High Monounsaturated Fat Diet Research Articles

Genotype–Phenotype Associations: Modulation by Diet and Obesity

Changes in diet are likely to reduce chronic disorders, but after decades of active research and heated discussion, the question still remains: what is the optimal diet to achieve this elusive goal? Is it a low-fat diet, as traditionally recommended by multiple medical societies? Or a high monounsaturated fat (MUFA) diet as predicated by the Mediterranean diet? Perhaps a high polyunsaturated fat (PUFA) diet based on the cholesterol-lowering effects? The right answer may be all of the above but not for everybody. A well-known phenomenon in nutrition research and practice is the dramatic variability in interindividual response to any type of dietary intervention. There are many other factors influencing response, and they include, among many others, age, sex, physical activity, alcohol, and smoking as well as genetic factors that will help to identify vulnerable populations/individuals that will benefit from a variety of more personalized and mechanistic-based dietary recommendations. This potential could and needs to be developed within the context of nutritional genomics that in conjunction with systems biology may provide the tools to achieve the holy grail of dietary prevention and therapy of chronic diseases and cancer. This approach will break with the traditional public health approach of "one size fits all." The current evidence based on nutrigenetics has begun to identify subgroups of individuals who benefit more from a low-fat diet, whereas others appear to benefit more from high MUFA or PUFA diets. The continuous progress in nutrigenomics will allow some time in the future to provide targeted gene-based dietary advice.

One-Year Comparison of a High–Monounsaturated Fat Diet With a High-Carbohydrate Diet in Type 2 Diabetes

OBJECTIVE—The purpose of this study was to compare the effects of high–monounsaturated fatty acid (MUFA) and high-carbohydrate (CHO) diets on body weight and glycemic control in men and women with type 2 diabetes.RESEARCH DESIGN AND METHODS—Overweight/obese participants with type 2 diabetes (n = 124, age = 56.5 ± 0.8 years, BMI = 35.9 ± 0.3 kg/m2, and A1C = 7.3 ± 0.1%) were randomly assigned to 1 year of a high-MUFA or high-CHO diet. Anthropometric and metabolic parameters were assessed at baseline and after 4, 8, and 12 months of dieting.RESULTS—Baseline characteristics were similar between the treatment groups. The overall retention rate for 1 year was 77% (69% for the high-MUFA group and 84% for the high-CHO group; P = 0.06). Based on food records, both groups had similar energy intake but a significant difference in MUFA intake. Both groups had similar weight loss over 1 year (−4.0 ± 0.8 vs. −3.8 ± 0.6 kg) and comparable improvement in body fat, waist circumference, diastolic blood pressure, HDL cholesterol, A1C, and fasting glucose and insulin. There were no differences in these parameters between the groups. A follow-up assessment of a subset of participants (n = 36) was conducted 18 months after completion of the 52-week diet. These participants maintained their weight loss and A1C during the follow-up period.CONCLUSIONS—In individuals with type 2 diabetes, high-MUFA diets are an alternative to conventional lower-fat, high-CHO diets with comparable beneficial effects on body weight, body composition, cardiovascular risk factors, and glycemic control.

Abstract 675: Contrasting Effects of Dietary Carbohydrate Compared to Mono-unsaturated Fat on Hepatic Production of ApoE and ApoC-III Containing VLDL, and Formation of LDL

The effects of substituting dietary carbohydrate (CHO) with mono-unsaturated fat (MUFA) on plasma apoB metabolism were evaluated in 12 adults: 6 with normal and 6 with high plasma triglyceride levels. They consumed for 3 weeks each time a high CHO diet (48% complex CHO, 8% MUFA) and a high MUFA diet (31% complex CHO, 24% MUFA). ApoB100 kinetic studies were performed at the end of each dietary intervention using stable isotope labeling with a bolus and a primed continuous infusion. Multiple VLDL, IDL, and LDL fractions were prepared according to their apoE and apoC-III content. Compared to the CHO diet, the MUFA diet increased the percentage of VLDL and IDL secreted with both apoE and apoC-III (45% on MUFA vs. 14% on CHO, p < 0.01) and reduced the percentage of VLDL and IDL secreted without either apoE or apoC-III (MUFA 19% vs. CHO 40%, p = 0.02). Total liver secretion rates of apoB100 lipoproteins were similar between diets (MUFA 11.6 vs. CHO 11.3 mg·day −1 ·kg −1 , p = NS). The dietary change did not affect the fractional catabolic rates and flux patterns of the lipoproteins. On both diets, VLDL and IDL that had apoE were rapidly cleared from the circulation, limiting LDL formation; whereas lipoproteins that did not have apoE or apoCIII mostly underwent lipolysis with little direct clearance, and were the main precursors of LDL. As a result, increased secretion of VLDL and IDL containing apoE and apoC-III caused by the MUFA diet was associated with higher direct clearance and lower LDL production rates (p = 0.02 vs. CHO), while the CHO diet increased LDL production due to increased secretion of VLDL without apoE or apoC-III. In conclusion, our results reveal a strong dietary effect on the secretion pattern of apoB100 lipoproteins. Substituting dietary complex carbohydrate with mono-unsaturated fat selectively promotes liver secretion of VLDL and IDL containing both apoE and apoC-III while suppressing the secretion of VLDL and IDL without apoE or apoC-III. This leads to significant downstream effects on LDL formation due to differential effects of apoE and apoC-III on apoB lipoprotein metabolism, resulting in enhanced particle clearance and reduced LDL formation with the MUFA diet compared to the CHO diet.

Long-term weight maintenance and cardiovascular risk factors are not different following weight loss on carbohydrate-restricted diets high in either monounsaturated fat or protein in obese hyperinsulinaemic men and women

The aim of this study was to determine after 52 weeks whether advice to follow a lower carbohydrate diet, either high in monounsaturated fat or low fat, high in protein had differential effects in a free-living community setting. Following weight loss on either a high monounsaturated fat, standard protein (HMF; 50 % fat, 20 % protein (67 g/d), 30 % carbohydrate) or a high protein, moderate fat (HP) (40 % protein (136 g/d), 30 % fat, 30 % carbohydrate) energy-restricted diet (6000 kJ/d) subjects were asked to maintain the same dietary pattern without intensive dietary counselling for the following 36 weeks. Overall weight loss was 6.2 (SD 7.3) kg (P < 0.01 for time with no diet effect, 7.6 (SD 8.1) kg, HMF v. 4.8 (SD 6.6) kg, HP). In a multivariate regression model predictors of weight loss at the end of the study were sex, age and reported percentage energy from protein (R2 0.22, P < 0.05 for the whole model). Fasting plasma insulin decreased (P < 0.01, with no difference between diets), 13.9 (SD 4.6) to 10.2 (SD 5.2) mIU/l, but fasting plasma glucose was not reduced. Neither total cholesterol nor LDL-cholesterol were different but HDL was higher, 1.19 (SD 0.26) v. 1.04 (SD 0.29) (P < 0.001 for time, no diet effect), while TAG was lower, 1.87 (SD 1.23) v. 2.22 (SD 1.15) mmol/l (P < 0.05 for time, no diet effect). C-reactive protein decreased (3.97 (SD 2.84) to 2.43 (SD 2.29) mg/l, P < 0.01). Food records showed that compliance to the prescribed dietary patterns was poor. After 1 year there remained a clinically significant weight loss and improvement in cardiovascular risk factors with no adverse effects of a high monounsaturated fat diet.

Obesity Management in Women with Polycystic Ovary Syndrome

Obesity and insulin resistance play an important role in initiating or maintaining ill health in polycystic ovary syndrome (PCOS). This implies that treatment that reduces body weight and insulin resistance would alleviate the symptoms of PCOS. Lifestyle modification has been found to be effective in restoring reproductive function in up to 80% of individuals who achieve at least 5% weight loss. However, long-term weight maintenance is a challenge. This article provides a review of reduced glycemic load diets, including low glycemic index, very low carbohydrate, high-protein and high monounsaturated fat diets, on metabolic and reproductive health in PCOS and non-PCOS populations. Dietary trials in non-PCOS women suggest that higher-protein, reduced glycemic load diets were probably more beneficial than the conventional low-fat, high-carbohydrate diet but further studies are required to confirm this in PCOS women. Similarly, the optimal exercise regime for PCOS women remains to be investigated.

Cholesteryl ester transfer protein inhibition, high-density lipoprotein metabolism and heart disease risk reduction

Cholesteryl ester transfer protein (CETP) inhibitors (JTT-705 and torcetrapib) are currently in clinical testing, and significantly raise high-density lipoprotein (HDL) cholesterol levels. Low HDL cholesterol is a significant independent predictor of coronary heart disease (CHD) and HDL raising has been associated with coronary heart disease risk reduction, but there is debate about whether CETP inhibition will reduce coronary heart disease risk. It has been documented in transgenic mouse models that apolipoprotein (apo) C-I inhibits CETP, and that high mono-unsaturated fat diets prevent the normal stimulation of CETP activity by dietary cholesterol. In rabbits, torcetrapib markedly decreases clearance of HDL cholesteryl ester via an indirect pathway, but has no effect on total plasma cholesteryl ester clearance. In humans, torcetrapib raises HDL apoA-I by modestly decreasing its fractional catabolic rate, while having a very profound effect on raising HDL cholesterol and large alpha-1 migrating HDL particles by more than 50%, with no effect on fecal cholesterol excretion. When JTT-705 at 600 mg/day was given to hypercholesterolemic patients already on pravastatin 40 mg/day, the combination was well tolerated and increases in HDL cholesterol of 28% were noted. In our view, CETP inhibitors in combination with statins will be profoundly beneficial in reducing human atherosclerosis, primarily because they normalize HDL particles and prevent the transfer of cholesteryl ester from HDL to atherogenic lipoproteins.

Randomized Clinical Trial Comparing a High-Monounsaturated Fat Diet and a Low-Fat Diet in Overweight and Obese Subjects with Type 2 Diabetes

Randomized Clinical Trial Comparing a High-Monounsaturated Fat Diet and a Low-Fat Diet in Overweight and Obese Subjects with Type 2 Diabetes

Effects of High Monounsaturated Fat and Low Fat Diets on Body Weight, Cardiovascular Risk Factors, and Glycemic Control in Persons With Type 2 Diabetes

Effects of High Monounsaturated Fat and Low Fat Diets on Body Weight, Cardiovascular Risk Factors, and Glycemic Control in Persons With Type 2 Diabetes

Flow-Mediated Dilatation Is Impaired by a High–Saturated Fat Diet but Not by a High-Carbohydrate Diet

It is unknown whether a low-fat diet, which may elevate triglycerides and lower high-density lipoprotein (HDL) cholesterol, harms the endothelium. Our aim was to determine whether a low-fat, high-carbohydrate (CARB) diet impaired endothelial vasodilation compared with high saturated fat (SFA), monounsaturated fat (MUFA), or polyunsaturated fat (PUFA) diets. Forty healthy subjects were randomly crossed over to 4, 3-week isocaloric diets high in PUFA, MUFA, or SFA, containing at least 25 g of the relevant fat or a low-fat, CARB, high-glycemic load diet. Flow-mediated dilatation (FMD), fasting blood lipids, high sensitivity C-reactive protein, plasma intercellular, and vascular adhesion molecules plasma E- and P-selectin were measured after each intervention. SFA impaired FMD compared with all other diets (5.41+/-2.45% versus 10.80+/-3.69%; P=0.01). FMD did not change on CARB relative to MUFA or PUFA, despite 23% to 39% rises in triglyceride and 10% to 15% falls in HDL cholesterol. P-selectin was highest after SFA (121+/-52.7 ng/mL) versus MUFA (98+/-44.5 ng/mL; P=0.001) and PUFA (96+/-36.4 ng/mL; P=0.001). High SFA caused deterioration in FMD compared with high PUFA, MUFA, or CARB diets. Inflammatory responses may also be increased on this diet.

Exercise Is Required for Visceral Fat Loss in Postmenopausal Women with Type 2 Diabetes

This study examined the effects of aerobic exercise without weight loss, a hypocaloric high monounsaturated fat diet, and diet plus exercise (D+E) on total abdominal and visceral fat loss in obese postmenopausal women with type 2 diabetes. Thirty-three postmenopausal women (body mass index, 34.6 +/- 1.9 kg/m(2)) were assigned to one of three interventions: a hypocaloric high monounsaturated fat diet alone, exercise alone (EX), and D+E for 14 wk. Aerobic capacity, body composition, abdominal fat distribution (magnetic resonance imaging), glucose tolerance, and insulin sensitivity were measured pre- and postintervention. Body weight ( approximately 4.5 kg) and percent body fat ( approximately 5%) were decreased (P < 0.05) with the D and D+E intervention, whereas only percent body fat ( approximately 2.3%) decreased with EX. Total abdominal fat and sc adipose tissue (SAT) were reduced with the D and D+E interventions (P < 0.05), whereas visceral adipose tissue (VAT) decreased with the D+E and EX intervention, but not with the D intervention. EX resulted in a reduction in total abdominal fat, VAT, and SAT (P < 0.05) despite the lack of weight loss. The reductions in total abdominal fat and SAT explained 32.7% and 9.7%, respectively, of the variability in the changes in fasting glucose levels, whereas the reductions in VAT explained 15.9% of the changes in fasting insulin levels (P < 0.05). In conclusion, modest weight loss, through either D or D+E, resulted in similar improvements in total abdominal fat, SAT, and glycemic status in postmenopausal women with type 2 diabetes; however, the addition of exercise to diet is necessary for VAT loss. These data demonstrate the importance of exercise in the treatment of women with type 2 diabetes.

Effects of a low-fat diet compared with those of a high-monounsaturated fat diet on body weight, plasma lipids and lipoproteins, and glycemic control in type 2 diabetes

An important therapeutic goal for patients with type 2 diabetes is weight loss, which improves metabolic abnormalities. Ad libitum low-fat diets cause weight loss in nondiabetic populations. Compared with diets higher in monounsaturated fat, however, eucaloric low-fat diets may increase plasma triacylglycerol concentrations and worsen glycemic control in persons with type 2 diabetes. We investigated whether, in type 2 diabetes patients, an ad libitum low-fat diet would cause greater weight loss than would a high-monounsaturated fat diet and would do this without increasing plasma triacylglycerol concentrations or worsening glycemic control. Eleven patients with type 2 diabetes were randomly assigned to receive an ad libitum low-fat, high-carbohydrate diet or a high-monounsaturated fat diet, each for 6 wk. The diets offered contained 125% of the estimated energy requirement to allow self-selection of food quantity. The response variables were body weight; fasting plasma lipid, lipoprotein, glucose, glycated hemoglobin A(1c), and fructosamine concentrations; insulin sensitivity; and glucose disposal. Body weight decreased significantly (1.53 kg; P < 0.001) only with the low-fat diet. Plasma total, LDL-, and HDL-cholesterol concentrations tended to decrease during both diets. There were no interaction effects between diet and the lipid profile response over time. Plasma triacylglycerol concentrations, glycemic control, and insulin sensitivity did not differ significantly between the 2 diets. Contrary to expectations, the ad libitum, low-fat, high-fiber diet promoted weight loss in patients with type 2 diabetes without causing unfavorable alterations in plasma lipids or glycemic control.

Very Low-Fat (12%) and High Monounsaturated Fat (35%) Diets Do Not Differentially Affect Abdominal Fat Loss in Overweight, Nondiabetic Women

Studies in women with type 2 diabetes demonstrated adverse effects on body fat distribution of a low-fat diet relative to a high monounsaturated fat diet. We performed a randomized 12-wk parallel design study of two 6000-kJ diets: 35% energy from fat (high monounsaturated fat diet, HIMO), or 12% energy from fat (very low-fat diet, VLF) to determine whether this also occurred in nondiabetic women. Body fat distribution, fasting plasma glucose, blood pressure, and fasting serum lipids were measured at wk 0 and 12 in 62 women (BMI > 27 kg/m(2)). Weight loss (9.5 +/- 2.4 vs. 9.4 +/- 3.4 kg, VLF vs. HIMO) and total fat loss (6.1 +/- 2.4 vs. 6.3 +/- 2.7 kg, VLF vs. HIMO) did not differ in the groups. There was a diet x menopausal status interaction in lean mass changes (P = 0.005) such that in premenopausal women, HIMO produced a lower loss of lean mass than the low-fat diet (0.4 +/- 2.3 vs. 2.9 +/- 2.7 kg, P = 0.006) with the opposite but nonsignificant effect seen in postmenopausal women. There was a greater decrease in total plasma cholesterol in women who consumed VLF compared with those who consumed HIMO (0.82 +/- 0.0.51 vs. 0.50 +/- 0.48 mmol/L, P < 0.001 for time, P < 0.05 for diet effect). This was also true for the change in HDL cholesterol (0.18 +/- 0.23 vs. 0.04 +/- 0.19 mmol/L, VLF and HIMO, respectively, P < 0.001 for time, P < 0.05 for diet effect). The LDL/HDL ratio was reduced in both groups with no effect of diet (0.16 +/- 0.51 vs. 0.16 +/- 0.45, VLF and HIMO, respectively, P < 0.05). In conclusion, weight, total fat mass, and regional fat mass loss did not differ in the 2 groups of women but there was an apparent preservation of lean mass in premenopausal women consuming HIMO.

Restoration of Normal Insulinemia and Insulin Sensitivity in Hyperinsulinemic Normoglycemic Men by a Hypoenergetic High Monounsaturated Fat Diet

Purpose: To test the hypothesis that the macronutrient composition of hypoenergetic diets is an important consideration in weight-reducing regimens of hyperinsulinemic normoglycemic obese subjects. Design: A 4-week randomized dietary intervention trial. Subjects and Methods: Sixteen male obese hyperinsulinemic normoglycemic subjects were recruited and 15 completed the study. The participants were divided into two groups and fed hypoenergetic diets providing 80% of their resting energy expenditure (REE). One group received a high carbohydrate diet (HC) (60% carbohydrate, 20% fat, 20% protein as a percentage of dietary energy) and the other group received a high monounsaturated fat diet (HM) (35% carbohydrate, 45% fat and 20% protein). Anthropometry, body composition, REE, serum glucose, insulin and lipid analyses were performed before and after the feeding period. Results: The subjects on the HC diet achieved comparable weight loss but without restoration of normoinsulinemia and insulin sensitivity. Fasting insulin levels, insulin to glucose ratio, and Homeostatic Model & Assessment Index decreased to normal ranges and were significantly lower in the HM group as compared with the HC group. Similarly, insulin sensitivity score (Mffm/I) increased significantly on the HM diet. Waist circumference measurements showed a significantly higher decrease on the HM than HC diet, whereas body weight, percentage body fat, glucose, plasma lipids, and REE decreased to the same extent whether subjects were fed the HC or HM diet. Conclusions: In this study, feeding a HM diet was more effective than a HC diet for restoring normoinsulinemia and insulin sensitivity. Therefore, hyperinsulinemic normoglycemic obese subjects may benefit from a diet lower in carbohydrates and higher in monounsaturated fats for decreasing cardiovascular disease risk factors while achieving the desired weight reduction.

Effects of a high-monounsaturated fat diet on glucose and lipid metabolisms in normal and diabetic mice.

The beneficial effects of high-monounsaturated fat (high-MUFA) diets on diabetic patients have been reported, whereas studies concerning the effects on animals have been few. Although experiments on animals should be useful in elucidating underlying mechanisms, it is not clear even whether there are benefits of a high-MUFA diet in animals. This study examined the short-term effects of a high-MUFA diet on normal and genetically diabetic mice. The high-MUFA diet supplied 38% of the total calories as fat (26% from MUFA), while a regular diet was 13% fat (3% from MUFA). Normal C5 7BL/6J and diabetic C57BL/KsJ-db/db mice were fed either the regular or the high-MUFA diet for 1 wk. Serum glucose and lipid levels were then measured. In normal mice, hepatic triglyceride production was also compared between the two dietary groups using the Triton WR1339 method. An oral glucose tolerance test was conducted on the diabetic mice. After 1 wk of feeding to normal mice, the high-MUFA diet was seen to lower serum triglyceride levels and reduce hepatic triglyceride production in comparison with the regular diet; it is suggested that the lowering of triglyceride consists of mechanisms including reduced hepatic triglyceride production. When diabetic mice were fed the high-MUFA diet with a controlled caloric intake, the serum glucose levels lowered without an accompanying deterioration in lipid metabolism and the impaired glucose tolerance was ameliorated. This study demonstrates that a high-MUFA diet can lower serum triglyceride levels in normal mice and improve disorders of glucose metabolism in diabetic mice.

CHANGES IN ABDOMINAL FAT DISTRIBUTION WITH DIET AND/OR EXERCISE TRAINING IN TYPE 2 DIABETIC WOMEN.

PURPOSE The aim of this study was to investigate the effects of a high-monounsaturated fat (HMF) diet treatment and an exercise and HMF diet treatment on the abdominal fat distribution of type 2 diabetic postmenopausal women. METHODS Seventeen type 2 diabetic postmenopausal women (age: 59.6±6 yrs, BMI: 32.9±4.1 kg/m2 were randomly assigned to one of two treatments: HMF diet (D) (n=7) or HMF Diet +Exercise (D+E) (n=10) for 14 weeks. Prior to and at the end of the 14 weeks, percent body fat (Bod Pod) and abdominal fat distribution (magnetic resonance imaging (MRI)) were measured. A 2x2 ANOVA with repeated measures was used for statistical analysis. RESULTS Subjects were matched for body weight (D: 87.9±17.3 kg, D+E: 87.0±11.7 kg) and percent body fat (D: 34.6±7.0%, D+E: 33.8±3.5%) at the onset of the study. Both the diet and diet+exercise treatment produced a significant reduction in body weight (D: −2.1±1.4 kg, D+E: −4.7±2.4 kg) and percent body fat (D: −3.9±0.3%, D+E: −4.3±0.27%). Furthermore, both treatments produced a significant reduction in total abdominal fat from pre to post (D: 13684±4847 to 13320±5416 cm3, D+E: 15464±3667 to 14123±3357 cm3, p < 0.05). No significant change was found in visceral fat and % visceral fat in either treatment, however, subcutaneous fat was significantly reduced from pre to post intervention in both treatments (D: 9163±3391 to 8790±3793 cm3, D+E: 9486±2560 to 8754±2374 cm3, p < 0.05). No differences between the two treatment groups were observed for any variable. CONCLUSION Regardless of the treatment, it was the weight lost that reduced total abdominal fat in type 2 diabetic postmenopausal women. The reduction in abdominal fat was due to a preferential reduction in the subcutaneous fat depot in both treatment groups. Supported by New York State Bridge Grant, EAS Research Grant from ACSM, and Woodrow Wilson-Johnson & Johnson Dissertation Grant in Women's Health.

Is There a Role for Monounsaturated Fat in the Dietary Management of Obesity?

Animal and human studies indicate that high saturated fat (SFA) diets can be obesogenic. Monounsaturated fat (MUFA) has acute (meal related) effects that influence energy metabolism. These include increased postprandial fat oxidation and greater diet induced thermogenesis, factors that attenuate weight gain. Chronic (diet related) studies for 12 weeks or more, demonstrate that people following high MUFA diets do not gain excessive weight even when eating ad libitum. In fact, we have observed greater body weight and fat loss in men following an ad libitum MUFA diet, when compared to a SFA diet. High MUFA diets designed for weight loss should also incorporate a high vegetable intake according to traditional Mediterranean patterns. Such diets will promote the utilisation of fat and also have a low energy density. In our experience these diets are well accepted, and offer the prospect of greater long-term adherence to dietary advice.

Results of use of metformin and replacement of starch with saturated fat In diets of patients with type 2 diabetes

To improve glycemic control by substituting saturated fat for starch, to identify any adverse effect on lipids masked by the extensive use of metformin and lipid-lowering drugs, and to attempt to separate dietary effects from effects of multiple drugs. We undertook a retrospective review of medical records of patients who completed 1 year of follow-up after dietary prescription. The study subjects included 151 patients in the diet group (whose dietary instructions included high saturated fat but starch avoidance) and 132 historical control subjects (who were allowed unlimited monounsaturated fat but had restriction of starch in their diets). Hemoglobin A1c (HbA1c) levels improved in both study groups (-1.4 +/- 0.2% [P<0.001]; 95% confidence interval [CI], -1.9 to -0.9). Use of metformin was associated with a decrease in HbA1c (-0.12 +/- 0.003%/mo [P<0.001]; 95% CI, -0.17 to -0.07). The diet group had an additional decrease of -0.7 +/- 0.2% (P<0.001; 95% CI, -1.1 to -0.3). Weight increase was associated with the use of insulin (+0.3 +/- 0.07 kg/mo [P<0.001]; 95% CI, 0.2 to 0.5), sulfonylurea (+0.18 +/- 0.06 kg/mo [P<0.01]; 95% CI, 0.05 to 0.30), and troglitazone (+0.7 +/- 0.2 kg/mo [P<0.005]; 95% CI, 0.3 to 1.2). Although not statistically significant, metformin therapy showed a trend for weight loss (-0.14 +/- 0.08 kg/mo; P = 0.07). An additional weight loss was noted in the diet group (-2.65 +/- 0.62 kg [P<0.001]; 95% CI, -3.87 to -1.44). Hydroxymethylglutaryl-coenzyme A reductase inhibitor use was associated with reduced total cholesterol level (-1.7 +/- 0.6 mg/dL per month [P<0.005]; 95% CI, -2.9 to -0.5). The diet group had an additional decrease of -13.0 +/- 4.5 mg/dL (P<0.001; 95% CI, -21.9 to -4.1). No significant effect of the diet on triglyceride, low-density lipoprotein, or high-density lipoprotein levels was detected. Addition of saturated fat and removal of starch from a high-monounsaturated fat and starch-restricted diet improved glycemic control and were associated with weight loss without detectable adverse effects on serum lipids.

Protective effect of dietary monounsaturated fat on arteriosclerosis: beyond cholesterol

The consumption of diets enriched in monounsaturated fat has been related to a lower rate of coronary heart disease. It is well known that this dietary model decreases LDL-cholesterol plasma levels when replacing a saturated fat enriched diet. For this reason, a high monounsaturated fat diet is now being advocated to prevent cardiovascular disease, especially in Mediterranean countries. However, some expert panels—the Joint Task Force of European and other Societies on Coronary Prevention and the International Task Force for Prevention of Coronary Heart Disease—recommend replacing dietary saturated fat by complex carbohydrates, limiting the intake of total fat to <30% of the energy and monounsaturated fat to no more than 10–15% of total calories, reaching a similar effect on LDL-cholesterol plasma levels to a high monounsaturated fat diet. The most appropriate nutritional model to prevent arteriosclerosis should be supported by research into other biological effects of both diets. Therefore, it is interesting to review the non-lipid effect of monounsaturated fat, starting with its influence on other cardiovascular risk factors, such as carbohydrate metabolism and blood pressure. Moreover, substantial evidence of the effect of dietary monounsaturated fat on a wide range of healthy benefits beyond cholesterol, which have been investigated in recent years, such as lipoprotein oxidation, coagulation, fibrinolysis and endothelium, will be discussed. Furthermore, many observational epidemiological studies suggest that a high intake of monounsaturated fat is associated with reduced coronary risk and this will be analyzed in accordance with the clinical evidence to discuss the best dietary model to prevent coronary artery disease.

Dietary management of obesity: is there a role for olive oil?

A high monounsaturated fat diet has not been advocated for obesity, due to concerns that its fat content would promote weight gain. Our studies indicate that olive oil based monounsaturated fat diets have acute (meal related) as well as chronic (diet related) effects that influence the regulation of body weight. These include an increased postprandial fat oxidation and greater diet induced thermogenesis, factors that attenuate weight gain. A review of the literature indicates that there are no differences in body weight between high monounsaturated fat diets and low fat diets, when fed ad libitum or in energy restricted amounts. There are fewer human studies that compare the effects of ad libitum monounsaturated fat versus saturated fat diets, at equivalent total fat intakes. While some have shown no difference, we have observed a greater weight and fat loss following a short term, ad libitum olive oil diet. High monounsaturated fat diets designed for weight loss should also incorporate traditional Mediterranean dietary patterns. Such vegetable-rich diets can have a low energy density, are well accepted and offer the prospect of greater long-term compliance with dietary advice. Further substantiation of the role of olive oil in the dietary management of obesity is required.

Low Fat and High Monounsaturated Fat Diets Decrease Human Low Density Lipoprotein Oxidative Susceptibility In Vitro

Oxidative modification of low density lipoprotein (LDL) is thought to play an important role in the development of atherosclerosis. Some studies have found that LDL enriched in monounsaturated fatty acids (MUFA) are less susceptible to oxidation than LDL enriched in polyunsaturated fatty acids (PUFA). A high MUFA diet is an alternative to a lower-fat blood cholesterol-lowering diet. Less is known about the effects of high MUFA versus lower-fat blood cholesterol-lowering diets on LDL oxidative susceptibility. The present study was designed to evaluate the effects of men and women consuming diets high in MUFA (peanuts plus peanut butter, peanut oil and olive oil) on LDL oxidative susceptibility, and to compare these effects with those of a Step II blood cholesterol-lowering diet. A randomized, double-blind, five-period crossover design (n = 20) was used to study the effects of the following diets on LDL-oxidation: average American [35% fat, 15% saturated fatty acids (SFA)], Step II (25% fat, 7% SFA), olive oil (35% fat, 7% SFA), peanut oil (35% fat, 7% SFA) and peanuts plus peanut butter (35% fat, 8% SFA). The average American diet resulted in the shortest lag time (57 +/- 6 min) for LDL oxidized ex vivo, whereas the Step II, olive oil and peanuts plus peanut butter diets resulted in a lag time of 66 +/- 6 min (P < or = 0.1). The slower rate of oxidation [nmol dienes/(min x mg LDL protein)] observed when subjects consumed the olive oil diet (24 +/- 2) versus the average American (28 +/- 2), peanut oil (28 +/- 2) and peanuts plus peanut butter diets (29 +/- 2; P < or = 0.05) was associated with a lower LDL PUFA content. The results of this study suggest that lower-fat and higher-fat blood cholesterol-lowering diets high in MUFA have similar effects on LDL oxidative resistance. In addition, our results suggest that different high MUFA sources varying in the ratio of MUFA to PUFA can be incorporated into a high MUFA diet without increasing the susceptibility of LDL to oxidation.