Less fat or a different fat?

Current dietary advice with a view to avoiding cardiovascular pathology is to replace fatty foodstuffs and those rich in saturated fat and cholesterol by food rich in complex carbohydrates. Although substitution of carbohydrates for fat lowers the blood level of low-density lipoprotein (LDL) cholesterol, it also lowers the level of high-density lipoprotein (HDL) cholesterol, thereby adversely influencing the risk profile for cardiovascular disease. Neither does a low fat diet appear to reduce obesity, another risk factor. A modern advice based on published research reads: obese persons should reduce their intake of saturated and trans-fatty acids by lowering the consumption of dairy fat, meat and hardened oils (bakery products and catering products fried in hardened fats), and in addition should consume less products with added sugars and refined starch. Carbohydrates should be provided by fruits, vegetables, leguminous plants and whole-wheat products. Persons of about the ideal weight should replace saturated and trans-fatty acids in their diet by unsaturated plant oils, and products with refined carbohydrates by fruits, vegetables and whole-wheat products.     

Origins of neural crest cell diversity

The effect of diets containing 50% of fat calories from butter, butter enriched with mono- and polyunsaturated fatty acids, and margarines with and without trans fatty acids on the serum lipids of 38 healthy men in a free-living condition have been determined. Serum lipid responses to the high level of individual dietary fats were unexpectedly small. The butter diet produced a small, but significant rise (5%) in the total serum cholesterol and low density lipoprotein (LDL)-cholesterol, relative to all other diets. Enrichment of butter with either olive oil (50/50) or sunflower oil (50/50) failed to reduce serum lipid levels below habitual diet values. Hard margarine, containing 29% trans fatty acids, caused a decrease in apolipoprotein A-I and B levels, but did not change total serum cholesterol or LDL-cholesterol levels, relative to habitual diet values. A soft margarine, high in linoleate, with no trans fatty acids reduced total cholesterol, LDL-cholesterol, and apolipoprotein B significantly, relative to all diets. Soft margarine high density lipoprotein (HDL)-cholesterol levels remained unchanged, but apolipoprotein A-I values were decreased relative to habitual and butter diets. The quantities of saturated fatty acids and the sum of monounsaturated and polyunsaturated fatty acids consumed on the hard and soft margarines were equal; therefore, the different response of serum cholesterol and LDL-cholesterol between these two diets is attributable to the trans fatty acids in the hard margarine. The data indicate that trans fatty acids are not metabolically equivalent to the natural cis isomers and that they affect the serum lipid profile adversely.     

Effect of dietary fats rich in lauric, myristic, palmitic, oleic or linoleic acid on plasma, hepatic and biliary lipids in cholesterol-fed hamsters

Effects of different dietary fats on plasma, hepatic and biliary lipids were determined in male golden Syrian hamsters (Mesocricetus auratus) fed on purified diets for 7 weeks. Diets were made by blending different fats containing characteristic fatty acids: butter (14:0 + 16:0), palm stearin (16:0), coconut oil (12:0 + 14:0), rapeseed oil (18:1), olive oil (18:1) and sunflowerseed oil (18:2). In all diets except the sunflowerseed oil diet dietary 18:2 was held constant at 2% energy. Total fat supplied 12% of energy and cholesterol was added at 4 g/kg diet. Plasma cholesterol and triacyglycerol concentrations were increased by dietary cholesterol. After 7 weeks, plasma cholesterol concentrations were highest with the palm stearin, coconut oil and olive oil diets (8.9, 8.9 and 9.2 mmol/l) and lowest with the rapeseed oil and sunflowerseed oil diets (6.7 and 5.5 mmol/l) while the butter diet was intermediate (8.5 mmol/l). Hepatic cholesterol concentration was highest in hamsters fed on the olive oil diet and lowest with the palm stearin diet (228 v. 144 mumol/g liver). Biliary lipids, lithogenic index and bile acid profile of the gall-bladder bile did not differ significantly among the six diets. Although the gallstone incidence was generally low in this study, three out of 10 hamsters fed on the palm stearin diet developed cholesterol gallstones. In contrast, no cholesterol gallstones were found with the other diets. Rapeseed and sunflowerseed oils caused the lowest plasma cholesterol and triacyglycerol concentrations whereas olive oil failed to demonstrate a cholesterol-lowering effect compared with diets rich in saturated fatty acids. Since 18:2 was kept constant at 2% of energy in all diets, the different responses to rapeseed and olive oils could possibly be attributed to their different contents of 16:0 (5.6% v. 12.8% respectively). Other possible explanations are discussed.     

Characterization of recombinant type II collagen: arthritogenicity and tolerogenicity in DBA/1 mice

Using new nonisotopic and isotopic methods, we showed previously that fatty acid synthesis was markedly stimulated in weight-stable normal volunteers by a very-low-fat formula diet with 10% of energy as fat and 75% as short glucose polymers. In this study, we determined whether fatty acid synthesis was equally stimulated by a very-low-fat solid diet made with foods consumed typically. Four normal volunteers consumed the same very-low-fat formula diet for 25 d and then an isoenergetic solid food diet with 10% of energy as fat and 75% as starch, simple sugars, and fiber for 25 d. To measure fatty acid synthesis, the fatty acid compositions of the diets were matched to the composition of each subject's adipose tissue and compared with the composition of VLDL-triacylglycerol. In all subjects, the large increases in newly formed palmitate and decreases in linoleate in VLDL-triacylglycerol were quickly reversed by the solid food diet, and the fraction of de novo synthesized fatty acids in fasting VLDL-triacylglycerol decreased from 30-54% to 0-1%. In a second group of subjects, the stimulation of fatty acid synthesis by the formula diet with 75% glucose polymers was similarly reduced by a formula diet with amounts of fat, starch, and sugar chosen to mimic those of the solid food diet, but persisted after the addition of fiber or a diet with 75% sugar. In conclusion, an increase in fatty acid synthesis and palmitaterich, linoleate-poor VLDL-triacylglycerol induced by very-low-fat, high-sugar diets may be reduced by the substitution of dietary starch for sugar with potentially beneficial effects on cardiovascular health.     

The effect of kind of carbohydrate in the diet and use of oral contraceptives on metabolism of young women. II. Serum lipid levels

The response of lipids in the blood between two groups of six young women was compared. Group 1 took oral contraceptives and group 2 had never taken oral contraceptives. Two experimental diets supplied about 13% of the calories from protein, 36% from fat, and 51% from carbohydrate. Of the carbohydrate, 84% was either sucrose or wheat starch. Each diet was fed for 4 weeks in a cross-over design. In the portion of the research presented here, subjects were fed a high sucrose meal before each dietary period and after weeks 1 and 3 of each dietary period. Blood lipids were measured before and 30, 60, 120, and 180 min after each meal. Cholesterol and lipoproteins were not affected by the sucrose meal, but free fatty acid levels decreased significantly in both groups. The serum levels of triglycerides, beta-lipoproteins, and cholesterol were significantly higher in users than in nonusers of oral contraceptives. Free fatty acid levels were affected by an interaction between diet and time, and the decrease in response was greater after the sucrose than after the wheat starch diet. Triglycerides, cholesterol, and total lipids were not significantly different after the two carbohydrate diets.     

Dietary fatty acid profile affects endurance in rats

Typically athletes are advised to increase their consumption of carbohydrates for energy and, along with the general population, to reduce consumption of saturated fats. It is now recognized that fats are not identical in their influence on metabolism, and we argue that the composition of the polyunsaturated fat component should not be ignored. The aim of this study was to manipulate the dietary fatty acid profile in a high-carbohydrate diet in order to investigate the effect of dietary polyunsaturates on submaximal endurance performance in rats. Rats were fed one of three isoenergetic diets containing 22 energy percentage (E%) fat for 9 wk. The diets comprised an essential fatty acid-deficient diet (containing mainly saturated fatty acids); a diet high in n-6 fatty acids, High n-6; and a diet enriched with n-3 fatty acids, High n-3. Submaximal endurance in rats fed the High n-3 diet was 44% less than in rats fed the High n-6 diet (P < 0.02). All rats were then fed a standard commercial laboratory diet for a 6-wk recovery period, and their performances were reevaluated. Although endurance in all groups was lower then at 9 wk, it was again significantly 50% lower in the High n-3 group than the High n-6 group (P < 0.005). Although n-3 fats are considered beneficial for cardiovascular health, they appear to reduce endurance times, and their side effects need to be further investigated.     

Nutrient intake and serum lipids in urban and rural Puerto Rican men

Dietary intake information was collected on 2,426 rural and 5,828 urban men free of coronary heart disease in the Pureto Rico Heart Health Program. Serum cholesterol and triglyceride, body weights, and related parameters were measured during a detailed cardiovascular examination. There were statistically significant differences between rural and urban values with respect to lipids, relative weight, and intake of many nutrients. Rural subjects had lower lipids and relative weights. Serum cholesterol was associated with relative weight in both rural and urban areas. In the urban areas, serum cholesterol was associated with intake of total fat, saturated fatty acids, polyunsaturated fatty acids, total carbohydrate, and starch (all measured as percent of calories). It was also related to percent carbohydrate from starch and dietary cholesterol intake, even after relative weight was taken into account. The associations were of a low order, although statistically significant. The association of fasting triglycerides with some of the carbohydrate variables was statistically significant after relative weight was taken into account in the urban area. Overall, diet and relative weight can account for at most 6% of the variability in serum cholesterol observed, with at most 2.5% of the variability due diet alone.     

Mycobacterium kansasii and human immunodeficiency virus co-infection in London

In a sample of 627 healthy German children and adolescents between the age of 1 and 18 years the intake of macronutrients (protein, fat, carbohydrates) and their specific subgroups (animal protein, saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), cholesterol, added sugars, dietary fiber) were assessed from 3d weighed diet records. The medians of the nutrient intake (% of energy) were 13% protein (2/3 animal), 38% fat, 49% carbohydrates, 17% SFA, 16% MUFA, 5% PUFA, 12% added sugars and (per MJ) 34 mg cholesterol, 1.9 g dietary fiber. The macronutrient patterns were almost uniform across the age and sex groups with the exception of lower fat, PUFA, and sugar intakes in the 1 year olds. The findings were almost in accordance with former and current dietary surveys in Germany and neighboring countries. Several findings, particularly the high SFA and low fiber intake, differed considerably from the diet for the prevention of the chronic diseases related to nutrition in western societies which is recommended for this age range. Based on the findings of this study, a preventive dietary concept for German children and adolescents was proposed.     

A study on the relationship between blood lead levels and anemia indicators in workers exposed to low levels of lead

To determine the effects of a vegetarian diet with avocado as a source of monounsaturated fat on serum lipids, thirteen patients with phenotype II (twelve with IIa and one with IIb) dyslipidemia were included in a prospective, transversal and comparative study in which three four-week diets randomly assigned were assessed. One vegetarian diet (ALVD) was composed of 70% carbohydrates, 10% proteins and 20% lipids. Another was composed of 60% carbohydrates, 10% proteins and 30% lipids, 75% of which was supplied by avocado (AVD). A third diet was an avocado-added free diet (FDWA). Body weight, body mass index (BMI), and serum lipids (total cholesterol (TC), high (HDL) and low density lipoprotein (LDL) cholesterol and triglycerides (TG)) were evaluated. AVD produced a significant decrease in LDL. ALVD did not change TC and LDL, while FDWA increased them slightly. The three diets reduced TG levels, but only ALVD did so significantly. All three diets reduced HDL levels, particularly ALVD, which produced the greatest reduction. Low-fat, carbohydrate-rich vegetarian diets may be harmful to hypercholesterolemic patients. The avocado addition to a vegetarian diet does not correct these undesirable effects. To obtain beneficial effects on lipid profile with avocado, lower amounts of carbohydrates and polyunsaturated fatty acids are probably needed.     

Plasma lipids are affected similarly by dietary lauric or palmitic acid in gerbils and monkeys

To compare the relative impact of dietary lauric acid (12:0) and palmitic acid (16:0) on plasma lipids, two fat-sensitive species, Mongolian gerbils and cebus monkeys, were fed cholesterol-free, purified diets enriched with either 12:0-rich or 16:0-rich fats, while all other fatty acids were held constant by selective blending of up to five natural fats or oils. The two gerbil diets (40 en% from fat) allowed for an 8 en% exchange between 12:0 and 16:0, and the monkey diets (31 en% from fat) allowed for 6 en% exchange between these two fatty acids. Eight gerbils received the diets for eight weeks, and 12 cebus monkeys were fed each diet in a cross-over design for up to 22 wk. Both diets resulted in similar plasma cholesterol, triglyceride, and high density lipoprotein cholesterol concentrations within each species. Additionally, separation of cebus lipoproteins by discontinuous density-gradient ultracentrifugation failed to show any dietary differences in concentration or composition of the three major lipoprotein classes (d < 1.019, 1.019-1.055, and 1.055-1.168 g/mL). Thus, in two species sensitive to manipulations in dietary fat while consuming cholesterol-free diets, 16:0 was not hypercholesterolemic relative to 12:0.     

Relationships between dietary fat, body fat, and serum lipid profile in prepubertal children

OBJECTIVE: The purpose of the study was to test the hypothesis that dietary fat components were associated with the serum lipid profile independent of ethnicity, body fat, and fat distribution in prepubertal children. RESEARCH METHODS AND PROCEDURES: Sixty-six children (45 African American and 21 Caucasian), aged from 4 to 10 years, were recruited into the study. Dietary total fat, saturated fat, monounsaturated fat, and polyunsaturated fat were estimated by averaging two 24-hour diet recalls. Fasting serum triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol were analyzed, and low-density lipoprotein cholesterol (LDL-C) was calculated by the method of Friedewald. Body composition and fat distribution were measured by dual energy X-ray absorptiometry and computed tomography. RESULTS: Children in both ethnic groups tended to overreport their dietary intake relative to total energy expenditure by 18%. African American children consumed more energy from total fat (35.3% vs. 31.5%, p<0.05), saturated fat (13.7% vs 12.2%, p<0.05), protein (16.4% vs. 13.2%, p=0.02), and less from carbohydrate (48% vs. 57.1%, p<0.01) than Caucasian children. There was no significant correlation between dietary fat and either serum lipids or body fat indices after adjusting for nonfat energy intake and total lean tissue mass. Total body fat (r=0.32), subcutaneous abdominal adipose tissue (r=0.39), and intra-abdominal adipose tissue (r=0.42) were positively related to serum triacylglycerol; these associations remained significant in a multiple linear regression model in which body fat indices were adjusted for ethnicity, total lean tissue, dietary total fat, and nonfat intake. DISCUSSION: Our results do not support a link between dietary fat and serum lipids; instead, our data suggest that body fat may play a more important role than dietary fat in the course of cardiovascular disease development in prepubertal children.     

Resistant starch decreases serum total cholesterol and triacylglycerol concentrations in rats

Rats were meal-fed semipurified diets containing a low (0.8 g/MJ) and a high (9.6 g/MJ) amount of resistant starch (RS) or various amounts of RS (0.8 to 9.6 g/MJ) and guar gum (0 to 8.8 g/MJ). In one experiment, rats were fed the low and high RS diets in three dietary regimens (ad libitum consuming, 12 h ad libitum/12 h food deprived, and meal fed). Effects of RS and guar gum on serum postprandial and postabsorptive concentrations of total cholesterol (TC) and triacylglycerol (TAG), growth, hydrogen excretion, tissue weights and contents of small intestine and cecum, and pH of cecal contents were investigated. In addition, effects of RS on food intake, de novo hepatic synthesis of fatty acids and neutral sterols, and on lipoprotein lipase activity and weight of epididymal fat pads were investigated. Compared with feeding the low RS diet, the high RS diet reduced the serum TC and TAG concentrations, with these effects observed after 1 and 2 wk of feeding, respectively. The dietary regimen did not influence the effect of RS on the serum TC and TAG concentrations, but it did affect the serum TAG concentration. Resistant starch had no effect on the hepatic synthesis of fatty acids and neutral sterols or on the lipoprotein lipase activity in epididymal fat pads. Guar gum also reduced the serum TC concentration, but it had no effect on serum TAG concentration. The tissue weights and contents of small intestine and cecum as well as hydrogen excretion increased with increasing amounts of dietary RS and guar gum, whereas the pH of cecal contents decreased. No effects of RS on food intake and total body weight gain were found, whereas guar gum decreased weight gain. Feeding the high RS diet also led to a lower weight of the epididymal fat pads. We conclude that dietary RS can reduce serum TC and TAG concentrations and fat accretion.     

Effects of spinach leaf protein concentrate on the serum cholesterol and amino acid concentrations in rats fed a cholesterol-free diet

The effects of spinach leaf protein concentrate (SPPC) on serum and liver lipid concentrations and on serum free amino acid concentrations were examined in rats fed a cholesterol-free diet containing 2 and 10% fats. The serum total cholesterol, triacylglycerol and phospholipid concentrations in the rats fed an SPPC diet containing 2% corn oil were significantly lower than those of the rats fed a corresponding casein diet. When 10% corn oil or lard was used, the serum cholesterol-lowering effect of the SPPC became insignificant, but the serum and liver triacylglycerol concentrations were kept at significantly lower levels. Both the amounts of fecal neutral steroids and bile acids were significantly higher in the rats fed the SPPC than those of the casein-fed rats. The concentrations of serum threonine, serine, glutamine, glycine, cystine, and isoleucine were significantly higher in the rats fed the SPPC diet containing 2% corn oil compared with those of the control rats, but when the dietary fat was raised to 10%, only glycine showed a higher serum concentration. These results indicate that the SPPC has a stronger cholesterol-lowering effect at a lower dietary fat level, 2%, and the activity is partly due to the inhibition of intestinal absorption of cholesterol and bile acid, and partly due to an increase in the concentration of some of the serum amino acids.     

Influence of cholesterol and fat feeding on hepatic lysosomal enzymes in guinea pigs

The activity of four lysosomal enzymes have been examined in liver cytoplasmic extract from guinea pigs fed three different diets: a) an ordinary diet, low in fat, high in carbohydrates; b) a semisynthetic diet containing 10% cottonseed oil (by weight) without and c) with 1% cholesterol. The cholesterol content in the liver was similar in control-fed and fat-fed animals, while there was a 10-fold increase in cholesterol + fat-fed animals, and most of this cholesterol was present as ester. We observed increased activity of beta-glucuronidase, beta-acetyl-glucosaminidase and cathepsin D during fat cholesterol feeding (diet c) while the activity of acid phosphatase decreased compared to control-fed animals. These findings probably mirror the increased hepatic accumulation of lipids and lipoproteins observed in cholesterol + fat-fed guinea pigs.     

The biological value of fats

Integral characteristics of animal development (weight increase, maturing of biological systems) used to date are not adequate to the requirements of detailed biological evaluation of dietary fats. The linoleic acid content in the dietary fat and the eicosatrienoic acid - eicosatetraenoic acid ratio (20:3/20:4 = HOLMAN coefficient) in the organism alone are also inadequate criteria. For this reason, the author attempted to establish metabolism-relevant law-like relationships between the fatty acid pattern of dietary fats and tissue lipids.     

Value of ovarian stromal blood flow velocity measurement after pituitary suppression in the prediction of ovarian responsiveness and outcome of in vitro fertilization treatment

BACKGROUND: The fatty acid composition of the diet is known to be partially reflected by the fatty acid composition of serum lipids. OBJECTIVE: We examined whether pentadecanoic acid (15:0) in serum lipids can be used as a marker for intake of milk fat, the major dietary source of 15:0. We also investigated the relations between intake of milk fat and cardiovascular disease risk factors. DESIGN: Sixty-two 70-y-old men completed 7-d dietary records. The intake of milk products was studied in relation to the proportions of 15:0 in serum cholesterol esters and phospholipids, as well as to the clinical characteristics of these men, by using Spearman's rank correlation. RESULTS: The proportions of 15:0 in serum cholesterol esters were positively related to butter intake (r = 0.36. P = 0.004) and to the total amount of fat from milk products (r = 0.46, P < 0.0001): 15:0 in phospholipids was related to the amount of fat from milk and cream (r = 0.34, P = 0.008) and to the total amount of fat from milk products (r = 0.34, P = 0.008). Inverse associations were found between intake of milk products and body mass index, waist circumference, LDL-HDL ratio, HDL triacylglycerols, and fasting plasma glucose, whereas relations to HDL cholesterol and apolipoprotein A-I tended to be positive. CONCLUSIONS: The results suggest that 15:0 in serum can be used as a marker for intake of milk fat. The explanation for the inverse associations between the intake of milk products and certain cardiovascular risk factors is not known.     

Independence of serum lipid levels and dietary habits. The Tecumseh study

Serum cholesterol and triglyceride levels were correlated with dietary habits of 4,057 adult participants in a prospective epidemiologic survey of cardiovascular disease in Tecumseh, Mich. Frequency of consumption of 110 different food items was determined for each participant and average weekly consumption rates of foods high in fat, sugar, starch, and alcohol content were calculated. Frequency of consumption of these nutrients was then correlated with serum cholesterol and triglyceride levels of individual subjects. Serum cholesterol and triglyceride values were not positively correlated with selection of dietary constituents. Positive correlations between serum lipid levels and adiposity were statistically significant. These findings suggest that serum cholesterol and triglyceride levels among Americans are more dependent on degree of adiposity than on frequency of consumption of fat, sugar, starch, or alcohol.     

Effect of high dietary copper on fatty acid composition of the chick

Three experiments were conducted to study the effect of varying levels of dietary copper on fatty acid composition of adipose and liver tissue of male broiler chicks. Chicks were fed the experimental diets to 4 weeks at which time leg adipose and liver samples were obtained for fatty acid determination. Adding 500 or more p.p.m. copper to either a practical or corn starch-soy basal diet caused significant changes in fatty acid composition but the differences were variable perhaps due to a depression of growth caused by these levels of copper. Fatty acid composition of the tissue was not greatly affected by adding 250 p.p.m. of copper to the practical diet which contained 1.5% poultry fat. When a corn starch-soy diet was fed with 0, 2, or 8% added corn oil, the ratio of 16:0 + 18:0 to 16:1 to 18:1 was not lowered in leg adipose lipids by copper supplementation (250 p.p.m.) with any level of added corn oil. With liver lipids copper appeared to reduced the ratios in birds fed the diets with 0 or 2% added corn, but the differences were not statistically significant. The results indicate that using copper levels in practical diets that do not depress growth rate will not have much effect on fatty acid composition of carcass lipids and probably not on physical characteristics of the fat.     

The impact of dietary fats, photoperiod, temperature and season on morphological variables, torpor patterns, and brown adipose tissue fatty acid composition of hamsters, Phodopus sungorus

We investigated how dietary fats and oils of different fatty acid composition influence the seasonal change of body mass, fur colour, testes size and torpor in Djungarian hamsters, Phodopus sungorus, maintained from autumn to winter under different photoperiods and temperature regimes. Dietary fatty acids influenced the occurrence of spontaneous torpor (food and water ad libitum) in P. sungorus maintained at 18 degrees C under natural and artificial short photoperiods. Torpor was most pronounced in individuals on a diet containing 10% safflower oil (rich in polyunsaturated fatty acids), intermediate in individuals on a diet containing 10% olive oil (rich in monounsaturated fatty acids) and least pronounced in individuals on a diet containing 10% coconut fat (rich in saturated fatty acids). Torpor in P. sungorus on chow containing no added fat or oil was intermediate between those on coconut fat and olive oil. Dietary fatty acids had little effect on torpor in animals maintained at 23 degrees C. Body mass, fur colour and testes size were also little affected by dietary fatty acids. The fatty acid composition of brown fat from hamsters maintained at 18 degrees C and under natural photoperiod strongly reflected that of the dietary fatty acids. Our study suggests that the seasonal change of body mass, fur colour and testes size are not significantly affected by dietary fatty acids. However, dietary fats influence the occurrence of torpor in individuals maintained at low temperatures and that have been photoperiodically primed for the display of torpor.     

Effects of dietary fatty acid composition on basal and hormone-stimulated hepatic lipogenesis and on circulating lipids in the rat

Thirty male rats were randomly assigned to one of three dietary groups in which the source of dietary fat was either a mixed oil, maize oil or fish oil. Effects of dietary fatty acid composition on in vitro rates of [U-14C]glucose incorporation into hepatic total lipids and into hepatic triacylglycerol were measured under basal, insulin (4 nM)-, gastric inhibitory polypeptide (GIP; 6 nM)- and insulin + GIP (4 nM + 6 nM)-stimulated conditions. Effects of the three diets on postprandial plasma triacylglycerol, cholesterol, insulin and GIP concentrations were also measured. The fish-oil diet decreased rates of basal glucose incorporation into hepatic total lipids (P < 0.05) and hepatic triacylglycerol, (P < 0.01) compared with the mixed-oil diet. The presence of insulin + GIP in the incubation medium stimulated glucose incorporation into hepatic total lipids in the maize-oil (P < 0.01) and fish-oil groups (P < 0.05), as well as into hepatic triacylglycerol in the maize-oil group (P < 0.005). In addition, the fish-oil diet decreased postprandial plasma triacylglycerol levels compared with both other dietary groups (P < 0.05 both cases), and the mixed-oil diet markedly increased postprandial plasma insulin levels compared with the other dietary groups (P < 0.001).