Preferential effect of lead exposure during lactation on non-essential fatty acids in maternal organs

This study determined the effects of lead exposure during the lactational period on maternal organ FA compositions in rat dams that were fed either an n−3 adequate (n−3 Adq) or deficient (n−3 Def) diet prior to conception. On giving birth, dams were subdivided into four groups in a 2×2 design with n−3 FA supply and Pb exposure as the dependent variables. Pb acetate (0.2 wt%) was administered in the drinking water from the time they gave birth to weaning 3 wk later. Following weaning, the dams were decapitated. and the liver, plasma, kidney, brain, and retina analyzed for FA composition. The n−3 deficient diets markedly decreased the percentages of total n−3 FA, including docosahexaenoic acid (DHA), and increased total n−6 FA including both arachidonic (AA) and n−6 docosapentaenoic acids in all tissues (P<0.05). The principal effects of Pb occurred in the liver and plasma, where 20–32% losses in total FA concentration concurrent with increased relative percentages of AA (P<0.05) were observed. In kidney, the percentages of AA and DHA also increased after Pb exposure (P<0.05) with lesser effects in the nervous system. There was a diet x Pb interaction for liver, plasma, and retinal 20-C n−6 PUFA (P<0.05). Generally, shorter-chain saturated and monounsaturated FA concentrations were decreased after Pb exposure. An analysis of the changes in the tissue concentrations induced by Pb indicated that the increases in the percentages of PUFA likely reflected a preferential loss of non-EFA. The mechanisms by which Pb affects saturated and monounsaturated FA concentration are unknown.     

n-3 long-chain FA decrease serum levels of TG and remnant-like particle-cholesterol in humans

A large number of papers have reported that administration of n−3 FA reduced serum TG concentrations in hypertriglyceridemic patients. However, few studies have examined the effect of n−3 FA on serum concentrations of remnant-like particle (RLP) cholesterol. Volunteers (n=41) whose serum TG concentrations were 100–300 mg/dL were recruited and randomly assigned to either an n−3 FA group or a control group with stratification by sex, age, and serum TG level in a double-blind manner. The subjects in the n−3 FA group were administered 125 ml of fermented soybean milk with fish oil containing 600 mg of EPA and 260 mg of DHA/d for 12 wk. The controls consumed control soybean milk with olive oil. Fasting blood samples were obtained before the start of administration and at 4, 8 and 12 wk. EPA concentrations in red blood cells increased significantly in all but one subject in the n−3 FA group, with no significant changes in the control group. TG levels decreased more in the n−3 FA group than in the control group at weeks 4 (P<0.05), 8 (P<0.01), and 12 (P<0.05) with their baseline as covariate. RLP cholesterol levels decreased more in the n−3 FA group than in the control at weeks 8 (P<0.01) and 12 (P<0.05) with their baseline as covariate. The groups did not differ in the other lipid levels. It is likely that n−3 long-chain FA may exert anti-atherosclerotic effects by lowering serum TG and RLP-cholesterol levels even at the dose of 860 mg/d.     

Assessment of dietary and genetic factors influencing serum and adipose fatty acid composition in obese female identical twins

Fourteen pairs of obese female monozygotic twins were recruited for a study of genetic influences on serum and adipose fatty acid (FA) composition. Following 1 wk of inpatient stabilization, fasting serum and adipose tissue obtained by surgical excision were analyzed by thin-layer and gas chromatography. Intrapair resemblances (IPR) for individual FA were assessed by Spearman rank correlation and by analysis of variance and were found in serum cholesteryl esters (CE), triglycerides (TG), and adipose TG. With two exceptions (CE linoleate and adipose eicosapentaenoate), these IPR were limited to the nonessential FA. Palmitate had significant IPR in four lipid fractions; in serum CE and adipose TG palmitate was strongly correlated with multiple measures of adiposity. In contrast to other lipid fractions, serum phosphatidylcholine (PC) FA had 12 IPR, of which 6 were essential FA including arachidonate (r=0.76, P<0.0005), eicosapentaenoate (r=0.78, P<0.0005), and docosahexaenoate (r=0.86, P<0.0001). The PC IPR could not be explained by analysis of preadmission 7-d food records. After dividing the pairs into two groups differing and nondiffering according to fat intake of individuals in the pair, there was no evidence of a gene-environment interaction between fat intake and FA composition. The IPR for nonessential FA indicate that there is active genetic control of either food choices or postabsorptive metabolic processing. The high level of IPR in the PC fraction in contrast to the other lipid fractions suggests strong genetic influence over selection of specific FA for this membrane fraction independent of diet.     

Blood pressure,serum lipids,and fatty acids in populations on a lake-fish diet or on a vegetarian diet in Tanzania

Major risk factors for coronary heart disease were assessed in two populations of Tanzania, one on a fish diet (FD) living along the coast of Lake Nyasa, and the other, mainly on a vegetarian diet (VD), living in a farming area. Lower blood pressure values were found in the FD subjects (n=618) vs. VD (n=618) (systolic blood pressure, SBP, 120±15 vs. 135±20,P<0.01; diastolic blood pressure, DBP, 70±9 vs. 78±11,P<0.01, respectively). In an FD subgroup (n=61), total cholesterol (TC) (122 vs. 136 mg/dL,P<0.01); triglycerides (TG) (82 vs. 105 mg/dL,P<0.01); and lipoprotein (a) [Lp(a)] (19.9±18.4 vs. 32.3±22.4,P<0.001) were lower than in a VD subgroup (n=55). Serum fatty acids (FA) in the FD subgroup were as follows: eicosapentaenoic acid (EPA) (20∶5) 2.48 vs. 0.72%, docosahexaenoic acid (DHA) (22∶6) 5.93 vs. 1.49%, vs. the VD, respectively. Arachidonic acid (AA) (20∶4n-6) also was higher in the FD vs. the VD group (9.85 vs. 8.30%,P<0.05), whereas 18∶2n-6 was about double (23.97 and 14.85%) in VD vs. FD. The peculiar serum FA pattern in FD reflected the FA of dietary fish. In fact, in four main species of lake fish, DHA was 8–19%, higher than EPA (1.8–4.2%), in contrast with the situation in cold-water fish, and AA was 5.8–8%, higher than in cold-water fish. The data, obtained in populations strictly on natural, unprocessed, low-fat diets, show that a diet based on freshwater fish results in lower BP, serum TC, TG, and Lp(a), and suggests that serum AA is not reduced when the major dietary n-3 is DHA rather than EPA.     

Dietary α-linolenic acid alters tissue fatty acid composition,but not blood lipids,lipoproteins or coagulation status in humans

We examined the effect of dietary α-linolenic acid (ALA) on the indices of lipid and coagulation status and on the fatty acid composition of serum and peripheral blood mononuclear cell (PBMNC) lipids in ten healthy men (age 21–37 yr) who consumed all their meals at the Western Human Nutrition Research Center for 126 d. There was a stabilization period of 14 d at the start when all 10 subjects consumed the basal diet (BD) containing 23.4 energy percent (en%) fat and two intervention periods of 56 d each. During the first intervention period, 5 subjects consumed the BD containing 23.4 en% fat, and 5 subjects consumed a diet providing 6.3% calories from α-linolenic acid [flaxseed oil (FSO) diet containing 28.8 en% fat]. Diets were crossed over between the two groups during the second intervention period. Feeding the FSO diet did not nignificantly alter serum triglycerides, cholesterol, highdensity lipoproteins, low-density lipoproteins, apoprotein A-I and apoprotein B when compared to the corresponding values in the subjects fed the BD, nor was there any effect of the FSO diet on the bleeding time, prothrombin time and partial prothrombin time for these subjects. Feeding the ALA-containing diet did cause a significant increase in ALA concentration in serum (P<0.001) and PBMNC lipids (P<0.05). It also caused a significant increase (P<0.05) in the eicosapentaenoic and docosapentaenoic acid contents of PBMNC lipids, and a decrease (P<0.01) in linoleic and eicosatrienoic acid contents of serum lipids. Thus, dietary ALA, fed for 56 d at 6.3% of calories, had no effect on plasma triglyceride or very low density lipoprotein levels or the common risk factors associated with atherosclerosis, although these parameters have been reported by others to be influenced by fatty acids, such as palmitic or linoleic acids, in the diet. Dietary ALA did significantly alter the fatty acid composition of plasma and PBMNC. The views expressed in the paper are those of the authors and do not reflect the official policy or position of the Department of Agriculture or Department of Defense, or the U.S. Government.     

Incorporation of n−3 fatty acids into plasma and liver lipids of rats: Importance of background dietary fat

The health benefits of long-chain n−3 PUFA (20∶5n−3 and 22∶6n−3) depend on the extent of incorporation of these FA into plasma and tissue lipids. This study aimed to investigate the effect of the background dietary fat (saturated, monounsaturated, or n−6 polyunsaturated) on the quantitative incorporation of dietary 18∶3n−3 and its elongated and desaturated products into the plasma and the liver lipids of rats. Female weanling Wistar rats (n=54) were randomly assigned to six diet groups (n=9). The fat added to the semipurified diets was tallow (SFA), tallow plus linseed oil (SFA-LNA), sunola oil (MUFA), sunola oil plus linseed oil (MUFA-LNA), sunflower oil (PUFA), or sunflower oil plus linseed oil (PUFA-LNA). At the completion of the 4-wk feeding period, quantitative FA analysis of the liver and plasma was undertaken by GC. The inclusion of linseed oil in the rat diets increased the level of 18∶3n−3, 20∶5n−3, and, to a smaller degree, 22∶6n−3 in plasma and liver lipids regardless of the background dietary fat. The extent of incorporation of 18∶3n−3, 20∶5n−3, and 22∶5n−3 followed the order SFA-LNA>MUFA-LNA>PUFA-LNA. Levels of 22∶6n−3 were increased to a similar extent regardless of the type of major fat in the rat diets. This indicates that the background diet affects the incorporation in liver and plasma FA pools of the n−3 PUFA with the exception of 22∶6n−3 and therefore the background diet has the potential to influence the already established health benefits of long-chain n−3 fatty acids.     

Maternal fish oil supplementation in lactation: Effect on visual acuity and n−3 fatty acid content of infant erythrocytes

Studies on formula-fed infants indicate a beneficial effect of dietary DHA on visual acuity. Cross-sectional studies have shown an association between breast-milk DHA levels and visual acuity in breast-fed infants. The objective in this study was to evaluate the biochemical and functional effects of fish oil (FO) supplements in lactating mothers. In this double-blinded randomized trial, Danish mothers with habitual fish intake below the 50th percentile of the Danish National Birth Cohort were randomized to microencapsulated FO [1.3 g/d long-chain n−3 FA (n−3 LCPUFA)] or olive oil (OO). The intervention started within a week after delivery and lasted 4 mon. Mothers with habitual high fish intake and their infants were included as a reference group. Ninety-seven infants completed the trial (44 OO-group, 53 FO-group) and 47 reference infants were followed up. The primary outcome measures were: DHA content of milk samples (0, 2, and 4 mon postnatal) and of infant red blood cell (RBC) membranes (4 mon postnatal), and infant visual acuity (measured by swept visual evoked potential at 2 and 4 mon of age). FO supplementation gave rise to a threefold increase in the DHA content of the 4-mon milk samples (P<0.001). DHA in infant RBC reflected milk contents (r=0.564, P<0.001) and was increased by almost 50% (P<0.001). Infant visual acuity was not significantly different in the randomized groups but was positively associated at 4 mon with infant RBC-DHA (P=0.004, multiple regression). We concluded that maternal FO supplementation during lactation did not enhance visual acuity of the infants who completed the intervention. However, the results showed that infants with higher RBC levels of n−3 LCPUFA had a better visual acuity at 4 mon of age, suggesting that n−3 LCPUFA may influence visual maturation.     

Hepatic lipid characteristics and histopathology of laying hens fed CLA or n−3 fatty acids

The effect of dietary CLA and n−3 PUFA on hepatic TAG accumulation, histopathology, and FA incorporation in lipid classes by laying chickens was investigated. One hundred twenty 30-wk-old single-comb white leghorn laying hens were distributed randomly to four treatments (3 replications of 10 birds) and were fed diets containing CLA and animal fat (Diet I), 18∶3n−3 (Diet II), or long-chain n−3 FA (Diet III). A sunflower oil (n−6 FA)-based diet was the control. Feeding Diet I resulted in an increase in hepatic total lipids (P<0.05). The liver TAG content was 32.2, 18.9, 29.4, and 18.7 mg/g for hens fed Diet I, Diet II, Diet III, and the control diet, respectively (P<0.05). The serum TAG was lowest in bilds fed Diet II (P<0.05). Diet I resulted in an increase in the total number of fat vacuoles and lipid infiltration in hepatocytes (P<0.05). The number of cells with 75% or higher lipid vacuolation was observed only in birds fed Diet I. Feeding diets containing CLA resulted in an increase in the content of the c9,t11 CLA isomer in liver TAG and PC (P<0.05). No difference was observed in the CLA concentration of hepatic PE fractions. The content of DHA (22∶6n−3) was higher in the TAG, PC, and PE of hens fed Diet II and Diet III than Diet I and the control (P<0.05). Feeding CLA resulted in an increase in total saturated FA in the TAG and PC fractions (P<0.05). Long-term feeding of CLA in laying birds leads to an increase in liver TAG and may predispose birds to fatty liver hemorrhagic syndrome.     

High-fat dairy product consumption increases Δ9c’ 11t−18∶2 (rumenic acid) and total lipid concentrations of human milk

Conjugated octadecadienoic acids (18∶2’ conjugated linoleic acids) have been shown to be anticarcinogenic and may influence growth and nutrient partitioning. The Δ9c’ 11t−18∶2 isomer (rumenic acid’ RA) is most common in both food sources and human tissues. To determine if maternal diet can influence milk RA concentration’ breastfeeding women (n=16) were enrolled in a 3-wk crossover study. Women initially consumed minimal amounts of food containing RA during week 1’ then were assigned randomly to consume diets rich in high-fat dairy foods (and thus RA) during week 2 or 3. Milk was collected by complete breast expression twice during each experimental week. Current and chronic RA intakes were estimated by 3-d dietary records and food frequency question-naires’ respectively. Estimated chronic RA intakes ranged from 49 to 659 mg/d. Dietary RA intake was greater during the high compared to the low dairy period (291±75 vs. 15±24 mg/d’ respectively; P<0.0001). Milk contained more RA during the high than the low dairy period (13.5±0.1 vs. 8.2±0.4 μmol/g lipid’ respectively; P<0.0001). Milk lipid concentration was influenced by diet’ such that lipid concentration was greater during the high than the low dairy period (46.6±5.0 vs. 38.3±1.6 mg/g milk’ respectively; P<0.05). Additionally’ multiple regression analyses suggested that body mass index was the primary predictor of milk RA and lipid concentrations. In summary’ these data indicate that both lipid and RA concentrations of human milk can be influenced by diet. Presented in part at the 1997 meeting of the Federation of American Sociieties for Experimental Biology’ FASEB J. 11’ A239.     

A High Legume Low Glycemic Index Diet Improves Serum Lipid Profiles in Men

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2–4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.     

Antioxidant-restricted diet reduces plasma nonesterified fatty acids in trained athletes

Nonesterified FA (NEFA) are a major fuel source for humans at rest and during moderate exercise. The effect of dietary antioxidant restriction on plasma NEFA levels and exercise performance in trained athletes was examined. Seventeen athletes followed a 2-wk restricted-antioxidant (R-AO) diet, which resulted in a threefold reduction in antioxidant intake (ascorbic acid, 139 to 49 mg; β-carotene, 5093 to 1142 μg) and a significant (P=0.001) reduction in the plasma NEFA. The amount and types of fat consumed were not different between the R-AO and habitual diets. Exercise time to exhaustion was not affected by the R-AO diet, but rating of perceived exertion (RPE) was significantly (P=0.03) elevated. The increase in RPE may have occurred as a result of the R-AO diet and subsequent reduction in plasma NEFA; however, further research is required to confirm this conclusion.     

Liver desaturase activities and FA composition in monkeys. Effect of a low-protein diet

The aim of the present study was to measure Δ9-, Δ6-, and Δ5-desaturase activities in liver microsomes, as well as phospholipid FA composition of liver and erythrocytes in monkeys fed a control or low-protein diet during the postweaning period. Ten Saimiri sciureus boliviensis (Cebidae) of both sexes were employed; at 12 mon of age they were separated into two groups fed ad libitum on a control or a low-protein diet for 24 mon. Saimiri sciureus had active Δ9, Δ6, and Δ5 liver desaturase enzymes, and these activities were influenced by the diet. A low-protein diet produced a significant reduction in Δ5-desaturation capacity, an increase in Δ9-desaturase activity, and no change in Δ6-desaturase activity (P<0.05). These changes, evoked by protein deprivation, were reflected in the liver phospholipid FA composition. Increases in the proportion of saturated FA and in monounsaturated oleic acid (18∶1n−9) and a decrease in the proportion of PUFA of the n−6 and n−3 series were produced in the animals fed a low-protein diet (P<0.0001). Differences between the two dietary groups were less pronounced in the FA composition of erythrocyte phospholipids. The authors are members of the Carrera del Investigador del Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.     

Influence of stearic acid on hemostatic risk factors in humans

Stearic acid has been claimed to be prothrombotic. Elevated plasma factor VII coagulant activity (FVIIc) may raise the risk of coronary thrombosis in the event of plaque rupture. Fibrinogen, an acute-phase protein, is necessary for normal blood clotting; however, elevated levels of fibrinogen increase the risk of coronary heart disease (CHD). Here I report the results of three controlled, human dietary intervention studies, which used a randomized crossover design to investigate the hemostatic effects of stearic acid-rich test diets in healthy young men. A diet high in stearic acid (shea butter) resulted in a 13% lower fasting plasma FVIIc than a high palmitic acid diet, and was 18% lower than a diet high in myristic and lauric acids (P=0.001) after 3 wk of intervention. The stearic acid-rich test fat increased plasma fibrinogen concentrations slightly compared with the myristic-lauric acid diet (P<0.01). When investigating the acute effects of fatty meals, those high in stearic acid (synthesized test fat) resulted in a smaller postprandial increase in FVII than those high in trans and oleic FA, indicating a smaller increase in activated FVII after ingesting stearic acid compared with fats high in monounsaturated FA, probably caused by lower postprandial lipemia. Thus, the present investigations did not find dietary stearic acid to be more thrombogenic, in either fasting effects compared with other longchain FA, or in acute effects compared with dietary unsaturated FA, including trans monounsaturated FA. The slightly increased effect on fasting plasma fibrinogen may be biologically insignificant, but it should be investigated further.     

A high-saturated fat diet enriched with phytosterol and pectin affects the fatty acid profile in guinea pigs

This paper presents the results of a study whose aim was to test the effects of several doses of pectin and phytosterols on the body weight gain and the FA content in emale guinea pigs. The treatments resulted from supplementing with pectin and plant sterol a guinea pig diet (rich in saturated FA), following a 3×3 factorial design, with three levels of pectin (0,3.67 and 6.93%) and three levels of phytosterols (0, 1.37, and 2.45%). Seventy-two female Dunkin Hartley guinea pigs were randomly assigned to the treatment groups (8 animals/group), the duration of the treatment being 4 wk. Pectin dietary intake led to a significant increase in body weight (P<0.001), food consumption (P=0.025), and feed efficiency (P<0.001), but no influence of phytosterols on weight gain or food consumption was detected. We found a significant negative effect of the addition of phytosterols on lauric, myristic, and palmitic acid concents in feces, and a positive effect on their concentration in plasma and liver, but no significant effect on stearic acid content. Apparent FA absorption was assessed by calculating the ratio of FA in feces and diets that the absorption of the different FA could be compared, and the negative effect of phytosterol supplementation on these ratios, especially for lauric and myristic acids, was established.     

Response of plasma lipids to dietary cholesterol and wine polyphenols in rats fed polyunsaturated fat diets

This experiment was designed to evaluate the effects of dietary red wine phenolic compounds (WP) and cholesterol on lipid oxidation and transport in rats. For 5 wk, weanling rats were fed polyunsaturated fat diets (n−6/n−3=6.4) supplemented or not supplemented with either 3 g/kg diet of cholesterol, 5 g/kg diet of WP, or both. The concentrations of triacylglycerols (TAG, P<0.01) and cholesterol (P<0.0002) were reduced in fasting plasma of rats fed cholesterol despite the cholesterol enrichment of very low density lipoprotein + low density lipoprotein (VLDL+LDL). The response was due to the much lower plasma concentration of high density lipoprotein (HDL) (−35%, P<0.0001). In contrast, TAG and cholesteryl ester (CE) accumulated in liver (+120 and +450%, respectively, P<0.0001). However, the cholesterol content of liver microsomes was not affected. Dietary cholesterol altered the distribution of fatty acids mainly by reducing the ratio of arachidonic acid to linoleic acid (P<0.0001) in plasma VLDL+LDL (−35%) and HDL (−42%) and in liver TAG (−42%), CE (−78%), and phospholipids (−28%). Dietary WP had little or no effect on these variables. On the other hand, dietary cholesterol lowered the α-tocopherol concentration in VLDL+LDL (−40%, P<0.003) and in microsomes (−60%, P<0.0001). In contrast, dietary WP increased the concentration in microsomes (+21%, P<0.0001), but had no effect on the concentration in VLDL+LDL. Cholesterol feeding decreased (P<0.006) whereas WP feeding increased (P<0.0001) the resistance of VLDL+LDL to copper-induced oxidation. The production of conjugated dienes after 25 h of oxidation ranged between 650 (WP without cholesterol) and 2,560 (cholesterol without WP) μmol/g VLDL+LDL protein. These findings show that dietary WP were absorbed at sufficient levels to contribute to the protection of polyunsaturated fatty acids in plasma and membranes. They could also reduce the consumption of α-tocopherol and endogenous antioxidants. The responses suggest that, in humans, these substances may be beneficial by reducing the deleterious effects of a dietary overload of cholesterol.     

Effects of dietary phenolic compounds on tocopherol, cholesterol, and fatty acids in rats

The effects of the phenolic compounds butylated hydroxytoluene (BHT), sesamin (S), curcumin (CU), and ferulic acid (FA) on plasma, liver, and lung concentrations of α- and γ-tocopherols (T), on plasma and liver cholesterol, and on the fatty acid composition of liver lipids were studied in male Sprague-Dawley rats. Test compounds were given to rats ad libitum for 4 wk at 4 g/kg diet, in a diet low but adequate in vitamin E (36 mg/kg of γ-T and 25 mg/kg of α-T) and containing 2 g/kg of cholesterol. BHT significantly reduced feed intake (P<0.05) and body weight and increased feed conversion ratio; S and BHT caused a significant enlargement of the liver (P<0.001), whereas CU and FA did not affect any of these parameters. The amount of liver lipids was significantly lowered by BHT (P<0.01) while the other substances reduced liver lipid concentrations but not significantly. Regarding effects on tocopherol levels, (i) feeding of BHT resulted in a significant elevation (P<0.001) of α-T in plasma, liver, and lung, while γ-T values remained unchanged; (ii) rats provided with the S diet had substantially higher γ-T levels (P<0.001) in plasma, liver, and lung, whereas α-T levels were not affected; (iii) administration of CU raised the concentration of α-T in the lung (P<0.01) but did not affect the plasma or liver values of any of the tocopherols; and (iv) FA had no effect on the levels of either homolog in the plasma, liver, or lung. The level of an unknown substance in the liver was significantly reduced by dietary BHT (P<0.001). BHT was the only compound that tended to increase total cholesterol (TC) in plasma, due to an elevation of cholesterol in the very low density lipoprotein + low density lipoprotein (VLDL+LDL) fraction. S and FA tended to lower plasma total and VLDL+LDL cholesterol concentrations, but the effect for CU was statistically significant (P<0.05). FA increased plasma high density lipoprotein cholesterol while the other compounds reduced it numerially, but not significantly. BHT, CU, and S reduced cholesterol levels in the liver TC (P<0.001) and percentages of TC in liver lipids (P<0.05). With regard to the fatty acid composition of liver lipids, S increased the n-6/n-3 and the 18∶3/20∶5 polyunsaturated fatty acids (PUFA) ratios, and BHT lowered total monounsaturated fatty acids and increased total PUFA (n−6+n−3). The effects of CU and FA on fatty acids were not highly significant. These results suggest some in vivo interactions between these phenolic compounds and tocopherols that may increase the bioavailability of vitamin E and decrease cholesterol in rats.     

Visual acuity and retinal function in infant monkeys fed long-chain PUFA

Previous randomized clinical trials suggest that supplementation of the human infant diet with up to 0.35% DHA may benefit visual development. The aim of the current study was to assess the impact of including arachidonic acid (AA) and a higher level of DHA in the postnatal monkey diet on visual development. Infant rhesus monkeys were fed either a control diet (2.0% α-linolenic acid as the sole n−3 FA) or a supplemented diet (1.0% DHA and 1.0% AA) from birth. Visual evoked potential acuity was measured at 3 mon of age. Rod and cone function were assessed in terms of parameters describing phototransduction. Electroretinogram (ERG) amplitudes and implicit times were recorded over a wide intensity range (−2.2 to 4.0 log scot td-sec) and assessed in terms of intensity response functions. Plasma DHA and AA were significantly increased (P <0.001) in the diet-supplemented monkeys compared with the control monkeys. There was an approximately equal effect of diet for the rod phototransduction parameters, sensitivity, and capacitance but in the opposite directions. Diet-supplemented monkeys had significantly shorter b-wave implicit times at low retinal illuminances (<−0.6 log scot td-sec). There were no significant effects of diet for visual acuity or the other 23 ERG parameters measured. The results suggest that supplementation of the infant monkey diet with 1.0% DHA and 1.0% AA neither harms nor provides substantial benefit to the development of visual acuity or retinal function in the first four postnatal months. This study was conducted at the Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852.     

Variations of <Emphasis Type="Italic">trans</Emphasis> octadecenoic acid in milk fat induced by feeding different starch-based diets to cows

The impact of starch sources differing in their velocities of ruminal degradation on the milk fat of dairy cows was studied. The animals received diets containing a slowly degradable (potatoes) or rapidly degradable (wheat) starch concentrate (40% of the dry matter) in a total mixed diet. Milk fat was the only animal performance factor affected: Cows produced significantly less milk fat when fed the wheat diet than the potato diet (−3.3 g/kg, −122 g/d; P<0.05). With the wheat diet, milk fat was poorer in short-chain FA and richer in unsaturated longchain FA, especially in trans octadecenoic acid (4.4 vs. 2.7% of the total FA, P<0.05). A very large increase in the isomer trans-10 18∶1 (+1.46% of the total FA) was observed. Because no difference in volatile FA concentrations in the rumen was revealed, the increase in trans octadecenoic acids, and particularly the isomer trans-10 18∶1, was associated with the larger postprandial drop in ruminal pH with wheat. Similar concentrate levels and FA profiles in both diets indicated that the decrease in milk fat was due to changes in the ruminal environment. Quicker degradation of wheat starch, and hence a greater drop in pH with this diet associated with the absence of any effect on volatile FA, strengthen the hypothesis developed in the literature of enzyme inhibition via increased levels of trans octadecenoic acids, especially the trans-10 isomer. Hence, milk fat can be decreased with rapidly degradable starch sources and not only with high levels of concentrates in the diet or added fat. More detailed work is necessary to elucidate the microorganisms involved and to determine whether metabolic pathways similar to those reported for high-concentrate diets are involved.     

Vitamin A deficiency enhances docosahexaenoic and Osbond acids in liver of rats fed an α-linoleic acid-adequate diet

The synthesis of docosahexaenoic (DHA, 22∶6n−3) and Osbond acid (OA, 22∶5n−6) is regulated by the heterodimer of peroxisome proliferator-activated receptor and retinoid X receptor (RXR). 9-Cis retinoic acid, a metabolite of vitamin A, is the most potent ligand of RXR. We tested whether vitamin A deficiency impairs DHA and OA synthesis in rats fed a vitamin A- and α-linolenic acid (ALA)-sufficient (VASALAS), vitamin A-sufficient and ALA-deficient (VASALAD), vitamin A-deficient and ALA-sufficient (VADALAS), or vitamin A- and ALA-deficient (VADALAD) diet. After 7 wk of feeding, liver and colon choline (CPG) and ethanolamine (EPG) phosphoglyceride FA were analyzed. The VADALAS compared with the VASALAS rats had elevated levels of both DHA (P<0.05) and OA (P<0.05) in liver CPG and EPG. In contrast, the VADALAD group had a lower DHA (P<0.01) and higher OA (P<0.005) level in CPG and EPG of both tissues than their VASALAD counterparts. ALA deficiency reduced DHA and enhanced OA levels in liver and colon CPG and EPG in both the vitamin A-sufficient (VASALAS vs. VASALAD) and-deficient (VADALAS vs. VADALAD) rats (P<0.005). The study demonstrates that ALA deficiency reduced DHA and enhanced OA levels in tissue membranes, and dietary vitamin A deficiency has a profound effect on membrane DHA and OA in rat tissues. Both vitamin A and DHA are involved in a myriad of vital physiological functions pertaining to growth and development and health. Hence, there is a need for a further study to unravel the mechanism by which vitamin A influences membrane DHA and OA.     

Effect of five cysteine-containing compounds on three lipogenic enzymes in Balb/cA mice consuming a high saturated fat diet

The in vivo effects of N-acetyl cysteine (NAC), S-allyl cysteine, S-ethy cysteine (SEC), S-methyl cysteine (SMC), and S-propyl cysteine (SPC) against hyperlipidemia development and oxidation stress in Balb/cA mice consuming a high saturated fat diet were examined. The influence of these agents on plasma levels of glucose, insulin, uric acid, TG, cholesterol, and the activity of three lipogenic enzymes—glucose-6-phosphate dehydrogenase, malic enzyme, and FA synthase—was determined. All mice consumed the coconut oil-basd, high saturated fat diet, water, and cysteine or one of the five cysteine-containing compounds for 4 wk. The diet with 18% saturated fat significantly elevated the activity of three lipogenic enzymes and significantly increased TG and cholesterol biosynthesis in plasma and liver (P<0.05). When compared with the water and cysteine groups, the treatments from five cysteine-containing agents significantly reduced high saturated fat diet-increased malic enzyme and FA synthase activities, and significantly lowered TG levels in plasma and liver (P<0.05); however, only NAC, SAC, and SMC treatments significantly reduced cholesterol levels in plasma and liver (P<0.05). The five cysteine-containing agents significantly restored high saturated fat diet-decreased glutathione peroxidase (GPX) activity in liver (P<0.05); however, only SMC and SPC significantly restored GPX activity in heart and kidney (P<0.05). These agents also significantly improved high saturated fat diet-related hyperglycemia, hyperuricemia, and oxidation stress (P<0.05). These data support the hypothesis that these compounds are potential multiply-protective agents for hyperlipidemia prevention or therapy.