Rats Fed Soybean Oil Research Articles

Dietary Fat Influences the Expression of Contractile and Metabolic Genes in Rat Skeletal Muscle

Dietary fat plays a major role in obesity, lipid metabolism, and cardiovascular diseases. To determine whether the intake of different types of dietary fats affect the muscle fiber types that govern the metabolic and contractile properties of the skeletal muscle, we fed male Wistar rats with a 15% fat diet derived from different fat sources. Diets composed of soybean oil (n-6 polyunsaturated fatty acids (PUFA)-rich), fish oil (n-3 PUFA-rich), or lard (low in PUFAs) were administered to the rats for 4 weeks. Myosin heavy chain (MyHC) isoforms were used as biomarkers to delineate the skeletal muscle fiber types. Compared with soybean oil intake, fish oil intake showed significantly lower levels of the fast-type MyHC2B and higher levels of the intermediate-type MyHC2X composition in the extensor digitorum longus (EDL) muscle, which is a fast-type dominant muscle. Concomitantly, MyHC2X mRNA levels in fish oil-fed rats were significantly higher than those observed in the soybean oil-fed rats. The MyHC isoform composition in the lard-fed rats was an intermediate between that of the fish oil and soybean oil-fed rats. Mitochondrial uncoupling protein 3, pyruvate dehydrogenase kinase 4, and porin mRNA showed significantly upregulated levels in the EDL of fish oil-fed rats compared to those observed in soybean oil-fed and lard-fed rats, implying an activation of oxidative metabolism. In contrast, no changes in the composition of MyHC isoforms was observed in the soleus muscle, which is a slow-type dominant muscle. Fatty acid composition in the serum and the muscle was significantly influenced by the type of dietary fat consumed. In conclusion, dietary fat affects the expression of genes related to the contractile and metabolic properties in the fast-type dominant skeletal muscle, where the activation of oxidative metabolism is more pronounced after fish oil intake than that after soybean oil intake.

Differential effects of dietary canola and soybean oil intake on oxidative stress in stroke-prone spontaneously hypertensive rats

BackgroundCanola oil shortens the life span of stroke-prone spontaneously hypertensive (SHRSP) rats compared with rats fed soybean oil when given as the sole dietary lipid source. One possible mechanism leading to the damage and deterioration of organs due to canola oil ingestion is oxidative stress. This study investigated the effect of canola oil intake on oxidative stress in this animal model.MethodMale SHRSP rats, were fed a defatted control diet containing 10% wt/wt soybean oil or a defatted treatment diet containing 10% wt/wt canola oil, and given water containing 1% NaCl. Blood pressure was measured weekly. Blood was collected prior to beginning the diets and at the end of completion of the study for analysis of red blood cell (RBC) antioxidant enzymes, RBC and plasma malondialdehyde (MDA), plasma 8-isoprostane and plasma lipids.ResultsCanola oil ingestion significantly decreased the life span of SHRSP rats compared with soybean oil, 85.8 ± 1.1 and 98.3 ± 3.4 days, respectively. Systolic blood pressure increased over time with a significant difference between the diets at the 6th week of feeding. Canola oil ingestion significantly reduced RBC superoxide dismutase, glutathione peroxidase and catalase activities, total cholesterol and low-density lipoprotein cholesterol compared with soybean oil. There were no significant differences in RBC MDA concentration between canola oil fed and soybean oil fed rats. In contrast, plasma MDA and 8-isoprostane concentration was significantly lower in the canola oil group compared to the soybean oil group.ConclusionIn conclusion, canola oil ingestion shortens the life span of SHRSP rats and leads to changes in oxidative status, despite an improvement in the plasma lipids.

Dietary Effect of Capric Acid Containing Soyphospholipids

A comparative evaluation of the dietary effect between capric acid (C10:0)-containing soyphospholipids and soyphospholipids without capric acid on the lipid profile of serum of rats when ingested at 5% or 10% level by weight in soybean oil was made. Rats were taken in five groups. One group was fed 20% soybean oil. Two groups received soybean oil containing 5% and 10% soyphospholipids by weight, respectively. Other two groups were fed soybean oil containing 5% and 10% capric acid containing soyphospholipids by weight, respectively. The other dietary components remained same for all the groups. The feeding was done for 4 weeks. At the end of feeding period there was no althrough significant change in weight gain, food intake and food efficiency ratio (FER). No significant change was observed in serum lipid profiles between the rats fed soybean oil and soybean oil with 5% or 10% soyphospholipids. There was significant decrease in serum total cholesterol (TC) and high density lipoprotein (HDL)-cholesterol level in the rats fed soybean oil blended with capric acid containing soyphospholipids at 5% level. The level of TC, triglyceride (TG), very low density lipoprotein (VLDL)-cholesterol decreased significantly when the rats were fed capric acid containing soyphospholipids at 10% level. There is overall significant change in TC, TG, VLDL- and LDL-cholesterol. The possible mechanism behind the reduction of serum lipid profile may be the reduction of interfacial tension of phospholipids could affect serum lipid profiles due to enhanced or much greater extent of emulsification of the both polar and nonpolar lipid components and their transfer from the intestine to the bile pathway.

Dietary Effect of Eicosapentaenoic Acid (EPA) Containing Soyphospholipid

In this study, we evaluated on a comparative basis the dietary effect between eicosapentaenoic acid (C20:5, EPA)- containing soyphospholipid and soyphospholipid without EPA when added at 5% or 10% level by weight in soybean oil as the dietary oil on the proportions of lipid components in serum of rats. Rats were taken in five groups. One group was fed 20% soybean oil. Two groups received soybean oil containing 5% and 10% soyphospholipid by weight, respectively. Two other groups were fed soybean oil containing 5% and 10% EPA- containing soyphospholipid by weight, respectively. The other dietary components remained same for all the groups. The feeding experiment was conducted for 4 weeks. After the feeding period there was no significant change in weight gain, food intake and food efficiency ratio (FER). No significant change was observed in serum lipid profiles between the rats fed soybean oil and soybean oil with 5% or 10% soyphospholipid. There was significant decrease in serum triglyceride (TG) level in the rats fed soybean oil blended with EPA containing soyphospholipid at 5% level. The contents of total cholesterol (TC), TG, very low density lipoprotein (VLDL)-cholesterol and low density lipoprotein (LDL)-cholesterol decreased significantly while high density lipoprotein (HDL)-cholesterol increased compared to the soyphospholipid group at 10% level.

Body weight, body composition, and energy metabolism in lean and obese Zucker rats fed soybean oil or butter

Dietary fat composition is thought to affect body weight regulation independent of the amount of fat ingested. We analyzed the feeding behavior, body weight gain, body composition, and energy metabolism in lean and obese rats fed a diet in which fat was in the form of either butter or soybean oil. Ten lean (Fa/?) and 10 obese (fa/fa) adult Zucker rats were divided into 4 groups according to a 2 x 2 experimental design. They were fed a normally balanced diet over 11 wk in which 30% of energy was either soybean oil or butter. Food intake, body weight gain, and body composition were measured. Indirect calorimetry was used to study energy metabolism at rest and in relation to feeding and activity. Food intake increased similarly in lean and obese rats after butter feeding. Body weight gain increased in obese rats and decreased in lean rats after butter feeding. Body weight gain in obese rats was due mainly to an increase in the weight of lean tissues besides muscle, whereas adiposity and distribution of fat between the various pads did not change. Resting metabolic rates and postprandial lipid oxidation increased in butter-fed obese rats. Lipid oxidation during exercise was not significantly different between obese and lean rats. Fat oxidation increased in butter-fed lean rats during treadmill running at moderate intensity. In obese rats, basal metabolism and postprandial lipid oxidation increased during butter feeding, which appeared to prevent fat accumulation in the long term. In lean rats, butter feeding favored lipid utilization by working muscles, an observation that deserves further investigation in terms of endurance and performance.

Marine and Freshwater Fish Oil Varying in Arachidonic, Eicosapentaenoic and Docosahexaenoic Acids Differ in their Effects on Organ Lipids and Fatty Acids in Growing Rats

Arachidonic acid [20:4(n-6)] and docosahexaenoic acid [22:6(n-3)] are important to normal neurodevelopment and visual function. Infants fed formula often have low blood lipid 20:4(n-6) and 22:6(n-3). Consumption of fish oils high in eicosapentaenoic acid [20:5(n-3)] and 22:6(n-3) with no 20:4(n-6) increases tissue 20:5(n-3) and 22:6(n-3) but decreases 20:4(n-6). Some freshwater fish oils contain higher 20:4(n-6) and lower 20:5(n-3) than usual marine fish oils, but their effects on tissue fatty acids are not well known. Therefore, the effects of feeding weaning rats 30 d with 12% (wt/wt) soybean oil [0.0% 20:4(n-6), 20:5(n-3) and 22:6(n-3)], 2% safflower oil with 10% marine fish oil [0.9% 20:4(n-6), 15.1% 20:5(n-3), 7.3% 22:6(n-3)] or 10% freshwater fish oil [3.3% 20:4(n-6), 5.9% 20:5(n-3), 8.0% 22:6(n-3)] on plasma, tissue and brain fatty acids was determined. Levels (g/100 g) of 20:4(n-6) were significantly higher and 20:5(n-3) lower in plasma, liver, kidney and brain of rats fed freshwater fish oil rather than marine fish oil. Marine fish oil, but not freshwater fish oil resulted in a higher brain 20:5(n-3) and 22:6(n-3), and lower 20:4(n-6) than soybean oil. Plasma and liver triglyceride concentrations were significantly lower in rats fed marine fish oil, but not in rats fed soybean oil when compared with those fed freshwater fish oil. The results indicate dietary 20:4(n-6) prevents the decline in plasma and tissue 20:4(n-6) caused by dietary 20:5(n-3) and/or 22:6(n-3). Oils with 20:4(n-6) may affect cholesterol and triglyceride metabolism differently than usual fish oils.

Effects of Dietary Safflower Oil or Soybean Oil on the Milk Composition of the Maternal Rat, and Tissue Fatty Acid Composition and Learning Ability of Postnatal Rats.

This study was done to identify the effects of dietary safflower oil or soybean oil on the milk composition of maternal rats and the tissue fatty acid composition in postnatal rats. Different types of dietary fats affected the fatty acid pattern in the dam's milk. They affected tissue weight, lipid content, and phospholipid fatty acid compositions in the liver and brain of young rats, showing a large amount of docosahexaenoic acid in soybean oil-fed rats, and a large amount of docosapentaenoic acid in safflower oil-fed rats. The learning ability of the soybean oil-fed rats, evaluated by a swimming test, was significantly superior to that of the safflower oil-fed rats. The presence of large amounts of docosahexaenoic acid in the tissue phospholipid of soybean oil-fed neonatal rats without an alteration of their arachidonic acid levels may contribute to the enhancement of learning ability in rats.

Lipid peroxidation in liver microsomes of rats fed soybean, olive, and coconut oil

The effect of varying unsaturation degree of dietary lipid on the oxidative response of rat liver microsomes was studied. Three groups of growing male rats were maintained for 6 weeks on 15% fat diets containing either soybean oil, olive oil, or coconut oil, with the same level of vitamin E. After 6 weeks, microsomal malondialdehyde, vitamin E, and fatty acid composition were measured in liver microsomes. The relative abundance of saturated and unsaturated fatty acids in the microsomes reflected the composition of the dietary lipid. When dietary requirement for vitamin E was satisfied, the increased polyunsaturated fatty acid intake from vegetable oils did not enhance lipid peroxidation in physiological conditions, as demonstrated by similar malondialdehyde concentrations found in the three groups. However, the somewhat lower vitamin E content measured in soybean oil-fed rats confirms an enhanced requirement for dietary antioxidant caused by the increased intake of polyunsaturated fatty acids. The susceptibility of liver microsomes to lipid peroxidation stimulated by the ADP/iron/ascorbate system was also studied. Membranes of soybean oil-fed rats exhibited the highest peroxidation rate, as shown by oxygen consumption and malondialdehyde and 4-hydroxy-2,3-trans-neonenal production, because of the lower concentration of vitamin E and of the higher content of polyunsaturated fatty acids. Microsomes of olive oil- and coconut oil-fed rats showed highest protection against lipid peroxidation.

Changes in Serum and Lipoprotein Fatty Acids of Growing Rats Fed Protein-Deficient Diets with Low or Adequate Linolenic Acid Concentrations

The effects of a protein-deficient diet associated with sunflower oil [adequate in 18:2(n-6), poor in 18:3(n-3)] or soybean oil [adequate in both 18:2(n-6) and 18:3(n-3)] on lipid serum and lipoprotein compositions were studied in growing rats. Four groups of rats were fed different diets: SFC (20% casein + 5% sunflower oil); SFd (2% casein + 5% sunflower oil); SC (20% casein + 5% soybean oil); Sd (2% casein + 5% soybean oil). After 28 d, both protein-deficient groups exhibited low concentrations of protein, phospholipid, triacylglycerol and total cholesterol in serum and VLDL. Compared with rats fed 20% casein diets, those fed low protein diets had lower 18:2(n-6) and 20:4(n-6) in phospholipids of serum, VLDL and HDL2–3, and the 20:4(n-6)/18:2(n-6) ratio was twofold higher in triacylglycerols of serum and VLDL. In the SFd-fed group, 22:5(n-6) was higher than in the SFC-fed group for both triacylglycerols and phospholipids in overall lipoprotein fractions studied. In addition, the 20:3(n-9)/20:4(n-6) ratio was 0.1 in HDL2–3 phospholipids of the SFd-fed group. Sunflower oil-fed rats compared with soybean oil-fed rats had greater monounsaturated fatty acids and lower total (n-3) fatty acids in both triacylglycerols and phospholipids of serum, VLDL and HDL2–3, as well as lower total (n-6) fatty acids in serum and VLDL triacylglycerols. Apolipoproteins (apo) of VLDL were drastically depressed in rats fed protein-deficient diets, whereas apo-AI of HDL2–3 showed a particular resistance. Likewise, sunflower oil-fed rats had enhanced apo-B48 of VLDL and apo-C, apo-AII and apo-AIV of HDL2–3. The present findings show that some effects of protein malnutrition were enhanced by α-linolenic acid deficiency, in particular reduced (n-6) and (n-3) fatty acid bioavailability.

Effect of low intake of n−3 fatty acids during development on brain phospholipid fatty acid composition and exploratory behavior in rats

The effect of dietary restriction of n-3 fatty acids during development on brain phospholipid fatty acid composition and exploratory behavior has been studied in male Sprague Dawley rats. Female rats were fed semipurified diets containing either 5.5% safflower oil or 6% soybean oil for 6 wk prior to mating and throughout gestation and lactation. Control rats were maintained on laboratory chow. The male pups were weaned to the diets of the dams except for one group which was switched from safflower to soybean oil at weaning. Behavioral studies and brain phospholipid analyses were conducted at 16-18 wk of age. Rats fed safflower oil showed significantly lower levels of 22:6n-3 in phospholipids of synaptic membranes and myelin than rats fed soybean oil or chow. The decrease in 22:6n-3 was compensated for by an increase in 22:5n-6, the total content of polyunsaturated fatty acids remaining approximately constant. The brain phospholipid fatty acid composition of rats switched from safflower to soybean oil at weaning was similar to that of rats fed soybean oil throughout the experiment. There was no difference in spontaneous locomotor activity among the different dietary groups. However, rats raised on safflower oil displayed a significantly lower exploratory activity (horizontal movements and rearings) in a novel environment than rats fed soybean oil or chow. In contrast to the brain phospholipid fatty acid composition, there was no recovery of exploratory behavior in rats raised on safflower oil and switched to soybean oil at weaning suggesting a specific requirement of n-3 fatty acids during development.

Effect of dietary palm oil and its fractions on rat plasma and high density lipoprotein lipids

Male Sprague Dawley rats were fed semipurified diets containing 20% fat for 15 weeks. The dietary fats were corn oil, soybean oil, palm oil, palm olein and palm stearin. No differences in the body and organ weights of rats fed the various diets were evident. Plasma cholesterol levels of rats fed soybean oil were significantly lower than those of rats fed corn oil, palm oil, palm olein or palm stearin. Significant differences between the plasma cholesterol content of rats fed corn oil and rats fed the three palm oils were not evident. HDL cholesterol was raised in rats fed the three palm oil diets compared to the rats fed either corn oil or soybean oil. The cholesterol-phospholipid molar ratio of rat platelets was not influenced by the dietary fat type. The formation of 6-keto-PGF1 alpha was significantly enhanced in palm oil-fed rats compared to all other dietary treatments. Fatty acid compositional changes in the plasma cholesterol esters and plasma triglycerides were diet regulated with significant differences between rats fed the polyunsaturated corn and soybean oil compared to the three palm oils.

Effects of Dietary Fatty Acid Composition on Macronutrient Selection and Synaptosomal Fatty Acid Composition in Rats

Our previous work showed that rats consuming 20% (wt/wt) lard diets selected more protein and less carbohydrate than did rats fed 20% (wt/wt) soybean oil diets. To determine if this effect is specific to saturated fat source and to measure changes in fatty acid composition of synaptosomal phospholipids, male Wistar rats were fed a 20% (wt/wt) soybean oil or tallow diet with 24% protein and 48% carbohydrate for 2 wk. Rats then self-selected from two diets with the same fat previously fed but different protein and carbohydrate composition (5% protein, 67% carbohydrate and 55% protein, 17% carbohydrate). Tallow-fed rats selected more protein and less carbohydrate than did soybean oil-fed rats. Dietary fat also affected fatty acid composition of synaptosomal phospholipids, phosphatidylcholine being most affected and phosphatidylinositol most resistant. Later studies determined if selection differences were due to taste. When rats self-selected without prior exposure to diets, tallow-fed rats selected more protein and less carbohydrate than did soybean oil-fed rats during the last 2 wk but not the first 2 wk. When rats selected from diets with identical protein and carbohydrate composition but different dietary fat, rats consumed slightly greater amounts of the tallow diet at each protein level. The relative intake of tallow and soybean oil diets, however, did not vary significantly with dietary protein treatment. These results confirm that rats fed saturated fat diets select more protein and less carbohydrate than do rats fed polyunsaturated fat diets and suggest this difference is not due to taste factors.

Brain Cell and Tissue Recovery in Rats Made Deficient in n-3 Fatty Acids by Alteration of Dietary Fat

Rats were fed a purified diet containing either 1.5% sunflower oil [940 mg linoleic acid [18:2(n-6)]/100 g diet; 6 mg alpha-linolenic acid [18:3(n-3)]/300 g diet] or 1.9% soybean oil [940 mg 18:2(n-6)/100 g diet; 130 mg 18:3(n-3)/100 g diet]. In all cases and tissues examined 22:6(n-3) was lower and 22:5(n-6) was higher in rats fed sunflower oil than in rats fed soybean oil. Levels of 22:4(n-6) and 20:4(n-6) were largely unaffected. Expressed as a percentage of that in soybean oil-fed rats, 22:6(n-3) in sunflower oil-fed rats was as follows: neurons, 49; astrocytes, 47; oligodendrocytes, 10; lung, 27; testes, 32; retina, 36; liver, 35 and kidneys, 45. Ten wk after the change in diet of 60-d-old rats from one containing sunflower oil to one containing soybean oil, the fatty acid composition of the brain cells had not reached control values, e.g., that obtained in animals continuously fed soybean oil; 22:6(n-3) was 77, 65 and 80% of control levels for astrocytes, oligodendrocytes and neurons, respectively. In contrast, the recovery measured by the decay of 22:5(n-6) was complete within 10 wk. For 22:6(n-3), it took approximately 2 wk for liver and kidney to recover to the control value, 3 wk for lung, 6 wk for retina and 10 wk for testes. The decrease of 22:5(n-6) was rapid: the control values were reached within 2 wk for kidney, liver and lung and within 6 wk for retina.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary fat on pain threshold, thermoregulation and motor activity in rats.

Groups of young male Sprague-Dawley (albino) or Long-Evans (hooded) rats were fed the same semi-purified diets containing 20% (w/w) fat in the form of soybean oil vs. lard, or a reference diet of standard Purina Chow (4.5% mixed fats) for 21 days. Behavioral testing after this time revealed that albino rats fed the diet containing soybean oil had increased paw-lick latencies on a 58 degrees C hot plate compared to chow-fed rats. In addition, both strains fed the diet containing soybean oil were protected from hypothermia induced by placing animals in a 4 degrees C cold room for 60 min following systemic injection of 10-15 mg/kg d-amphetamine. Rats of both strains fed the lard diet displayed paw-lick latencies similar to those shown by rats fed chow and hypothermic changes intermediary to those shown by rats fed soybean oil vs. chow diets. Horizontal crossings as well as rearings in a 15 min test of open field activity were the same for all diet groups within strains. No substantial differences were observed in the number of calories consumed, amount of body weight gained or basal colonic temperatures across diet conditions. The results suggest that a soybean oil-based diet can alter physiological mechanisms which mediate these indices of pain perception and thermoregulation. More generally, they indicate that qualitative changes in dietary fat content may be capable of altering certain behavioral states.

Catabolism of Newly Formed Triglyceride-Rich Lipoproteins and Serum High Density Lipoproteins in Rats Fed Soybean Phospholipid and Soybean Oil

Previous research has shown that serum cholesterol and apolipoprotein (apo) A-I were lower and serum apoB was higher in rats fed soybean phospholipid (PL) than in rats fed soybean oil. Secretion of cholesterol and apoA-I, but not apoB, from the liver and intestine was lower in rats fed soybean PL. In the present study catabolism of newly formed triglyceride (TG)-rich lipoproteins, from the liver and intestine, and of serum high density lipoproteins (HDL) were compared in rats fed soybean PL and in rats fed soybean oil. The following results were seen: Feeding of soybean PL was related to more TG and less cholesterol in intestinal lymph chylomicrons (CM) and hepatic very low density lipoproteins (VLDL) than was feeding of soybean oil. A lesser amount of the TG, labeled with [3H]oleate in CM and hepatic VLDL, was incorporated into the adipose tissue and muscle in vivo. The clearance of CM-TG from plasma was higher, but that of VLDL-TG and apoB labeled with [3H]lysine was lower. The catabolism of 125I-labeled HDL from the plasma was lower while hepatic uptake of 125I-labeled HDL, in vivo and in vitro, was higher. These results indicate that soybean PL modifies the catabolism of the respective serum lipoproteins. Therefore, we suggest that changes in both the catabolism and secretion of lipoproteins are responsible for the altered serum lipid and apolipoprotein patterns found in rats fed soybean PL.

The Contrasting Effect of Dietary Phosphatidylethanolamine and Phosphatidylcholine on Serum Lipoproteins and Liver Lipids in Rats

The effect of dietary phosphatidylethanolamine (PE) and phosphatidylcholine (PC) added to cholesterol-free semipurified diet on serum lipoprotein and hepatic and fecal lipids was compared to the effect on rats fed soybean oil (controls). The dietary PE, but not PC, caused a decrease in serum cholesterol, phospholipid, apolipoprotein A-I (apoA-I) and apoE and an increase in high molecular weight apoB. The simultaneous addition of PC and ethanolamine also decreased serum apoA-I and cholesterol. The distribution patterns of phospholipid subclasses in the liver and fatty acid composition of hepatic and plasma phospholipids were also altered by dietary PE. Both PE and PC increased to a similar extent the excretion of fecal neutral steroids and hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity compared to the controls. The present study, therefore, demonstrated for the first time that the PE in the soybean phospholipid preparation is responsible for the alterations of profiles of serum lipids and apoproteins in rats.

Effect of dietary supplementation with stearic acid on the severity of myocardial lesions

Histological studies were conducted on ventricular myocardium obtained from male rats of the Sprague-Dawley strain after 16 weeks of feeding diets containing 20 per cent (w/w) soybean oil, low erucic acid rapeseed oil or high erucic acid rapeseed oil. Additional groups of rats were fed similar diets supplemented with up to 8 g/kg of tristearin. Increasing dietary intake of stearic acid normalised the plasma ratio of C16:0 to C18:0 for rapeseed oil treatments to ratios analogous to that observed for rats fed soybean oil. Tristearin supplementation did not have a significant effect on myocardial lesion incidence but decreased the severity of lesions observed for rapeseed oil treatments.

Accumulation and depletion of trans octadecenoic acid in rat peripheral nerve phospholipid

The accumulation and depletion of trans 18:1 acids in the sciatic nerve phospholipids was studied in rats fed a diet containing 18% partially hydrogenated soybean oil of which 45% was trans 18:1. The nerve phospholipid of rats fed partially hydrogenated soybean oil beginning at weaning age reached a maximum incorporation of trans 18:1 of 0.8% in 4 weeks; whereas the nerve phospholipid of 18-day-old pre-weanling pups of mothers fed the partially hydrogenated soybean oil diet since their weaning contained 3.3% trans 18: l. The trans content decreased rapidly after the weaning of these second-generation rats to a steady-state level 50% higher than the maximum level reached in the first generation. Upon removal of partially hydrogenated soybean oil from the diet, the trans 18:1 of nerve phospholipid decreased much more slowly than from liver or heart phospholipid. Essential fatty acid deficiency had no influence on incorporation or removal of trans 18:1 in nerve phospholipid. The accumulation and depletion of frans 18:1 in nerve phospholipid of second-generation partially hydrogenated soybean oil-fed rats parallelled the changes of polyunsaturated fatty acids and was quite different from the changes observed in 18:0 and cis 18:1. Polyunsaturated fatty acids increased in nerve phospholipid from second but not first-generation rats fed partially hydrogenated soybean oil and declined rapidly when partially hydrogenated soybean oil was removed from the diet.

Nutrition-physiological properties of frying fats. 8. Hematological and blood-chemical studies

The hematological and chemical examination of the 3rd generation of rats fed soy bean oil used for fish frying showed not any abnormal data.

Origin of the high saturated fatty acid content of rat fecal lipids.

AbstractThe biohydrogenation of unsaturated fatty acids and the preferential absorption of unsaturated fatty acids over long chain saturated fatty acids from the gut have been investigated to find the origin of the high saturated fatty acid content of the facal lipids of rats fed soybean oil. Label from dietary (1‐14C)‐linoleic acid was recovered in the saturated and monounsaturated fatty acids of the fecal lipid. However, when (9,10‐3H)‐stearic acid and (1‐14C)‐linoleic acid were fed together, the isotope ratio (3H/14C) of the fecal lipid was 1.9 times that of the diet. It is concluded that both processes occur.