Myocardial alterations resulting from feeding partially hydrogenated marine oils and peanut oil to rats

Myocardial alterations were observed in 5 groups of rats fed diets containing 20% fat for 16 weeks. The incidence was comparable to that from other studies and uniform at 6/20 in hearts from rats fed: partially hydrogenated herring oil to give dietary levels of either 16.7% or 4.6% 22∶1; partially hydrogenated redfish/flatfish oil to give 4.5% 22∶1 in the dietary fat; and peanut oil (of unknown origin) containing 0.1% 22∶1. The incidence was 9/20 in the hearts of rats fed an unrefined and unprocessed redfish oil at a dietary level of 16.0% 22∶1 in fatty acids.     

Testing a short-term feeding trial to assess compositional and histopathological changes in hearts of rats fed vegetable oils

Male, female and castrated rats, three wk of age, were fed a low-fat diet for 14 wk followed by high-fat diets (20% by weight) for one wk containing graded levels of erucic acid from 1 to 50%, to evaluate the effect of short-term feeding and interaction of male sex hormones on formation of heart lesions. Some rats within each group were returned to the low-fat diet for one wk after the test period. For comparison, one group of three-wk-old male rats was fed the high fat 50% erucic acid diet for 15 wk. Erucic acid depressed growth rate and food consumption and increased cardiac lipidosis and triglycerides proportional to the erucic acid content of the diet. There were no sex differences, and the effects disappeared once rats were returned to the low-fat diet for one week. There was a significance (P<0.05) in the incidence of myocardial necrosis among male rats fed increased levels of erucic acid for one week, but the response was not linear to the increase in dietary erucic acid. Furthermore, the response was much less than in males fed the 50% erucic acid diet continually for 15 weeks. These results suggest that the short-term model is not a suitable substitute for the long-term feeding trial to test the cardiopathogenicity of a vegetable oil. The significantly lower incidence in myocardial lesions in female and castrated male rats compared with male rats suggests involvement of sex hormones. However, the process appears to be long term, since changes in cardiac lipids and their fatty acid pattern between sexes became evident after one wk on diet but was significant only after long-term feeding. Deceased.     

Effects of long-term feeding of marine oils with different positional distribution of eicosapentaenoic and docosahexaenoic acids on lipid metabolism, eicosanoid production, and platelet aggregation in hypercholesterolemic rats

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were distributed mainly in the sn-1,3 positions of seal oil triglyceride and in the sn-2 position of squid oil triglyceride. Seal oil-rich or squid oil-rich fats having constant saturated/monounsaturated/polyunsaturated fatty acid (PUFA) and n−6/n−3 PUFA ratios were fed to exogenously hypercholesterolemic rats for 160 d. The control fat contained linoleic acid as the sole PUFA. Before starting the experimental diets, rats were orally treated with high doses of vitamin D for 4 d to accelerate atherogenesis. The percentage of arachidonic acid in phosphatidylcholine and phosphatidylethanolamine of liver, platelets, and aorta was lower in the marine oil groups than in the control group, seal oil being more effective than squid oil. Maximal platelet aggregation induced by collagen was significantly lower both marine oil groups. Platelet thromboxane (TX) A₂ production induced by collagen or thrombin was markedly reduced by feeding seal or squid oils, the reduction being more pronounced in the seal oil than in the squid oil group. Aortic prostacyclin (PGI₂) production was the same among the three groups. The ratio of the productions of aortic PGI₂ and platelet TXA₂ was significantly higher in the seal oil than in the control group. Although there was no difference in intimal thickness among the three groups, the aortic cholesterol content was significantly lower in the marine oil groups than in the control group. These results showed that the main effects in rats of the different intramolecular distributions of EPA and DHA in dietary fats were on arachidonic acid content in tissue phospholipids and on platelet TXA₂ production.     

Influence of partially hydrogenated vegetable and marine oils on lipid metabolism in rat liver and heart

Partially hydrogenated marine oils containing 18∶1-, 20∶1- and 22∶1-isomers and partially hydrogenated peanut oil containing 18∶1-isomers were fed as 24–28 wt % of the diet with or without supplement of linoleic acid. Reference groups were fed peanut, soybean, or rapeseed oils with low or high erucic acid content. Dietary monoene isomers reduced the conversion of linoleic acid into arachidonic acid and the deposition of the latter in liver and heart phosphatidylcholine. This effect was more pronounced for the partially hydrogenated marine oils than for the partially hydrogenated peanut oil. The content oftrans fatty acids in liver phospholipids was similar in groups fed partially hydrogenated fats. The distribution of various phospholipids in heart and liver was unaffected by the dietary fat. The decrease in deposition of arachidonic acid in rats fed partially hydrogenated marine oils was shown in vitro to be a consequence of lower Δ6-desaturase activity rather than an increase in the peroxisomal β-oxidation of arachidonic acid. The lower amounts of arachidonic acid deposited may be a result of competition in the Δ6-desaturation not only from the C22-and C20-monoenoic fatty acids originally present in the partially hydrogenated marine oil, but also from C18- and C16-monoenes produced by peroxisomal β-oxidation of the long-chain fatty acids. Part of this work was presented at the ISF-AOCS Congress, New York City, 1980.     

Essential fatty acid-deficient rats: III. Distribution of lipid classes in rat testes after feeding partially hydrogenated oils

Total and relative amounts of neutral lipids (NL) and phospholipids (PL) as well as the distribution of various lipid classes in these were determined in testes of rats fed different types of partially hydrogenated oils for 5,15 and 26 weeks. The dietary fats were partially hydrogenated arachis oil (HAO), partially hydrogenated soybean oil (HSO), partially hydrogenated herring oil (HHO) and, for comparison, arachis oil (AO). An additional series of animals was reared on a fat-free diet throughout the entire experiment. The total amount of NL is decreased by EFA deficiency parallel with the development of the degenerative changes of the spermatogenic tissue. The relative amounts of NL in the testis are not influenced by EFA deficiency during the first stages of degeneration. However, feeding of HHO for 26 weeks resulted in a marked decrease in NL. The total content of PL is directly related to tissue degeneration. This observation is supported by the data obtained after 5 weeks of feeding HHO and by the correspondence between the results found after 15 and 26 weeks on HAO and the fat-free diets, respectively. The relative amount of PL is less influenced by EFA deficiency, but severe degenerations as found for the group fed HHO are followed by decreases. The neutral lipids had three main fractions: triglycerides (TG), free fatty acids (FFA) and cholesterol (Chol). FFA was found to be the main fraction of NL after 5 weeks, whereas TG was the main component of NL after 15 and 26 weeks, especially in the animals with degenerated testes. The presence of the large quantities of FFA is discussed. Cholesterol was decreased markedly in the EFA deficient rats fed partially hydrogenated oils, but not in the fat-free reared groups. The variations in the PL distribution during the experiment were small with regard to the two main PL classes, the phosphatidylcholines and the phosphatidylethanolamines. The most remarkable change among the PL classes was an increase in the percentage of sphingomyelins when the spermatogenic degenerations developed.     

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

Studies 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. This article represents part of an extensive experiment carried out by Agriculture Canada to investigate the nutritional value of rapeseed oils (see ref. 15). Contribution No. 497 from the Animal Research Institute.     

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 oftrans 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 notrans 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 value 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. All groups fed HMO had similar contents oftrans fatty acids, mainly 16∶1 and 18∶1, in their phospholipids, irrespective of the dietary 18∶2 levels, and these contents were lower than in the HSOY group. High levels of linoleic acid consistently found in triglycerides of liver, heart and adipose tissue of rats fed HMO indicated that feeding HMO resulted in a reduction of the conversion of linoleic acid into long chain PUFA that could not be overcome by increasing the dietary level of linoleic acid.     

Comparative hypocholesterolemic effects of six dietary oils in cholesterol-fed rats after long-term feeding

Rats (8 wk of age) fed a conventional diet were shifted to diets containing 10% Oenothera biennis Linn oil (OBLO, linoleic acid +γ-linolenic acid) from a wild plant, evening primrose oil (EPO, linoleic acid +γ-linolenic acid) from a cultivated plant, bio-γ-linolenic acid oil from mold (BIO, palmitic acid+oleic acid+linoleic acid+γ-linolenic acid), safflower oil (linoleic acid), palm oil (PLO, palmitic acid+oleic acid+linoleic acid), or soybean oil (linoleic acid+α-linolenic acid) with 0.5% cholesterol for 13 wk. Though there were no significant differences in the food intake among the groups, the body weight gain of the OBLO group was significantly lower than that of other groups except for the BIO and PLO groups, and that of the EPO and SPO groups were the highest among the groups. The liver weight of the OBLO group was significantly lower than that of other groups, and that of the PLO group was the highest among the groups. The serum total cholesterol and very low density lipoprotein (VLDL)+intermediate density lipoprotein (IDL)+low density lipoprotein (LDL) cholesterol concentrations of the OBLO and EPO groups were consistently lower than those in the other groups. However, those of the BIO group were higher than those in the OBLO and EPO groups. The liver cholesterol concentration of the PLO group was the highest among all groups except for the EPO group. The fecal neutral sterol and bile acid extraction of the BIO group tended to increase compared to other groups. The results of this study demonstrate that OBLO and EPO inhibit the increasing of serum total cholesterol and VLDL+IDL+LDL-cholesterol concentrations in the presence of excess cholesterol in the diet compared with the other dietary oils.     

Fatty acid composition of carotenoid esters in soybean and rapeseed oils

The amounts of the different carotenoids (lutein, lutein monoesters and diesters) in soybean and rapeseed oil were determined through a combination of column chromatography and UV spectrometry. The lutein diesters in the oils have been isolated by a combination of column and thin layer chromatography. Identification and determination of the amount of the various fatty acids of the lutein diesters have been carried out by means of gas chromatography after transesterification of the fatty acids to their methyl esters. Comparison of the fatty acids of the lutein diesters with those of the triglycerides of the oils revealed a striking difference. First, the fatty acids of the lutein diesters have shorter chains than the triglycerides acids. Secondly, the lutein fatty acids are more saturated than the fatty acids of the triglycerides of the corresponding oils. However the amount of linoleic acid in the case of the fatty acids of the lutein diesters in rapeseed oil is greater than that in the fatty acids of the triglycerides in rapeseed oil. Deceased, October 26, 1971.     

Effect of evening primrose extracts on oxidative stability of sunflower and rapeseed oils

Antioxidative activities of evening primrose seed meal extracts in sunflower and rapeseed oils were compared with that of commercially used antioxidants, namely butylated hydroxytoluene (BHT), ascorbylpalmitate as well as Grindox‐118. The study was carried out under Schaal oven conditions at 60 °C and the weight gain was followed up by p‐anisidine value measurement following the oxidation. An Oxidograph apparatus monitored the oxidation of oils at 110 °C. Among the examined extracts, the ethyl acetate extract (0.2%), containing only 87 mg/g of total phenolics, exhibited a stronger antioxidant activity than BHT (0.01%) and effectively stabilised both oils. A strong antioxidative effect was also noted for the ethanol‐ethyl acetate extract (168 mg/g of total phenolics). The study showed that addition of ethyl acetate and ethanol‐ethyl acetate extracts could extend the sunflower and rapeseed oils shelf‐life by protecting oils from further decomposition that naturally occurs during thermal treatments.     

Influence of oxygen and copper concentration on lipid oxidation in rapeseed oil

The influence of oxygen concentration and copper on lipid oxidation in rapeseed oil during storage at 40°C was investigated. The oil was stored in air, or with 1.1%, 0.17%, or 0.04% oxygen in the headspace, and 70 or 0.07 ppm copper was added. Volatile oxidation products and oxygen consumption were monitored. Addition of 70 ppm copper to the sample in air resulted in a 70-fold higher hexanal concentration after 35 d of storage, compared to the sample without added copper. The addition of 0.07 ppm copper to the sample stored in air gave a doubled hexanal concentration, compared to the sample without copper, after 35 d of storage. For the samples with 70 ppm copper at 0.17% and 0.04% oxygen, all oxygen was consumed after 7 d of storage. The results show the importance of minimizing the oxygen available for oxidation, especially when pro-oxidants are present. In the sample with 70 ppm added copper, in air, the hexanal increase was 65 times larger than for the same sample in 0.04% oxygen. A comparison of the effect of oxygen or copper on oxidation shows that the addition of 70 ppm copper to the 0.04% oxygen sample gave the same increase in hexanal content as an oxygen increase to 0.17%.     

Metabolism of erucic acid in perfused rat liver: Increased chain shortening after feeding partially hydrogenated marine oil and rapeseed oil

The metabolism of [14-¹⁴C] erucic acid was studied in perfused livers from rats fed on diets containing partially hydrogenated marine oil or rapeseed oil for three days or three weeks. Control rats were given groundnut oil. Chain-shortening of erucic acid, mainly to 18∶1, was found in all dietary groups. In the marine oil and rapeseed oil groups, the percentage of chain-shortened fatty acids in very low density lipoproteins-triacylglycerols (VLDL-TG) exported from the liver increased after prolonged feeding. A similar increase was found in liver TG only with partially hydrogenated marine oil. This oil, rich intrans fatty acids, thus seemed to be more effective in promoting chain-shortening. The fatty acid composition of the secreted and stored TG differed both with respect to total fatty acids and radioactively labeled fatty acids, indicating that at least 2 different pools of TG exist in the liver. The lack of lipidosis in livers from rats fed dietary oils rich in 22∶1 fatty acids is discussed in relation to these findings. In conclusion, a discussion is presented expressing the view that the reversal of the acute lipidosis in the hearts of rats fed rapeseed oil or partially hydrogenated marine oils is, to a large extent, derived from the increased chain-shortening capacity of erucic acid in liver.     

Effects of soy proteins containing trypsin inhibitors in long term feeding studies in rats

Pancreatic hypertrophy that occurs in rats fed raw soy flour containing about 1200 mg tripsin inhibitor (TI)/100 g diet was reversed by switching the rats to control diets or to diets containing 30% toasted defatted soy flour. No pancreatic hypertrophy occurs in rats fed commercial, edible grade soy flours, concentrate or isolate from time of weaning to adulthood (ca. 300 days). TI content of the soy diets ranged from 178–420 mg/100 g. Except for pancreas enlargement in rats fed raw soy flour, gross and microscopic examination of pancreata revealed no abnormalities. The gross appearance of heart, kidney, spleen, and liver was normal. Soy flour, protein concentrate, and protein isolate in a formulated corn-soy diet provided optimum growth and maintained body weight only if supplemented with vitamin B-12 in long term feeding studies with rats. In the absence of such supplementation, rats fed soy diets initially grew at a rate equal to or greater than those fed a comparable corn-casein control diet; but, with continued feeding for ca. 300 days, body weight of rats fed the casein control was significantly greater than that of the soy flour-fed rats. Those fed soy isolate ceased to grow; and rats fed soy concentrate lost weight. No significant differences were found in organ weights between groups fed soy products and casein, except for increased kidney, liver, and testes weights relative to body weight with the group fed soy concentrate. Supplementation of the soy diets with vitamin B₁₂ stimulated growth to the greatest extent, calcium pantothenate or riboflavin had an intermediate effect, other vitamins had little or no effect; whereas a complete mineral mix was detrimental. Supplementation of the soy diets with vitamin B₁₂ stimulated growth to the greatest extent, calcium pantothenate or roboflavin had an intermediate effect, other vitamins had little or no effect; whereas a complete mineral mix was detrimental. Supplementation of the control diet was without effect. The dietary protein level in these diets was 20%, with casein or soy protein representing 75% of total protein. When fed continuously to rats from weaning to adulthood, properly processed soy protein products, when balanced with essential nutrients, can provide growth comparable to corn-casein diets.     

Effect of type of diet and feeding status on modulation of hepatic HMG-CoA reductase in rats

The effect of diet type and feeding status on hepatic HMG-CoA reductase (HMGR) [mevalonate: NADP⁺ oxidoreductase (acylating CoA); EC 1.1.1.34] was studied in rats. Animals fed a ground, commercial, stock diet exhibited higher expressed and total activities of HMGR in the fed state than animals fed a semi-purified diet. The differences did not appear in meal-trained animals when measured before the onset of the meal after a 22-hr fast. When expressed activity was taken as a per cent of total activity, fed animals from both diet groups used about 10% of their available activity. When animals on commercial diets were fasted, 20% of the activity was expressed. Fasted animals on the semi-purified diet also increased the per cent of expressed reductase activity, but this increase was not as great (13.3%). These data suggest that, in the rat, regulation of cholesterol synthesis in response to decreased total HMGR during fasting and increased levels after a meal results from alterations in the percentage of enzyme which is expressed. The semi-purified diet used here resulted in consistently lower levels of HMG-CoA reductase activity than the commercial diet regardless of feeding pattern.     

Nutritive value of marine oils. II. Effects ofin vivo antioxidants in feeding menhaden oil to swine

Five pair-groups of swine were fed diets composed of crude feed materials to which 10% of clay-bleached, light cold-pressed menhaden oil was added. The oil was allowed to oxidize under controlled conditions and aliquots of fresh and oxidized oil were removed at peroxide values (PV) of 2.6, 15.5, and 61—each of which was fed to one group of animals. Two additional animal groups received diets containing the highly oxidized oil (PV=61) plus either alpha-tocopherol acetate or ethoxyquin. All oils were stored frozen and were mixed with the diets daily. Lard was fed at a similar 10% level to a control group of pigs. Both feed intakes and weight gains were progressively reduced as the diet oil was more highly oxidized. As oxidation of the oil increased, intensity of “yellow fat” increased and hemoglobin and hematocrit levels were progressively decreased. Both alpha-tocopherol acetate and ethoxyquin actedin vivo to improve feed intake, rate of gain, and blood condition, and eliminated the incidence of steatitis. Paper I in this series appeared in the Journal of Nutrition79, 323–332 (1963). Carried out under Contract No. 14-17-0001-352, U.S.D.I. Bureau of Commercial Fisheries. Technical Paper 1615, Oregon Agricultural Experiment Station.     

Long-term feeding of dietary oils alters lipid metabolism, lipid peroxidation, and antioxidant enzyme activities in a teleost (Anabas testudineus bloch)

Anabas testudineus (climbing perch), average body weight 21±1 g, were maintained in culture tanks and fed a 35% protein feed plus an additional supplementation of three dietary oils (20% each of coconut oil, palm oil, or cod liver oil). Body weight gain was similar among all groups. However, several hepatic lipogenic enzymes such as malic enzyme (ME), NADP-isocitrate dehydrogenase (ICDH), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and β-hydroxy-β-methyl glutaryl CoA reductase (HMG CoA reductase) were assayed, and they responded differently. Hepatic ME and G6PDH activities showed a significant decrease in the coconut oil and palm oil groups, but there was no significant change in ICDH activity. The 6PGDH activities were reduced, whereas HMG CoA reductase activity was increased in the palm oil-treated group. Cholesterol synthesis in the liver and muscle increased in the palm oil-treated group, but liver phospholipids did not show any significant change in fish supplemented with oils rich in saturated fatty acids. Triacyl-glycerol and free fatty acid concentrations were high in the coconut oil- and palm oil-supplemented groups. Lipid peroxidation products such as thiobarbituric acid-reactive substances and conjugated dienes decreased in the same two groups. Antioxidant potential was high in all groups as evidenced by increased activity of superoxide dismutase, glutathione peroxidase, and glutathione content. The results of this study indicate that in fish, dietary lipids depress hepatic lipogenic activity as well as lipid peroxidation products by maintaining high levels of antioxidant enzymes.     

Economic status of the fats and oils industry

Summary In summary, production of fats from domestie materials has increased over 40% since prewar. The world shortage of edible fats of early postwar years has been overcome through increased production, and, with petroleum derivatives replacing fats in some industrial uses, the United States has a surplus of fats over domestic needs. Inventories have increased. The government, through price programs, has acquired substantial stocks of cottonseed oil, linseed oil, and butter. Recent trends offer little promise of change in the high-inventory position unless extraordinary measures are taken. Lard output, now relatively low, will rise again, beginning next fall. And the effect of 1954 cotton acreage restrictions on oil production will be more than offset by increased soybean and flaxseed plantings. Although exports of low-priced tallow and greases have been gaining, exports of edible oils have deelined. Domestic disappearance of fats in food uses is rising in line with population growth, but industrial use is falling particularly in the manufacture of soap. With an abundant supply of certain inedible fats available, there is opportunity and need for chemical discovery to support now uses based on quality products and for expansion of outlets in markets here-tofre little used.     

Glycerolysis of marine oils and the preparation of acetylated monoglycerides

Conclusions The glycerolysis reaction was applied to menhaden, tuna, herring, sardine, and salmon-egg oils. Optimum reaction time for the preparation of α-monoglycerides was found to vary, reproducibly, from 45 to 60 min., depending on the particular kind of marine oil employed. The method was suitable for the preparation of kilogram quantities. A laboratory method for the prepagation of kilogram quantities of highly pure acetylated α-mono-glycerides was developed. Both the glycerolysis mixtures from marine oils and their acetylated products were light in color and substantially free of odor. Thin-layer silicic acid chromatography, as described here, was found suitable for the analysis of acetoglycerides from marine oils. The work indicated that the method may have wide use for the separation and identification of other lipid classes as well. This is Contribution No. 497 from the technological laboratories of the Bureau of Commercial Fisheries, Fish and Wildlife Service, U. S. Department of the Interior. This is a laboratory of the Division of Industrial Research and Services, Bureau of Commercial Fisheries, U. S. Fish and Wildlife Service, Department of the Interior.     

Analysis of arsenic and bromine in marine and terrestrial oils

Samples of marine and terrestrial oils of both plant and animal origin have been analyzed for arsenic and bromine content. Two oil samples (cod liver oil and oil extracted from mackerel fillets) were fractionated on silica gel columns and bromine was determined in the different fractions. The results obtained indicate that lipid soluble bromine and arseno organic compounds are characteristic components of marine animal and marine plant oils (seaweed). The results also show that the bromine is not localized in any particular compound or type of compounds. The bromine-containing compounds seem to be relatively stable, but the arseno-containing compounds are not. When oils containing arsenic and bromine were saponified, some of the arsenic and bromine compounds were found in the fatty acid fraction while others appeared in the water soluble fraction.     

The effects of original and randomized rapeseed oils containing high or very low levels of erucic acid on cardiac lipids and myocardial lesions in rats

The nutritional status of the very lowerucate rapeseed oil,Brassica napus var. ‘Tower,’ was compared with that of the high-erucate oil,Brassica napus var. ‘Target’, as well as with corn oil. The effect of randomization on the nutritional qualities of rapeseed oil was investigated as well. The feeding of diets containing the original and randomized ‘Tower” oil or the original ‘Target’ oil, at the 20% level by weight, gave growth rates which were not significantly different from that for corn oil. However, the randomized ‘Target’ oil gave growth rates which were significantly less than all other groups. The growth results could not be explained simply on the basis of food consumption. The level of triglycerides in the hearts of rats fed the very low-erucate oils was not significantly different from the corn oil group. Triglyceride concentrations in the hearts of animals given the high-erucate oils were 7–12 times greater than all other groups. The level of total fatty acids in tissue phospholipids was the same regardless of dietary treatment. Fatty acid compositions of the tissue lipids were the same in animals fed either the original or randomized rapeseed oils. A much higher incidence of focal myocardial necrosis was found in animals receiving high-erucate rapeseed oil relative to animals given the corn oil. The incidence in rats fed diets containing very low-erucate rapeseed oil was intermediate between these latter two extremes.