Correlation of serum fatty acid composition with dietary intake data in children and young adults.

The percentage compositions of fatty acids in serum cholesteryl esters and phospholipids were analysed with gas chromatography in 759 nine- to 24-year-old Finns. The correlations of serum fatty acids with dietary fat intake data were calculated from a 48-h recall survey. The dietary P/S ratio had correlations of r = 0.50 and r = 0.40 with linoleate (18:2) in serum cholesteryl esters and phospholipids, respectively. The intake of fish and fish products correlated positively with the percentages of eicosapentaenoate (20:5 n-3) and docosahexaenoate (22:6 n-3) in both cholesteryl esters and phospholipids. Dietary intake of saturated fat correlated positively with the percentages of all saturated fatty acids in cholesteryl esters and with myristate (14:0) in phospholipids. The intake of monounsaturated fats did not correlate positively with serum monoenes. In conclusion, the dietary P/S ratio is well reflected in the fatty acid composition of serum cholesteryl esters and phospholipids, the intake of saturated fats less well, and the intake of monounsaturated fats not at all.     

Effects of oleate-rich and linoleate-rich diets on the susceptibility of low density lipoprotein to oxidative modification in mildly hypercholesterolemic subjects.

We report the results of feeding oleate- or linoleate-enriched diets for 8 wk to mildly hypercholesterolemic subjects and the resulting alterations in composition and functional properties of their plasma LDL and HDL. LDL isolated from subjects on oleate-enriched diets was less susceptible to copper-mediated oxidation, as measured by conjugated diene and lipid peroxide formation, and less susceptible to LDL-protein modification, as evidenced by reduced LDL macrophage degradation after copper- or endothelial cell-induced oxidation. For all subjects, the percentage of 18:2 in LDL correlated strongly with the extent of conjugated diene formation (r = 0.89, P < 0.01) and macrophage degradation (r = 0.71, P < 0.01). Oxidation of LDL led to initial rapid depletion of unsaturated fatty acids in phospholipids followed by extensive loss of unsaturated fatty acids in cholesteryl esters and triglycerides. Changes in HDL fatty acid composition also occurred. However, HDL from both dietary groups retained its ability to inhibit oxidative modification of LDL. This study demonstrates that alterations in dietary fatty acid composition can effectively alter the fatty acid distribution of LDL and HDL in hypercholesterolemic subjects and that susceptibility to LDL oxidation is altered by these changes. Substitution of monounsaturated (rather than polyunsaturated) fatty acids for saturated fatty acids in the diet might be preferable for the prevention of atherosclerosis.     

Platelet fatty acid composition in relation to fatty acid composition in plasma and to serum lipoprotein lipids in healthy subjects with special reference to the linoleic acid pathway

The fatty acid composition in platelet phospholipids and in the plasma lipid esters as well as the serum lipoprotein lipid concentrations were determined in 67 healthy male subjects in order to establish the relationships between blood lipids and platelets. A positive correlation was found between the concentrations of the triglyceride rich serum lipoprotein lipids and the relative percentage of saturated and monounsaturated fatty acids in plasma. The correlations were also positive between the serum high density lipoprotein-cholesterol concentration and the relative content of linoleic acid in the plasma cholesterol esters and phospholipids. Negative correlations were found between the relative percentage of saturated and monounsaturated fatty acids in the plasma lipid esters versus linoleic acid in plasma and in the platelets. On the other hand there were positive correlations between linoleic acid in the plasma lipid esters and in the platelet phospholipids. These results indicate a direct dietary influence on the platelet phospholipid fatty acid composition. The correlations between the fatty acids of the n-6 series within plasma and platelets as well as between plasma and platelets indicate that a high linoleic acid content is not associated with an increased arachidonic acid concentration. The results also indicate that the limiting metabolic step in the conversion of linoleic acid into arachidonic acid may be located at different levels in plasma and in the platelets.     

Lipoprotein(a), essential fatty acid status and lipoprotein lipids in female Australian vegetarians.

In the present study we investigated serum lipoprotein(a) [Lp(a)] levels, plasma lipids, the serum phospholipid polyunsaturated fatty acid profile and correlates of serum Lp(a) in healthy free-living female vegetarians (n=50) and omnivores (n=24) to assess differences which may have implications for cardiovascular risk. Dietary saturated fat and total plasma cholesterol were significantly lower in the vegetarians compared with omnivores. The mean serum Lp(a) concentration was lower in the vegetarians (171 mg/l) than in the omnivores (247 mg/l). The serum Lp(a) concentration was significantly negatively correlated with carbohydrate intake (as % of energy), and positively correlated with plasma total cholesterol. Compared with the omnivores, the vegetarians had significantly lower concentrations of 20:3,n-6, 20:4,n-6, 22:5,n-6, 20:5,n-3, 22:6,n-3 and total n-6 and n-3 polyunsaturated fatty acids, and a lower n-3/n-6 polyunsaturated fatty acid ratio, in serum phospholipids. Lower concentrations of plasma total cholesterol, serum phospholipid total fatty acids, total saturated fatty acids and arachidonic acid, and a tendency towards a lower serum Lp(a) concentration, in vegetarians may have beneficial effects on cardiovascular disease risk. However, the decreased concentration of serum phospholipid n-3 polyunsaturated fatty acids may potentially promote thrombotic risk. Based on the present data, it would seem appropriate for omnivores to reduce their dietary intake of total fat and saturated fat in order to decrease their plasma cholesterol, and vegetarians should perhaps increase their dietary intake of n-3 polyunsaturated fatty acids, and thus improve the balance of n-3/n-6, in order to reduce any thrombotic tendency that might increase their generally low risk of cardiovascular disease.     

Effects of nicotinic acid treatment on fatty acid composition of plasma lipids and adipose tissue in hyperlipidaemia.

Effects of 6-week treatment with 4 g daily of nicotinic acid on fatty acid composition in different serum lipids and in adipose tissue glycerides were studied in 31 hyperlipidemic patients. The percentages of eight fatty acids in triglycerides, phospholipids and cholesteryl esters of whole plasma as well as in subcutaneous adipose tissue glycerides were measured. Nicotinic acid treatment produced decreases in triglyceride and total cholesterol concentrations of VLDL and LDL, whereas HDL total cholesterol levels in serum increased after drug therapy, all p less than 0.01. There were reductions in the relative contents of myristic acid in plasma phospholipids (from 0.4% to 0.3%; p less than 0.05) and cholesteryl esters (from 0.9% to 0.7%; p less than 0.001). There were decreases in the percentages of stearic acid in plasma phospholipids (from 17.0% to 15.0%) and cholesteryl esters (from 1.2% to 1.0%; both p less than 0.001). The relative contents of polyunsaturated fatty acids, mainly linoleic acid, in plasma phospholipids were increased (from 32% to 33.5%; p less than 0.05). There were reductions in the linolenic acid contents of adipose tissue (from 1.5% to 1.1%) and plasma triglycerides (from 1.1% to 0.8%), both p less than 0.05, possibly indicating increased conversion of linolenic acid to prostaglandins. There was no relationship between changes in the percentages of individual fatty acids and changes in triglyceride or total cholesterol levels of whole serum and its VLDL, LDL and HDL fractions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatic origin of cholesteryl oleate in coronary artery atherosclerosis in African green monkeys. Enrichment by dietary monounsaturated fat.

Relationships among plasma lipoprotein cholesterol, cholesterol secretion by the isolated, perfused liver, and coronary artery atherosclerosis were examined in African green monkeys fed diets containing cholesterol and 35% of calories as fat enriched in polyunsaturated, monounsaturated, or saturated fatty acids. The livers of animals fed monounsaturated fat had significantly higher cholesteryl ester concentrations (8.5 mg/g wet wt) than the livers of the other diet groups (3.65 and 3.37 mg/g wet wt for saturated and polyunsaturated fat groups, respectively) and this concentration was highly correlated with plasma cholesterol and apoB concentrations in each diet group. Cholesteryl oleate was 58 and 74. 5% of the liver cholesteryl ester in the saturated and monounsaturated fat groups. In each diet group, perfusate cholesteryl ester accumulation rate was highly correlated to liver and plasma cholesterol concentrations, and to plasma LDL cholesteryl ester content. Cholesteryl oleate was 48 and 67% of the cholesteryl esters that accumulated in perfusate in the saturated and monounsaturated fat animals, and this percentage was very highly correlated (r = -0.9) with plasma apoB concentration. Finally, in these two diet groups, liver perfusate cholesteryl ester accumulation rate was well correlated (r >/= 0.8) to coronary artery cholesteryl ester concentration, a measure of the extent of coronary artery atherosclerosis that occurred over the five years of diet induction in these animals. These data define an important role for the liver in the cholesteryl oleate enrichment of the plasma lipoproteins in the saturated and monounsaturated fat groups, and demonstrate strong relationships among hepatic cholesteryl ester concentration, cholesteryl ester secretion, and LDL particle cholesteryl ester content. The high correlation between liver cholesteryl ester secretion and coronary artery atherosclerosis provides the first direct demonstration of the high degree of importance of hepatic cholesteryl ester secretion in the development of this disease process. The remarkable degree of enrichment of cholesteryl oleate in plasma cholesteryl esters of the monounsaturated fat group may account for the relatively high amount of coronary artery atherosclerosis in this group.     

Effect of acute hyperinsulinemia on fatty acid composition of serum lipids in non-insulin-dependent diabetics and healthy men.

The fatty acid pattern of serum phospholipids, cholesteryl esters, triglycerides and free fatty acids was measured before and after a 5-h two-step euglycemic hyperinsulinemic clamp (75 and 1400 microU/ml) in 21 non-insulin-dependent diabetics and 14 age-, weight-, and sex-matched healthy controls. Acute hyperinsulinemia was associated with a statistically significant increase in essential fatty acid and a decrease in non-essential fatty acid contents in triglycerides while the levels of serum triglycerides and free fatty acids dropped in both groups. The fatty acid composition of phospholipids and cholesteryl esters remained unchanged as did the levels of serum phospholipids, total cholesterol and HDL cholesterol.     

The effect of orlistat on the fatty acid composition of serum lipid fractions in obese subjects.

OBJECTIVE: To determine whether there are any changes in the fatty acid composition of serum triglycerides, cholesterol esters, and phospholipids induced by administration of orlistat three times a day compared with placebo as combined with a low-fat hypocaloric diet. METHODS: After 4 weeks of placebo administration, 75 obese subjects were randomized to receive either one capsule (120 mg) of orlistat or placebo three times a day with meals for 1 year in conjunction with a nutritionally balanced hypocaloric diet. Food records were kept to estimate the nutrient intake. The fatty acid composition of serum lipids were analyzed with gas chromatograph. The molar percentage proportions of fatty acids in serum lipid fractions were calculated. RESULTS: Compared with placebo, there was a significant decrease in the proportion of linoleic acid in triglycerides, cholesterol esters, and phospholipids in the orlistat group, even after the effect of the decrease in the linoleic acid dietary intake (percent of energy), weight change, and gender were taken into account. However, the use of orlistat explained only 9% to 13% of the decrease in the proportion of linoleic acid in serum cholesterol esters, triglycerides, and phospholipids. CONCLUSION: The long-term treatment with orlistat may result in a small decline in the proportion of diet-derived fatty acids in serum lipid fractions when used in conjunction with low-fat diet.     

Increased removal of remnants of triglyceride-rich lipoproteins on a diet rich in polyunsaturated fatty acids

We studied the effect of two diets, one rich in polyunsaturated and the other in saturated fatty acids, on the postprandial processing of exogenous and endogenous triglyceride-rich lipoproteins (chylomicrons, very-low-density lipoproteins, and their remnants). For this purpose, 12 normolipidaemic young volunteers were fed, in a cross-over design of 9 days on each diet, either a diet rich in saturated fat (21% of their daily energy intake from saturated fat, 12% from monounsaturated fat, and 3% from polyunsaturated fat) or a diet rich in polyunsaturated fat (10% saturated fat, 9% monounsaturated fat, and 18% polyunsaturated fat) (P/S ratios 0.14 and 1.8, respectively). On the last day of each dietary period blood samples were drawn six times over a 24-h period for determination, by densitometric scanning of SDS gels, of the diurnal pattern of apoprotein B-48 and B-100 in the d less than 1.019 g ml-1 fractions, as estimates for the processing of chylomicrons and very-low-density lipoproteins. In addition to the usual decrease in the fasting and diurnal concentrations of total serum cholesterol and of cholesterol in the low-density lipoprotein fractions (between 15 and 21%), the diet rich in polyunsaturated fat resulted in 43% lower daily concentrations of chylomicrons and their remnants. This was due to differences in the clearance rate of chylomicrons and their remnants, rather than to differences in the absorption rate of exogenous fat. In addition, the concentrations of very low density lipoproteins and their remnants during the day were 20% lower on the diet rich in polyunsaturated fat.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary fatty acids and vitamin E levels in HL-60 cell proliferation

BACKGROUND: Fatty acids have shown to be both modulators and messengers of signals triggered at the level of cell membranes. There is, however, controversy about the role of fatty acids in cell proliferation kinetics, and it is still unknown whether cell proliferation can be regulated by fatty acid dietary intake in humans. Our objective was to investigate whether feasible changes in the human dietary food intake that induce significant changes in lipids, fatty acids and the oxidative state were able to influence proliferation kinetics of the leukaemia cell line HL-60. MATERIALS AND METHODS: Healthy men and women were subjected to four consecutive dietary periods with increasing degree of unsaturation: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), n-6 polyunsaturated fatty acids (n-6 PUFAs), n-3 polyunsaturated fatty acids (n-3 PUFAs). Plasma lipids and oxidation parameters were controlled during each period. Serum from each subject in the four dietary periods was incubated for 3 days with the leukaemia cell line, HL-60 (250 x 10(3) cell mL-1), to study cell proliferation. RESULTS: In men, an n-3 polyunsaturated fatty acid-enriched diet showed a significant inhibition of DNA duplication with respect to a saturated-enriched diet, but the effect is not sufficient in blocking cell proliferation. However, as expected, the in vitro addition of fatty acids to HL-60 cells significantly halted proliferation. In addition, the HL-60 growth ratio was shown to be inversely correlated with plasma vitamin E (P = 0.0004) and oleic acid in phospholipids (P = 0.01) in plasma of the individuals in the dietary intervention study. CONCLUSIONS: Our results demonstrate that changes in serum fatty acid composition obtained with dietary changes, without extreme variations of the regular diets of a free-living population, cannot block HL-60 cell proliferation.     

Impaired microsomal oxidation of the atypical antipsychotic agent clozapine in hepatic steatosis

Hepatic lipid infiltration (steatosis) is a complication of the metabolic syndrome and can progress to nonalcoholic steatohepatitis and severe liver injury. Microsomal cytochrome P450 (P450) drug oxidases are down-regulated in experimental steatosis. In this study we evaluated the separate and combined effects of lipid accumulation and P450 down-regulation on the microsomal oxidation of the antipsychotic agent clozapine (CLZ), the use of which is associated with an increased incidence of the metabolic syndrome. Several important drug oxidizing P450s were down-regulated, and the formation of N-desmethyl-CLZ (norCLZ) and CLZ N-oxide was decreased in microsomal fractions from orotic acid-induced early steatotic rat liver. Inclusion of lipids extracted from steatotic, but not control, liver decreased the free concentration of CLZ in microsomes and suppressed norCLZ formation; CLZ N-oxidation was unchanged. Triglycerides increased in steatotic liver to 15-fold of control, whereas increases in the monounsaturated oleic acid to 10-fold of control and total polyunsaturated and saturated fatty acids to 4- and 5-fold of control also occurred. Addition of triglycerides containing esterified omega-6 and omega-3 fatty acids inhibited the microsomal formation of norCLZ but not that of CLZ N-oxide; triglycerides esterified with unsaturated and monounsaturated fatty acids were inactive. Thus, drug oxidation may be suppressed in steatosis by P450 down-regulation and the accumulation of polyunsaturated fatty esters. In contrast, the activity of the flavin-containing monooxygenase that mediates CLZ N-oxidation was unimpaired. Lipid deposition in livers of patients with the metabolic syndrome may necessitate dosage adjustments for toxic drugs, including CLZ.     

COMPOSITION AND SYNTHESIS OF LIPIDS IN RESTING AND PHAGOCYTIZING LEUKOCYTES

The lipid content of rabbit polymorphonuclear leukocytes, obtained from peritoneal exudates, constituted 8.7 ± 2.9 per cent of the dry weight of these cells; 60 per cent of all lipids were phospholipids, 20 per cent triglycerides, and the remainder cholesterol and cholesterol esters and a small amount of non-esterified fatty acids (2 to 4 per cent). The composition of the fatty acids in leukocytes, as determined by gas-liquid chromatography, was slightly different from rabbit serum and red blood cells, but markedly different from the dietary fat. The synthesis, turnover, and composition of lipids in rabbit leukocytes at rest and during phagocytosis in vitro were compared. Lipid content and composition were not affected by the phagocytic process. However, active phagocytosis resulted in an increase in the rate of turnover of lipids. This stimulation of lipid metabolism was more marked in triglycerides and cholesterol esters than in phospholipids. It is suggested that the increased turnover of lipid during phagocytosis may reflect a general metabolic stimulation accompanying this process, rather than a specific synthesis of phospholipid for the production of new cell membrane.     

Dietary Fats and Platelet Function among Finnish Men

The aim of this study was to elucidate the role of platelet aggregation as a risk factor for ischemic heart disease (IHD) and the relationship between fatty acids and platelet function. Platelet aggregation upon adenosine diphosphate (ADP), adrenaline and thrombin were measured in middle aged men in east and west, two regions of Finland with a nearly twofold difference in IHD mortality. Platelet aggregation results were correlated with the fatty acid compositions of plasma lipid fractions, adipose tissue triglycerides and platelet phospholipids.

There was no significant east-west difference in platelet reactivity to ADP, adrenaline and thrombin. ADP-induced platelet aggregation showed significant negative correlations with all the platelet C20-C22 n-3 polyunsaturated fatty acids (PL)FA), but significant positive correlations with the percentage of 18:2n-6 in adipose tissue and plasma cholesterol esters (CE) and triglycerides (TG). Adrenaline-induced aggregation correlated negatively with the percentage of 20:5n-3 in plasma CE and TG, and positively with the total percentage of saturated fatty acids in platelets. Aggregation upon thrombin had a negative correlation with the 20:3n-6/20:4n-6 ratio in plasma CE and a positive correlation with 18: 2n-6 in adipose tissue.

The percentages of the major PUFA in platelets correlated sgnificantly with the same fatty acids in plasma CE and phospholipids PL. Platelet 20: 5n-3 had a highly significant negative correlation with the percentage of 18:2n-6 in plasma and adipose tissue lipids. Platelet 20: 4n-6 was unrelated to its precursors in plasma. The percentage of 18: 2n-6 in plasma and adipose tissue lipids was consistently lower in men from eastern than western Finland, whereas the percentage of platelet 20: 5n-3 was higher in the eastern men.

The results indicate, that (1) platelet function may not play a role in the regional gradient in IHD rate in Finland, (2) in a free-living population, relatively small changes in plasma and platelet fatty acids may have significant influence on platelet aggregation and on thrombosis tendency and (3) an increase in dietary PUFA content may not affect platelet function favourably, unless attention is paid to the maintaining of the n-3/n-6 ratio in the diet.     

Dietary fats and platelet function among Finnish men

The aim of this study was to elucidate the role of platelet aggregation as a risk factor for ischemic heart disease (IHD) and the relationship between fatty acids and platelet function. Platelet aggregation upon adenosine diphosphate (ADP), adrenaline and thrombin were measured in middle aged men in east and west, two regions of Finland with a nearly twofold difference in IHD mortality. Platelet aggregation results were correlated with the fatty acid compositions of plasma lipid fractions, adipose tissue triglycerides and platelet phospholipids. There was no significant east-west difference in platelet reactivity to ADP, adrenaline and thrombin. ADP-induced platelet aggregation showed significant negative correlations with all the platelet C20-C22 n-3 polyunsaturated fatty acids (PUFA), but significant positive correlations with the percentage of 18:2n-6 in adipose tissue and plasma cholesterol esters (CE) and triglycerides (TG). Adrenaline-induced aggregation correlated negatively with the percentage of 20:5n-3 in plasma CE and TG, and positively with the total percentage of saturated fatty acids in platelets. Aggregation upon thrombin had a negative correlation with the 20:3n-6/20: 4n-6 ratio in plasma CE and a positive correlation with 18:2n-6 in adipose tissue. The percentages of the major PUFA in platelets correlated significantly with the same fatty acids in plasma CE and phospholipids PL. Platelet 20: 5n-3 had a highly significant negative correlation with the percentage of 18: 2n-6 in plasma and adipose tissue lipids. Platelet 20: 4n-6 was unrelated to its precursors in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of a monounsaturated diet vs. a polyunsaturated fatty acid-enriched diet on blood pressure in normotensive women and men

The effect on blood pressure of monounsaturated and (n-6)polyunsaturated fatty acids was studied under strict dietary control in normotensive subjects. For 17 days 31 women and 27 men received a control diet providing 19.3% of energy as saturated fat. Then subjects were randomized over two test diets: one diet provided 15.1% of energy from monounsaturated and 7.9% from polyunsaturated fatty acids ('mono diet'), and the other diet provided 10.8% from monounsaturated and 12.7% from polyunsaturated fatty acids ('poly diet'). Saturated fat intake was now 12.8% on both diets. Mean blood pressure at the end of the control period was 116/69 mmHg for the mono group and 117/73 mmHg for the poly group. After 5 weeks on the test diet, blood pressure was 115/67 mmHg for the mono group and 117/72 mmHg for the poly group (difference in changes between the two diet groups was not significant). These findings suggest that at a high fat intake, linoleic acid, when providing more than 7.9% of energy intake, does not influence blood pressure relative to oleic acid in normotensive women and men.     

A modified method for the preparation of methyl esters of a mixture of medium-chain and long-chain fatty acids Application to the determination of serum triglyceride and non-esterified fatty acid composition and concentration by gas-liquid chromatography

A modified method for the preparation of methyl esters from triglycerides and NEFA-containing fatty acids, both medium- and long-chain, saturated and poly-unsaturated, is described (carbon chain length C₈–C₁₈). The addition of a suitable internal standard (triheptadecanoin or heptadecanoic acid) prior to methylation permits the quantification of serum triglycerides and NEFA in mixtures containing fatty acids saturated and polyunsaturated from C₈–C₁₈.     

Lack of association between arterial blood pressure and erythrocyte fatty acid composition in an Italian population sample

The relation between arterial blood pressure and erythrocyte fatty acid composition was investigated in a large urban female population aged 20-69 years. No significant differences in the relative amounts of saturated, monounsaturated and polyunsaturated (n-6 and n-3 series) fatty acids and in the mean polyunsaturated/saturated and linoleic/oleic ratios were observed in the different quartiles of both systolic and diastolic blood pressure. Moreover, there was no significant correlation between individual erythrocyte fatty acids and their ratios and either blood pressure or other risk factors for atherosclerosis (age, body mass index, total serum cholesterol and triglycerides). In the multivariate analysis no independent correlations between systolic and diastolic blood pressure and the individual erythrocyte fatty acids were observed; age and body mass index were strongly related to blood pressure. Our results do not confirm for erythrocyte fatty acids the reported associations between plasma fatty acids and blood pressure.     

Disorders of lipid metabolism in patients with chronic diseases of the small intestine

Lipid metabolism was evaluated in patients with chronic enteritis, celiac disease, general variable immunodeficiency (GVI), short-bowel syndrome. In chronic enteritis with malabsorption syndrome degree I and II changes in metabolism were characterized by hyperlipidemia due to high lipid fractions, mainly triglycerides; in malabsorption syndrome degree III (celiac disease, general variable immunodeficiency, short-bowel syndrome) by a drop of serum total lipids, phospholipids, cholesterol, beta-lipoproteins, free fatty acids, elevated concentrations of triglycerides. Changes in fatty acid composition of blood serum in patients with malabsorption syndrome degree III manifested by derangement of polyunsaturated fatty acids ratio. Arachidonic acid concentration was reduced in 100% of cases, linolenic acid in 45%. In all the patients with celiac disease and malabsorption syndrome degree III there was hypoactivity of lipolytic blood enzymes lipase and tributyrinase.     

Quality of dietary fatty acids, insulin sensitivity and type 2 diabetes.

Epidemiological evidence and intervention studies clearly indicate that the quality of dietary fat influences insulin sensitivity in humans, in particular, saturated fat worsens it, while monounsaturated and omega-6 polyunsaturated fats improve it. Long chain omega-3 fatty acids do not seem to have any effect on insulin sensitivity, at least in humans. Moreover, there is also good epidemiological evidence that the quality of dietary fat may influence the risk of type 2 diabetes, again with saturated fat increasing and unsaturated fat decreasing this risk. No intervention study is available at the moment on this specific point, even if in the Finnish Diabetes Prevention Study the incidence of type 2 diabetes was reduced by a multifactorial intervention, which also included a reduction of saturated fat intake.     

Effects of dietary fat saturation on eicosanoid production, platelet aggregation and blood pressure

The effects of dietary fat saturation on eicosanoid urinary excretion, platelet aggregation (PA) and blood pressure (BP) were studied in 42 healthy subjects. They consumed four consecutive diets differing in their fat saturation [saturated (SFA); monounsaturated (MUFA); polyunsaturated n -6 (PUFA n -6); and polyunsaturated n -6/ n -3, (PUFA n -3)]. Each diet period lasted 5 weeks. There were no differences in 24-h 2,3-dinor-6-keto-prostaglandin F_1α excretion among dietary periods. A significant effect was noted regarding the excretion of 11-dehydro-thromboxane B₂ ( P  < 0.0001). During the PUFA n -6 phase the excretion was significantly higher than during SFA and MUFA periods. Dietary fatty acid composition had a significant effect on ADP (1 μmol L⁻¹) and collagen (2 mg L⁻¹) induced PA. Dietary fat also had a significant effect on systolic and diastolic blood pressure ( P  < 0.0001). Both were significantly higher during the SFA period than during the other three periods. Our findings suggest that changes in dietary fatty acids may have mild, but significant, effects on eicosanoid production, platelet aggregation and blood pressure.