Maternal dietary n-3 fatty acids alter cardiac ventricle fatty acid composition, prostaglandin and thromboxane production in growing chicks

The effects of feeding n-6 and n-3 fatty acids to broiler hens on cardiac ventricle fatty acid composition, and prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) production of hatched chicks were investigated. Fertile eggs obtained from hens fed diets supplemented with 3.5% sunflower oil (Low n-3), 1.75% sunflower+1.75% fish oil (Medium n-3), or 3.5% fish oil (High n-3) were incubated. The hatched chicks were fed a diet containing 18:3 n-3, but devoid of longer chain n-6 and n-3 fatty acids for 42 days. Arachidonic acid content was lower in the cardiac ventricle of High n-3 and Medium n-3 compared to Low n-3 birds for up to 2 weeks (P<0.002). Long chain n-3 fatty acids were higher in the cardiac ventricle of chicks from hens fed High and Medium n-3 diets when compared to chicks from hens fed the Low n-3 diet. Differences in long chain n-3 fatty acids persisted up to four weeks of age (P<0.001). Peripheral blood mononuclear cells (PBMNC) of 7-day-old High n-3 broilers produced significantly lower PGE2 and TXA2 than PBMNC from Low n-3 and Medium n-3 birds. These results indicate that maternal dietary n-3 fatty acids increases cardiac ventricle n-3 fatty acids while reducing arachidonic acid and ex vivo PGE2 and TXA2 production during growth in broiler chickens.     

Reversibility of the effects of dietary fish oil on the fatty acid composition of the brain and retina of growing chicks.

Dietary fish oil increases levels of (n-3) fatty acids in the brain and retina of younger animals but has less effect in adults. The duration of the effects of fish oil in young animals, as well as the extent of reversibility of the effects, are unknown. Laying hens were fed either a fish oil diet or a soybean oil-based control diet. Resulting chicks were assigned to three diet groups: chicks from fish oil and soybean oil hens were continued on fish oil and soybean oil diets, respectively, for 0, 3, 6, or 9 weeks, and additional chicks from the fish oil hens were fed the fish oil diet for 0, 3, or 6 weeks and then reversed to the soybean oil diet for a period of 3 weeks. The fatty acid composition of the brain, retina, liver, and serum of the reversal chicks was compared with chicks fed the fish oil diet only or the soybean oil diet only. Brain levels of docosahexaenoic acid (22:6(n-3)) decreased substantially when reversal from the fish oil diet to the control diet was begun at hatching, but did not decrease when reversal was begun at later times. Other (n-3) fatty acids in the brain, docosapentaenoic acid (22:5(n-3)) and eicosapentaenoic acid (20:5(n-3)), decreased substantially at all ages, and to a greater extent than 22:6(n-3). Brain arachidonic acid (20:4(n-6)), which was low in fish oil chicks, rose to control after reversal at hatching, but recovered only partially when reversal was begun at later times. A similar patterns was observed in the retina. Serum and liver (n-3) fatty acids fell to control in all reversal chicks, and (n-6) fatty acids increased to control, except in chicks reversed at 6 weeks. This study demonstrates that by 3 weeks of age the chick brain strongly resists diet-induced lowering of high levels of 22:6(n-3).     

Alteration of rat adipose tissue lipolytic response to norepinephrine by dietary fatty acid manipulation.

The present study clearly shows that, by feeding rats a semi-synthetic diet of known composition enriched with saturated fatty acids, the epididymal fat pad responsiveness to norepinephrine $\text{in}\text{vitro}$ can be abolished relative to fat pads from animals fed a similar diet but enriched with polyunsaturated fatty acids. Addition of varying concentrations of norepinephrine to the incubation medium produced a clear dose-response relationship in fat pads from animals fed diet enriched with polyunsaturated fatty acids while no effect of norepinephrine was apparent at any dose level in fat tissue from animals fed saturated fatty acids. These changes in lipolytic responsiveness were concurrent with alterations in fatty acid compositions of adipose tissue phospholipids and triglycerides as well as in total tissue contents of phospholipids and cholesterol.     

Role of mevalonate-5-pyrophosphate decarboxylase in the regulation of chick intestinal cholesterogenesis

The response to different dietary conditions of the enzymes responsible for the transformation of mevalonic acid to isopentenyl pyrophosphate has been studied for the first time in the small bowel of the chick to elucidate the role of these enzymes in the regulation of intestinal cholesterogenesis. Feeding a 2% cholesterol diet from hatching resulted in a small but significant inhibition of mevalonate-5-pyrophosphate decarboxylase, while mevalonate kinase and mevalonate-5-phosphate kinase remained unaltered. Similar results were obtained for the three enzymes when 13-day-old chicks fed a standard fat-free diet were switched to a 5% cholesterol diet. Starved chicks exhibited lower intestinal decarboxylase activity than chicks fed a standard diet, while refeeding resulted in levels of activity similar or slightly greater than controls. None of the enzymes effecting the conversion of mevalonate to isopentenyl pyrophosphate in the small intestine presented diurnal variations. Results obtained suggest that mevalonate-5-pyrophosphate decarboxylase may play a significant role in the regulation of cholesterol synthesis in the small intestine.     

Alterations in the Fatty Acid Composition of Rat Brain Cells (Neurons, Astrocytes, and Oligodendrocytes) and of Subcellular Fractions (Myelin and Synaptosomes) Induced by a Diet Devoid of n-3 Fatty Acids

Abstract: Rats were fed through four generations with a semisynthetic diet containing 1.0% sunflower oil (6.7 mg/ g n-6 fatty acids, 0.04 mg/g n-3 fatty acids). Ten days before mating, half of the animals received a diet in which sunflower was replaced by soya oil (6.6 mg/g n-6 fatty acids, 0.8 mg/g n-3 fatty acids) and analyses were performed on their pups. Fatty acid analysis in isolated cellular and subcellular material from sunflower-fed animals showed that the total amount of unsaturated fatty acids was not reduced in any cellular or subcellular fraction (except in 60-day-old rat neurons). All material from animals fed with sunflower oil showed an important reduction in the docosahexaenoic acid content, compensated (except in 60-day-old rat neurons) by an increase in the n-6 fatty acids (mainly C22:5 n-6). When comparing 60-day-old animals fed with soya oil or sunflower oil, the n-3/n-6 fatty acid ratio was reduced 16-fold in oligodendrocytes, 12-fold in myelin, twofold in neurons, sixfold in synaptosomes, and threefold in astrocytes. No trienes were detected. Saturated and monounsaturated fatty acids were hardly affected. This study provides data on the fatty acid composition of isolated brain cells.     

Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios

Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.     

Influence of dietary fat on the lipid composition of rat brain synaptosomal and microsomal membranes.

The modulation of rat brain microsomal and synaptosomal membrane lipid by diet fat was examined. Brain synaptosomal and microsomal membrane composition was compared for rats fed on diets containing either soya-bean oil (SBO), SBO plus choline, SBO lecithin, sunflower oil (SFO), chow or low-erucic acid rape-seed oil (LER) for 24 days. Cholesterol and phosphatidylcholine levels in both membranes were altered by diet. Diet fat also affected the microsomal content of sphingomyelin. Change in membrane phosphatidylcholine level was related to the relative balance of omega-6, omega-3 and monounsaturated fatty acids within the diets fed. The highest phosphatidylcholine levels appeared in membranes of animals fed on SBO lecithin and the lowest in those fed on LER. Microsomal membrane cholesterol and sphingomyelin content increased by feeding on SBO lecithin. In both synaptosomal and microsomal membranes a highly significant correlation was observed between membrane phosphatidylcholine and cholesterol content. The fatty acyl composition of phospholipids from both membranes also altered with diet and age. Alteration in fatty acid composition was observed in response to dietary levels of omega-6, omega-3 and monounsaturated fatty acids, but the unsaturation index of each phospholipid remained constant for all diet treatments. These changes in lipid composition suggest that dietary fat may be a significant modulator in vivo of the physicobiochemical properties of brain synaptosomal and microsomal membranes.     

Effect of long-term feeding olive and sunflower oils on fatty acid composition and desaturation activities of liver microsomes

Changes in microsomal fatty acid composition, delta 9- and delta 6-desaturase activities and cholesterol and phosphorus liver content were studied in dogs fed olive and sunflower oil diets. No changes were observed in the saturated fatty acids between dietary groups. The level of monounsaturated fatty acids was more elevated in animals fed the OO diet, because of its high relative content in this diet although the in vitro delta 9-desaturase activity was similar in microsomes from the two groups. The proportion of arachidonic acid was similar in SO and OO fed animals. This similar level occurred despite a significant increase in the level of linoleic acid in membrane lipids as a result of feeding the SO supplement. The in vitro delta 6-desaturase activity in liver microsomes showed no differences between dogs fed the two diets. Thus, the higher desaturation presented in vivo by microsomes from OO group may be related to the inhibition by linoleic acid of delta 6-desaturase in dogs fed the SO diet. The polyunsaturated fatty acids (PUFA) from the n-3 series were higher in microsomal phosphatidylcholine and phosphatidylethanolamine from animals fed the OO supplemented diet. The cholesterol/phosphorus molar ratio was higher in the SO group in which the unsaturation index was only slightly affected in phospholipids.     

Maternal dietary n-3 fatty acids alter immune cell fatty acid composition and leukotriene production in growing chicks

The effect of feeding different amounts of n-6 and n-3 fatty acids (FA) to hens on immune tissue FA composition and leukotriene production of hatched chicks was investigated. Hens were fed diets supplemented with either 3.0% sunflower oil (Diet I), 1.5% sunflower+1.5% fish oil (Diet II), or 3.0% fish oil (Diet III) for 46 days. The hatched chicks were fed a diet containing C18:3n-3, but devoid of longer chain n-6 and n-3 FA, for 21 days. Spleen docosahexaenoic acid (DHA) content was higher in chicks from hens fed Diet III (P<0.05). The bursa content of arachidonic acid was lower in chicks hatched from hens fed Diet III (P<0.05), and the ratio of n-6 to n-3 FA was significantly higher in bursa of chicks hatched to hens fed Diet I (P<0.05). Eicosapentaenoic acid (EPA) and DHA contents were higher in bursa of chicks hatched from hens fed Diet III (P<0.05). Thrombocytes from chicks hatched to hens fed Diet III produced the most leukotriene B(5) (LTB(5)). The ratio of LTB(5) to LTB(4) concentrations was also highest (P<0.05) in chicks hatched to hens fed Diet III. These results indicate that modulating maternal dietary n-6 and n-3 FA may alter leukotriene production in chicks, which could lead to less inflammatory-related disorders in poultry.     

Dietary obesity caused by a specific circadian eating pattern

The eating pattern is altered by high-fat diet-induced obesity. To clarify whether this is dependent on the fatty acid profile of the diet, the authors conducted two studies on adult female Sprague-Dawley rats fed normal-fat chow or high-fat diets with varying fatty acid composition. Eating pattern and body weight were assessed in rats fed canola-based (low in saturated fatty acids) or lard-based (moderate in saturated fatty acids) diets for 7 days, and in animals fed chow or canola- or butter-based diets (rich in saturated fatty acids) for 43 days. These parameters were also determined when restricted amounts of low-fat canola- or butter-based diets were consumed for 25 days. Early exposure to canola or lard high-fat feeding or prolonged access to canola- or butter-based fat-rich diets (relative to chow feeding) did not alter the normal light-dark distribution of food and energy intake. All animals ingested most of their food during the dark phase. However, feeding the high-fat canola- and butter-based diets produced an altered eating pattern during the light phase characterized by a smaller number of meals, longer intermeal interval, and enhanced satiety ratio, and consumption of shorter-lasting meals than chow-fed animals. Relative to canola or chow feeding, butter-fed animals consumed a lower number of meals during the dark phase and had a higher eating rate in the light phase, but ate larger meals overall. Only butter feeding led to overeating and obesity. When given a restricted amount of low-fat canola- or butter-based diet at the start of the light phase, rats ate most of their food in that phase and diurnal rather than nocturnal feeding occurred with restriction. These findings underscore the role of saturated fatty acids and the resulting eating pattern alteration in the development of obesity.     

Correlation between changes in membrane lipid composition induced by dietary lipid and membrane-bound enzyme activity in chick liver

The activity of acyl-CoA: cholesterol acyltransferase in the liver-microsomal fraction was considerably reduced in chicks fed on diet containing unsaturated fat, whereas the activity of HMG-CoA reductase and NADPH cytochrome c reductase was not affected. The fatty acid composition of the microsomes was modified appreciably by this dietary condition and there was no change in the phospholipid or cholesterol levels. The addition of cholesterol to the fat supplemented diet resulted in a considerable increase in the microsomal cholesterol content. A decrease in HMG-CoA reductase and an increase ACAT activity was observed compared with the corresponding values from both the groups fed on a standard diet and a fat supplemented diet with no cholesterol. These results suggest that acyl-CoA: cholesterol acyltransferase is modulated by alteration in the fatty acid composition of the microsomal membrane, while the cholesterol content of the microsomes shows a close relationship with the HMG-CoA reductase activity.     

Effect of long term feeding of rice bran oil upon lipids and lipoproteins in rats

The effects of feeding two levels of rice bran oil (RBO) on the growth, lipid parameters, and fatty acid composition of the plasma and liver of rats (Wistar strain) were compared with those produced on animals which had been fed the same levels of peanut oil (PNO). The control animals were fed synthetic diets containing 5 and 20% peanut oil (PNO) and the experimental groups were fed similar diets, containing the same level of rice bran oil (RBO). There was no significant difference with respect to the organ weights between the control and the experimental groups. In general, groups fed 20% oil gained more weight than groups fed 5% oil. The animals which received rice bran oil in their diet had, in general, comparatively lower levels of cholesterol, triglycerides and phospholipids. On the other hand, animals receiving 20% rice bran oil in their diet, showed an increase of 20% in high density lipoproteins (HDL-C), within 18 weeks (p<0.05), when compared to the animals fed with peanut oil. Similarly, low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) were lower in RBO-fed groups, than in the PNO-fed groups. There was, however, no significant differences in the cholesterol/phospholipid (C/P) ratio of the two groups. Analysis of plasma and of liver fatty acids indicated, in a general way, the type of fat consumed. There were no significant difference in the P/S ratio, nor any in the oleic/linoleic, oleic/stearic, palmitoleic/palmitic, oleic/palmitic, and oleic/palmitoleic ratios. Furthermore, levels of saturated (SAFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identical in both the groups. Thus, our results suggest that feeding a high level of rice bran oil (RBO) has no deleterious effect on the growth and blood lipid profile of rats.Abbreviations PNO peanut oil - RBO rice bran oil - HDL-C high density lipoprotein cholesterol - LDL-C low density lipoprotein cholesterol - VLDL-C very low density lipoprotein cholesterol - SAFA saturated fatty acids - MUFA mono-unsaturated fatty acids     

The effect of starvation and starvation followed by feeding on enzyme activity and the metabolism of [U-14C]glucose in liver from growing chicks

1. The conversion of [U-(14)C]glucose into carbon dioxide, cholesterol and fatty acids in liver slices and the activities of ;malic' enzyme, citrate-cleavage enzyme, NADP-linked isocitrate dehydrogenase and hexose monophosphate-shunt dehydrogenases in the soluble fraction of homogenates of liver were measured in chicks that were starved or starved then fed. 2. In newly hatched chicks the incorporation of [U-(14)C]glucose and the activity of ;malic' enzyme did not increase unless the birds were fed. The response to feeding of [U-(14)C]glucose incorporation into fatty acids increased as the starved chicks grew older. 3. Citrate-cleavage enzyme activity increased slowly even when the newly hatched chicks were unfed. On feeding, citrate-cleavage enzyme activity increased at a much faster rate. 4. In normally fed 20-day-old chicks starvation decreased the incorporation of [U-(14)C]glucose into all three end products and depressed the activities of ;malic' enzyme and citrate-cleavage enzyme. Re-feeding increased all of these processes to normal or higher-than-normal levels. 5. In both newly hatched and 20-day-old chicks starvation increased the activity of isocitrate dehydrogenase and feeding or re-feeding decreased it. 6. Very little change in hexose monophosphate-shunt dehydrogenase activity was observed during the dietary manipulations. 7. The results indicate that increased substrate delivery to the liver is the principal stimulus to the increased rate of glucose metabolism observed in newly hatched chicks. The results also suggest that changes in the activities of ;malic' enzyme and citrate-cleavage enzyme are secondary to an increased flow of metabolites through the glucose-to-fatty acid pathway and that the dehydrogenases of the hexose monophosphate shunt play a minor role in NADPH production for fatty acid synthesis.     

Evidence for critical-period programming of intestinal transport function: variations in the dietary ratio of polyunsaturated to saturated fatty acids alters ontogeny of the rat intestine

2-week isocaloric modifications in the dietary ratio of polyunsaturated/saturated fatty acids (P/S) alters intestinal transport in rats. This study was undertaken to test the hypotheses that (1) the fatty acid composition of a nutritionally adequate diet in early life has lasting consequences for active and passive intestinal transport processes; and (2) early life feeding experiences with diets of varying fatty acid composition influence the intestines' ability to adaptively up- or down-regulate intestinal transport in later life. Female Sprague-Dawley rats were weaned onto S or P and were maintained on these diets for 2, 10 or 12 weeks. An in vitro uptake technique was used in which the bulk phase was vigorously stirred to reduce the effective resistance of the intestinal unstirred water layer. P decreased and S increased the uptake of glucose, and this effect was progressive from 2 to 12 weeks. Switching from a P to an S diet decreased jejunal but increased ileal uptake of glucose, whereas switching from an S to a P diet was associated with a decline in both the jejunal and the ileal uptake of glucose. The ileal uptake of galactose increased as the animals grew on either P or S. Switching from P to S resulted in a decline in ileal uptake of galactose, whereas the opposite effect was observed when switching from S to P. The effect of feeding P or S on hexose uptake was influenced by the animals' dietary history: ileal glucose and galactose uptake was lower in animals fed P at an early age (PSP) than in animals fed P for the first time in later life (SSP). Jejunal glucose and galactose uptake was also lower in animals fed S at an early age (SPS) than in those fed S for the first time in later life (PPS). The alterations in the uptake of long-chain saturated and unsaturated fatty acids and cholesterol did not progress with longer periods of feeding, and in the jejunum, lipid uptake did not change when switching from P to S or S to P. Early feeding with P (PSP vs. SSP) was associated with lower jejunal uptake of 18:3 and lower ileal uptake of 12:0, whereas previous feeding with S (SPS vs. PPS) was associated with lower ileal uptake of cholesterol. The changes in uptake of hexoses and lipids was not explained by differences in the animals' food consumption, body or intestinal weight or mucosal surface area.(ABSTRACT TRUNCATED AT 400 WORDS)     

Rapid modulation of the n-3 docosahexaenoic acid levels in the brain and retina of the newly hatched chick

The newly hatched chick obtains its fatty acids almost completely from the lipids of the egg yolk as these are transferred to the developing embryo during its 21-day period of incubation. Since the diet of the laying hen greatly influences the fatty acid composition of the egg lipids, and presumably also the fatty acid composition of the resulting chick, we tested how quickly and to what extent varying the amount of n-3 fatty acids in the diet of the hen would modulate the level of n-3 fatty acids in the brain and retina of the newly hatched chick. White Leghorn hens were fed commercial or semi-purified diets supplemented with 10% fish oil, linseed oil, soy oil, or safflower oil. Eggs, together with the brain, retina, and serum of newly hatched chicks, were then analyzed for fatty acid composition. The fatty acids of egg yolk responded quickly to the hen's diet with most of the change occurring by 4 weeks. There was a linear relationship between the linolenic acid content of the diets and levels of this fatty acid in egg yolk and chick serum. In chicks from hens fed the fish oil diet, the total n-3 fatty acids, including 22:6(n-3), were elevated twofold in the brain and retina and sevenfold in serum relative to commercial diet controls. The safflower oil diet led to a very low n-3 fatty acid content in egg yolks and only 25% of the control n-3 fatty acid content in the brain and retina of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fatty liver produced by dietary deficiencies: its pathogenesis and potentiation by ethanol

In a study of the pathogenesis of hepatic fat accumulation under experimental conditions mimicking chronic alcoholism, rats were fed a low-fat diet, deficient in amino acids and choline, containing either ethanol or isocaloric amounts of carbohydrate. Dietary deficiencies alone produced a moderately fatty liver after 24 days. The combination of ethanol and dietary deficiencies resulted in enhanced lipid accumulation, which was apparent after only 11 days. In an investigation of the origin of hepatic triglyceride fatty acids, the experiment was repeated after the adipose lipids had been marked by the feeding of oils containing characteristic fatty acids (linseed oil, containing linolenate, or coconut oil, containing laurate and myristate). In all animals, the fatty acid composition of the hepatic triglycerides differed markedly from that of adipose tissue; it had a larger percentage of endogenously synthesized fatty acids and a five times smaller percentage of the marker fatty acids. In addition, ethanol feeding resulted in a greater retention of the marker fatty acids in the adipose tissue. Thus, the deposition of hepatic triglycerides produced by the feeding of deficient diets is markedly potentiated by ethanol; the triglyceride fatty acids accumulated under these conditions appear to originate, for the most part, not from mobilization of depot fat, but from endogenous synthesis.     

Effect of fish oil and coconut oil diet on the LDL receptor activity of rat liver plasma membranes

The influence of 4 weeks treatment with fish oil and coconut oil enriched diets on the chemical composition of rat liver plasma membranes and LDL and on the binding of LDL to liver membranes was investigated. Rats fed fish oil diet showed a total, LDL and HDL plasma cholesterol concentration lower than the values observed in rats fed coconut oil and to a lesser extent lower than those of rats fed standard laboratory diet. LDL of rats on fish oil diet had a relative percentage of cholesterol and phospholipid lower, while that of triacylglycerol was greater. Furthermore, fish oil feeding was associated with a greater concentration of n - 3 fatty acids and a lower arachidonic and linoleic acid content in LDL. Liver plasma membranes isolated from fish oil rats showed a higher percentage of n - 3 fatty acids, while only a trace amount of these fatty acids was found in control and coconut oil fed animals. In binding experiments performed with LDL and liver membranes from fish oil fed rats and control rats, binding affinity (Kd = 3.47 +/- 0.93 and 4.56 +/- 1.27, respectively) was significantly higher (P less than 0.05) as compared to that found using membranes and lipoprotein from coconut oil fed rats (Kd = 6.82 +/- 2.69). In cross-binding experiments performed with fish oil LDL and coconut oil liver plasma membranes or coconut oil LDL and fish oil liver plasma membranes, the LDL binding affinity was comparable and similar to that found in fish oil fed animals. No difference was found in the Bmax among all the groups of binding experiments. Our data seem to indicate that during fish oil diet the higher binding affinity of LDL to liver plasma membranes might be partly responsible of the hypocholesterolemic action of marine oil rich diet as compared to saturated diet. Furthermore, the modifications of binding affinity induced by changes of LDL and membrane source, suggest that lipoprotein and liver plasma membrane composition may be an important variable in binding studies.     

Effect of dietary fish oil on tumor-induced hyperlipidemia and tumor growth in rats implanted with a methylcholanthrene-induced sarcoma

Male Fischer 344 rats implanted with a methylcholanthrene-induced sarcoma (MCS), along with normal (or control) animals, were fed diets containing either 10% com oil (CO) or 2% CO + 8% fish oil (FO), designated as diets CO and FO, respectively, in a study designed to determine the effect of dietary FO on serum lipids (in the presence or absence of a tumor) and the growth and fatty acid composition of the MCS. For both diets, MCS-bearing rats had significantly (p < 0.05) higher serum levels of triglycerides, cholesterol, phospholipids, and total lipids than controls. For both controls and tumor-bearers, serum levels of all these lipids were, with the exception of cholesterol for the tumorbearers, significantly lower in rats receiving the FO diet than for the corresponding groups receiving the CO diet. Relative to rats fed the CO diet, those fed the FO diet had significantly higher serum levels of some fatty acids (e.g., 20:5n-3) but significantly lower levels of others (e.g., 18:2n-6), regardless of tumor status. For the tumor-bearers, differences in the levels of fatty acids in MCS tissue reflected differences in the fatty acid composition of total serum lipids. Sarcoma growth was unaffected by diet. Thus, feeding dietary FO resulted in changes in the lipid status of both control and tumor-bearing rats. Since sarcoma growth was unaffected by diet, the reduction in the severity of MCS-induced hyperlipidemia by FO appears to be due to an effect of the oil per se.     

Dietary saturated fatty acid content affects lymph lipoproteins: studies in the rat

We examined effects on intestinal absorption of cholesterol and triglycerides and intestinal lipoprotein formation by feeding rats diets in which saturated fatty acids (palmitic plus stearic) comprised 78%, 68%, 48%, or 38% of triglyceride fatty acids. Absorption into lymph of radiolabeled cholesterol was proportional to triglyceride absorption. The rates of absorption of these lipids were related inversely to the % saturated fatty acids fed. The distribution of newly absorbed cholesterol and triglyceride into intestinal lipoproteins differed. With increasing cholesterol absorption more was recovered in very low density lipoproteins in contrast to the appearance preferentially in chylomicrons of larger quantities of fatty acid. Lymph lipid content did not reflect a consistent pattern in relation to the experimental diet fed. The fatty acid composition of triglyceride-rich lymph lipoproteins resembled the diet closely. One-quarter of the intestinal lymph particles from rats fed the highly saturated diets was flattened and polygonal as judged by electron microscopy if cooled to room temperature; whereas with the same diets, particles collected and isolated at 37 degrees C were round. Proportions of A-I and C apolipoproteins in triglyceride-rich intestinal particles varied inversely; apoA-I increased as fat/cholesterol absorption was greater. Diet-induced alterations in plasma lipoproteins and increased circulating triglycerides in this study in rats were unrelated to the variations in intestinal absorption or lymph lipoprotein formation.     

Effects of whole linseed supplementation and treatment duration on fatty acid profile and endogenous bioactive compounds of beef muscle

Diet supplementation with oilseeds is known to improve the fatty acid profile of meat, but few studies have been carried out to determine the time required for the incorporation of a significant quantity of n-3 polyunsaturated fatty acids (PUFA) into meat from steers. Therefore, the present study aimed to assess the effects of linseed supplementation and feeding duration on the fatty acid profile, cholesterol and bioactive compounds of bovine meat. In total, 54 Friesian steers were randomly allocated during the finishing period into six experimental treatments following a 2×3 factorial design. The six treatments consisted of two diets, the control diet (CO) with no supplemental fat and the linseed diet (LS) containing 10% whole linseed, fed 40, 75 or 120 days before slaughter. At the end of each finishing period, steers from the CO and LS groups were slaughtered. After 8 days of ageing chemical analysis, the fatty acid profile, cholesterol content and bioactive compounds were determined from the longissimus thoracis muscle. Including linseed in the diet increased the content of monounsaturated fatty acids, CLA and n-3 PUFA, and reduced the proportion of saturated fatty acids and n-6 PUFA. The percentage of myristic fatty acid increased with the duration of feeding, regardless of diet and a decrease in PUFA and n-6 PUFA was observed in the CO and LS diets, respectively. Furthermore, meat from steers fed linseed showed an increased percentage of n-3 PUFA, linolenic acid, and EPA from 40 to 75 days of feeding, whereas vaccenic acid, CLA 9c,11t, and total CLA increased from 40 and 75 days but declined at 120 days. Beef from the linseed group had a higher content of bioactive substances such as creatine, carnosine and anserine than beef from the control group. The duration of feeding significantly affected the creatine concentrations, with an increase in the LS group from 40 to 75 days of feeding. Feeding linseed did not modify the cholesterol content, on average and the lowest cholesterol content was found in meat after 75 days of linseed administration. This study demonstrates that a short-term diet manipulation is sufficient to improve the nutritional properties of meat, including n-3 PUFA and bioactive compounds.