Effects of dietary monounsaturated fatty acids on plasma lipids in humans

In order to test whether monounsaturated fatty acids (MUFA, M) would lower plasma cholesterol and/or triglycerides (TG), 14 young men were studied in a metabolism ward. They were given two experimental diets with the same P/S ratio (P: polyunsaturated; S:saturated fatty acids) but different P + M/S ratios in composition of dietary fatty acids. Six men were in experiment I. In two groups of three, each group was given either the high or the low P + M/S ratio diet for 6 weeks. In experiment II, two groups of four men were subjected to a 3-week cross-over feeding trial (total of 6 weeks). We found in the crossover study that when the dietary P/S ratio was fixed at 1.0, those subjects given a diet with the higher P + M/S ratio of 4.5 showed significantly higher plasma total TG, very low density lipoprotein (VLDL)-TG, low density lipoprotein (LDL)-TG, and LDL-cholesterol than when given a diet with a lower P + M/S ratio of 1.5. Plasma total cholesterol, apoprotein A-I, and apoprotein B-100 were not significantly different between the two dietary periods. Plasma fatty acid patterns showed a significantly higher plasma MUFA level during the period of a higher P + M/S diet. In contrast to some recent reports, our studies indicate that a large amount of dietary MUFA may raise some fractions of plasma lipids in humans.     

Polyunsaturated fatty acids in plasma and erythrocyte membrane lipids of diabetic children

While insulin is a potent activator of essential fatty acid metabolism, portal hypoinsulinemia is common in Type 1 diabetes. Fatty acids were determined by high-resolution capillary gas-liquid chromatography in plasma and erythrocyte membrane lipids in diabetic children (n = 40) and in age-matched healthy controls (n = 40). In plasma phospholipids, values of linoleic acid (23.00 [2.35] vs. 18.13 [2.54], % by wt, median [range from the first to the third quartile], P<0.000l) and alpha-linolenic acid (0.12 [0.06] vs. 0.07 [0.07], P<0.05) were significantly higher in diabetic children than in controls. In contrast, values of arachidonic acid (10.73 [2.34] vs. 11.53 [2.50], P<0.05) and docosahexaenoic acid (2.23 [0.63] vs. 2.77 [0.98], P<0.01) were significantly lower in diabetic children than in controls. Reduced availability of long-chain polyunsaturates in diabetic children suggests that an enhanced dietary supply of long-chain polyunsaturates may be beneficial.     

Age-associated changes in rat plasma lipids, platelet fatty acids and prostacyclin release

The effect of age on plasma lipids, platelet fatty acids and prostacyclin release was studied in the rat. The contents of arachidonic acid, cholesterol, bile acids and free fatty acids in the plasma of aged rats (15 months old) were higher than those of young rats (3 months old). No significant differences in fatty acid composition of platelet lipids and release of prostacyclin from aortas between young and aged rats were observed. The data suggest that plasma lipids may play a more important role in the development of cardiovascular disease with increasing age than prostaglandins do.     

The glyconeogenicity of fatty acids in mammals

Although excess glucose can be readily converted to fatty acids in mammals, most textbooks state that glucose cannot be formed from fatty acids. Whilst this remains largely true, several pathways have now been discovered in mammals in which fatty acids are potentially gluconeogenic.     

The effects of n-3 and n-6 polyunsaturated fatty acids on plasma lipids and fatty acids of treated phenylketonuric children

Dietary-treated phenylketonuric patients (PKUs) display low levels of long-chain polyunsaturated fatty acids (PUFA) in plasma lipids. In a 6-month clinical trial we observed a decrease of triglycerides and an increase of n-3 long-chain PUFA in plasma of PKUs supplemented with fish oil, while no major differences in respect to the baseline values were found in a group supplemented with blackcurrant oil. A more complete source of long-chain PUFA of both the n-6 and n-3 series should be investigated for dietary supplementation of PKU patients.     

Fatty acids and carbohydrate-containing lipids in four Micrococcaceae strains

Fatty acid composition and lipidic carbohydrate to lipidic phosphorus molar ratio of yellow pigmented micrococci are compared to red pigmented ones and may be summarized by three indexes. These bacteria show wide differences in their fatty acid composition: three strains possess saturated branched chain fatty acids and one has unsaturated straight chain ones. A significant increase in 'anteiso/iso indexes' is observed between pink (M. roseus) and yellow colored bacteria (M. lysodeikticus, S. lutea). There is no significant difference (P greater than 0.05) between the 'unsaturation indexes' of the red pigmented parental D. radiodurans strain and its colorless mutant. Radioresistant strains exhibit a higher 'carbohydrate/phosphorus index' than other strains. There seems to be a relationship between a high carbohydrate-containing lipid content and a high resistance to physical and chemical agents, in particular to radiations. These differences observed in the lipid composition have implications in taxonomy and in establishing an evolutionary scheme.     

Silver ion chromatography of lipids and fatty acids

Silver ion chromatography as applied to the analysis of lipids is reviewed. Thin-layer, column, high-performance liquid and supercritical fluid chromatography in the silver ion mode are included. The lipid types covered are fatty acids, triacylglycerols and complex lipids. Separations are divided into those according to number, geometry and position of double bonds, as well as acyl positional isomers for triacylglycerols. The mechanism of silver ion chromatography is discussed in relation to recent studies using silver ion high-performance liquid chromatographic methodology.     

Bone lipids and fatty acids of Peru fish

The neurocranium of the vieja, Pimelometopon darwini, and the cojinoba, Seriolella violacea, contained 29.5 and 26% lipid (as percent dry weight), mostly as triacylglycerol. The anchoveta, Engraulis ringens; sardina, Sardinops sagax sagax; doncella, Halichoeres dispilis; and mackerel, Scomber japonicus, contained less lipid in the neurocranium (3.3–18.4%). Polyunsaturated fatty acids, dominated by 20:5 and 22:6, were highest for S. violacea (10.6–56.1%) and P. darwini (12.2–28.9%). Lower levels of polyunsaturated fatty acids were found in E. ringens. The major monosaturated fatty acids in all Peruvian fish included 16:1n7, 18:1n9 + 11, and 18:n7, whereas the major saturated fatty acids were 14:0 and 16:0 with lesser amounts of 18:0.     

Changes in the composition of fatty acids in blood plasma lipids and in various organs in traumatic shock

The composition of fatty acids of the total lipids of the myocardium, lungs, liver, intestine, adipose tissue, and blood plasma was studied during traumatic shock reproduced in dogs by crush of soft tissues of the hip. The formation of the shock process was accompanied by a rise in the percentage content of linoleic and arachidonic acids in the blood plasma and some organs; a close correlation existed between the linoleic acid content in the adipose tissue and the blood. Oleic acid deficiency was revealed in the lipids of the organs under study.     

Total fatty acids of hair lipids in cystic fibrosis

In a preliminary study, total fatty acids of lipids removed from hair of subjects of either sex with cystic fibrosis (n = 17; average age 8.3 years) and controls (n = 24; average age 9.1 years) were analyzed by gas chromatography. In contrast to the blood lipids in cystic fibrosis which display various fatty acid changes as a depression in 18:2 and increases in 16:0, 16:1, and 18:1, such profiles did not occur with the hair lipids. With the latter, total fatty acids in cystic fibrosis showed decrements in 18:1 and in the lesser concentrations of 20:1 and members below C14 as compared to the respective control series.     

Changes in liver microsome lipids and plasma fatty acids induced by dietary orotate in the weanling rat.

1. Dietary orotate produced a decrease in total plasma fatty acids which was reflected in low values of saturated, monounsaturated and polyunsaturated fatty acids longer than 18 carbon atoms of the n-6 series. The relative content of saturated fatty acids in microsomes of animals fed orotate was also decreased. 2. Rat liver delta-9 desaturase activity was lower in the group fed orotate. However, delta-6 desaturase activity did not show significant differences between the groups. 3. Microsomal cholesterol content was lower in rats fed orotate than in controls but phospholipid phosphorus contents were similar. These results suggest a direct effect of dietary orotate on the key enzymes which regulates cholesterol liver metabolism.     

Low contribution of n-3 polyunsaturated fatty acids to plasma and erythrocyte membrane lipids in diabetic young adults

Hypoinsulinemia characteristic to type 1 diabetes may theoretically inhibit the conversion of essential fatty acids to their longer-chain metabolites. Fatty acids were determined in plasma and erythrocyte membrane lipids in young diabetic adults (n=34) and in age-matched healthy controls (n=36). Values of linoleic acid (56.01 [5.02] versus 51.05 [7.32], % by wt, median [range from the first to the third quartile], P<0.00l) and arachidonic acid (AA) (11.17 [2.98] versus 9.69 [1.95] P<0.001) were significantly higher in diabetic subjects than in controls. However, alpha-linolenic acid values did not differ, and docosahexaenoic acid (0.43 [0.12] versus 0.57 [0.29], P<0.01) values were significantly lower in diabetic than in control subjects. Significant inverse correlations were found between AA and hemoglobin A(1c) values in the phospholipid (r=-0.40, P<0.05) and sterol ester (r=-0.40, P<0.05) fractions. The data obtained in the present study suggest that the availability of n-3 long-chain polyunsaturated fatty acid may be reduced in young diabetic adults.     

Composition of lipids, fatty acids and sterols in Okinawan corals

A survey of lipid composition was made for 15 cnidarians from Okinawa, Japan. Eleven zooxanthellate scleractinian corals, an azooxanthellate scleractinian coral Tubastrea sp., a soft coral Lobophytum crassum, a hydroid coral Millepora murrayi and a sea anemone Boloceroides sp. were examined to elucidate the total lipid content, fatty acid composition for each lipid class and sterol composition. All specimens contained monoalkyldiacylglycerol which migrated between the triacylglycerols and esters on thin layer chromatography (TLC). Analysis by high performance thin layer chromatography (HPTLC) and Gas chromatography-mass spectrometry (GC-MS) revealed that these cnidarians were rich in wax ester and triacylglycerol, and that palmitic acid (16:0) was the most abundant fatty acid component of these lipid classes, followed by stearic (18:0) and oleic (18:1, n-9) acid in order of concentration. Of 11 sterols separated, four sterols were identified. It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition.     

Neutral lipids, phospholipids and higher fatty acids in bull's testes

The lipid fractions were studied in the testicular tissue of mature bulls, of the lowland black-and-white breed. It was found that the main component of neutral lipids was cholesterol (48%) followed by triglycerides (24%), cholesterol esters (16%) and free fatty acids (12%). In cholesterol esters the main component was palmitic acid (41%) followed by oleic acid (22%), stearic acid (14%) and linoleic acid (14%). In phospholipids the main fraction was composed of lecithins (48%) followed by phosphatidylethanolamine (20%) and phosphatidic acids and phosphatidylglycerol (13%). Palmitic acid was found mainly in the fractions of lecithins and sphingomyelins, stearic acid in fractions of phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. Linoleic acid was found in the fractions of phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. Arachidonic, docosatetraenoic and docosapentaenoic acids in the fractions of phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and phosphatidylcholine.     

Minor amounts of plasma medium-chain fatty acids and no improved time trial performance after consuming lipids.

Medium-chain triacylglycerols (MCT) have a potential glycogen-saving effect during exercise due to rapid hydrolysis and oxidation. However, studies comparing intake of carbohydrates (CHO) plus 80-90 g MCT with intake of CHO alone have revealed different results. The present study tested performance after consumption of specific structured triacylglycerol, consisting of a mixture of medium-chain fatty acids and long-chain fatty acids, to prevent the adverse effects observed by MCT (pure medium-chain fatty acids) regarding gastrointestinal distress. Seven well-trained subjects cycled 3 h at 55% of maximum O2 uptake during which they ingested CHO or CHO plus specific structured triacylglycerols. Immediately after the constant-load cycling, the subjects performed a time trial of approximately 50-min duration. Breath and blood samples were obtained regularly during the experiment. Fatty acid composition of plasma triacylglycerols, fatty acids, and phospholipids was determined. Performance was similar after administration of CHO plus specific structured triacylglycerol [medium-, long-, and medium-chain fatty acid (MLM)] compared with CHO (50.0 +/- 1.8 and 50.8 +/- 3.6 min, respectively). No plasma 8:0 was detected in the plasma lipid classes, but the amount of phospholipid fatty acids was significantly higher after CHO+MLM compared with CHO intake. The lacking time trial improvement after intake of medium-chain fatty acids might be due to no available 8:0 in the systemic circulation. A higher level of plasma phospholipid fatty acids in the CHO+MLM compared with the CHO group was probably due to endogenous phospholipid release into chylomicrons.