Oxidative stress,circulating antioxidants,and dietary preferences in songbirds

Oxidative stress is an unavoidable consequence of metabolism and increases during intensive exercise. This is especially problematic for migratory birds that metabolize fat to fuel long-distance flight. Birds can mitigate damage by increasing endogenous antioxidants (e.g. uric acid) or by consuming dietary antioxidants (e.g. tocopherol). During flight, birds may increase protein catabolism of lean tissue which may increase circulating uric acid and many birds also consume an antioxidant-rich frugivorous diet during autumn migration. We evaluated three related hypotheses in a migratory passerine: (1) protein consumption is positively related to circulating antioxidants, (2) a dietary oxidative stressor [i.e. polyunsaturated fatty acid (PUFA)] influences antioxidant capacity and oxidative damage, and (3) oxidative stress influences dietary antioxidant preferences. White-throated Sparrows (Zonotrichia albicollis) consuming a high protein diet increased circulating uric acid; however, uric acid, antioxidant capacity, and oxidative stress did not differ between birds consuming a high PUFA versus a low PUFA diet, despite increased oxidative damage in high PUFA birds. Birds did not prefer antioxidant-rich diets even when fed high PUFA, low protein. We conclude that White-throated Sparrows successfully mitigated oxidative damage associated with a high PUFA diet and mounted an endogenous antioxidant response independent of uric acid, other circulating antioxidants, and dietary antioxidants.     

Effect of sex,dietary glycerol or dietary fat during late fattening,on fatty acid composition and positional distribution of fatty acids within the triglyceride in pigs

The effect of sex, source of saturated fat (lard v. palm oil) and glycerol inclusion in the fattening diet on composition and fatty acid positional distribution in the triglyceride molecule was studied in pigs from 78 to 110 kg BW. Average daily gain and carcass characteristics, including ham and loin weight, were not affected by dietary treatment but sex affected backfat depth (P<0.01). A significant interaction between sex and glycerol inclusion was observed; dietary glycerol increased lean content in gilts but not in barrows (P<0.05 for the interaction). Individual and total saturated fatty acid (SFA) concentrations were greater in barrows than in gilts. In contrast, the concentration of total polyunsaturated fatty acids (PUFA) and of C18:2n-6, C18:3n-3, C20:3n-9 and C20:4n-6 in the intramuscular fat (IMF) was higher (P<0.05) in gilts than in barrows. Sex did not affect total monounsaturated fatty acids (MUFA) concentration in the IMF. The proportion of SFA in the subcutaneous fat (SF) was higher in barrows than in gilts (P<0.001). Within the individual SFA, sex affected only the concentrations of C14:0 and C16:0 (P<0.001). Dietary fat did not affect total SFA or PUFA concentrations of the IMF but the subcutaneous total MUFA concentration tended to be higher (P=0.079) in pigs fed lard than in pigs fed palm oil. Dietary glycerol increased total MUFA and C18:1n-9 concentration in the IMF and increased total MUFA and decreased C18:2n-6, C18:3n-3 and total PUFA concentrations in the SF. The data indicate that altering the fatty acid composition of the triglyceride molecule at the 2-position, by dietary intervention during the fattening phase, is very limited.     

The effect of dietary fish oils on eicosanoid biosynthesis in peritoneal macrophages is influenced by both dietary N-6 polyunsaturated fats and total dietary fat

Recent research has implicated dietary fish oils in the reduction of eicosanoids formed from arachidonic acid and amelioration of chronic diseases such as coronary heart disease, atherosclerosis and inflammation. Feeding studies were conducted to determine if the efficacy of dietary n-3 polyunsaturated fatty acids (PUFA) from fish oils was influenced by the quantity of n-6 polyunsaturated fatty acids and the total level of fat in the diet. Groups of mice were fed diets composed of 5 and 20% total fat with varying proportions of linoleic acid as a source of n-6 PUFA. Menhaden oil as a source of n-3 PUFA was fed at two levels of n-6 at each level of total fat. Eicosanoid biosynthesis was stimulated and assayed in the mouse peritoneum using zymosan as an inflammatory stimulus. Production of LTE4 and PGE2 was enhanced by increasing n-6 PUFA in the diet at both levels of total fat. High dietary fat significantly suppressed leukotriene (LT) synthesis. Dietary menhaden oil reduced LTE4 and PGE2 synthesis at both levels of dietary n-6 in the low fat study. In animals on 20% dietary fat menhaden oil significantly reduced LT synthesis only at a relatively low dietary n-6 PUFA. On a high n-6 PUFA high fat diets, menhaden oil did not significant affect LTE4 synthesis in response to zymosan stimulation. The results suggest that the effectiveness of fish oils in reducing eicosanoids in response to specific stimulation is influenced by the level of n-6 and the total quantity of fat in the diet.     

Components of Total Energy Expenditure in Healthy Young Women Are Not Affected after 14 Days of Feeding with Medium-Versus Long-Chain Triglycerides

PAPAMANDJARIS, ANDREA A., MATTHEW D. WHITE, AND PETER J. H. JONES. Components of total energy expenditure in healthy young women are not affected after 14 days of feeding with medium-versus long-chain triglycerides. Obes Res. Objective: To examine the effect of consumption of medium-chain triglycerides (MCT) vs. long-chain triglycerides (LCT) on total energy expenditure (TEE) and its components in young women during the second week of a 2-week feeding period. Research Methods and Procedures: Twelve healthy lean women (age: 22. 7±0. 7 years, body mass index [BMI]: 21. 5±0. 8 kg/m²) were fed weight maintenance diets containing 15% of energy as protein, 45% as carbohydrate, and 40% as fat, 80% of which was treatment fat, for 2 weeks in a randomized cross-over design separated by a 2-week washout period. Dietary fat was composed of triglycerides containing either 26% medium-chain fatty acids (MCFA) and 74% long-chain fatty acids (LCFA), or 2% MCFA and 98% LCFA. Free-living TEE was measured from day 7 to 14 on each dietary treatment using doubly labeled water (DLW). Basal metabolic rate (BMR) and thermic effect of food (TEF) were measured on days 7 and 14 using respiratory gas exchange analysis (RGE) for 30 minutes and 330 minutes, respectively. Activity-induced energy expenditure (AIEE) was derived as the difference between TEE and the sum of BMR and TEF. Results: The average TEE while consuming the MCT diet (2246±98 kcal/day) did not differ from that of the LCT diet (2186±138 kcal/day. BMR was significantly higher on the MCT diet on day 7 (1219±38 kcal/day vs. 1179±42 kcall day), but not on day 14; there was no effect of diet on TEF. There were no differences in BMR, TEF, or AIEE between diets when expressed as percentages of TEE. On average, BMR, TEF, and AIEE represented 54. 6%, 8. 2%, and 37. 2%, respectively, of TEE. Discussion: Results suggest that between day 7 and day 14 feeding of MCT vs. LCT at these levels, TEE is not affected and that increases seen in energy expenditure following MCT feeding may be of short duration. Thus, compensatory mechanisms may exist which blunt the effect of MCT on energy components over the longer term.     

Dietary omega-6 fatty acid lowering increases bioavailability of omega-3 polyunsaturated fatty acids in human plasma lipid pools

BackgroundDietary linoleic acid (LA, 18:2n-6) lowering in rats reduces n-6 polyunsaturated fatty acid (PUFA) plasma concentrations and increases n-3 PUFA (eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)) concentrations.ObjectiveTo evaluate the extent to which 12 weeks of dietary n-6 PUFA lowering, with or without increased dietary n-3 PUFAs, alters unesterified and esterified plasma n-6 and n-3 PUFA concentrations in subjects with chronic headache.DesignSecondary analysis of a randomized trial. Subjects with chronic headache were randomized for 12 weeks to (1) average n-3, low n-6 (L6) diet; or (2) high n-3, low n-6 LA (H3–L6) diet. Esterified and unesterified plasma fatty acids were quantified at baseline (0 weeks) and after 12 weeks on a diet.ResultsCompared to baseline, the L6 diet reduced esterified plasma LA and increased esterified n-3 PUFA concentrations (nmol/ml), but did not significantly change plasma arachidonic acid (AA, 20:4n-6) concentration. In addition, unesterified EPA concentration was increased significantly among unesterified fatty acids. The H3–L6 diet decreased esterified LA and AA concentrations, and produced more marked increases in esterified and unesterified n-3 PUFA concentrations.ConclusionDietary n-6 PUFA lowering for 12 weeks significantly reduces LA and increases n-3 PUFA concentrations in plasma, without altering plasma AA concentration. A concurrent increase in dietary n-3 PUFAs for 12 weeks further increases n-3 PUFA plasma concentrations and reduces AA.     

Effects of corn oil- and fish oil-supplemented diets on phospholipid fatty acid composition of rat liver nuclei

The effects of dietary fat on fatty acid compositions of phospholipids in liver nuclei were investigated. By feeding a diet containing 5% corn oil or fish oil to rats, the proportions of n -6 or n -3 polyunsaturated fatty acids (PUFA), respectively, were increased in phospholipids of the liver nuclei. By feeding a fat-free diet, endogenous PUFA were increased. Even after feeding the fat-free diet for 40 weeks, the n - 6 still remained at about 10% in both phosphatidylcholine (PC) and phosphatidylethanolamine (PE), while the n -3 PUFA remained at about 5 and 16% in PC and PE, respectively. The fatty acid compositions of phospholipids in the liver nuclei were influenced by dietary fat and were roughly similar to those in the microsomes. The proportion of n - 3 PUFA was high in PE of both the nuclear membrane and matrix. The proportion of n - 6 was higher in both PC and PE of the nuclear matrix than in those of the membrane.     

Dietary gangliosides increase the content and molecular percentage of ether phospholipids containing 20:4n-6 and 22:6n-3 in weanling rat intestine

This study was conducted to determine whether dietary ganglioside (GG) increases the content of ether phospholipids (EPL) in intestinal mucosa. Weanling Sprague-Dawley rats were fed a semipurified diet consisting of 20% fat as a control diet. Two experimental diets were formulated by adding either 0.1% (w/w fat) GGs (GG diet) or 1.0% (w/w fat) sphingomyelin (SM diet) to the control diet. Fatty acid methyl esters from the alkenylacyl, alkylacyl and diacyl subclasses of phospholipids were measured to determine total and molecular percentage of EPL comprising the choline phosphoglyceride (CPG) and ethanolamine phosphoglyceride (EPG) fraction. Animals fed the GG diet significantly increased total EPL content both in CPG (by 36%) and in EPG (by 66%), and the molecular percentage of EPL in CPG (by 76%) and in EPG (by 59%) compared to animals fed the control diet. Dietary GG-induced increase in EPL resulted in a higher level of polyunsaturated fatty acids (PUFA) specifically in 20:4n-6 and 22:6n-3 compared to control animals, leading to a decrease in the ratio of saturated fatty acids (SFA) to PUFA both in CPG and in EPG. Feeding animals the SM diet showed a higher level of EPL than control animals with a concomitant increase in 22:6n-3 in EPL. The present data demonstrate that dietary GG increases the content and composition of EPL containing PUFA in the weanling rat intestine.     

Reproductive performance of carp, Catla catla (Ham.), reared on a formulated diet with PUFA supplementation

Effect of dietary supplementation of n‐3 and n‐6 polyunsaturated fatty acids (PUFA) on reproductive performances in both sexes of an Indian major carp, Catla catla (Ham.), were investigated in terms of sperm quality, spawning response, fecundity and spawn recovery over a consecutive 2‐year period. Sperm count and spermatocrit value were in the range of 3.2–3.8 × 10⁷ ml⁻¹ and 80–82%, respectively, in fish fed the PUFA‐enriched test diet, and significantly higher (P < 0.01) than in fish fed control diet (2.3–2.5 × 10⁷ ml⁻¹ and 64–70%). Spawning response in the test diet group was quite high (96%) compared to 76% in the control. Egg and larval quality were superior in the test diet group as evidenced by the significantly higher fertilization rate and larval survival in the range of 91–92% and 93.3%, respectively. Fatty acid profile of fertilized eggs and larvae showed that the quantities of 18:3 (n‐3), 20:5 (n‐3) and 22:6 (n‐3) were significantly (P < 0.01) increased in the test group while 18:1, 18:2 (n‐6) and 20:4 (n‐6) remained at higher levels in control. The results indicated that enrichment of n‐3 PUFA in the broodfish diet not only improved the quality of eggs and larvae in terms of recovery, but also enhanced the physiological response of broodfish to induced spawning. Oil enrichment in the broodfish diet should therefore be mandatory to ensure the optimum n‐3 PUFA content for warmwater carp for quality seed production.     

Conjugated nonadecadienoic acid is more potent than conjugated linoleic acid on body fat reduction

Conjugated linoleic acid (CLA) has shown a number of health benefits, particularly on controlling body fat while improving lean mass. As one of CLA cognates, conjugated nonadecadienoic acid (CNA, 19-carbon conjugated fatty acid) has been previously reported to have greater efficacy on body fat control. In this report, we compared the efficacy of dietary CLA and CNA on body fat regulation and also compared the mechanism of body fat control using a mouse model. Effects of 0.1% dietary CNA on body fat reduction were comparable to that of 0.5% dietary CLA. The mechanisms of dietary CNA on body fat control were similar to those of CLA: increased energy expenditure and increased fatty acid β-oxidation. Dietary CNA, but not CLA, also improved expression of hormone-sensitive lipase from white adipose tissue, and this may help explain how CNA has better efficacy on body fat control than CLA. Dietary CNA had similar effects as CLA on liver weights; however, unlike CLA, CNA improved glucose tolerance. Thus, CNA has potential to be used as a pharmacological agent to assist current efforts to reduce obesity with less adverse effects than CLA.     

Fatty acid synthase and adipsin mRNA levels in obese and lean JCR:LA-cp rats: effect of diet.

In Sprague-Dawley rats, fatty acid synthase (FAS) activity is suppressed by dietary fat. To test the hypothesis that a defect in regulation of de novo fatty acid synthesis exists in massive obesity, we investigated the effect of diet on FAS mRNA levels in genetically obese JCR:LA-corpulent (cp) rats. We also determined levels of mRNA encoding adipsin, a fat cell-derived protein possibly associated with lipid metabolism. Hepatic FAS mRNA levels were elevated five-fold in obese compared to lean cp rats and were unsuppressed by dietary fat. Dietary sucrose increased FAS mRNA levels in lean cp rats, but, in contrast to Sprague-Dawley rats, little deposition of lipid resulted. Adipsin mRNA levels were fivefold lower in obese cp and Sprague-Dawley rats than in lean cp rats and were unaffected by diet. We conclude that exaggerated de novo fatty acid synthesis may play a major role in the pathogenesis of obesity in obese JCR:LA-corpulent rats.     

Changes in fatty acid composition,cholesterol and fat‐soluble vitamins during development of eggs and larvae in shabbout (Barbus grypus,Heckel 1843)

Changes in fatty acid composition, cholesterol and fat‐soluble vitamins were studied during development (fertilized eggs, yolk‐sac larvae, and after yolk resorption of shabbout, Barbus grypus). Significant differences were found in the monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFA), PUFA/saturated fatty acids (SFA), ∑n‐3 and eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) ratios between eggs and larvae (P < 0.05). Significant differences were also observed in the C14:0, C16:1n‐7, C18:1n‐9, C18:3n‐6, C20:0, C20:4n‐6, C24:0, C24:1, C22:6n‐3 fatty acids between eggs and larvae after yolk‐sac resorption (P < 0.05). Vitamin α‐ Tocopherol and retinol content increased during embryogenesis, but changes were insignificant in retinol acetate, δ‐Tocopherol, K1, K2 and cholesterol content between eggs and larvae after yolk resorption (P > 0.05).     

Saturated, but not n-6 polyunsaturated, fatty acids induce insulin resistance: role of intramuscular accumulation of lipid metabolites.

Consumption of a Western diet rich in saturated fats is associated with obesity and insulin resistance. In some insulin-resistant phenotypes this is associated with accumulation of skeletal muscle fatty acids. We examined the effects of diets high in saturated fatty acids (Sat) or n-6 polyunsaturated fatty acids (PUFA) on skeletal muscle fatty acid metabolite accumulation and whole-body insulin sensitivity. Male Sprague-Dawley rats were fed a chow diet (16% calories from fat, Con) or a diet high (53%) in Sat or PUFA for 8 wk. Insulin sensitivity was assessed by fasting plasma glucose and insulin and glucose tolerance via an oral glucose tolerance test. Muscle ceramide and diacylglycerol (DAG) levels and triacylglycerol (TAG) fatty acids were also measured. Both high-fat diets increased plasma free fatty acid levels by 30%. Compared with Con, Sat-fed rats were insulin resistant, whereas PUFA-treated rats showed improved insulin sensitivity. Sat caused a 125% increase in muscle DAG and a small increase in TAG. Although PUFA also resulted in a small increase in DAG, the excess fatty acids were primarily directed toward TAG storage (105% above Con). Ceramide content was unaffected by either high-fat diet. To examine the effects of fatty acids on cellular lipid storage and glucose uptake in vitro, rat L6 myotubes were incubated for 5 h with saturated and polyunsaturated fatty acids. After treatment of L6 myotubes with palmitate (C16:0), the ceramide and DAG content were increased by two- and fivefold, respectively, concomitant with reduced insulin-stimulated glucose uptake. In contrast, treatment of these cells with linoleate (C18:2) did not alter DAG, ceramide levels, and glucose uptake compared with controls (no added fatty acids). Both 16:0 and 18:2 treatments increased myotube TAG levels (C18:2 vs. C16:0, P < 0.05). These results indicate that increasing dietary Sat induces insulin resistance with concomitant increases in muscle DAG. Diets rich in n-6 PUFA appear to prevent insulin resistance by directing fat into TAG, rather than other lipid metabolites.     

Lipid composition of lactational diets influences the fatty acid profile of the progeny before and after suckling

The purpose of the present study was to compare the influence of adding no or 8% fat of varying sources (coconut oil, fish oil, rapeseed oil and sunflower oil) to diets for sows 1 week prior to farrowing and during lactation on the composition of fatty acids in plasma and tissues of the progeny while sucking and 3 weeks after weaning from the sow. A control diet without supplemental fat and four diets supplemented with 8% of coconut oil, rapeseed oil, fish oil or sunflower oil were provided to lactating sows (n = 15), and during the post-weaning period the same weaner diet was provided to all piglets (n = 15 litters), which were housed litterwise. The dietary ratio of n-6:n-3 fatty acids of the maternal diets largely influenced the progeny, as the ratio varying from 1.2 (fish oil) to 12.2 (sunflower oil) in the sow milk was reflected in plasma and adipose tissues of the sucking progeny. The liver showed similar variations according to dietary treatments, but a lower n-6:n-3 fatty acids ratio. From day 4 to later on during the suckling period, the concentration of C14:0, C16:0 and C18:1 in the liver of the piglets decreased, irrespective of the dietary treatments of sows. In plasma and liver, the total concentration of saturated fatty acids (SAFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) did not differ markedly in piglets sucking sows fed different dietary fatty acids, whereas the adipose tissue of piglets sucking sows fed sunflower oil and coconut oil showed the highest proportion of PUFA and SAFA, respectively. Weaning lowered the concentration of lipid-soluble extracts in plasma and the concentration of fatty acids in the liver of the piglets. Within the post-weaning period, dietary treatments of sows, rather than age of piglets, influenced the fatty acid composition of plasma and adipose tissue of the piglets, whereas the hepatic fatty acid profile was more affected by the age of the piglets during the post-weaning period. This study shows that the fatty acid profile of plasma and tissues of the progeny is highly dependent on the maternal dietary composition, and that the dietary impact persists for up to 3 weeks after the suckling period.     

Maternal and umbilical fatty acid status in relation to maternal diet

The aim of this study was to describe the dietary fat intake during pregnancy and to study the relationship between the intake of polyunsaturated fatty acids (PUFAs) and the fatty acid composition of maternal and umbilical plasma phospholipids (PLs) and cholesterol esters (CEs) at delivery. In addition, the contribution of food groups to the intake of total fat and fatty acids in the diet was quantified.Maternal and umbilical blood samples were collected at delivery from 30 healthy pregnant women. The women completed a food frequency questionnaire during the first and third trimesters. The total fat intake during pregnancy is 85 (SD 24) g/day. The mean intake of saturated fatty acids (SFAs) is 33.4 g/day, of monounsaturated fatty acids (MUFAs) 28.6 g/day and of PUFA 15.2 g/day. Major sources of fat, MUFA and PUFA are fats, oils and sauces. Major sources of SFA are meat and poultry followed by cheese and eggs. Meat and poultry contribute the most to the intake of 20:4n-6 whereas fish is the major source of 20:5n-3 (EPA) and 22:6n-3 (docosahexaenoic acid (DHA)) in the diet. Linoleic acid, EPA and DHA (w%) in PL of maternal plasma are positively related to the intake of these fatty acids during pregnancy. No association is found between the maternal intake of the two parent essential fatty acids (18:2n-6 and 18:3n-3) and their fraction in umbilical PL or CE. EPA and the sum of n-6 fatty acids (w%) in umbilical plasma PL are positively correlated with the dietary intake of these fatty acids.     

The ability of genetically lean or fat slow-growing chickens to synthesize and store lipids is not altered by the dietary energy source

The increasing use of unconventional feedstuffs in chicken’s diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.     

Fat Intake Affects Adiposity,Comorbidity Factors,and Energy Metabolism of Sprague‐Dawley Rats

Objective: Childhood obesity is an emerging health problem. This study assesses the effects of three levels of dietary fat (10%, 32%, and 45% measured by kilocalories) on weight gain, body composition, energy metabolism, and comorbidity factors in rats from weaning through maturation. Research Methods and Procedures: The role of dietary fat on the susceptibility to obesity was assessed by feeding diets containing three levels of dietary fat to rats from weaning through 7 months of age. Body composition was analyzed by DXA after 6 and 12 weeks of dietary treatment. Energy metabolism was measured by indirect calorimetry. Results: Energy intake, weight gain, fat mass, and plasma glucose, cholesterol, triglyceride, free fatty acid, leptin, and insulin levels increased dose‐dependently with increased dietary fat. No difference in absolute lean mass among the three groups was observed. Therefore, the differences in weight gain are accounted for primarily by increased fat accretion. Compared with rats that were relatively resistant to obesity when on a 45% fat diet, diet‐induced obesity‐prone rats were in positive energy balance and had an elevated respiratory quotient, indicating a switch in energy substrate use from fat to carbohydrate, which promotes body‐fat accretion. Discussion: Our data support the hypothesis that administration of increasing amount of dietary fat to very young rats enhances susceptibility to diet‐induced obesity and its comorbidities.     

Dietary trans-18:1 raises plasma triglycerides and VLDL cholesterol when replacing either 16:0 or 18:0 in gerbils

To compare the relative impact of trans-18:1 with the two main dietary saturated fatty acids it replaces, plasma lipid response was assessed in Mongolian gerbils fed diets rich in 16:0 (24%en),18:0 (10%en), or trans-18:1 (4 or 6%en). The diets were designed such that the 18:0-rich diet substituted 7%en as 18:0 for 16:0, whereas 4%en and 6%en from trans-18:1 was substituted for 16:0 in the two trans diets. The control group was fed a diet formulated according to the fatty acid balance of American Heart Association (AHA), but provided 40%en as fat. Gerbils (n = 10 per dietary group) were fed one of the five diets for 8 weeks. The control diet, with 4 times the polyunsaturated fatty acids (PUFA) content and a P:S ratio about 10 times greater than the test diets, resulted in the lowest plasma TC, LDL cholesterol (LDL-C) and VLDL cholesterol (VLDL-C). Among the test diets, plasma TC and TG were lowest with the 18:0-rich diet. TC in gerbils fed the 16:0-rich diet and 4%en-trans were 20% higher than the 18:0-rich diet, while the 6%en-trans diet was 35% higher. VLDL-C was significantly higher in the 6%en-trans diet compared to all other groups at 8 weeks. Both trans fatty acid diets elevated plasma TG approximately 2- and 3-fold, respectively, compared to the 16:0-rich and 18:0-rich diets at 8 weeks. Further, plasma TG continued to rise over time with trans fatty acids compared to 16:0 or 18:0. Thus, in the fatty acid-sensitive gerbil, impaired TG metabolism represents a major aspect of the hyperlipemia caused by trans fatty acid substitution for major saturated fatty acids.     

Specific phospholipid fatty acid composition of brain regions in mice. Effects of n-3 polyunsaturated fatty acid deficiency and phospholipid supplementation

This study examined the effects of dietary alpha-linolenic acid deficiency followed or not by supplementation with phospholipids rich in n;-3 polyunsaturated fatty acid (PUFA) on the fatty acid composition of total phospholipids in 11 brain regions. Three weeks before mating, mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or deficient in alpha-linolenic acid. Pups were fed the same diet as their dams. At the age of 7 weeks, a part of the deficient group were supplemented with n;-3 polyunsaturated fatty acids (PUFA) from either egg yolk or pig brain phospholipids for 2 months. Saturated and monounsaturated fatty acid levels varied among brain regions and were not significantly affected by the diet. In control mice, the level of 22:6 n-3 was significantly higher in the frontal cortex compared to all regions. alpha-Linolenic acid deficiency decreased the level of 22:6 n-3 and was compensated by an increase in 22:5 n-6 in all regions. However, the brain regions were affected differently. After the pituitary gland, the frontal cortex, and the striatum were the most markedly affected with 40% reduction of 22:6 n-3. Supplementation with egg yolk or cerebral phospholipids in deficient mice restored a normal fatty acid composition in brain regions except for the frontal cortex. There was a regional distribution of the fatty acids in the brain and the impact of deficiency in alpha-linolenic acid was region-specific. Dietary egg yolk or cerebral phospholipids are an effective source of n-3 PUFA for the recovery of altered fatty acid composition induced by a diet deficient in n-3 PUFA.     

Changes in fatty acid composition of Mytilus galloprovincialis (Lmk) fed on microalgal and wheat germ diets

Dietary fatty acid incorporation and changes in various lipid and phospholipid classes in the mussel Mytilus galloprovincialis subjected to three different dietary regimens were analysed and compared. Group A was unfed; group B received a diet consisting of 100% Thalassiosira weissflogii, exhibiting the typical fatty acid composition of diatoms, and group C received a diet consisting of 100% wheat germ conferring a 18:2:n-6 abundance. Biochemical analyses of diets and mussels were carried out at the beginning and at the end of the 30-day experimental period. Starvation and T. weissflogii based diet poorly affected mussel growth and fatty acid composition which remained unchanged. On the contrary, the wheat germ-based diet increased the condition index and deeply affected the fatty acid profile of all lipid and phospholipid classes. The high dietary 18:2n-6 level drastically reduced tissue content of 20:4n-6, 20:5n-3 and 22:6n-3. The biosynthesis of Non Methylene Interrupted (NMI) dienoic fatty acid appeared to be insensitive to the high input of 16:1n-7 and 18:1n-9 respectively from diet B and C, and to the PUFA shortage of diet C. Nevertheless the two NMI trienoic derivatives, 20:3Δ5,11,14 and 22:3Δ7,13 16, were found higher in C with respect to other groups, presumably due to the high 18:2n-6 content of this diet.     

Tissue fatty acid composition of pigs fed different fat sources

Dietary fat influences the physico-chemical properties of meat, and fatty acid (FA) composition may have implications on human health. The objectives of the experiment were to study tissue FA partitioning and the effect of dietary fat source on tissue FA composition. Seventy crossbred gilts (61.8 ± 5.2 kg BW average) were fed one of seven treatments: a diet containing a very low level of fat (no fat (NF)) and six fat-supplemented diets (10%: tallow (T), high-oleic sunflower oil (HOSF), sunflower oil (SFO), linseed oil (LO), fat blend (FB: 55% tallow, 35% SFO, 10% LO) and fish oil blend (FO: 40% fish oil, 60% LO). Differential tissue FA depositions were observed, with flare fat being the most saturated, followed by intermuscular, and subcutaneous being the least saturated. Monounsaturated fatty acid (MUFA) deposition showed an opposite tissue pattern. Subcutaneous fat showed the highest MUFAs, intermuscular fat showed intermediate values and flare fat showed the lowest MUFAs. Intramuscular polyunsaturated fatty acid (PUFA) content was less susceptible to dietary treatment modifications compared with other depots. Significant tissue FA modifications were observed due to dietary treatments, mainly in diets rich in PUFA. The saturated fatty acids (SFA) were high in NF-fed and low in HOSF-fed animals, MUFA were high in HOSF-fed and low in SFO-, LO- and FO-fed animals, while PUFA were high in SFO- and LO-fed and low in HOSF-, T- and NF-fed animals. Pigs fed LO and FB showed detectable levels of EPA, which depended on the linolenic content of the diet. The only effective way to increase tissue DHA contents was to add DHA in the diet through FO feeding. Araquidonic acid was high in SFO diets and low in LO and FB diets, and also high in intramuscular fat compared with other tissues. EPA and DHA were also high in intramuscular fat compared with other fat depots. The deposition of oleic and linoleic acids depended on the composition of dietary fat, as their deposition varied between diets, even at similar levels of intake of each FA. The NF diet resulted in the greatest proportion of SFAs (palmitic and stearic) of all treatments tested. SFAs were less susceptible to modification than MUFA in response to the different PUFA levels supplemented in the diet. T resulted in less fat deposition in some of the fat depots and more in others, suggesting that T could partition fat differently among fat depots.