Effects of diets rich in saturated fatty acids with or without added cholesterol on plasma lipids and lipoproteins

Semi-synthetic diet I which contained 16% hydrogenated coconut oil and 5% cholesterol, and diet II, identical to I but without cholesterol supplement, were fed to dogs for four months to determine the effects of added cholesterol on lipemia produced by diets high in saturated fatty acids (FA) and lacking essential FA. In addition, diet I was fed to another group of dogs for 12 to 16 months. The initiation of lipemia was very similar in all experimental animals. Plasma from dogs on diets I and II showed significant increases in lipid concentration and changes in FA per cent composition within the first week, as compared to controls, while during the first month there was no difference in lipid concentration or FA distribution in all lipid fractions between I and II. At the 10th and 16th weeks plasma total and free cholesterol and phospholipid were significantly higher in the group on diet I, with the cholesterol supplement, than on diet II with no added cholesterol, but there was no difference in triglyceride concentration between these groups. Dogs on diet I for 12 to 16 months showed a further and substantial increase in plasma FA concentration; these changes were most marked in cholesteryl esters. Little or no lipoprotein with electrophoretic and ultracentrifugal properties of alpha-lipoprotein was present in the plasma. Immunotechniques showed that it was present. The composition of dietary FA had great influence in producing this hyperlipemia. Lipemia produced was not a simple reflection of the FA in these diets as evidenced by the increase in some FA, e.g., C_16∶1, which was absent in the experimental diets and C_18∶1, which contributed only 3.4% of the FA. Large increases in palmitoleate and oleate indicate synthesis or mobilization or both from other tissues. Diets composed predominantly of saturated medium chain length fatty acids, with or without added cholesterol were equally effective in the initiation of hyperlipemia. Data also suggest that added cholesterol is necessary for sustaining hyperlipemia. Presented in part at the AOCS Annual Meeting, New Orleans, April 1970.     

Dietary effects of conjugated octadecatrienoic fatty acid (9 cis, 11 trans, 13 trans) levels on blood lipids and nonenzymatic in vitro lipid peroxidation in rats

The present study examined the antioxidant activity of conjugated octadecatrienoic fatty acid (9 cis, 11 trans, 13 trans-18∶3), α-eleostearic acid, of karela seed (Momordica charantia), fed to rats for 4 wk. The growth pattern of rats and the effect on plasma cholesterol and high density lipoprotein (HDL) cholesterol and peroxidation of plasma lipid, lipoprotein, eryhrocyte membrane, and liver lipid were measured. Rats were raised on diets containing sunflower oil mixed with three different levels of conjugated trienoic fatty acid (9c,11t,13t-18∶3) 0.5,2, and 10% by weight; the control group was raised with sunflower oil as dietary oil as the source of linoleic acid (9c,12c-18∶2). The growth pattern of the three experimental groups of rats showed no significant difference compared to the control group of rats, but the group with 10% 9c,11t,13t-18∶3 had slightly higher body weight than the control group of rats. Concentrations of total cholesterol, HDL-cholesterol, and non-HDL-cholesterol in plasma were similar in all four groups. Plasma lipid peroxidation was significantly lower in the case of 0.5% 9c,11t,13t-18∶3 group than the control group and the 2 and 10% 9c,11t,13t-18∶3 dietary groups as well. Lipoprotein oxidation susceptibility test with 0.5,2 and 10% 9c,11t,13t-18∶3 dietary groups was significantly less susceptible to lipoprotein peroxidation when compared with sunflower oil dietary group, and the dietary group with 0.5% 9c,11t,13t-18∶3 showed least susceptibility. There was significant lowering in erythrocyte ghost membrane lipid peroxidation in the 0.5,2, and 10% 9c,11t,13t-18∶3 dietary groups compared to the sunflower oil groups. Nonenzymatic liver tissue lipid peroxidation was significantly lower in the group of rats raised on 0.5% 9c,11t,13t-18∶3, but the groups on 2 and 10% 9c,11t,13t-18∶3 acid did not show any significant difference compared with the control group of rats.     

Effect of modified dairy fat on postprandial and fasting plasma lipids and lipoproteins in healthy young men

Fatty acid profile of milk fat can be modified by cow feeding strategies. Our aim was postprandially and after 4 wk to compare the effect of a modified milk fat (M diet) [with 16% of the cholesterolemic saturated fatty acid (C12–16) replaced by mainly oleic and stearic acids] with the effect of D diet, including a conventional Danish milk fat on plasma lipids and lipoproteins. A side effect of the cow feeding regime was a 5% (w/w) increase in trans fatty acid in M diet. Eighteen subjects were fed for two periods of 4 wk strictly controlled isoenergetic test diets with 40% of energy from total fat and the same content of dietary cholesterol in a randomized study with cross-over design. Contrary to expectations, fasting low density lipoprotein (LDL) cholesterol concentration did not differ after the experimental periods. However, M diet resulted in a higher fasting total triacylglycerol concentration compared to D diet (P=0.009). Postprandial samples were taken at two different occasions (i) at day 21, after breakfast and lunch and (ii) on the last day of the study 2, 4, 6, and 8 h after a fat load. Postprandial plasma triacylglycerol and chylomicron triacylglycerol showed higher peak values after D diet than M diet (interaction effect, diet × times P<0.05). In conclusion, M diet did not lower LDL cholesterol compared to D diet. Thus any cholesterol-lowering effect of oleic and stearic acids may have been obscured by the high content of cholesterol-raising saturated fatty acids in milk fat. A higher content of the trans fatty acids in M diet might have counteracted the cholesterol neutral/decreasing effect and increased plasma triacylglycerol.     

Gradients of n-heptane and acetonitrile in silver-ion high-performance liquid chromatography analyses of cis and trans bonds in lipids

Cis and trans isomers of fatty acid methyl esters, fatty alcohols, and triacylglycerols were analyzed with a silverion high-performance liquid chromatography system. Gradients of n-heptane and acetonitrile were used to elute molecules with up to nine cis double bonds. The analyses were as fast and reliable and had a resolution similar to that of the best published analyses. However, published analyses were performed with chlorinated solvents, and these solvents are carcinogenic and mutagenic. The solvents we used, heptane and acetonitrile, are less dangerous to the analyst.     

BR中顺反结构含量测定

试验研究红外光谱法测定BR中不同结构含量。结果表明,利用BR中各种结构红外吸收中吸光度或透过率的测定值,可计算BR中顺式1,4-结构、顺式1,2-结构和反式1,4-结构的含量。该方法简便、快速,为BR结构分析和控制提供了一种有效手段。     

Determination of FA composition and total trans FA of Turkish margarines by capillary GLC

In this research, FA composition and total trans FA contents of 16 different brands of margarine (8 hard-type and 8 soft-type) sold in Turkey were determined by capillary GLC method. According to the results, the contents of saturated FA, monounsaturated FA, and PUFA were within the ranges of 23.9–32.3, 44.0–61.9, and 14.2–24.1%, respectively, in hard-type margarines, and 27.0–39.9, 21.0–40.9, and 32.0–53.7%, respectively, in soft-type margarines. Hard-type margarines contained total trans FA concentrations of 20.1–34.3%, whereas soft-type margarines contained less than 8.9% total trans FA. C_18∶1 trans acid content was within the range of 18.5–29.8% in hard-type margarines, and it was significantly higher than the range in soft margarines (0.7–8.1%). C_18∶1 trans acid was the major trans FA in all margarines, and C_18∶3 trans acid concentrations were less than 0.2%.     

Dietary triacylglycerol structure and saturated fat alter plasma and tissue fatty acids in piglets

Human and pig milk triacylglycerols contain a large proportion of palmitic acid (16:0) which is predominately esterified in the 2-position. Other dietary fats contain variable amounts of 16:0, with unsaturated fatty acids predominantly esterified in the 2-position. These studies determined if the amount or position of 16:0 in dietary fat influences the composition or distribution of liver, adipose tissue, lung, or plasma fatty acids in developing piglets. Piglets were fed to 18 d with sow milk or formula with saturated fat from medium-chain triglyceride (MCT), coconut or palm oil, or synthesized triacylglycerols (synthesized to specifically direct 16:0 to the 2-position) with, in total fatty acids, 30.7, 4.3, 6.5, 27.0, and 29.6% 16:0, and in 2-position fatty acids, 55.3, 0.4, 1.3, 4.4, and 69.9% 16:0, respectively. The percentage of 16:0 in the 2-position of adipose fat from piglets fed sow milk, palm oil, and synthesized triacylglycerols were similar and higher than in piglets fed MCT or coconut oil. Thus, the amount, not the position, of dietary 16:0 determines piglet adipose tissue 16:0 content. The effects of the diets on the plasma and liver triacylglycerols were similar, with significantly lower 16:0 in total and 2-position fatty acids of the MCT and coconut oil groups, and significantly higher 16:0 in the plasma and liver triacylglycerol 2-position of piglets fed the synthesized triacylglycerols rather than sow milk or palm oil. The lung phospholipid total and 2-position 16:0 was significantly lower in the MCT, coconut, and palm oil groups, but similar in the synthesized triacylglycerol group and sow milk group. The lung phospholipid total and 2-position percentage of arachidonic acid (20:4n-6) was significantly lower in all of the formula-fed piglets than in milk-fed piglets. The physiological significance of this is not known.     

Physico-mechanical properties of cis and trans polyisoprene binary networks

Summary In the present paper we report the physico mechanical properties of elastomeric systems obtained vulcanizing mixtures of cis and trans polyisoprene.The presence of the trans polymer strongly affects the physical behaviour that is typical of a biphasic system,where a plastic component is segregated in the elastomeric matrix.The experimental results are reported and discussed giving particular attention to the structural features and to the general problem of the physical behaviour of elastomeric systems.     

Dietary lipids and arteriosclerosis

A great deal of attention has been given to the question of whether dietary fats in general and certain fats in particular play an important part in such arteriosclerotic complications as heart attacks and strokes. Milk fats have been widely accepted as desirable nutritional fats. Cow milk fat, or butter, contains a wide variety of fatty acid derivatives, including the important, medium chain acids. The structural configuration of butter triglycerides facilitates absorption of the palmitate present in butter. However, there have been objections to the use of butter and other forms of milk fat because of the preoccupation of many investigators with the unproven lipid theory of arteriosclerosis, and because serum cholesterol levels are relatively high after the intake of milk fat. Reevaluation of the lipid theory suggests that cholesterol can hardly be an atherogenic factor. Cholesterol occurs under conditions of tissue repair, and it may well be that the high serum levels in arteriosclerotic conditions are a consequence of such processes. The low serum levels occurring after the consumption of polyunsaturated vegetable oils are often associated with high tissue levels of cholesterol. Long term clinical studies and population surveys suggest that this century’s changes in mortality and morbidity are much less related to dietary factors (other than over-eating) than is claimed. New insights in the fields of immunology and microbiology may be vastly more important for an understanding of some etiological factors in arteriosclerosis.     

Changes in plasma lipids,lipoproteins, triglyceride secretion and removal in chicks with estrogen implants

Estradiol implants in chicks resulted in marked elevation of all major plasma lipids with greatest increase in triglyceride (TG) followed by phospholipid (PL) and cholesterol (C). During the two-wk period, plasma TG level in estrogen (E)-treated chicks increased to about 45 times that of controls (139.6 vs 6,368.3 mg/dl). The level of cholesterol also increased steadily during the same period, attaining nearly a six-fold increase in comparison with the control (150.7 vs 871.8 mg/dl), and the level of PL was markedly elevated from 209 to 2,861 mg/dl. Besides the induction of hyperlipidemia, E treatment also resulted in a notable alteration in the fatty acid composition of plasma lipids; there was an increase in oleic acid concomitant with a decrease in polyunsaturated fatty acids, particularly, linoleic acid. One day after implantation, the percentage of oleic acid in TG fraction increased from 39.2 to 43.7%, reaching 55.4% of the total fatty acids at day 14. In contrast, the levels of linoleic and arachidonic acid decreased significantly from 16.1 to 8.3% and 4.3 to 0.6%, respectively, during the same period. In cholesteryl ester (CE) and PL, the oleic acid level also increased from 25.2 to 47.3% in the former and from 11.9 to 29.6% in the latter, reflecting enhanced hepatic lipogenesis. Analysis of plasma lipoproteins in E-treated chicks revealed dramatic alterations in the concentrations of lipids and protein in individual lipoprotein fractions, especially very low density lipoprotein (VLDL) fraction. The respective levels of TG, C and PL in the VLDL fractions were 10.0, 0.6 and 1.0 mg/dl in the control, and 3,904.4, 530.3 and 1,365.2 mg/dl in chicks implanted with estrogen for seven days. The concentrations of TG, C and PL also were markedly increased in the low density lipoprotein (LDL) fraction in these birds. However, the cholesterol content of the high density lipoprotein (HDL) fraction was decreased dramatically in E-treated chicks (47.1) relative to the control (121.5 mg/dl). The protein level in the VLDL fraction from E-treated chicks was profoundly elevated to a level 300-fold greater than controls. TG secretion rates were measured in vivo following the administration of Triton WR-1339. In control chicks, plasma TG secretion rate was 2.29 mg/min; whereas, chicks treated with E for one and three days showed significantly higher TG secretion rates of 3.18 and 5.27 mg/min, respectively. TG removal rates were measured in vivo after administration of a 10% fat emulsion. Although plasma TG concentrations were different between control and E-treated birds, no significant differences were found in TG removal rates in those birds, indicating no impairment of TG clearance in E-treated chicks.     

The metabolism of triglycerides containing cis and trans octadecenoic fatty acids

Summary Weanling rats were fed diets containing triglycerides composed of bothcis andtrans fatty acids for 16 days. The animals were sacrificed, and the lipides were extracted quantitatively from the heart, liver, feces, and the rest of the carcass. Infrared analyses were carried out to determine the fate of thetrans acids.Trans acids with the double bond either in the 8 or 9 position are metabolized efficiently by the rat organism. Armour Fellow, University of Illinois, 1955–56.     

HPLC Characterization of cis and trans Mixtures of Double-Decker Shaped Silsesquioxanes

Silicon - HPLC was used as the quantitative analysis technique in determining the molar ratio of cis and trans isomers in the double-decker shaped silsesquioxanes (DDSQ). Different experiments were...     

Effects of the ratio of polyunsaturated and monounsaturated fatty acid to saturated fatty acid on rat plasma and liver lipid concentrations

The effects of dietary monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid+MUFA/saturated fatty acid (PUFA+MUFA/SFA) ratio on plasma and liver lipid concentrations were studied. In experiment I, when rats were fed with 40% fat (energy%, PUFA/SFA ratio 1.0) and 1% (w/w) cholesterol (C) diets for 21 d, a large amount of MUFA (28.1 energy%, PUFA+MUFA/SFA=5.7) in the diet was found to increase the plasma total C, triacylglycerol (TAG), and phospholipid (PL) as compared with the low-MUFA diet (7.0 energy%, PUFA+MUFA/SFA=1.4). The plasma very low density lipoprotein (VLDL)-C, VLDL-TAG, VLDL-PL, and low density lipoprotein (LDL)-C increased significantly in the high-MUFA diet group, but high density lipoprotein (HDL)-C did not change significantly. The high-MUFA diet resulted in greater accumulation of liver C but lesser accumulation of TAG. In experiment II, when dietary SFA was fixed at a certain level (13.2 energy%; PUFA+MUFA/SFA=2.0), rats given a larger amount of MUFA (23.1 energy%; PUFA/MUFA=0.2; MUFA/SFA=1.8) showed higher plasma and liver C levels than did the low-MUFA diet (7.7 energy%; PUFA/MUFA=2.5; MUFA/SFA=0.6). When PUFA was fixed at a certain level (24.4 energy%), there was not a significant difference in the plasma C level between the high-and low-MUFA dietary groups (PUFA+MUFA/SFA=4.8 and 8.4), but the higher PUFA+MUFA/SFA diet, which was high in MUFA/SFA ratio, significantly decreased the plasma HDL-C and TAG levels. However, when MUFA content was fixed at a certain level (16.4 energy%), no significant difference was observed between the two groups with different PUFA/SFA ratios of 0.2 and 4.1, but liver C level was raised in the higher PUFA/SFA diet. It appears that the PUFA/SFA ratio alone is unsuitable to predict the change of plasma C level, because a large amount of dietary MUFA may lead to an increase of plasma and liver lipids in rats. It seems that the prerequisites for keeping low plasma and liver C are (i) low MUFA/SFA ratio, (ii) high PUFA/MUFA ratio, and (iii) PUFA+MUFA/SFA ratio not to exceed 2.     

Conversion of 18∶3 Δ9cis, 12cis, 15trans in rat liver microsomes

Several years ago, it was established that the Δ15 trans isomer of α-linolenic acid is converted in vivo into fatty acids containing 20 and 22 carbons (geometrical isomers of eicosapentaenoic and docosahexaenoic acids). The present study focused on the in vitro Δ6 desaturation, the first step of the biosynthesis of the n-3 long-chain polyunsaturated fatty acids from 18:3n-3. For that purpose, rat liver microsomes were prepared and incubated with radiolabeled 18∶3 Δ9cis, 12cis, 15cis (18∶3 c,c,c) or 18∶3 Δ9cis, 12cis, 15trans (18∶3c,c,t) under desaturation conditions. The data show that 18∶3c,c,t is converted at a lower rate compared with α-linolenic acid. The product of conversion of 18∶3 c,c,t may be 18∶4 Δ6cis, 9cis, 12cis, 15trans resulting from a Δ6 desaturation of the trans substrate. Moreover, the conversion of radiolabeled 18∶3c,c,t was strongly decreased by the presence of 18∶3c,c,c (up to 48%) while the 18∶3c,c,t only slightly decreased the conversion of radiolabeled 18∶3c,c,c. Thus, the desaturation enzyme presented a higher affinity for the native all-cis n-3 substrate.     

The effects of fat-free,saturated and polyunsaturated fat diets on rat liver and plasma lipids

The liver and plasma lipids and fatty acid composition of rats fed synthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a high carbohydrate, fat-free diet for 48 hr. They were then divided into three groups and fed for an additional 48 hrs the following: group 1, the fat-free diet; group 2, a diet containing 44% of calories from corn oil; and group 3, a diet containing 44% calories from completely hydrogenated soybean oil. The total lipid concentration of the liver in the animals on the fat-free diet was elevated at 72 and 96 hr. The addition of either saturated or unsaturated fat in the diet at 48 hr prevented this accumulation. The total phospholipid and cholesterol concentrations of the liver were relatively uninfluenced by any diet in this study. Plasma total fatty acid concentration was elevated at 72 hr in the animals on a fat-free diet compared to those fed the stock diet, starved for 48 hr or fed the fat-containing diets. By 96 hr, however plasma fatty acid concentrations in all groups were similar to those in animals fed only the stock diet. The release of de novo synthesized fatty acids into plasma from the liver was strongly inhibited by dietary fat, either saturated or polyunsaturated. With the fat-free diet there was a significant increase in the saturated and monounsaturated fatty acids in both liver and plasma. The addition of corn oil to the diet facilitated a reversion of the fatty acid composition in liver and plasma to that found in the animals fed the stock diet ad libitum, but saturated fat did not. No effect of diet on the fatty acid composition of the red cells was observed during the course of this study. Exogenous saturated fatty acids, although similar chemically to the fatty acids synthesized by the liver, may have physiological actions that differ from endogenously synthesized fat.     

Dietary saturated,monounsaturated, n−6 and n−3 fatty acids,and cholesterol influence platelet fatty acids in the exclusively formula-fed piglet

Platelet lipid composition is important to normal platelet morphology and function, and is influenced by dietary fatty acids and cholesterol. The fatty acid composition and cholesterol content of infant formulas differs from those of human milk, but the possible effects on platelet lipids in young infants is not known. This was studied in piglets fed from birth to 18 d of age with one of eight formulas differing in saturated fatty acid chain length, or content of 18∶1, 20∶5n−3 plus 22∶6n−3, or cholesterol. A reference group of piglets fed sow milk was also studied. Sow milk has a fatty acid composition and cholesterol content similar to that of human milk. Piglets fed formulas high in 18∶1 (34.9–40.8% wt fatty acids) and low in 16.0 (≤6.5% wt fatty acids) had lower platelet counts and greater platelet size than piglets fed sow milk (40.4% 18∶1, 30.7% 16∶0). Piglets fed formulas high in 16∶0 (27–29.6%) and 18∶1 (40–40.6%), or low in both 16∶0 (5.9–6.1%) and 18∶1 (10.8–11.2%), had similar platelet counts and size to piglets fed sow milk. Platelet phospholipid % 20∶4n−6 was lower in all the groups of piglets fed formula than in the group fed sow milk. Addition of fish oil with 20∶5n−3 plus 22∶6n−3 to the formula further decreased platelet phospholipid 20∶4n−6. Addition of cholesterol to the formula increased the platelet phospholipid % 20∶4n−6 and platelet volume.     

Gas chromatographie separation of cis and trans isomers of long chain amines

There are important differences in the physical properties of the cis and trans isomers of unsaturated long chain amines. Because of these differences, it is desirable to know the ratio of the cis and trans isomers. This separation can be accomplished by capillary column gas chromatography of the amine derivatives; however, the use of capillary columns is too slow for routine analysis. It was found that the cis and trans isomers of unsaturated amines can be rapidly separated on packed columns containing cyanopropyl-phenylsilicone liquid phases (Apolar 10C). The primary amines are converted to the trifluoroacetamides and separated on 6- to 10-ft columns containing 10% Apolar 10C at 180 C. The technique has been applied to unsaturated long chain primary amines and diamines. Useful information on the isomerization of these compounds during their synthesis can be obtained.     

Occurrence of n−5 monounsaturated fatty acids in jujube pulp lipids

The pulp lipids of jujube (Zizyphus jujuba var.inermis) fruit have been shown by chromatographic, spectrometric and chemical analyses to contain a series ofcis-monoenoic fatty acids with n−5 unsaturation as major acyl moieties. The total concentration of these n−5 fatty acids, such as 14∶1n−5, 16∶1n−5 and 18∶1n−5, ranged from 22 to 54% of total fatty acids in the pulp lipids of 11 different sources. The main component of the n−5 homologues was 16∶1n−5 in all cases. Other monoenoic acids with n−7 unsaturation, namely palmitoleic (cis-9-hexadecenoic) acid andcis-vaccenic (cis-11-octadecenoic) acid, as well as with n−9 unsaturation, namely oleic acid, were also identified. In the seed lipids of jujube fruit, none of the n−5 monoenoic acids could be detected. Thus the jujube pulp lipids are characterized by the predominance of n−5 monoenoic acid isomers.     

FA composition of plasma,red blood cell,and liver phospholipids of newborn piglets fed trans isomers of alpha-linolenic acid

The effects of dietary cis and trans α-linolenic acid (18∶3n−3) on the FA composition of plasma, red blood cell, and liver phospholipids were studied in newborn piglets. Animals were fed for 14 d with one of three diets: a control diet (group A) containing cis 18∶3n−3 at a level of 2.0% of total FA, a diet (group B) in which a part of the 18∶3n−3 acid was isomerized (1.3% of cis 18∶3n−3 and 0.7% of trans 18∶3n−3), or a diet (group C) with 2.0% cis 18∶3n−3 and 0.7% trans 18∶3n−3. Feeding animals with diets containing trans 18∶3n−3 resulted in the presence of trans isomers of 18∶3n−3, trans isomers of EPA, and trans isomers of DHA in phospholipids; however, the level of total trans n−3 PUFA in tissues was less than 0.3% of total tissue FA. In group B, the reduction of dietary amounts of cis 18∶3n−3 was associated with a decrease in individual and total cis n−3 PUFA. In contrast, in group C there was no decrease in tissue n−3 PUFA despite the increased dietary level of trans 18∶3n−3. These results suggest that the isomerization of a part of dietary n−3 PUFA, leading to the reduction of their levels in the diet, could induce a decrease in n−3 PUFA in phospholipids. The physiological effects of trans PUFA are not known and should be considered in future studies.