Apical release of base-labile fatty acyl groups commensurate with stimulation of glycoprotein sialosyl Lewis(a) secretion in colorectal carcinoma cells

The rate of polarized secretion of a putative adhesion ligand, sialosyl Lewis(a) (19-9), by SW1116 colorectal carcinoma cells is stimulated at least 20-fold after pre-incubation with, and the incorporation of, retinoic acid (RA). In order to investigate the possible involvement of fatty acylation in the export of the epitope, purified ligands from carcinoma-cell membranes, membrane subfractions and media were analyzed during RA-induced secretion. Incorporation of radioactivity from (3H)palmitate into membrane subfractions and purified sialosyl Lewis(a) antigenic molecular species of M(r) > 150,000 (SiaLeams) was stimulated by RA treatment. Most of the intracellular lipid radioactivity which bound to solid-phase 19-9 antibody behaved chromatographically, either like ganglioside or like NH2 OH-labile acyl groups, but most of the (3H) bound to SiaLeams of post-incubation media behaved like base-labile fatty acyl groups, or free fatty acid. Release of base-labile lipid radioactivity after 3 hr (associated with antigen) was almost exclusively into the apical media of membrane inserts. Gas-liquid chromatography/mass spec. analyses of purified Sialeams revealed the presence of palmitate (16:0), as well as stearate (18:0) and oleate (18:1) fatty acyl groups. Our results suggest that fatty acylation of SiaLeams may be co-ordinated with alterations in glycosylation and participate in directing these molecules to the apical surface. Lipid analyses were consistent with ganglioside chaperonage of SiaLeams to the apical surface, where N-fatty-acylated gangliosides remain for the most part integrated into the bilayer, but some oxyester or thioester bonds may be cleaved to permit release of SiaLeams to the apical medium.

Triacylglycerol synthesis by purified triacylglycerol synthetase of rat intestinal mucosa. Role of acyl-CoA acyltransferase

The activities of the proposed triacylglycerol synthetase complex, acyl-CoA ligase, acyl-CoA acyltransferase (AAT), monoacylglycerol acyltransferase (MGAT), and diacylglycerol acyltransferase (DGAT), coeluted upon Cibacron blue 3GA-agarose affinity chromatography of detergent-solubilized rat intestinal microsomes. The AAT activity is associated with a 54-kDa protein, that binds covalently an acyl group from acyl-CoA via a thiol ester linkage (Lehner, R. and Kuksis, A. (1993) J. Biol. Chem. 268, 24726-24733). Reagents that prevent the acyl-AAT formation inhibit triacylglycerol synthesis as does the removal of AAT from the complex by immunoprecipitation. In the absence of mono- and diacylglycerol acceptors, the acyl group is transferred to water. It is proposed that triacylglycerol synthesis proceeds via a sequential transfer of acyl groups from acyl-CoA ligase to the AAT, from which they are passed to the mono- and diacylglycerol acyltransferases for incorporation into the di- and triacylglycerols depending on the availability of the acyl acceptors.

Biosynthesis of chylomicron triacylglycerols by rats fed glyceryl or alkyl esters of menhaden oil fatty acids

We have previously shown great similarity in the distribution of fatty acids in the sn-1 and sn-3 positions of the chylomicron triacylglycerols (TG) from rats fed menhaden oil or its ethyl esters, and have proposed that the acylglycerol products of the phosphatidic acid (PA) pathway (ester feeding) are hydrolyzed to 2-monoacylglycerols (2-MG) prior to reconversion to TG via the 2-MG pathway (oil feeding) and secretion as chylomicrons. As the composition of the sn-2-position would also be retained if the TG were hydrolyzed only to the X-1,2-diacylglycerol (DG) stage before resynthesis, we have now retested the hypothesis by determining the molecular association and reverse isomer content of the sn-1,2- and sn-2,3-DG derived from the chylomicron TG and the PA resulting from the two feedings. The new data demonstrate a better than 90% homology among the molecular species of the PA from the oil and ester feeding, along with the characteristic association of the saturated acids with sn-1- and the unsaturated acids with sn-2-position. Due to increased proportion of unsaturated acids in the sn-1-position of the TG, there was only a 15-20% homology between the PA and the sn-1,2-DG moieties of the chylomicron TG from the oil and ester feeding. A lack of homology was also observed between the PA and free sn-1,2-DG, as well as between the free sn-1,2-DG and the sn-1,2-DG moieties of the chylomicron TG. On the basis of molecular association and the sn-1-/sn-3- reverse isomer content of the chylomicron TG a better than 90% homology was recognized between the chylomicron TG resulting from the oil and ester feeding. It is therefore concluded that hydrolysis to 2-MG followed by reesterification via the 2-MG pathway constitutes the most plausible mechanism for the transfer to chylomicrons of the TG arising from alkyl ester feeding.

Plasma fatty acid profiles of Canadian Inuit and Siberian Ganasan

Cross-sectional data from 86 male and 59 female coastal Inuit of Igloolik (69 degrees 40'N, 81 degrees W) showed a steep age-related increase in the percentage of plasma n-3 fatty acids, with parallel trends in 20:5 and 22:6 but not 18:3 n-3 fatty acid concentrations. Omega-7 + 9 (p < .001) and omega-9 fatty acid concentrations (P < .001 in M, .008 in F) also decreased with age. A tundra-based Siberian indigenous population (30 male and 11 female nGanasan) had similar percentages of n-3 and n-6 fatty acids to the young Inuit, with little age-related change in either measure. Correlation matrices for the Inuit men showed quite strong negative associations of n-3 fatty acid percentages with total triglycerides (r = .34, p < .001) and phosphatidylcholine/free cholesterol ratio (r = -.36, p < .001). In the Inuit women, n-3 percentages were strongly related to phosphatidylcholine/free cholesterol ratio (r = -.60, p < .001), but not to triglyceride readings. The phosphatidylcholine/free cholesterol ratio was also correlated with n-6 percentages (r = -.55, p < .001). In the nGanasan men, triglyceride levels were correlated with n-6 (r = -.35, p < .050), but the size of the female sample was insufficient to establish useful correlations. The present data suggest that as the younger coastal Inuit are abandoning their traditional country foods, plasma levels of n-3 fall. Reasons why n-3 fatty acid levels are negatively related to the plasma phosphatidyl choline/free cholesterol ratio merit further investigation.

Origin of triacylglycerol moiety of plasma very low density lipoproteins in the rat: structural studies

We have compared the molecular species composition of the glycerolipids of rat liver and rat plasma very low density lipoproteins (VLDL). There were differences in the stereospecific distribution of the fatty acids in the triacylglycerols (TG) of the liver and of VLDL. While chiral and reversed phase chromatography with mass spectrometry (LC/MS) revealed great similarities in positional distribution and molecular association of the fatty acids between the sn-1,2-diacylglycerol (DG) moieties of the VLDL and liver TG, the corresponding sn-2,3-DG were distinctly different. The free hepatic sn-1,2-DG and the sn-1,2-DG moiety contained within hepatic phosphatidic acid showed a maximum 60% homology to the sn-1,2-DG contained within the TG of the liver and of VLDL. By contrast, the smaller pool of hepatic free sn-2,3-DG was nearly identical to the sn-2,3-DG moiety contained in the TG of the liver. These differences between hepatic and VLDL TG indicate that direct transfer of hepatic triacylglycerols is not a major mechanism of VLDL TG formation. On the other hand, the results suggest that stored hepatic TG are largely hydrolyzed to sn-1,2-DG and then reesterified to TG before being secreted as VLDL TG. Although an involvement of 2-monoacylglycerol pathway could not be excluded, it probably plays a minor role in VLDL TG formation. Our data suggest that a minimum of 60% of the VLDL TG could have been derived via hydrolysis to DG and reesterification, and a maximum of 40% could have originated via the conventional phosphatidic acid pathway.

Complementary chromatographic analysis of free diacylglycerols and potential glycerophospholipid precursors in human SH-SY5Y neuroblastoma cells following incubation with lithium chloride

We performed detailed chromatographic analyses on the molecular species of the major glycerophospholipids (GPLs) and free sn-1,2-diacylglycerols (DAGs) from SH-SY5Y human neuroblastoma cells following incubation with or without LiCl. For this comparison the inositol, choline, ethanolamine and serine GPLs were dephosphorylated with phospholipase C and the released sn-1,2-diacylglycerols along with the DAGs were subjected to high-temperature GLC on polar and non-polar capillary columns as their trimethylsilyl and tert.-butyl-dimethylsilyl ethers. A 30-min incubation with 10 mM LiCl increased the total amount of human neuroblastoma DAGs by 32-58% (P < 0.05) to 2.6 pmol/micrograms cell protein. This was accompanied by a limited qualitative shift in the molecular species pattern, the most obvious of which was the increase (13%) in the major saturated-polyunsaturated molecular species and the ca. 46% increase in the minor 18:1-18:1 species over control levels. The DAGs originated mainly from the inositol GPLs (IGPLs), as indicated by the high levels of the characteristic 18:0-20:4n6 (18:0-20:3n9) species in both IGPLs and DAGs, and to a lesser extent from the choline GPLs (CGPLs), as indicated by the high proportion in CGPLs of the oligoenoic species, which were largely absent from IGPLs. Alkenylacylglycerols were not detected in DAGs, although they made up some 60% of the total ethanolamine GPLs (EGPLs). No significant changes in the molecular species composition of the cellular GPLs, including IGPLs, were detected after exposure to LiCl.

Kinetics of lipolysis of very low density lipoproteins by lipoprotein lipase. Importance of particle number and noncompetitive inhibition by particles with low triglyceride content

Our objective was to identify the major compositional factor(s) of very low density lipoprotein which determines its properties as a substrate for lipoprotein lipase. Human very low density lipoprotein was fractionated by preparative electrophoresis. The apparent Km was significantly lower for pre-beta very low density lipoprotein compared with beta very low density lipoprotein when calculated on the basis of triglyceride concentration. When the triglyceride concentration was adjusted for the triglyceride/apolipoprotein B ratio, the apparent Km was not different among very low density lipoprotein fractions. This implied that very low density lipoprotein particle number was of primary importance. To test this hypothesis further, rabbit cholesterol-rich very low density lipoprotein and human intermediate density lipoprotein and low density lipoprotein, from a patient with hepatic lipase deficiency, were added to the incubations. Each of these fractions functioned as noncompetitive inhibitors of lipolysis. We speculate that the saturation of lipoprotein lipase by an excess number of particles is a characteristic of human hyperlipoproteinemias that predispose to coronary heart disease and that are commonly classified as familial combined hyperlipoproteinemia or hyperapobetalipoproteinemia.

A cross-species comparison of neutral lipid composition of milk fat of prosimian primates

The fatty acid composition of milk fat is known to be affected by dietary and genetic differences, while the milk triacylglycerol structure is believed to be attuned to the needs of the subsequent lipolysis during gastrointestinal passage. The availability of milk samples from eight species of prosimian primates, whose milk triacylglycerol structure had not been analyzed, offered an opportunity to further assess these ideas. The milk samples were collected by manual expression and the lipids extracted with chloroform/methanol (2:1, vol/vol). The lipid classes were resolved by thin-layer chromatography, and the neutral lipids subjected to detailed analyses by capillary gas-liquid chromatography of fatty acids and molecular species of triacylglycerols using nonpolar and polarizable liquid phases. The milk samples were found to differ greatly in total fat content (4-73%) and in the composition of the neutral lipid classes and molecular species. The concentration of triacylglycerols ranged from 88-95%, free fatty acids from 0.5-10%, alkyldiacylglycerols from 0.5-5.0%, and diacylglycerols, monoacylglycerols and free and esterified cholesterol made up the remainder. The fatty acid chain length ranged from C8-C24, with palmitic (16-31%) and oleic (13-40%) acids being the major components in most of the species. In all instances, the molecular association of the fatty acids differed from random distribution by a higher proportion of the monoacid (trioleoyl) and diacid (dipalmitoyloleoyl) glycerols. The phylogenetic influences on neutral milk lipid composition, however, remained unclear, as some of the differences between closely related species were greater than those between more distantly related ones.

Comparison of the effect of hyperinsulinemia on acyl-CoA:cholesterol acyltransferase activity in the liver and intestine of the rat

Recent studies have suggested that cholesteryl ester synthesis plays a critical role in the assembly of VLDL apo B and triacylglycerol in the liver. Chronic hyperinsulinemia is associated with increased TG production and since cholesteryl ester synthesis depends on acyl CoA:cholesterol acyltransferase (ACAT), we investigated the possibility that chronic hyperinsulinemia might increase ACAT activity. We also measured ACAT activity in the intestinal mucosa, where it has been suggested to play a role in induction of diabetes-associated hypercholesterolemia. Chronically hyperinsulinemic rats were produced by injecting insulin (2 weeks, 6U/day). To prevent profound hypoglycemia, these rats were given 10% sucrose in place of drinking water. Acute hyperinsulinemia was produced by injecting a single dose of 0.5 U insulin ip. Chronic hyperinsulinemia led to a significant increase in free cholesterol, cholesteryl esters, triacylglycerols and phospholipids in the whole liver (27%, P < 0.05; 60%, P < 0.05; 70%, P < 0.01; 37%, P < 0.01, respectively) and an increase in hepatic microsomal triacylglycerol (P < 0.05). In contrast, the microsomal lipids of the intestinal mucosa decreased significantly. In chronically hyperinsulinemic rats there was no change in hepatic ACAT, while ACAT in the intestine actually decreased (26%-50%, P < 0.01).

CONCLUSIONS

since the effect of chronic hyperinsulinemia on hepatic ACAT did not parallel that seen previously on VLDL secretion, the effect of chronic hyperinsulinemia on VLDL production cannot be explained by its effect on hepatic ACAT. However, chronic hyperinsulinemia was associated with reduced ACAT activity in the intestine and this might result in decreased lipoprotein production in the hyperinsulinemic intestine.

Purification of an acyl-CoA hydrolase from rat intestinal microsomes. A candidate acyl-enzyme intermediate in glycerolipid acylation

We have purified to apparent homogeneity an acyl-CoA hydrolase activity from rat intestinal villus cell microsomes by heparin and anion exchange and affinity chromatography. The purified 54-kDa acyl-CoA hydrolase along with several microsomal proteins form a covalent acyl-protein bond upon incubation with an activated fatty acid (acyl-CoA). The acyl moiety of the acylated acyl-CoA hydrolase is stable to denaturation and extraction with organic solvents, but is displaced by neutral hydroxylamine or mercaptoethanol, indicating a labile high energy (thio)ester linkage. The enzyme activity is inhibited by thiol-directed reagents and activated by the presence of dithiothreitol suggesting the presence of a cysteine residue(s) at or near the active site. Common serine-esterase inhibitors (NaF, phenylmethylsulfonyl fluoride) and activators (Mg2+, Ca2+) had no effect on the hydrolase activity. The enzyme hydrolyzed (transferred to water) 14-20 carbon acyl-CoA with similar efficiencies and did not utilize glycerophospholipids or mono- and diacylglycerols as potential acyl donors/acceptors. Phospholipids and mono- and diradylglycerols at concentrations below 100 microM or polyclonal antibodies raised against the purified hydrolase did not inhibit the enzyme activity. However, the acyl-CoA hydrolase activity could be immunoprecipitated from solubilized microsomes or purified enzyme preparations with corresponding decrease of the hydrolase activity in the supernatant of the immunoprecipitate. Immunoblotting studies show cross-reactivity with a protein of an identical molecular mass in other rat or human tissues. It is concluded that the microsomal acyl-CoA hydrolase deserves consideration as a candidate acyl-enzyme intermediate in glycerolipid synthesis when associated with appropriate acyltransferases.

Quantitation of plasma lipids by gas-liquid chromatography on high temperature polarizable capillary columns

We have previously demonstrated the potential usefulness of capillary columns coated with a high temperature polarizable phenylmethylsilicone liquid phase in plasma lipid profiling (Kuksis, A., J.J. Myher, and P. Sandra. 1990. J. Chromatogr. 500: 427-441). The present study reports improved operating conditions along with a practical application to the analysis of a series of human plasma samples in comparison to capillary gas-liquid chromatography on nonpolar columns. For this purpose the plasma lipids were dephosphorylated with phospholipase C and converted to the trimethylsilyl ethers. The molecular species of the plasma lipids were identified by comparing the relative retention times to reference standards. The species were quantitated using tridecanoylglycerol as internal standard. The recoveries of the lipid classes were determined by summing the molecular species within each carbon number and comparing the proportion of the carbon numbers obtained on polar and nonpolar columns. The relative recoveries varied with the lipid class and sample load and averaged as follows: FA C16, 78%; FA C18, 78%; FC, 99%; tridecanoylglycerol (TD), 100% (by definition); CER 34:1, 92%; DG C34, 103%; DG C36, 98%; CE C16, 73%; CE C18, 61%; TG C50, 93%; TG C52, 60%; TGC54, 32%. We conclude that high temperature polarizable capillary columns are suitable for qualitative and quantitative assessment of plasma lipids and provide more information per man-hour, instrument time, and unit cost than any other analytical method known.

Triacylglycerol synthesis by an sn-1,2(2,3)-diacylglycerol transacylase from rat intestinal microsomes

A membrane-associated sn-1,2(2,3)-diacylglycerol transacylase activity was purified 550-fold from the microsomes of rat intestinal villus cells. The enzyme was solubilized with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate and was isolated and purified by sequential chromatography on hydroxylapatite, an anion exchanger, Affi-Gel heparin and Cibacron blue A-agarose. SDS-polyacrylamide gel electrophoresis revealed two major closely migrating polypeptides of apparent molecular mass of 50 and 52 kDa. Incubation of the isolated enzyme with sn-1,2(2,3)dioleoyl-[2-3H]glycerol yielded trioleoyl[2-3H]glycerol and 2-oleoyl[2-3H]glycerol. The synthesis of triacylglycerols was independent of acyl-CoA, as indicated by the absence of incorporation of radioactivity from [1-14C]oleoyl-CoA into mono-, di-, or triacylglycerols under these conditions. The transacylase did not hydrolyze triacylglycerols readily and was not affected by the acyltransferase inhibitors, N-ethylmaleimide and 4,4'-diisothiocyanostilbene-2,2'-disulfonate, while the lipase/hydrolase inhibitors NaF, phenylmethylsulfonyl fluoride, and diethyl p-nitrophenyl phosphate caused partial inactivation. The enzyme was specific toward 1(3)-positions of rac 1,2-diacylglycerols but did not utilize the -1,3-diacylglycerols or other neutral lipid esters effectively and was not capable of removing fatty acids from phosphatidylcholine or of transfer of fatty acids from X (unspecified enantiomer)-1,2-diacylglycerol to lysophosphatidylcholine. Since the diacylglycerol transacylation did not lead to accumulation of either sn-1,2- or sn-2,3-diacylglycerols during incubation with the racemates, it is concluded that both sn-1,2- and sn-2,3-s are utilized at similar rates.

Identification of core aldehydes among in vitro peroxidation products of cholesteryl esters

Synthetic cholesteryl 5-oxovalerate and 9-oxononanoate were used as reference standards for the isolation and identification of cholesteryl ester core aldehydes from tert-butyl hydroperoxide/Fe++ oxidation of synthetic and natural cholesteryl esters. The core aldehydes were recovered from the peroxidation products by thin-layer chromatography as the free aldehydes or the 2,4-dinitrophenylhydrazones and were identified, respectively, by gas-liquid chromatography (GLC) and by GLC combined with mass spectrometry (GC/MS) or by reverse-phase high-performance liquid chromatography (HPLC) and by HPLC with MS (LC/MS). The core aldehydes produced by peroxidation of cholesteryl linoleate were identified as mainly 9-oxononanoates of cholesterol and oxycholesterols, with smaller amounts of the 8-oxooctenoates, 10-oxodecenoates, 11-oxoundecenoates and 12-oxododecenoates. Peroxidation of cholesteryl arachidonate yielded 5-oxovalerates of cholesterol and the oxycholesterols as the main products with smaller amounts of the 4-oxobutyrates, 6-oxohexenoates, 7-oxoheptenoates, 8-oxooctenoates, 9-oxononenoates, 9-oxononadienoates and 10-oxodecadienotes. The oxycholesterols resulting from the peroxidation of the steroid ring were identified as mainly 7-keto-, 7 alpha-hydroxy- and 7 beta-hydroxy-cholesterols and 5 alpha,6 alpha- and 5 beta,6 beta-epoxy-cholestanols. Cholesteryl palmitate and oleate did not yield core aldehydes in the present peroxidation system. In these esters, the sterol and linoleic acid moieties appeared to be oxygenated at about the same rate, while the arachidonic acid moiety reacted more rapidly than did the sterol moiety.

Molecular species of glycerophospholipids and diacylglycerols of cultured SH-SY5Y human neuroblastoma cells

Total lipid extracts were obtained from SH-SY5Y human neuroblastoma cells grown to confluency in mycoplasma-free 10% fetal calf serum. The major glycerophospholipid classes and free diacylglycerols (DAG) were isolated and quantitated by silicic acid and DEAE-cellulose column and thin-layer chromatography. The choline (CGPL), ethanolamine (EGPL), serine (SGPL), and inositol (IGPL) glycerophospholipids were converted to the corresponding diradylglycerols by phospholipase C. The molecular species of the diradylglycerols were determined by capillary gas-liquid chromatography of the trimethylsilyl or t-butyldimethylsilyl ethers. The CGPL was rich in the oligoenoic species and IGPL was rich in the polyenoic species, especially the 18:0-20:4(n-6). The EGPL contained 30-40% diacyl, 60-64% alkenylacyl, and 1-3% alkylacyl species, which were also rich in polyenoic derivatives. Small amounts of alkenylacyl species were detected also in CGPL. The cellular DAG possessed a molecular species composition halfway between those of the DAG moieties of CGPL and IGPL. The cells grown in the presence of 10% calf serum exhibited great variability in the content of 20:3(n-9) fatty acid, which was found to substitute for the 20:4(n-6) acid in the molecular species with 18:0 in both IGPL and DAG. The 20:3(n-9) was largely absent from the CGPL, but occurred also in EGPL, where it was preferentially associated with 18:0 in the diacyl but with 18:1 in the alkylacyl and alkenylacyl species. The detailed documentation of molecular species of glycerophospholipids of the neuroblastoma cells offers new opportunities for identification of the source of free DAG released in transmembrane signalling.

Stereospecificity of monoacylglycerol and diacylglycerol acyltransferases from rat intestine as determined by chiral phase high-performance liquid chromatography

Using chiral phase high-performance liquid chromatography of diacylglycerols, we have redetermined the ratios of 1,2-/2,3-diacyl-sn-glycerols resulting from acylation of 2-monoacylglycerols by membrane bound and solubilized triacylglycerol synthetase of rat intestinal mucosa. With 2-oleoyl[-3H]glycerol as the acyl acceptor and oleoyl-CoA as the acyl donor, 97-98% of the diacylglycerol product was 1,2(2,3)-dioleoyl-sn-glycerol, 90% of which was the sn-1,2- and 10% the sn-2,3-enantiomer. The remaining diacylglycerol (less than 3%) was the sn-1,3-isomer. The overall yield of acylation products was 70%, of which 60% were diacylglycerols and 40% triacylglycerols. With 2-oleylglycerol ether as the acyl acceptor and [1-14C]oleoyl-CoA as the acyl donor, 90% of the diradylglycerol was 1-oleoyl-2-oleyl-sn-glycerol and 10% was the 2-oleyl-3-oleoyl-sn-glycerol. The diradylglycerols made up 96% and the triradylglycerols 4% of the radioactive product. With 1-palmitoyl-sn-glycerol as the acyl acceptor and [1-14C]oleoyl-CoA as the acyl donor, the predominant reaction product was 1-palmitoyl-3-oleoyl-sn-glycerol. The 3-palmitoyl-sn-glycerol was not a suitable acyl acceptor. Both 1,2- and 2,3-diacyl-sn-glycerols were substrates for diacylglycerol acyltransferase as neither isomer was favored when 1,2-dioleoyl-rac-[2-3H]glycerol was used as the acyl acceptor. There was a marked decrease in the acylation of the 1(3)-oleoyl-2-oleyl-sn-glycerol to the 1,3-dioleoyl-2-oleyl-sn-glycerol. It is concluded that neither monoacylglycerol nor diacylglycerol acyltransferase exhibit absolute stereospecificity for acylglycerols as fatty acid acceptors.

Gas chromatographic profiles of plasma total lipids as indicators of dietary history. Correlation with carbohydrate and alcohol intake based on 24-h dietary recall

Quantitative gas chromatographic estimates of the major lipid classes and molecular species in fasting plasma were correlated with total carbohydrate, starch, fibre, sucrose and alcohol intake based on 24-h dietary recall. Spearman coefficients (rs) and tests of significance (P) were obtained for groups of 775 males and 471 females aged 20-59 years from a Toronto-McMaster Lipid Research Clinics Population Study. The most significant correlations varying from rs 0.1 to 0.2 and P 0.001 to 0.0005 (n = 400-773) were between increased intake of alcohol and increased ratios of C50/C54 triacylglycerols, C34/C36 phosphatidylcholines and phosphatidylcholine/free cholesterol (PC/FC) of plasma. Increase in total dietary carbohydrate, starch and fibre correlated with decreasing C50/C54 triacylglycerol, C34/C36 phosphatidylcholine and PC/FC ratios (rs = -0.1-0.2; P less than 0.002-0.04; n = 400-773). In contrast, consumption of high levels of alcohol was associated with increasing C50/C54 triacylglycerol, C34/C36 phosphatidylcholine and PC/FC ratios. A high intake of alcohol (50-150 ml per day) distinguished itself from other simple carbohydrate-induced lipid profiles by its marked effect on increased C50/C52 triacylglycerol and PC/FC ratio.