Rapeseed Oil Diet Research Articles

Relationship between erucic acid and myocardial changes in male rats.

The back and belly fat of pigs fed a diet containing 20% by wt rapeseed oil (22% erucic acid) for 16 weeks was rendered into oil. This rendered pig fat, which contained 5.6% erucic acid, was fed to male rats in three separate experiments at 20% by wt of the diet for 16 weeks. In experiment I rendered pig fat was compared only to Brassica campestris var. Span rapeseed oil containing 4.8% erucic acid. In experiments II and III, rendered pig fat was compared to commercial lard containing 0.2% docosenoic acid, commercial lard to which 5.4% free erucic acid was added, and Span rapeseed oil. There was no significant (P less than 0.01) differences observed in the level of erucic acid in the hearts of rats fed diets of rendered pig fat, Span rapeseed oil, or commercial lard plus erucic acid. However, the incidence (P less than 0.001) and severity (P less than 0.01) of cardiac lesions were significantly higher in Span rapeseed oil fed rats compared to rats fed control diets. The number of rats affected or the severity of lesions in the rendered pig fat fed group was not significantly different from controls. The results of this study indicate that the myocardial lesions associated with feeding 20% rapeseed oil diets are not related to the content of erucic acid per se. The possible reasons why rapeseed oil causes cardiac lesions in rats are discussed. It is suggested that a triglyceride imbalance in the oil might play an important role in causing these lesions in rats.

GROWTH, CARCASS QUALITY AND CARDIOPATHOLOGY OF BOARS AND GILTS FED DIETS CONTAINING RAPESEED AND SOYBEAN OILS

Eighty-one boars and 81 gilts were fed to market weight (87 kg) diets containing 5 or 10% soybean oil and rapeseed oils (Brassica napus cv. Oro, B. campestris cv. Span and a mixture of B. campestris cv. Arlo and Echo) or a control diet to which no oil was added. Differences in growth rate were evident only up to the 4th wk of feeding, when rate of growth was higher (P <.05) with the soybean oil (SB) diets than with the control diet. Efficiency of feed conversion was highest (P <.05) for pigs fed the SB diets, and the higher level of oil increased significantly (P <.10) the depth of backfat. The performance of the boars surpassed that of the gilts for both growth and carcass quality measurements. In a second experiment, in which three groups each of 24 boars were fed for 112 days the control diet unsupplemented or supplemented with 20% soybean oil or 20% rapeseed oil (B. campestris cv. Arlo plus Echo), less feed was consumed (P <.01) by boars fed either oil diet than the control diet. Bodyweight gain by boars fed the rapeseed oil (RS) diet was inferior (P <.05) to those fed either the SB or the control diet. In none of the control, SB- and RS-fed boars were traces of fat accumulation detected in the heart. Small foci of necrosis accompanied by mononuclear cell infiltration were found in one control pig, one SB pig and three RS pigs. All pigs, except for two controls and one from each of the oil groups, showed degenerative calcified lesions in the left atrial endocardium.

Failure of dietary erucic acid to impair oxidative capacity or ATP production of rat heart mitochondria isolated under controlled conditions

1. Male, 8-week old rats were fed Purina Rat Chow or semi-synthetic diets containing 20% by weight of rapeseed oil or corn oil for 3 days. 2. The hearts from the animals fed the three diets were analyzed for total lipid, phospholipid, free fatty acids, cholesterol esters, tri-, di- and monoacylglycerols. There was a seven-fold increase in the levels of triacylglycerols in the hearts of rats fed rapeseed oil diet compared to the levels in the hearts of animals fed the other two diets. Smaller increases in the content of other neutral lipid fractions were also observed. 3. Heart mitochondria from the three groups of animals were isolated under controlled conditions in the presence or absence of heparin. The rates of oxidation of different substrates and of ATP synthesis by these mitochondria were compared. 4. Mitochondria isolated in the absence of heparin from rapeseed oil-fed rats had much lower rates of oxidation and ATP synthesis than mitochondria isolated similarly from rats fed the other two diets. 5. With mitochondria freshly isolated in the presence of heparin, no significant differences in rates of oxidation or ATP synthesis were found among the three groups of animals. 6. It is concluded that, when properly isolated, mitochondria from rapeseed oil-fed rats are functionally intact with respect to oxidation and energy-coupling capacity.

Erucic acid metabolism by rat heart preparations.

Rat heart preparations metabolized erucic acid at much slower rates than palmitic acid. This applied for activation reaction, for the conversion of acyl-CoA to acylcarnitine, and for the utilization of acyl group for oxidation. As compared to palmityl-CoA, erucyl-CoA exhibited a lower affinity for carnitine palmityltransferase (EC 2.3.1.23), the respective apparent Michaelis constants were 43 and 83 muM. Presence of erucyl-CoA or erucyl-carnitine slowed the mitochondrial oxidation of palmityl groups apparently because of the slower oxidation of erucyl groups. However, presence of erucate did not inhibit the activation of palmitate. Heart mitochondria obtained from rats fed rapeseed oil (50 cal %) or corn oil diet for 3 days showed similar abilities for the coupled oxidation of various substrates and similar carnitine palmityltransferase activities. Thus, a suggestion of gross mitochondrial malfunction following rapeseed oil consumption was not confirmed.

The Effect of Dietary Rape-Seed Oil on Cholesterol-Ester Metabolism and Cholesterol-Ester-Hydrolase Activity in the Rat Adrenal

The effects of stock diet and stock diet supplemented by olive oil and rape seed on rat adrenal cholesterol ester metabolism have been studied. Rats fed rape seed oil failed to gain weight at the same rate as rats fed olive oil. A prominent feature of the rats fed rape seed oil was an accumulation of high concentrations of cholesterol erucate in the adrenal lipid droplets. When these rats were subjected to an ether stress no percentage decrease in the amount of cholesterol erucate was observed. Adrenal cholesterol ester hydrolase activity was higher in rats fed the olive oil and rape seed oil diets than rats fed the stock diet. In rats fed stock or olive oil diets, a ten-minute ether anaesthesia stress resulted in a two-fold increase in activity of adrenal cholesterol ester hydrolase. Cofactor addition of ATP, cyclic AMP and MgCl-2 in vitro resulted in a stimulation of cholesterol ester hydrolase to a similar activity in both quiescent and ether-stressed rats. By contrast rats fed the rape seed oil diet gave no significant stimulation of cholesterol ester hydrolase activity when given an ether stress or when cofactors were added in vitro. Cholesterol erucate was hydrolysed at only 25% to 30% of the rate of cholesterol oleate in vitro in all groups of animals. Oleic acid added in vitro gave an inhibition of cholesterol ester hydrolase activity in rats fed stock diet while erucic acid activated the enzyme. The accumulation of cholesterol erucate in the adrenal when rats are fed rape seed oil could be due to the reduced ability of cholesterol ester hydrolase to hydrolyse this ester.

PERFORMANCE AND HISTOLOGICAL CHANGES IN TISSUES OF PIGS FED DIETS CONTAINING HIGH OR LOW ERUCIC ACID RAPESEED OILS OR SOYBEAN OIL

Three experiments were conducted to compare high (20.6%) or low (4.0%) erucic acid rapeseed oils with soybean oil when the oils were fed at a level of 15% of the diet for pigs from 25 to 90 kg liveweight. The low erucic acid rapeseed oil originated from Brassica campestris cv. Span. A fourth diet containing no supplemental oil served as a control. In one experiment, 48 crossbred pigs were fed ad libitum in groups of three pigs replicated four times. In a second experiment, 48 pigs were individually fed at a level of 80% of the daily caloric intake of the pigs in the first experiment. In a third experiment, 16 pigs in four groups were allowed continuous free-choice access to the four diets. Serial slaughter and digestibility data were obtained. The incorporation of high or low erucic acid rapeseed oil in the diets did not reduce pig performance when such diets were fed either ad libitum or at a restricted level. When given a choice of feed, pigs selected less of the high erucic acid rapeseed oil diet. When not given a choice of feed, pigs consumed as much of a high erucic acid rapeseed oil diet as they did of the other diets. Digestibility coefficients for energy, nitrogen and lipids were not significantly different for any of the three oil-containing diets. Histological examination of the heart, liver and spleen revealed no marked differences due to feeding any of the oil-based diets.

Observations on lipid composition with particular reference to cardiolipin of rat heart after feeding rapeseed oil.

The influence of dietary rapeseed oil on the lipid classes and fatty acid pattern of rat heart homogenate and mitochondria has been investigated after feeding a diet with 9.8 weight- % erucic acid for 10 days and 1.4 and 2.6% erucic acid for 28 days. The rats treated with 9.8% erucic acid showed a significant increase in the triglycerides of the heart mitochondria. This tendency was much less pronounced in rats treated with 1.4 resp. 2.6% erucic acid. These results confirm those of other investigators. A slight increase in the cholesterol esters of the mitochondria could be seen in all the treated rats. The total phospholipids were decreased in the experiment with 9.8% erucic acid and slightly increased in experiments with 1.4 and 2.6% erucic acid. The concentration of phosphatidylcholine showed a tendency to increase and the concentration of phosphatidylethanolamine to decrease in the experiment with 9.8% erucic acid in the diet. The concentration of cardiolipin was mainly unchanged. In all experiments the triglycerides of the heart mitochondria showed a high content of erucic acid. The fatty acids of the cholesterol esters of the heart mitochondria were also influenced of dietary rapeseed oil but to a less extent than the triglycerides. The fatty acids of phosphatidylcholine, phosphatidylethanolamine and cardiolipin were all influenced by the dietary rapeseed oil, but the erucic acid seemed to have a specific affinity to cardiolipin. Cardiolipin of rat heart mitochondria was isolated and identified with gas chromatography and mass spectrometry. The isolated cardiolipin was found to contain 12 per cent erucic acid after feeding 9.8% erucic acid as rapeseed oil for 10 days. Similar results were obtained after feeding glyceryl trierucate for 5 days to rats. The incorporation of erucic acid into cardiolipin was followed by a corresponding decrease of linoleic acid. This observation is of great interest because the molecular structure of fatty acids in lipid molecules has a profound influence of the packing of these molecules in a bilayer. Since cardiolipin is a component of the inner membrane of mitochondria its high affinity for erucic acid might influence the normal function of the inner membrane of heart mitochondria.

Physiopathological effects of rapeseed oil: a review.

Rapeseed oil has a growth retarding effect in animals. Some investigators claim that the high content of erucic acid in rapeseed oil alone causes this effect, while others consider the low ratio saturated/monounsaturated fatty acids in rapeseed oil to be a contributory factor. Normally erucic acid is not found or occurs in traces in body fat, but when the diet contains rapeseed oil erucic acid is found in depot fat, organ fat and milk fat. Erucic acid is metabolized in vivo to oleic acid. The effects of rapeseed oil on reproduction and adrenals, testes, ovaries, liver, spleen, kidneys, blood, heart and skeletal muscles have been investigated. Fatty infiltration in the heart muscle cells has been observed in the species investigated. In long-term experiments in rats erucic acid produces fibrosis of the myocardium. Erucic acid lowers the respiratory capacity of the heart mitochondria. The reduction of respiratory capacity is roughly proportional to the content of erucic acid in the diet, and diminishes on continued administration of erucic acid. The lifespan of rats is the same on corn oil, soybean oil, coconut oil, whale oil and rapeseed oil diet. Rats fed a diet with erucic acid or other docosenoic acids showed a lowered tolerance to cold stress (+4 degrees C). In Sweden erucic acid constituted 3-4% of the average intake of calories up to 1970 compared with about 0.4% at present.

Effect of dietary rapeseed oil on hepatic hexobarbital metabolism in mice.

The effect of dietary rapeseed oil (RSO) on hepatic hexobarbital metabolism has been studied in short-term experiments in mice by measuring both the activity of mixed function oxidase system in microsomal preparations in vitro and the in vivo hexobarbital-induced sleeping time. Moreover, the fatty acid pattern of liver tissue, with particular regard to erucic and gadoleic acids, was analyzed gas-chromatographically. The hexobarbital metabolism in young RSO-fed (RSO containing 52% of erucic acid and 7.4% of gadoleic acid; 50 cal% for 3 days) is lower by about 44% than in controls treated in the same way with peanut oil, independently of sex. RSO did not have a statistically significant effect of hexobarbital metabolism in adult animals of both sexes. As to the dose-response study, the prolongation of the hexobarbital-induced sleeping time in young male is statistically significant when fed with 30 cal% in RSO for 3 days, while it is not more statistically significant in mice fed 15 cal% in RSO. In RSO mice (50 cal%) erucic and gadoleic acid account both for about 10% of the total fatty acids in the liver tissue, while they are quite absent in controls. It causes a relative deficiency of linoleic and arachidonic acids, known to be essential for synthesis and maintenance of the membranes supporting hepatic microsomal enzymes responsible for the metabolism of some drugs.

Lipid changes in tissues of young boars fed rapeseed oil or corn oil.

Fully refined rapeseed oil, Brassica campestris var. Arlo plus Echo, and corn oil were fed at 20% by weight of a basal diet to young Yorkshire boars. A serial slaughter technique was employed whereby 3 boars from each dietary treatment were killed at 0,1,2,3,4 and 8 weeks of the experiment. The fatty acid profiles of heart, liver, adrenals and testes lipids were investigated. The typical fatty acids of rapeseed oil, erucic and eicosenoic acids, were incorporated at different levels into the tissue lipids examined. After feeding the rapeseed oil diet for 1 week, the relative concentration of these fatty acids increased in the adrenals, while remaining similar in the heart, liver and testes. The relative concentration of eicosenoic acid was greater than that of erucic acid in all organs examined, except for the heart which contained equal amounts of these acids. Tissue levels of these acids in boars were compared to those found in rats fed the same rapeseed oil in previous studies.

Studies on phospholipids with particular reference to cardiolipin of rat heart after feeding rapeseed oil.

AbstractThe influence of dietary rapeseed oil on the lipid classes and fatty acid pattern of rat heart homogenate and mitochondria has been investigated after feeding a diet with 9.8% by wt erucic acid for 10 days and 1.4% and 2.6% erucic acid for 28 days. The rats treated with 9.8% erucic acid showed a significant increase in the triglycerides of the heart mitochondria. This tendency was much less pronounced in rats treated with 1.4 and 2.6% erucic acid, respectively. In all experiments, the triglycerides of the heart mitochondria showed a high content of erucic acid. The fatty acids of phosphatidylcholine, phosphatidylethanolamine, and cardiolipin were all influenced by the dietary rapeseed oil, but the erucic acid seemed to have a specific affinity to cardiolipin. Cardiolipin of rat heart mitochondria was isolated and identified with gas chromatography and mass spectrometry. The isolated cardiolipin was found to contain 12% erucic acid after feeding 9.8% erucic acid as rapeseed oil for 10 days. Similar results were obtained after feeding glyceryl trierucate for 5 days to rats. The incorporation of erucic acid into cardiolipin was followed by a corresponding decrease of linoleic acid. This observation is of great interest because the molecular structure of fatty acids in lipid molecules has a profound influence on the packing of these molecules in a bilayer. Since cardiolipin is a component of the inner membrane of mitochondria its high affinity for erucic acid might influence the normal function of the inner membrane of heart mitochondria.

Activity of Microsomal Enzymes in the Livers of Rats Fed Rapeseed Oil

Young Wistar rats were fed either a 3-percent (30 g/kg) or a 20-percent (200 g/kg) rapeseed oil diet during 6, 8 days or 16 weeks. The control animals were given either a 3-percent (30 g/kg) or a 20-percent (200 g/kg) peanut oil diet. The liver concentration of cytochrome P 450 was measured after 6 days, and the following liver enzyme activities assayed after 8 days and 16 weeks: glucose-6-phosphatase, azoreductase, either with butter yellow or with amaranth as substrate, aminopyrine-A-demethylase and BHT oxidase (this one only after 8 days). The only observed change concerned glucose-6-phosphatase activity under the influence of the rapeseed oil diet. As referred to total liver, it was decreased after 8 days of feeding the rapeseed oil diet. As expressed for 100 mg tissue or protein, it was lowered after 16 weeks. Rapeseed oil would then be a liver toxic, altering the phospholipid composition of the endoplasmic reticulum.

Influence des huiles de colza et de canbra sur les lipides plasmatiques du rat<sup>1</sup>

Rapeseed oil fed to male weanling rats as 15% by weight of the diet for 2 months does not influence the plasma content of triglycerides (TG), phospholipids (PL), nonesterified fatty acids (NEFA) and cholesterol esters (CE), as compared to peanut oil and canbra oil (‘zero erucic acid’ rapeseed oil). However, the fatty acid spectra are changed: erucic acid and eicosénoïque acid from dietary rapeseed oil are mainly incorporated in TG and NEFA, less in PL and practically not at all in CE. Feeding time has little effect. Therefore, the immediate but temporary cardiac steatosis which is obtained in weanling rats fed rapeseed oil cannot be explained by modifications of the plasma TG or NEFA concentration and/or their fatty acid composition. Rapeseed and canbra oil increase the percentages of ω3-polyunsaturated fatty acids and of nervonic acid in plasma PL.

Utilization of rapeseed oils of high and low erucic acid content.

In an experiment involving 4-week-old chickens the effects of feeding different levels of rapeseed oils of high and low erucic acid content on the weight, lipid content and fatty acid composition of various tissues was studied. The results obtained indicated that: (1) On the average, the kind of oil or fat fed did not appear to influence heart-to-body-weight ratio. Only regular rapeseed oil increased liver-to-body-weight ratio by more than 10 %. The data also show that the feeding of rations containing regular rapeseed oil or Canbra oil (a low erucic type) produced the smallest spleens while feeding rations containing soybean oil or lard resulted in the highest spleen-to-body-weight ratios. (2). The total lipid content of the heart of chickens fed regular rapeseed oil and Canbra oil-containing diets was significantly (p ≤ 0.05) lower than those receiving Span oil, soybean oil or lard-containing diets. The total lipid content of liver or spleen was not influenced by the kind of oil or fat included in the ration. (3). The fatty acid composition of the feed fats altered the fatty acid pattern of the total lipids of heart, liver, spleen and breast muscle. Feeding the rapeseed oil-containing diets led to a decrease in the concentration of saturated fatty acids in the organs with increasing additions of oil to the diets, whereas the concentration of mono-unsaturated fatty acids increased. This increase was mainly due to increases in the concentration of eicosenoic (C 20:1) and erucic (C 22:1) acids in tissue lipids. Addition of the low erucic acid rapeseed oils (Canbra and Span) to the rations led to similar but smaller changes in the composition of the tissue lipids of the chickens. Feeding increasing levels of soybean oil in the diet led to an increase in the concentration of polyunsaturated fatty acids in the total lipids of liver, spleen and breast muscle, whereas with feeding of increasing levels of lard in the diet the concentration of saturated fatty acids in these tissue lipids tended to increase.

Changes in liver lipid composition of male rats fed rapeseed oil diets.

AbstractStudies are reported on the effect of feeding diets containing rapessed oils differing in their erucic acid content to male weanling rats for 16 weeks. Rapeseed oil high in erucic acid depressed growth. Total lipids, lipid phosphorous and cholesterol, in the livers were not significantly different between the experimental groups. The fatty acid composition of the total liver lipids, the neutral lipids, phosphatidylethanolamine and phosphatidylcholine are documented. Erucic and eicosenoic acids were found in all lipid classes at the same relative concentration; the amount being incorporated was proportional to that found in the dietary oil. The positional analysis of phosphatidylethanolamine and phosphatidylcholine are presented. Erucic acid was incorporated preferentially at position two of these phospholipids, whereas, twice the level of eicosenoic acid was found at position one, compared to that which occurred at the two position.

Pathological Effects of Dietary Rapeseed Oils with High or Low Erucic Acid Content in Ducklings

A rapeseed oil containing 50% erucic acid (RSO) and one containing 8.5% erucic acid (LER) were compared for pathogenicity in ducklings after feeding for 2 weeks or 3 months. RSO caused growth retardation, severe mortality, hydropericardium and pathological changes especially in heart, liver, skeletal muscles and spleen. After 3 months, cardiac fibrosis was observed. The animals fed LER for 2 weeks showed normal growth and no mortality, but some of them exhibited vacuolar changes of the heart and skeletal muscles. Hydropericardium was absent. After 3 months the lesions had largely disappeared leaving no permanent tissue alterations. These data show that an intake of ca. 4 cal.% erucic acid is well tolerated by ducklings.

Short-term and long-term pathological effects of glyceryl trierucate and of increasing levels of dietary rapeseed oil in rats.

Diets containing rapeseed oil (RSO) or glyceryl trierucate (GTE), each supplying 25 cal% erucic acid, were compared for their effect on the cardiac morphology in male Wistar rats after 1 week, and on growth, pathology and heart and kidney weights after 24 weeks. Sunflowerseed oil (SSO) and a rapeseed oil supplying ca. 4 cal% erucic acid (LER) served as control fats. The RSO and GTE diets produced similar effects. After 1 week, cardiac lipidosis was observed in both dietary groups; after 24 weeks, lipidosis had decreased remarkably and cellular scars were the main pathological feature. The severity of the lipidosis and of the fibrotic changes was similar in both groups. Growth and the relative weights of the heart and kidneys were significantly different – mutually as well as in comparison with the control rats fed SSO. It was concluded that erucic acid is the main pathogenic fatty acid in RSO, but other long-chain fatty acids may also play a minor role. The animals fed LER showed normal growth and organ weights compared with the SSO group. Slight cardiac lipidosis was observed after 1 week. After 24 weeks, some animals showed cardiac cellular scars varying in intensity from slight to moderate. In a second experiment, Sprague-Dawley rats were fed 0, 5, 10, 15, 20, 25 or 30 cal% RSO in diets made isocaloric in fat by addition of SSO. The rats were killed after 3 and 6 days and 32 weeks. All rats fed RSO for 3 and 6 days showed a dose-related lipidosis of the heart. The groups fed RSO for 32 weeks showed myocardial changes which were already manifest in a few animals on the 5 cal% RSO diet. Incidence and severity of these changes increased according as the RSO content of the diet was increased.

The Effect of Dietary Fat and Storage Temperature on the Storage Stability of Turkey Meat

The abdominal depot fat of turkeys fed 11.4% dietary rapeseed oil became rancid when stored for eight months at −12°C., but not at −22°C. The depot fat of birds fed 11.4% palm oil was stable at both storage temperatures. A similar trend in thigh meat was not significant. Storage temperature did not affect the stability of breast meat. The instability of carcass fat of birds fed rapeseed oil in comparison to palm oil was associated with higher levels of linoleic and linolenic acids in the tissues.

Effect of dietary rapeseed oil on the adrenocorticotrophin-induced production of prostaglandins in the rat adrenal

Inclusion of rapeseed oil in the diet of rats resulted m an increase in the total cholesteryl ester content of the adrenal. This increase was attributable to deposition of cholesteryl erucateand cholesteryl eicosenoate. Incubation of rat adrenal homogenates with adrenocorticotrophin resulted in a stimulation in the production of prostaglandins E 2, F 2α and, to a lower degree. F 1α. Stimulation of prostaglandin production by adrenocorticotrophin was considerably lower in adrenals from rats receiving rapeseed oil rather than corn oil.

Digestibility, efficiency and other metabolic effects of dietary rapeseed oil in rats.

Rats were fed diets containing 60 cal% rapeseed oil (RSO) or sunflowerseed oil (SSO) for periods up to 64 weeks. When the animals were allowed to eat <i>ad libitum, </i>the food consumption in the RSO group was significantly lower than in the SSO group. It was shown that the RSO diet is less readily digested than the SSO diet. This is due solely to the lower digestion coefficient of the RSO and of its erucic acid fraction in particular, which can be explained by its chain length. The digestion coefficient of the non-fat calories is equal in both groups. The digestion capacity is not a limiting factor in RSO digestion. The absorbed erucic acid is almost totally metabolized. Rats fed a RSO-containing diet utilize the digested calories less efficiently than animals offered an SSO diet. Moreover, their oxygen consumption and water-vapour release are higher. It is assumed that the lower efficiency of the RSO diet is caused by a slightly uncoupled oxidative phosphorylation and a greater heat increment.