a microperoxisome-enriched fraction from mucosal scrapings. This activity was increased 1.9-fold by a soya-bean-oil diet, and 2.7-fold by a diet containing partially hydrogenated marine oil.

Fatty Acid Composition of Danish Margarines

AbstractThree groups, including a total of 30 Danish margarines containing at least 10 %, 20 %, or 40 % of linoleic acid, respectively, were analyzed by gas‐liquid chromatography using both a 50 m Sil 88 capillary column and two packed columns, SP 2330 and OV‐275. The total contents of trans fatty acids ranged as follows: 3.1 %‐29.0, 2.9 %‐18.3 %, and 2.6 %‐8.3 %, respectively, for the three groups. Only in low linoleic acid margarines significant levels of C 20‐ and C 22‐monoenes were found, indicating that these margarines contained partially hydrogenated marine oils. In all samples, the content of trans, trans linoleic acid was less than 1 %.

Effects of high fat diets on the activity of palmitoyl‐CoA hydrolase in rat liver

Palmitoyl-CoA hydrolase [EC 3.1.2.2.] activity in rat liver was found to be enhanced by high fat diets. Partially hydrogenated marine oil and high-erucic acid rapeseed oil diets produced a greater increase than a diet containing soybean oil. With diets containing from 5 to 30% (w/w) of partially hydrogenated marine oil the increase in palmitoyl-CoA hydrolase activity was similar to the increase observed in peroxisomal beta-oxidation activity (correlation coefficient r = 0.94). A positive correlation (r = 0.86) also was observed between the activity of palmitoyl-CoA hydrolase and previously determined levels of long-chain acyl-CoA. The results presented may suggest a common "induction" mechanism for palmitoyl-CoA hydrolase and peroxisomal beta-oxidation enzymes, possibly exerted through an increased cellular level of long-chain acyl-CoA.

Effect of Dietary Fats on Experimental Hypertension

In an experiment on 95 Wistar rats weighing 330 g the effect was studied of partially hydrogenated marine oil and cod-liver oil as well as sunflowerseed oil and animal fat on arterial hypertension induced with administration of 1.5% NaCl in drinking water. During 5 weeks the animals received diets containing 37.8 kcal% derived from the studied fats. After the first week of 1.5% NaCl solution administration a significant rise of the systolic blood pressure and heart rate was observed in all animals without regard to the fat received by them with the diet. The rise of the blood pressure was greatest in the group of rats kept on the diet with animal fat, while in the groups of rats receiving diets with sunflowerseed oil or marine oils this rise was significantly smaller, especially with cod-liver oil. The hypotensive effect of marine oils, particularly cod-liver oil, was more pronounced than that of sunflowerseed oil. The hypotensive effect of partially hydrogenated fish oil was less pronounced than that of cod-liver oil. Our experiments demonstrated a significant effect of the amount of dietary fat on the development of experimental hypertension. Greater intake of salt and animal fats in human diet may be one of the causes of essential hypertension.

Effect of dietary fats on arachidonic acid and eicosapentaenoic acid biosynthesis and conversion to C 22 fatty acids in isolated rat liver cells

The desaturation, chain elongation and esterification of [1- 14C]eicosapentaenoic acid, [1 14C]arachidonic acid, [1- 14C]eicosatrienoic acid, [1- 14C]linolenic acid and [1- 14C]linoleic acid were studied in isolated liver cells. Rats fed diets with either 15% hydrogenated coconut oil or 15% partially hydrogenated marine oil, both deficient in essential fatty acids, 15% soybean oil or standard pellet diet with 6% fat, were used. The Δ 4-desaturation of 22:5( n−3) and 22:4( n−6) as well as the Δ 6-desaturase activity was distinctly higher in cells from animals fed coconut or marine oil than with soybean oil or standard pellet. The rate of Δ 5-desaturation of 20:3( n−6) and 20:4( n−3) was nearly the same in cells from rats fed coconut, marine and soybean oils and higher than with standard pellet. The chain elongation of 20:5( n−3) to 22:5( n−3) was distinctly more pronounced than the elongation of 20:4( n−6) with all four diets. 20:5( n−3) was mainly esterified in the phospholipids with marine and coconut oils, and mainly in triacylglycerol with standard pellet and soybean oils. The proportion of [1- 14C]20:4( n−6) in the phospholipids to that in triacylglycerol decreased in the order marine oil > coconut oil > standard pellet > soybean oil. The different endogenous arachidonic acid content in the phospholipids induced by the different diets increased in the same order. 20:5( n−3) was rapidly esterified in triacylglycerol and phospholipids, then liberated especially from the triacylglycerol fraction, chain elongated to 22:5( n−3) and reesterified.

Long-chain Acyl-CoA levels in liver from rats fed high-fat diets: is it of significance for an increased peroxisomal beta-oxidation?

The levels of long-chain acyl-CoA in the livers of rats given diets containing various amounts of dietary oils were investigated. Increasing the amount of soybean oil in the diet from 5% to 25% (w/w) led to a 40% increase in long-chain acyl-CoA. With partially hydrogenated marine oil, a sigmoidal dose-response curve was obtained, giving a 60% increase when 20% or more of this oil was in the diet. All high-fat diets tested resulted in higher levels of long-chain acyl-CoA than the low-fat control containing soybean oil. The increase was most prominent with partially hydrogenated marine and rapeseed oils. With diets containing partially hydrogenated marine oil, the ratio of long-chain acyl-CoA to acid-soluble CoA was increased after 3 days, but decreased after 3 weeks, to a value similar to that observed in animals fed soybean oil because of an extensive increase in acid-soluble CoA. Increased levels of long-chain acyl-CoA were also observed after clofibrate was administered, but the increase was less prominent than observed with high-fat diets. When comparing the levels of long-chain acyl-CoA observed after 3 days on different diets with the peroxisomal beta-oxidation activity previously determined after 3 weeks on the corresponding diets, a straight line was obtained. These results are discussed in relation to the possibility that long-chain acyl-CoA induces peroxisomal beta-oxidation activity.