A polymorphism exon 1 variant at the locus of the scavenger receptor class B type I (SCARB1) gene is associated with differences in insulin sensitivity in healthy people during the consumption of an olive oil-rich diet

Scavenger receptor class B type I (SCARB1) was described as the first high-density lipoprotein receptor. Increasing evidence indicates that SCARB1 plays additional roles particularly in type 2 diabetes mellitus. Our aim was to determine whether the presence of an exon 1 (G-->A) polymorphism at the SCARB1 gene modifies the insulin sensitivity to dietary fat. METHODS: We studied 59 healthy volunteers (30 men and 29 women, 42 G/G homozygous and 17 G/A heterozygous). Subjects consumed three diets for 4 wk each: a saturated fatty acid (SFA)-rich diet (38% fat, 20% SFA), followed by a carbohydrate (CHO)-rich diet (30% fat, 55% CHO) or a monounsaturated fatty acid (MUFA)-rich diet (38% fat, 22% MUFA) after a randomized crossover design. For each diet, we investigated peripheral insulin sensitivity with the insulin suppression test. RESULTS: Steady-state plasma glucose after the MUFA diet was lower in G/A compared with G/G subjects (P = 0.030). This effect was not observed after CHO and SFA diets (P = 0.177 and 0.957, respectively). Plasma nonesterified free fatty acid values were lower in subjects carrying the A allele for all the diet periods. CONCLUSIONS: Our findings show that carriers of the G/A genotype have significant increases in insulin sensitivity after a MUFA-rich diet compared with G/G individuals.     

Consumption of diets with different type of fat influences triacylglycerols-rich lipoproteins particle number and size during the postprandial state

Background and aims

Previous evidence suggests that dietary fat could influence the composition and size of triacylglycerols-rich lipoproteins (TRL). In a controlled intervention study on healthy subjects, we evaluated the influence of 3 dietary interventions, with different types of fat on postprandial TRL particle size and number.

Methods and results

Volunteers followed three different diets for four weeks each, according to a randomized crossover design. Western diet: 15% protein, 47% carbohydrates (CHO), 38% fat (22% saturated fatty acid (SFA)); Mediterranean diet: 15% protein, 47% CHO, 38% fat (24% monounsaturated fatty acid (MUFA)); high CHO enriched with ALNA diet: 15% protein, 55% CHO, <30% fat (8% polyunsaturated fatty acid (PUFA)). After a 12-h fast, volunteers consumed a breakfast with 1 g fat and 7 mg cholesterol per kg body weight and a fat composition similar to that consumed in each of the diets: Butter meal: 35% SFA; Olive oil meal: 36% MUFA; Walnut meal: 16% PUFA, 4% α-linolenic acid. Tryglicerides (TG) in TRL (large and small TRL) were determined by ultracentrifugation and size and number of lipoprotein particles were measured with Nuclear Magnetic Resonance Spectroscopy at different time points. The olive oil meal reduced the number of total TRL postprandial particles compared with the other meals (P = 0.002). Moreover, the olive oil meal also increased the TRL particle size compared with the walnut meal (P = 0.001).

Conclusion

Our data showed that short-term intake of the Mediterranean diet and the acute intake of an olive oil meal lead to the formation of a reduced number and higher-size TRL particle compared with other fat sources. These novel findings have implications for understanding the postprandial lipoprotein mechanisms, and could favour the lower cardiovascular risk in Mediterranean countries.     

Effect of a high monounsaturated fatty acids diet and a Mediterranean diet on serum lipids and insulin sensitivity in adults with mild abdominal obesity

Background and aimsDiets high in monounsaturated fatty acids (MUFA) such as a Mediterranean diet may reduce the risk of cardiovascular diseases by improving insulin sensitivity and serum lipids. Besides being high in MUFA, a Mediterranean diet also contains abundant plant foods, moderate wine and low amounts of meat and dairy products, which may also play a role. We compared the effects of a high MUFA-diet with a diet high in saturated fatty acids (SFA) and the additional effect of a Mediterranean diet on insulin sensitivity and serum lipids.Methods and resultsA randomized parallel controlled-feeding trial was performed, in 60 non-diabetics (40–65 y) with mild abdominal obesity. After a two week run-in diet high in SFA (19 energy-%), subjects were allocated to a high MUFA-diet (20 energy-%), a Mediterranean diet (MUFA 21 energy-%), or the high SFA-diet, for eight weeks. The high MUFA and the Mediterranean diet did not affect fasting insulin concentrations. The high MUFA-diet reduced total cholesterol (?0.41 mmol/L, 95% CI ?0.74, ?0.09) and LDL-cholesterol (?0.38 mmol/L, 95% CI ?0.65, ?0.11) compared with the high SFA-diet, but not triglyceride concentrations. The Mediterranean diet increased HDL-cholesterol concentrations (+0.09 mmol/L, 95% CI 0.0, 0.18) and reduced the ratio of total cholesterol/HDL-cholesterol (?0.39, 95% CI ?0.62, ?0.16) compared with the high MUFA-diet.ConclusionReplacing a high SFA-diet with a high MUFA or a Mediterranean diet did not affect insulin sensitivity, but improved serum lipids. The Mediterranean diet was most effective, it reduced total and LDL-cholesterol, and also increased HDL-cholesterol and reduced total cholesterol/HDL-cholesterol ratio.     

Interaction between specific fatty acids,GLP-1 and insulin secretion in humans

AIMS/HYPOTHESIS: Fatty acids affect insulin secretion in vivo, but little is known about the effects of specific fatty acids. Our aim was to investigate differential effects of acutely increased plasma monounsaturated, polyunsaturated and saturated fatty acids on glucose-stimulated insulin secretion in healthy humans. METHODS: A new experimental protocol was used to increase plasma monounsaturated (MUFA test), polyunsaturated (PUFA test) or saturated (SFA test) non-esterified fatty acids for 2 h by repeated oral fat feeding and continuous intravenous heparin infusion. This was followed by a hyperglycaemic clamp (10 mmol/l) to test insulin secretion in response to a prior plasma NEFA increase. RESULTS: Total plasma NEFA concentrations were increased during the fat tests compared to the control visit (1.7-fold increase for MUFA and SFA tests and 1.4-fold increase for PUFA test; p<0.001). Exaggerated responses in plasma insulin, C-peptide and proinsulin concentrations were seen during the hyperglycaemic clamp after increasing plasma NEFA concentrations compared with the control (p<0.01). The effects were greatest for the MUFA test followed by the PUFA test and SFA test (p<0.01). Plasma GLP-1 concentrations increased during fat feeding, with a higher response during the MUFA test compared to PUFA and SFA tests (p<0.01). CONCLUSION/INTERPRETATION: Increasing plasma NEFA concentrations by oral fat feeding with heparin infusion augments glucose-stimulated insulin secretion with the greatest effect for monounsaturated fatty acids and the lowest effect for saturated fatty acids. Monounsaturated fatty acids also increase GLP-1 more than saturated fatty acids. Therefore, the exaggerated insulin concentrations could be due to both NEFA and GLP-1.     

Differential effects of monounsaturated, polyunsaturated and saturated fat ingestion on glucose-stimulated insulin secretion, sensitivity and clearance in overweight and obese, non-diabetic humans

Aims/hypothesis Prolonged elevation of plasma specific fatty acids may exert differential effects on glucose-stimulated insulin secretion (GSIS), insulin sensitivity and clearance.Subjects and methods We examined the effect of oral ingestion, at regular intervals for 24 h, of an emulsion containing either predominantly monounsaturated (MUFA), polyunsaturated (PUFA) or saturated (SFA) fat or water (control) on GSIS, insulin sensitivity and insulin clearance in seven overweight or obese, non-diabetic humans. Four studies were conducted in each individual in random order, 4–6 weeks apart. Twenty-four hours after initiation of oral ingestion, subjects underwent a 2 h, 20 mmol/l hyperglycaemic clamp to assess GSIS, insulin sensitivity and insulin clearance.Results Following oral ingestion of any of the three fat emulsions over 24 h, plasma NEFAs were elevated by ∼1.5- to 2-fold over the basal level. Ingestion of any of the three fat emulsions resulted in reduction in insulin clearance, and SFA ingestion reduced insulin sensitivity. PUFA ingestion was associated with an absolute reduction in GSIS, whereas insulin secretion failed to compensate for insulin resistance in subjects who ingested SFA.Conclusions/interpretation Oral ingestion of fats with differing degrees of saturation resulted in different effects on insulin secretion and action. PUFA ingestion resulted in an absolute reduction in insulin secretion and SFA ingestion induced insulin resistance. Failure of insulin secretion to compensate for insulin resistance implies impaired beta cell function in the SFA study.Electronic Supplementary Material Supplementary material is available for this article at     

The APOB -516C/T polymorphism has no effect on lipid and apolipoprotein response following changes in dietary fat intake in a healthy population

Our goal was to determine whether the presence of the −516C/T polymorphism in the APOB gene promoter modifies the lipid response to changes in the amount and quality of dietary fat. We studied 97 young healthy volunteers (70 males and 27 females), 62 homozygotes for the −516C allele (C/C) (47 males and 15 females), 34 heterozygotes for the −516T allele (C/T) (22 males and 12 females) and one male homozygote for the −516T allele (T/T). Subjects consumed three different diets in successive 4-week dietary periods. During the first 28 days, all subjects consumed a saturated fatty acid (SFA)-rich diet (38% fat and 20% SFA). Then, using a randomized crossover design, subjects were assigned a carbohydrate (CHO)-rich diet (30% fat and 55% carbohydrate) or a monounsaturated fatty acid (MUFA)-rich diet (38% fat and 22% MUFA). At the end of each dietary period, plasma concentrations of triacylglycerols and of total, LDL, and HDL cholesterol were measured. No differences in plasma lipid and apolipoprotein response were found after changes in dietary fat intake in relation to the −516C/T polymorphism in our study population. In conclusion, our data suggest that the APOB −516C/T polymorphism has no effect on the lipid profile after changes in dietary fat intake in a healthy population.     

Liver fat and insulin resistance are independently associated with the -514C>T polymorphism of the hepatic lipase gene

CONTEXT: Liver fat predicts insulin resistance in humans. So far, there is not much information on genetic determinants of liver fat. Hepatic lipase is a liver-specific enzyme that regulates lipid metabolism. OBJECTIVE: First, our object was to investigate whether the functional -514C>T polymorphism of the hepatic lipase gene is associated with liver fat content and with insulin sensitivity. Second, because this polymorphism displays gene-nutrient interactions, we assessed gene-gene interactions with the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma(2) on liver fat content and insulin sensitivity. DESIGN AND METHODS: Cross-sectional data from a total of 1070 nondiabetic subjects were analyzed. Insulin sensitivity was estimated from a 75-g oral glucose tolerance test. A subgroup of 115 subjects underwent measurements of liver fat. RESULTS: The -514C>T polymorphism of the hepatic lipase gene was associated with higher liver fat content (P = 0.005) and lower insulin sensitivity (P = 0.02), both after adjustment for age, gender, and percentage of body fat. This was independent of serum adiponectin concentrations (P = 0.01 and 0.03). However, there was an interaction of the -514C>T polymorphism with the Pro12Ala variant on liver fat (P = 0.09) and insulin sensitivity (P = 0.01). Subjects carrying the -514C>T polymorphism had higher liver fat content and were insulin resistant only before the background of the Pro/Pro genotype of the Pro12Ala polymorphism. CONCLUSIONS: The -514C>T polymorphism of the hepatic lipase gene is associated with higher liver fat content and lower whole-body insulin sensitivity. However, these effects are modulated by the common Pro12Ala polymorphism in peroxisome proliferator-activated receptor-gamma(2). These findings may be relevant for intervention strategies to prevent increase in liver fat content and insulin resistance.     

Compared with saturated fatty acids, dietary monounsaturated fatty acids and carbohydrates increase atherosclerosis and VLDL cholesterol levels in LDL receptor-deficient, but not apolipoprotein E-deficient, mice

Heart-healthy dietary recommendations include decreasing the intake of saturated fatty acids (SFA). However, the relative benefit of replacing SFA with monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), or carbohydrates (CARB) is still being debated. We have used two mouse models of atherosclerosis, low density lipoprotein receptor-deficient (LDLRKO) and apolipoprotein E-deficient (apoEKO) mice to measure the effects of four isocaloric diets enriched with either SFA, MUFA, PUFA, or CARB on atherosclerotic lesion area and lipoprotein levels. In LDLRKO mice, compared with the SFA diet, the MUFA and CARB diets significantly increased atherosclerosis in both sexes, but the PUFA diet had no effect. The MUFA and CARB diets also increased very low density lipoprotein-cholesterol (VLDL-C) and LDL-cholesterol (LDL-C) in males and VLDL-C levels in females. Analysis of data from LDLRKO mice on all diets showed that atherosclerotic lesion area correlated positively with VLDL-C levels (males: r = 0.47, P < 0.005; females: r = 0.52, P < 0.001). In contrast, in apoEKO mice there were no significant dietary effects on atherosclerosis in either sex. Compared with the SFA diet, the CARB diet significantly decreased VLDL-C in males and the MUFA, PUFA, and CARB diets decreased VLDL-C and the CARB diet decreased LDL-C in females. In summary, in LDLRKO mice the replacement of dietary SFA by either MUFA or CARB causes a proportionate increase in both atherosclerotic lesion area and VLDL-C. There were no significant dietary effects on atherosclerotic lesion area in apoEKO mice. These results are surprising and suggest that, depending on the underlying genotype, dietary MUFA and CARB can actually increase atherosclerosis susceptibility, probably by raising VLDL-C levels through a non-LDL receptor, apoE-dependent pathway.     

Effects of lipid-lowering diets enriched with monounsaturated and polyunsaturated fatty acids on serum lipoprotein composition in patients with hyperlipoproteinaemia.

Controlled comparisons of the effects of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) as a part of lipid-lowering diets in persons with hyperlipoproteinaemia are sparse. The present study was carried out at a metabolic ward. Forty hyperlipidaemic patients (25 hypercholesterolaemic and 15 hypertriglyceridaemic) were given a 3-week diet rich in either MUFA (saturated fatty acids 7.3 energy% (E%), MUFA 14.6 E%, PUFA 4.8 E%) or PUFA (saturated fatty acids 7.8 E%, MUFA 8.4 E%, PUFA 10.4 E%), but otherwise with an identical composition. The mean serum cholesterol reduction on the MUFA diet was 12% (P < 0.001), with a low density lipoprotein cholesterol reduction of 11% (P < 0.001). The corresponding reductions on the PUFA diet were 15% (P < 0.001) and 16% (P < 0.001). The serum apolipoprotein B and A-I concentrations decreased highly significantly by 13% and 11% on the MUFA diet and by 14% and 11% on the PUFA diet. None of these changes differed between the two diets. Neither were there any differences between the diets regarding the effects on blood glucose, serum insulin and plasma fibrinogen, but there was a significant decrease in serum insulin with a significant reduction of the insulin/glucose ratio after the MUFA diet. The results of this study indicate that MUFA and PUFA are interchangeable within the given frames in lipid lowering diets even in patients with hyperlipidaemia.     

Comparison of a high-carbohydrate and a high-monounsaturated fat, olive oil-rich diet on the susceptibility of LDL to oxidative modification in subjects with Type 2 diabetes mellitus.

AIMS: To compare the effects of a high-carbohydrate (CHO) diet and a high-monounsaturated fatty acid (MUFA) diet on LDL oxidative resistance in free-living individuals with Type 2 diabetes mellitus. METHODS: Twenty-two men and women out-patients with Type 2 diabetes, with mean age 61 years and in fair metabolic control (HbA1c<8.0%), were enrolled at a university hospital lipid clinic in a randomized, crossover feeding trial comparing two isocaloric diets for 6 weeks each: CHO (fat, 28% energy) and MUFA (fat, 40% energy) based on virgin olive oil. Outcome measurements were changes in LDL susceptibility to oxidation, body weight, glycaemic control, and lipoprotein profiles. RESULTS: Planned and observed diets were well matched. Participants preferred the MUFA diet over the CHO diet. The lag time of conjugated diene formation during Cu2+-induced LDL oxidation was similar after the CHO and MUFA diets (36.4 +/- 12.2 min and 36.0 +/- 13.7 min, respectively). Body weight, glycaemic control, total triglycerides, and total, LDL- and HDL-cholesterol levels also were similar after the two diets. Compared with the CHO diet, the MUFA diet lowered VLDL-cholesterol by 35% (P=0.023) and VLDL triglyceride by 16% (P=0.016). CONCLUSIONS: Natural food-based high-CHO and high-MUFA diets have similar effects on LDL oxidative resistance and metabolic control in subjects with Type 2 diabetes. A MUFA diet is a good alternative to high-CHO diets for nutrition therapy of diabetes because it also has a beneficial effect on the lipid profile and superior patient acceptance.     

The G-250A polymorphism in the hepatic lipase gene promoter is associated with changes in hepatic lipase activity and LDL cholesterol: The KANWU Study

Background and aimsHepatic lipase (HL) catalyzes the hydrolysis of triglycerides and phospholipids from lipoproteins, and promotes the hepatic uptake of lipoproteins. A common G-250A polymorphism in the promoter of the hepatic lipase gene (LIPC) has been described. The aim was to study the effects of the G-250A polymorphism on HL activity, serum lipid profile and insulin sensitivity.Methods and resultsAltogether 151 healthy subjects (age 49 ± 8 years, BMI 26.5 ± 3.0 kg/m²) were randomly assigned for 3 months to an isoenergetic diet containing either a high proportion of saturated fatty acids (SFA diet) or monounsaturated fatty acids (MUFA diet). Within groups there was a second random assignment to supplements with fish oil (3.6 g n-3 FA/day) or placebo. At baseline, the A-250A genotype was associated with high serum LDL cholesterol concentration (P = 0.030 among three genotypes). On the MUFA diet carriers of the A-250A genotype presented a greater decrease in LDL cholesterol concentration than subjects with other genotypes (P = 0.007 among three genotypes). The rare -250A allele was related to low HL activity (P < 0.001 among three genotypes). The diet did not affect the levels of HL activity among the genotypes.ConclusionThe A-250A genotype of the LIPC gene was associated with high LDL cholesterol concentration, but the MUFA-enriched diet reduced serum LDL cholesterol concentration especially in subjects with the A-250A genotype.     

Unsaturated fatty acids intake and all-causes mortality: a 8.5-year follow-up of the Italian Longitudinal Study on Aging

Recent evidence suggested a protective role of dietary monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) intakes against several chronic diseases and, therefore, an increased human longevity. After a median follow-up of 8.5 years, we investigated the possible role of MUFA, PUFA, and other selected food groups in protecting against all-causes mortality in a population-based, prospective study, conducted in one of the eight centers of the Italian Longitudinal Study on Aging (ILSA), Casamassima, Bari, Italy. Out of 704 elderly subjects (65-84 years), 278 nondemented persons agreed to participate at the first survey (1992-1993). During the follow-up, there were 91 deaths. A semi-quantitative food frequency questionnaire evaluating macronutrient daily intakes were performed at the first survey. Higher MUFA intake was associated with an increase of survival (hazard ratio 0.81, 95% CI 0.66-0.99), a higher unsaturated fatty acids (UFA) to SFA ratio (hazard ratio 1.20, 95% CI 0.99-1.45) increased total mortality only marginally, while no effect about other selected food groups were found. In conclusion, in this prospective study on older nondemented subjects with a typical Mediterranean diet, a higher MUFA intake increased survival, while a higher UFA/SFA ratio increased total mortality, but only marginally.     

Olive oil and reduced need for antihypertensive medications

BACKGROUND: The blood pressure (BP) effects of changing the total fat intake and saturated-unsaturated fat ratio are still controversial, despite evidence that saturated fat-enriched diets are associated with higher BP levels. This double-blind, randomized crossover study evaluated a possible difference between antihypertensive effects of monounsaturated (MUFA) (extra-virgin olive oil) and polyunsaturated fatty acids (PUFA) (sunflower oil). METHODS: Twenty-three hypertensive patients were assigned randomly to MUFA or PUFA diet for 6 months and then crossed over to the other diet; effects were evaluated on the basis of daily antihypertensives needed. RESULTS: Diets high in MUFA and PUFA differed from the habitual diet for reduced total and saturated fats, whereas they differed from each other for MUFA (17.2% vs 10.5%) and PUFA content (3.8% vs 10.5%). Resting BP was significantly lower (P = .05 for systolic BP; P = .01 for diastolic BP) at the end of the MUFA diet compared with the PUFA diet. Blood pressure responses during sympathetic stimulation with the cold pressor test and isometric exercise were similar. Daily drug dosage was significantly reduced during the MUFA but not the PUFA diet (-48% vs - 4%, P<.005). All patients receiving the PUFA diet required antihypertensive treatment, whereas 8 of those receiving the MUFA diet needed no drug therapy. CONCLUSIONS: A slight reduction in saturated fat intake, along with the use of extra-virgin olive oil, markedly lowers daily antihypertensive dosage requirement, possibly through enhanced nitric oxide levels stimulated by polyphenols.     

Dietary lipids and NAFLD: suggestions for improved nutrition

Non-alcoholic fatty liver disease (NAFLD) ranges from steatosis and hepatic insulin resistance to non-alcoholic steatohepatitis (NASH), advanced fibrosis and cirrhosis. NAFLD is now considered as the hepatic manifestation of the metabolic syndrome, and both are triggered by mechanisms including inflammation, lipid overload and oxidative stress in adipose tissue and liver. Despite accumulation of numerous data on NAFLD physiopathology, therapeutic modulation of the pathways involved appear insufficiently efficient or associated with serious adverse effects. The increased prevalence of NAFLD and metabolic syndrome during the last decades was associated with deep modifications of dietary habits, especially increased fat intakes. Recent literature provides clues of increased saturated (SFA) and n-6 polyunsaturated fatty acids (PUFA) as well as reduced n-3 PUFA in the diet of NAFLD and NASH patients. Indeed, strong data support the detrimental role of high SFA and n-6/n-3 ratio as well as low monounsaturated fatty acids (MUFA) and n-3 PUFA on metabolic parameters, which are ameliorated by administration of n-3 PUFA and MUFA. Despite governments and health associations having revised their recommendations for n-3 PUFA intakes upward during the last decade, those are still inferior to levels proved of therapeutic efficiency and are still not reached in the general population. This short review discusses these issues and provides consequent pragmatic suggestions for enhanced dietary measures for prevention of NAFLD and metabolic syndrome in the general population.     

Insulin sensitivity after a reduced-fat diet and a monoene-enriched diet in subjects with elevated serum cholesterol and triglyceride concentrations

BACKGROUND AND AIMS: To investigate the effect of a reduced-fat diet and a monoene-enriched diet (MUFA diet) on serum lipids, glucose and insulin metabolism in subjects with elevated cholesterol and triglyceride concentrations. METHODS AND RESULTS: Eighteen subjects with elevated serum cholesterol and triglyceride concentrations consumed the MUFA diet (39% of energy (E%) as fat and 21 E% monoenes) and the reduced-fat diet (34 E% fat, 16 E% monoenes) for 4 weeks according to a randomized cross-over design. Both periods were preceded by consumption of a standardized baseline diet for 2 weeks. Serum lipid and lipoprotein concentrations were determined at the beginning and end of each diet period. A frequently sampled intravenous glucose tolerance test was performed after the MUFA diet and the reduced-fat diet. Insulin sensitivity index (SI) was 40% higher after the reduced-fat diet than after the MUFA diet (2.42 +/- 0.42 vs 1.73 +/- 0.24 10(-4) min-1 U-1 ml-1, p = 0.018). This change in insulin sensitivity was seen in 13 subjects and was most evident in those who began with the MUFA diet. Compared to the baseline diet (high in saturated fat), both experimental diets lowered serum total and LDL cholesterol concentrations (6.6-6.9%, p < 0.05 and 7.4-8.0%, p < 0.05 respectively). CONCLUSIONS: Both diets were equally effective in lowering serum lipid concentrations, but the reduced-fat diet resulted in better insulin sensitivity.     

Dietary Monounsaturated Fatty Acids Appear Not to Provide Cardioprotection

Dietary interventions have been consistently proposed as a part of a comprehensive strategy to lower the incidence and severity of coronary heart disease (CHD), in the process providing long-term cardioprotection. Replacement of dietary saturated fatty acids (SFA) with higher intakes of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) has been reported to be inversely associated with risk of CHD. The observed lower incidence of CHD among populations consuming a Mediterranean-type diet, mainly enriched in MUFA from olive oil, has long supported the belief that MUFA are an optimal substitution for SFA. However, both epidemiologic and interventional studies suggest that although substituting MUFA-rich foods for SFA-rich foods in the diet can potentially lower total plasma cholesterol concentrations, this substitution does not lower the extent of coronary artery atherosclerosis. In addition, although recent evidence suggests that the source of MUFA (animal fat vs vegetable oils) may differentially influence the correlation between MUFA intake and CHD mortality, animal studies suggest that neither source is cardioprotective.     

Interaction between smoking and the Sstl polymorphism of the apo C-III gene determines plasma lipid response to diet

BACKGROUND: It has recently been demonstrated that the lipid profile of smokers improves if they follow a Mediterranean diet. AIM: To establish whether the Sstl polymorphism of the apo C-III gene interacts with smoking and determines the lipid response to diet in healthy subjects. METHODS AND RESULTS: Fifty-nine volunteers (18 smokers: 8 with the S1S1 genotype, and 10 with the S2 allele; 41 non-smokers: 29 with the S1S1 genotype and 12 with the S1S2 genotype) consecutively followed three different diets: a diet enriched in saturated fatty acids (SFA) (38% fat, 20% SFA) followed by a randomised, cross-over period during which they ate a diet enriched in carbohydrates (NCEP-1) (30% fat, 10% SFA, 55% carbohydrates) and a diet enriched in monounsaturated fatty acids (MUFA) (8% fat, 22% MUFA). Cholesterol, triacylglycerol, LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels were measured at the end of each dietary period. The smokers carrying the S1S1 genotype were not influenced by any of the diets, but the atherogenic ratio decreased in the carriers of the S2 allele when they changed from the diet rich in SFA to a diet rich in olive oil or carbohydrates (p < 0.039). No significant difference was observed when the non-smoking carriers of the S2 allele changed from one diet to another, but there was a decrease in the LDL-C/HDL-C ratio when the subjects with the S1S1 genotype changed from the saturated diet to either of the other diets (p < 0.001). CONCLUSIONS: Smoking interacts with the apo CM polymorphism and determines the level of lipid response to dietary changes.     

A high-monounsaturated-fat/low-carbohydrate diet improves peripheral insulin sensitivity in non-insulin-dependent diabetic patients

It is commonly believed that high-carbohydrate (CHO) diets improve peripheral insulin sensitivity; however, this concept is based on anecdotal evidence. Furthermore, it has been demonstrated that in non-insulin-dependent diabetic patients treated with insulin, a high-monounsaturated-fat (MUFA) diet is more effective than a high-complex-CHO diet in reducing blood glucose levels. The aim of our study was to compare the effect of a high-MUFA diet and a high-CHO diet on peripheral insulin sensitivity and metabolic control in non-insulin-dependent diabetic patients. Ten non-insulin-dependent diabetic patients aged 52 +/- 8 years with a body mass index (BMI) of 26.7 +/- 3.5 kg/m2 who were being treated with diet alone (n = 5) or with diet plus glibenclamide (n = 5) were randomly assigned to a 15-day period of either a high-MUFA/low-CHO diet (CHO, 40%; fat, 40%; protein, 20%; fiber, 24g) or a low-MUFA/high-CHO diet (CHO, 60%; fat, 20%; protein, 20%; fiber, 24g) and were then crossed-over to the other diet. Diets were similar in their content of monosaccharides, disaccharides, and saturated fats, and were administered to the patients in a metabolic ward. The dosage of hypoglycemic drugs was maintained at a constant level throughout the study. With the high-MUFA/low-CHO diet, a decrease in both postprandial glucose (8.76 +/- 2.12 v 10.08 +/- 2.76 mmol/L; P < .05) and plasma insulin (195.0 +/- 86.4 v 224.4 +/- 75.6 pmol/L; P < .02) levels was observed. Furthermore, fasting plasma triglyceride levels were reduced after the high-MUFA fat/low-CHO diet (1.16 +/- 0.59 v 1.37 +/- 0.59 mmol/L; P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of the type of dietary fat on postprandial fat oxidation rates: monounsaturated (olive oil) vs saturated fat (cream)

OBJECTIVE: To compare postprandial whole-body fat oxidation rates in humans, following high-fat (43% of total energy) mixed breakfast meals, of fixed energy and macronutrient composition, rich in either monounsaturated fat (MUFA) from extra virgin olive oil or saturated fat (SFA) from cream. DESIGN: Paired comparison of resting metabolic rate (RMR), thermic effect of a meal and substrate oxidation rates following consumption of isocaloric breakfast meals, differing only in the type of fat, administered in random order 1-2 weeks apart. SUBJECTS: Fourteen male volunteers, body mass index (BMI) in the range 20-32 kg/m(2), aged 24-49 y and resident in Melbourne, Australia, were recruited by advertisement in the local media or by personal contact. MEASUREMENTS: Body size and composition was determined by anthropometry and dual energy X-ray absorptiometry (DEXA). Indirect calorimetry was used to measure RMR, thermic effect of a meal, post-meal total energy expenditure and substrate oxidation rate. Blood pressure and pulse rates were measured with an automated oscillometric system. Fasting and 2 h postprandial glucose and insulin concentrations and the fasting lipid profile were also determined. RESULTS: In the 5 h following the MUFA breakfast, there was a significantly greater postprandial fat oxidation rate (3.08+/-4.58 g/5 h, P=0.017), and lower postprandial carbohydrate oxidation rate (P=0.025), than after the SFA breakfast. Thermic effect of a meal was significantly higher (55 kJ/5 h, P=0.034) after the MUFA breakfast, in subjects with a high waist circumference (HWC > or = 99 cm) than those with a low waist circumference (LWC<99 cm). This difference was not detected following the SFA breakfast (P=0.910). CONCLUSION: If postprandial fat oxidation rates are higher after high MUFA, rather than SFA meals, then a simple change to the type of dietary fat consumed might have beneficial effects in curbing weight gain in men consuming a relatively high-fat diet. This may be particularly evident in men with a large waist circumference.     

Maternal diet rich in saturated fats has deleterious effects on plasma lipids of mice

BACKGROUND AND OBJECTIVES: High dietary fat intake has been reported to cause an alteration in lipid metabolism that is associated with an increased risk of cardiovascular disease. In the present study, an animal model was used to evaluate the effects of feeding diets rich in different fatty acids to mothers during pregnancy and lactation, and the effects of the maternal diet on parameters of lipid metabolism in adult offspring. The interaction between the offspring's own diet and the programming due to the maternal diet was also evaluated. METHODS: Female C57BL/6 mice were fed a high-fat diet (20% fat [weight to weight]) rich in either saturated fatty acids (SFA) or polyunsaturated fatty acids (PUFA) for two weeks before mating, during pregnancy and until weaning. The offspring were divided into two groups; each group was fed a high-fat diet enriched in either SFA or PUFA for eight weeks after weaning. The groups were designated as SFA/SFA (diet of the mother/diet of the offspring), SFA/PUFA, PUFA/PUFA and PUFA/SFA. Blood and tissues were collected at the end of the eight-week feeding period after an overnight fast. RESULTS: The plasma total cholesterol and low density lipoprotein cholesterol concentrations were significantly higher in the SFA/SFA group than in all other groups, whereas the PUFA/PUFA group had the lowest total cholesterol and low density lipoprotein cholesterol concentrations. Plasma high density lipoprotein cholesterol concentrations were significantly higher in the PUFA/SFA group than in the PUFA/PUFA and SFA/PUFA groups, whereas plasma triglyceride concentrations were not different among the groups. CONCLUSIONS: The data suggest that high maternal dietary fat intake during pregnancy affects lipid metabolism in the adult offspring. However, it appears that the offspring's own diet is also important in maintaining the regulation of lipid metabolism.