Plasma lipid and lipoprotein concentrations of men consuming a low-fat, high-fiber diet.

This study assessed the influence of a low-fat, high-fiber diet on blood lipid concentrations of 42 men with desirable or moderately elevated cholesterol concentrations. A low-fat diet (19% fat, 4% saturated fatty acids, 4.6 g fiber/MJ) was compared with a high-fat diet (41% fat, 15% saturated fatty acids, 2.0 g fiber/MJ) and with subjects' self-selected diets. Substituting the low-fat for the high-fat diet decreased total, low-density-lipoprotein, and high-density-lipoprotein cholesterol by 17-20%. Lipid changes between 6 and 10 wk were minor. A reduction in plasma cholesterol of greater than 0.52 mmol/L was achieved with the low-fat diet in 59% of men changing from their self-selected diets and in 79% changing from the high-fat diet. Percent reduction was independent of subjects' cholesterol classification. Results indicate that significant reductions in plasma cholesterol can be achieved by the majority of men committing to a low-fat, high-fiber diet.     

Weight-for-height measurement and saturated fatty acid intake are predictors of serum cholesterol level in children.

To assess the relationship of serum cholesterol level to anthropometric measurements and dietary intake, we measured serum cholesterol, height, weight, triceps skinfold, and 24-hour dietary intake in 80 children (mean age = 9.8 years) during April 1989. The mean serum cholesterol level was 3.95 mmol/l. In comparison with national data, weight-for-height and triceps skinfold measurements exceeded the 90th percentile in 18 (23%) and 26 (33%) of the children, respectively. Mean cholesterol and fat intakes were 114 mg/1,000 kcal and 36% of energy, respectively. In multiple stepwise regression analyses, weight-for-height measurement and saturated fatty acid intake were most predictive of serum cholesterol levels. Diets of children who consumed 30% of energy or less from fat (low-fat group) met or exceeded the Recommended Dietary Allowances except for energy and vitamin E and were higher in percentage of energy from carbohydrate, dietary fiber, magnesium, iron, and copper than were diets of children who consumed 31% of energy or more from fat (high-fat group). Children in the high-fat group ate more red/processed meats, baked desserts, and fats/oils than children in the low-fat group. Our data indicate that programs to reduce risk of cardiovascular disease in children may need to focus on maintaining ideal body weight and reducing saturated fatty acid intake.     

Replacing cows' with sheep's dairy fat lowers plasma cholesterol concentration in participants consuming dairy fat-rich diets

OBJECTIVE: To determine the effects on plasma cholesterol concentration of replacing cows' dairy fat with sheep's dairy fat. DESIGN: Randomised crossover dietary intervention. SETTING: General community, Dunedin, New Zealand. SUBJECTS: Volunteer sample of 41 healthy adults with initial plasma cholesterol concentration between 4.8 and 7.8 mmol/l. INTERVENTIONS: Participants were asked to follow a self-selected low-fat background diet throughout the study to which, during each of the 2, 3-week dairy diets, they were asked to add sheep's or cows' dairy products. MAIN OUTCOME MEASURES: Energy and nutrient intakes, plasma triacylglycerol fatty acids, and plasma cholesterol. RESULTS: Energy and nutrient intakes on the sheep-dairy and cow-dairy diets were very similar, with total, saturated, monounsaturated and polyunsaturated fat contributing 34, 18-19, 9, and 3% of total energy intake, respectively. Participants consumed approximately 50 g/day of dairy fat on each diet. Replacing cows' with sheep's dairy fat led to a 0.33 (0.11-0.56, 95% CI) mmol/l decrease (6%) in plasma total cholesterol concentration, from 5.53 (0.90, s.d.) to 5.20 (0.90) mmol/l. Plasma low-density lipoprotein (LDL) cholesterol was 0.18 (0.02-0.33) mmol/l lower on the sheep-dairy diet as was the concentration of plasma high-density lipoprotein (HDL) cholesterol, 0.11 (0.02-0.20) mmol/l. The LDL to HDL cholesterol ratio at the end of the sheep-dairy diet, 2.91 (1.10), was not significantly different (P>0.05) from the cow-dairy diet, 2.73 (0.83). CONCLUSIONS: Within the context of a diet high in dairy fat (50 g/day), replacing cows' milk fat with sheep's milk fat leads to a small reduction in plasma cholesterol concentration, but no change in the ratio of LDL to HDL cholesterol.     

Comparison of Effects of Long-Term Low-Fat vs High-Fat Diets on Blood Lipid Levels in Overweight or Obese Patients: A Systematic Review and Meta-Analysis

Dietary fat plays an important role in the primary prevention of cardiovascular disease, but long-term (≥12 months) effects of different percentages of fat in the diet on blood lipid levels remain to be established. Our systematic review and meta-analysis focused on randomized controlled trials assessing the long-term effects of low-fat diets compared with diets with high amounts of fat on blood lipid levels. Relevant randomized controlled trials were identified searching MEDLINE, EMBASE, and the Cochrane Trial Register until March 2013. Thirty-two studies were included in the meta-analysis. Decreases in total cholesterol (weighted mean difference –4.55 mg/dL [–0.12 mmol/L], 95% CI –8.03 to –1.07; P=0.01) and low-density lipoprotein (LDL) cholesterol (weighted mean difference –3.11 mg/dL [–0.08 mmol/L], 95% CI –4.51 to –1.71; P<0.0001) were significantly more pronounced following low-fat diets, whereas rise in high-density lipoprotein (HDL) cholesterol (weighted mean difference 2.35 mg/dL [0.06 mmol/L], 95% CI 1.29 to 3.42; P<0.0001) and reduction in triglyceride levels (weighted mean difference –8.38 mg/dL [–0.095 mmol/L], 95% CI –13.50 to –3.25; P=0.001) were more distinct in the high-fat diet groups. Including only hypocaloric diets, the effects of low-fat vs high-fat diets on total cholesterol and LDL cholesterol levels were abolished. Meta-regression revealed that lower total cholesterol level was associated with lower intakes of saturated fat and higher intakes of polyunsaturated fat, and increases in HDL cholesterol levels were related to higher amounts of total fat largely derived from monounsaturated fat (of either plant or animal origin) in high-fat diets (composition of which was ～17% of total energy content in the form of monounsaturated fatty acids, ～8% of total energy content in the form of polyunsaturated fatty acids), whereas increases in triglyceride levels were associated with higher intakes of carbohydrates. In addition, lower LDL cholesterol level was marginally associated with lower saturated fat intake. The results of our meta-analysis do not allow for an unequivocal recommendation of either low-fat or high-fat diets in the primary prevention of cardiovascular disease.     

Effects of isoenergetic high-carbohydrate compared with high-fat diets on human cholesterol synthesis and expression of key regulatory genes of cholesterol metabolism

BACKGROUND: High-carbohydrate diets improve plasma cholesterol concentrations but increase triacylglycerol concentrations; the latter effect increases the risk of cardiovascular disease (CVD). Triacylglycerol concentrations increase only during very-high-carbohydrate diets consisting mainly of simple sugars. OBJECTIVE: We compared the CVD risk profile, cholesterol metabolism, and glucose tolerance of 7 healthy subjects during 2 isoenergetic diets: a high-fat, low-carbohydrate diet (HF diet) and a moderately high-carbohydrate, low-fat diet (HC diet). DESIGN: In a randomized crossover study, we measured the effects of the HF diet [40% carbohydrate and 45% fat (15% saturated, 15% monounsaturated, and 15% polyunsaturated)] and HC diet [55% carbohydrate (mainly complex) and 30% fat (10% saturated, 10% monounsaturated, and 10% polyunsaturated)] (3 wk each) on plasma lipid concentrations, oral glucose tolerance, cholesterol synthesis rate, and the messenger RNA (mRNA) concentrations of beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, the LDL receptor, and the LDL-receptor-related protein (LRP). RESULTS: Compared with the HF diet, the HC diet lowered total, LDL, and HDL cholesterol (P < 0.05 for all) without modifying the ratio of LDL to HDL cholesterol; triacylglycerol concentrations were unchanged. Lower cholesterol concentrations occurred despite a higher cholesterol synthesis rate (P < 0.05) and higher HMG-CoA reductase mRNA concentrations (P < 0.05). LDL receptor mRNA concentrations were unchanged, LRP mRNA concentrations were lower (P < 0.01), and oral glucose tolerance was better (P < 0.05) with the HC diet. CONCLUSION: The beneficial effects of the HC diet on glucose tolerance and plasma cholesterol concentrations without increases in triacylglycerol show that this diet had favorable effects on both insulin sensitivity and the plasma lipid profile.     

Lack of efficacy of a food-frequency questionnaire in assessing dietary macronutrient intakes in subjects consuming diets of known composition

BACKGROUND: We compared the validity of a semiquantitative food-frequency questionnaire in assessing intakes of macronutrients (absolute amounts and percentages of energy) by 19 subjects fed natural-food diets of known composition. In small subsets (n = 5 or 6), we also tested 3-d diet records. OBJECTIVE: The objective of this study was to investigate the efficacy of food-frequency questionnaires and diet records in subjects fed natural-food diets of known composition. DESIGN: Each subject consumed 3 different diets for >/=6 wk and self-reported his or her food intake by using a food-frequency questionnaire and a diet record. The diets varied in their chemically analyzed contents of fat (15-35% energy), saturated fat (5-14%), monounsaturated fat (5-14.5%), polyunsaturated fat (2.5-10.5%), carbohydrate (49-68%), and cholesterol (108-348 mg/d). RESULTS: The food-frequency questionnaire significantly underestimated fat, saturated fat, monounsaturated fat, and protein intakes and significantly overestimated carbohydrate intake with the high-fat diet. The percentage of energy from fat was significantly underestimated for the high-fat diet and significantly overestimated for the very-low-fat diet. Estimates from the food-frequency questionnaire differed significantly from actual intakes for fat (absolute and percentage), saturated fat (absolute and percentage), monounsaturated fat (absolute and percentage), and protein (percentage) in the high-fat diet and for polyunsaturated fat (absolute and percentage), saturated fat (percentage), fiber (absolute), and cholesterol (daily absolute; in mg/d) in the lower-fat diet. Estimates from the diet records better agreed with actual intakes than did estimates from the food-frequency questionnaire except for monounsaturated fat (absolute and percentage) in the high-fat diet and polyunsaturated fat (percentage) in the lower-fat diet and the very-low-fat diet. CONCLUSION: Our data indicated that the food-frequency questionnaire did not provide reliable estimates of absolute amounts of dietary fats or cholesterol.     

Double-blind, randomized feedback control fails to improve the hypocholesterolemic effect of a plant-based low-fat diet in patients with moderately elevated total cholesterol levels

OBJECTIVE: To determine whether the cholesterol-lowering effect of a plant-based low-fat diet can be improved by a flexible control design that controls the extent of fat reduction based on the individual response of blood cholesterol. DESIGN: Randomized, double-blind intervention study. SETTING: A hotel in Prerow, Germany. SUBJECTS: A total of 32 participants (21 female and 11 male participants) with total cholesterol level > 5.7 mmol/l. INTERVENTION: The control group consumed a plant-based low-fat diet with constantly 20% of energy as fat; the intervention group received a diet with either 20 or 15% of energy as fat, depending on the serum cholesterol response of the preceding week. A flexible control design based on the individual cholesterol response during a run-in period of 1 week was used within a low-fat intervention. RESULTS: During the run-in period, the consumption of a plant-based low-fat diet led to a reduction in total cholesterol by 18+/-6 mmol/l (P < 0.001), in LDL cholesterol by 19+/-9 mmol/l (P < 0.001) and triglycerides by 13+/-3 mmol/l (P < 0.001). During the feedback control period, an additional reduction in total cholesterol by 13+/-8 (P < 0.001) and in LDL cholesterol by 17+/-11 (P < 0.001) was observed compared to 15+/-15 and 7+/-18 in the control group. The effect of an additional feedback control was only marginal and not statistically significant compared to the effect of the low-fat diet alone. CONCLUSIONS: On a level of fat intake already reduced to 20% of energy, the use of a feedback control to adapt the fat content of the diet depending on the individual serum cholesterol response was not more effective in reducing blood cholesterol levels than a plant-based low-fat diet alone.     

The effect of breakfast cereal on diet and serum cholesterol: a randomized trial in North Karelia, Finland.

OBJECTIVE: To test the hypothesis that a high carbohydrate breakfast with breakfast cereal leads to a meaningful reduction in dietary energy intake from fat, especially from saturated fat, and thus lower serum cholesterol levels. DESIGN: An open randomized controlled cross-over trial. The subjects were randomized into intervention breakfast cereal or usual breakfast (control) groups. SETTING: Free-living subjects aged 29-71 y in Eastern Finland SUBJECTS: 224 enrolled, 209 completed the study. The subjects were recruited from a survey of a random population sample and from other sources, and their serum cholesterol was not lower than 5.0 mmol/l. Recruited persons did not have any chronic disease or very low saturated fat intake. INTERVENTION: The cereal group consumed 80 g (men) or 60 g (women) cereal at breakfast and the control group continued their usual dietary habits for six weeks. After a wash out of six weeks, a cross-over with another six week trial period took place. Measurements (including serum samples and a 3 d food record) took place before and after the two trial periods. RESULTS: The intervention period led to 2.5 en% (energy percent units) reduction in saturated fatty acids intake. The reduction in total fat intake was 5.5 en%. This was compensated for by increased intake of carbohydrates. The reduction in saturated fatty acids intake led to modest (but in group 1 significant) 0.15 mmol/l (2.5%) reduction in total serum cholesterol level. CONCLUSIONS: The trial showed that regular cereal breakfast can lead to reduced intake of total and saturated fatty acids of the daily diet and consequently to reduction in serum cholesterol level.     

Snack chips fried in corn oil alleviate cardiovascular disease risk factors when substituted for low-fat or high-fat snacks

BACKGROUND: The perception that all high-fat snacks are unhealthy may be wrong. OBJECTIVE: We aimed to assess whether replacing low-fat and high-fat snacks with snacks rich in polyunsaturated fatty acids (PUFAs) and low in saturated and trans fatty acids would improve cardiovascular health. DESIGN: Thirty-three adults participated in a randomized crossover trial of 3 controlled feeding phases of 25 d each in which a different type of snack was provided: low-fat (30.8% of energy from fat, 5.2% of energy from PUFAs), high-PUFA (36.3% of energy from fat, 9.7% of energy from PUFAs), or high-fat (37.9% of energy from fat, 5.8% of energy from PUFAs) snack. RESULTS: Each diet reduced LDL- and total cholesterol concentrations, but reductions were greater with the low-fat and the high-PUFA diets than with the high-fat diet: LDL cholesterol (11.8% and 12.5% compared with 8.8%, respectively; P = 0.03 and 0.01), total cholesterol (10.5% and 10.7% compared with 7.9%, respectively; P = 0.03 and 0.02). The high-PUFA diet tended to reduce triacylglycerol concentrations (9.4%; P = 0.06), and this change was greater than that with the low-fat (P = 0.028) and high-fat (P = 0.0008) diets. CONCLUSIONS: These data show that snack type affects cardiovascular health. Consuming snack chips rich in PUFA and low in saturated or trans fatty acids instead of high-saturated fatty acid and trans fatty acid or low-fat snacks leads to improvements in lipid profiles concordant with reductions in cardiovascular disease risk.     

Effect of high-fat diet on cholesterol distribution in plasma lipoproteins, cholesterol esterifying activity in leucocytes, and erythrocyte membrane components studied: importance of body weight

Effects of isocaloric changes in dietary fat on plasma lipoproteins and lipids and enzymes of erythrocytes and leucocytes were assessed. Subjects with a higher Brocca index showed increase in total and LDL cholesterol, significant reduction in HDL cholesterol, and increased total cholesterol:HDL cholesterol ratio after high-fat diet consumption. Due to high-fat diet feeding, erythrocyte membrane and leucocyte cholesterol and phospholipid contents were increased, cholesterol:phospholipid molar ratio was elevated, and erythrocyte enzymes (G6PD and 6PGD) and leucocyte enzymes (CEH and CES) were elevated. Erythrocyte membrane glycoprotein components showed marked increase, indicating possible alterations of membrane surfaces. The metabolic alterations were reversed slowly after resumption of the normal (low-fat) diet. Body weight plays an important role in the alterations in major lipoprotein cholesterol contents in response to changes in dietary fat composition. Cellular changes indicate alterations in structure and function of blood cells due to high-fat diet feeding.     

Long-term effects of ad libitum low-fat, high-carbohydrate diets on body weight and serum lipids in overweight subjects with metabolic syndrome.

BACKGROUND: Overweight individuals with metabolic syndrome are at increased risk of type 2 diabetes and coronary vascular disease. Weight gain and features of the syndrome may be ameliorated by dietary intervention. OBJECTIVE: We investigated the effects of replacing one-quarter of daily fat intake by complex or simple carbohydrate on body weight and intermediary metabolism. DESIGN: Forty-six subjects with > or =3 metabolic syndrome risk factors were randomly assigned to receive a control diet; a low-fat, complex carbohydrate diet (LF-CC); or a low-fat, simple carbohydrate diet (LF-SC) for 6 mo. Thirty-nine subjects completed the trial. About 60% of daily dietary intake was provided free of charge through a grocery store. Energy intake was ad libitum. Body weight, body mass index (BMI), blood pressure, and blood lipids were measured at months 0, 2, 4, and 6. RESULTS: There was a significant diet x time interaction on body weight and BMI (P < 0.001). Weight loss was greatest with the LF-CC diet [change in body weight: control diet, 1.03 kg (NS); LF-CC diet, -4.25 kg (P < 0.01); LF-SC diet, -0.28 kg (NS)]. Total cholesterol decreased by 0.33 mmol/L, 0.63 mmol/L, and 0.06 mmol/L in subjects consuming the control, LF-CC, and LF-SC diets, respectively (difference between the LF-CC and LF-SC groups: P < 0.05). There were no significant changes in LDL cholesterol, whereas HDL cholesterol decreased over time in all 3 groups (P < 0.0001). Triacylglycerol concentrations were higher in the LF-SC group than in the other 2 groups (P < 0.05). CONCLUSIONS: A low-fat, high-polysaccharide diet in overweight individuals with abnormal intermediary metabolism led to moderate weight loss and some improvement in serum cholesterol. Increasing simple carbohydrates did not promote weight gain, but nor was there improvement in body weight or lipid profile.     

Does provision of additional dietary information affect actual or only reported compliance to a low-fat diet over 12 weeks in hyperlipidaemic individuals? Report of a pilot study

This randomized controlled pilot study was designed to measure the effect of additional dietary information on change in reported percentage energy from fat (% fat), total daily energy intake (TDEI), body mass index (BMI) and serum cholesterol in 13 hyperlipidaemic subjects, referred from the Cardiology Unit of St. Bartholomew's Hospital, over 12 weeks. At baseline (visit 1), % fat and TDEI were assessed using a validated food frequency questionnaire (Paisley et al ., 1996), and BMI and fasting lipids were measured. «Standard>> low-fat dietary advice was given to all patients. Subjects were randomized at 4 weeks (visit 2) to receive either further «standard>> dietary advice (control group) or further «standard>> dietary advice plus an additional information package (intervention group). At 12 weeks (visit 3), % fat, TDEI, BMI and fasting lipids were reassessed. Both groups reported a significant reduction in % fat; a 23% reduction ( P =0.00) in the intervention group, and an 11% reduction ( P =0.005) in the control group. However, there was no significant difference in the reported % fat at the end of the study between the two groups ( P =0.57). Plasma cholesterol was not significantly reduced in either the intervention or the control group (mean 7.3–6.7 mmol/l, 7.2–6.6 mmol/l, respectively). Reported energy intake was significantly reduced in both groups, but the extent of energy reduction was not reflected in the degree of weight lost. These results suggest that the provision of additional dietary information affects reported rather than actual compliance to a low-fat diet.     

Dietary fat and menstrual-cycle effects on the erythrocyte ghost insulin receptor in premenopausal women

The effect of high- and low-fat diets with different levels of fatty acid unsaturation on insulin receptors of erythrocyte ghosts was studied during different phases of the menstrual cycle in 31 healthy premenopausal women. Subjects were divided into two groups and consumed controlled diets containing 39% fat with a ratio of polyunsaturated to saturated fatty acids (P:S) of either 0.30 or 1.00 for four menstrual cycles. They were switched to 19% fat at the same P:S for another four cycles. Fasting blood samples were collected during the follicular and luteal phases. Insulin receptors were measured from right-side-out ghosts. Insulin binding was significantly lower due to fewer receptors when subjects were fed the low-fat, high-carbohydrate diet compared with the high-fat, low-carbohydrate diet. There was no significant effect of level of unsaturation or time of menstrual cycle on insulin binding. Thus, insulin receptors on erythrocytes respond to dietary lipids.     

A very low-fat diet is not associated with improved lipoprotein profiles in men with a predominance of large, low-density lipoproteins

BACKGROUND: We found previously that men with a predominance of large LDL particles (phenotype A) consuming high-fat diets (40-46% fat) show less lipoprotein benefits of low-fat diets (20-24% fat) than do men with a high-risk lipoprotein profile characterized by a predominance of small LDL (phenotype B). Furthermore, one-third of men with phenotype A consuming a high-fat diet converted to phenotype B with a low-fat diet. OBJECTIVE: We investigated effects of further reduction in dietary fat in men with persistence of LDL subclass phenotype A during both high- and low-fat diets. DESIGN: Thirty-eight men who had shown phenotype A after 4-6 wk of both high- and low-fat diets consumed for 10 d a 10%-fat diet (2.7% saturates) with replacement of fat with carbohydrate and no change in cholesterol content or ratio of polyunsaturates to saturates. RESULTS: In 26 men, phenotype A persisted (stable A group) whereas 12 converted to phenotype B (change group). LDL cholesterol did not differ from previous values for 20-24%-fat diets in either group, whereas in the change group there were higher concentrations of triacylglycerol and apolipoprotein B; greater mass of HDL, large LDL-I, small LDL-III and LDL-IV, and HDL3; lower concentrations of HDL cholesterol, apolipoprotein A-I; and lower mass of large LDL-I and HDL2. CONCLUSIONS: There is no apparent lipoprotein benefit of reduction in dietary fat from 20-24% to 10% in men with large LDL particles: LDL-cholesterol concentration was not reduced, and in a subset of subjects there was a shift to small LDL along with increased triacylglycerol and reduced HDL-cholesterol concentrations.     

Dietary intake and changes in lipoprotein lipids in obese, postmenopausal women placed on an American Heart Association Step 1 diet

BACKGROUND: Dietary intake and changes in lipoprotein lipids in obese, postmenopausal women placed on an American Heart Association Step 1 diet. OBJECTIVE: The purpose of this study was to determine the specific dietary factors associated with the commonly observed decrease in HDL-C concentration in obese, postmenopausal women placed on a low-fat diet. DESIGN/SUBJECTS/INTERVENTION: Dietary intake, lipoprotein lipid concentrations, and body weight were measured before and after 10 weeks of instruction in the principles of the American Heart Association (AHA) Step 1 diet in 55 overweight and obese (body mass index=33+/-4 kg/m2), sedentary, postmenopausal women (mean age 59+/-5 years). RESULTS: The percent of energy obtained from total fat, monounsaturated, polyunsaturated, saturated fat, and dietary cholesterol decreased significantly after dietary intervention, while the polyunsaturated:saturated ratio and the percent of energy obtained from total carbohydrate, complex carbohydrate, and simple carbohydrate increased. On average, the women lost a small, but significant, amount of body weight (2%+/-3%, P<.0001). Adherence to the AHA diet reduced total cholesterol (-8%+/-8%), LDL-C (-6%+/-11%), and HDL-C (-16%+/-10%). The only dietary change that predicted decreases in HDL-C concentrations was the increase in the percent of energy from simple sugar (r=-0.32, P<.05). There were no relationships between changes in HDL-C and changes in percent of energy from fat (r=0.16), saturated fat (r=0.07), polyunsaturated fat (r=0.04), or monounsaturated fat (r=0.09). APPLICATIONS/CONCLUSIONS: In postmenopausal women, a dietary reduction in total fat, saturated fat, and cholesterol reduces body weight, total cholesterol, and LDL-C, but substitution of simple sugar for dietary fat may lead to a reduction in HDL-C. Further research is needed to determine which specific simple sugars are contributing to diet-induced reductions in HDL-C in older women placed on a low-fat diet.     

Effect on blood pressure of two diets differing in total fat but not in saturated and polyunsaturated fatty acids in healthy volunteers

The effects of a low-fat, carbohydrate-rich and a high-fat, olive-oil-rich diet on blood pressure were studied under strict dietary control. Forty-seven healthy normotensive men and women were fed a diet high in saturated fatty acids (20 en%) and total fat (38 en%) for 17 d. Twenty-four subjects then received a low-fat, carbohydrate-rich diet (total fat 22 en%) and the other 23 a high-fat, olive-oil-rich diet (oleic acid 24 en%, total fat 41 en%) for 36 d. Both test diets had the same level of saturated fatty acids (7-10 en%) and linoleic acid (4 en%). Systolic blood pressure fell by 2.3 and diastolic by 4.7 mm Hg in the carbohydrate group and by 2.7 and 4.4 mm Hg in the olive-oil group, respectively (differences between diets groups not significant). These results suggest that a high-fat diet rich in monounsaturated fatty acids has no deleterious effect on blood pressure in healthy normotensive subjects in comparison with a low-fat, carbohydrate-rich diet.     

Flow-mediated vasodilation is not impaired when HDL-cholesterol is lowered by substituting carbohydrates for monounsaturated fat

Low-fat diets, in which carbohydrates replace some of the fat, decrease serum cholesterol. This decrease is due to decreases in LDL-cholesterol but in part to possibly harmful decreases in HDL-cholesterol. High-oil diets, in which oils rich in monounsaturated fat replace some of the saturated fat, decrease serum cholesterol mainly through LDL-cholesterol. We used these two diets to investigate whether a change in HDL-cholesterol would change flow-mediated vasodilation, a marker of endothelial function. We fed thirty-two healthy volunteers two controlled diets in a weeks' randomised cross-over design to eliminate variation in changes due to differences between subjects. The low-fat diet contained 59.7 % energy (en%) as carbohydrates and 25.7 en% as fat (7.8 en% as monounsaturates); the oil-rich diet contained 37.8 en% as carbohydrates and 44.4 en% as fat (19.3 en% as monounsaturates). Average (sd) serum HDL-cholesterol after the low-fat diet was 0.21 (sd 0.12) mmol/l (8.1 mg/dl) lower than after the oil-rich diet. Serum triacylglycerols were 0.22 (sd 0.28) mmol/l (19.5 mg/dl) higher after the low-fat diet than after the oil-rich diet. Serum LDL and homocysteine concentrations remained stable. Flow-mediated vasodilation was 4.8 (SD 2.9) after the low-fat diet and 4.1 (SD 2.7) after the oil-rich diet (difference 0.7 %; 95 % CI -0.6, 1.9). Thus, although the low-fat diet produced a lower HDL-cholesterol than the high-oil diet, flow-mediated vasodilation, an early marker of cardiovascular disease, was not impaired.     

Influence of caloric contribution and saturation of dietary fat on plasma lipids in premenopausal women

Total cholesterol, HDL cholesterol, and triglycerides were measured in 31 premenopausal women randomized into one of two diet groups: one diet with a P:S ratio of 1.0 and one diet with a P:S ratio of 0.3. Both groups were fed a high-fat diet (40% of energy from fat) for four menstrual cycles per subject followed by a similar interval on a low-fat diet (20% of energy from fat). Changing from the high-fat to the low-fat diet resulted in a nonsignificant mean decrease of 7% in total cholesterol. HDL-cholesterol response to the low-fat regimen was influenced by the P:S ratio. Women in the high P:S group showed no change; mean HDL cholesterol in women in the low P:S group decreased 12%. Plasma triglycerides increased in both groups on the low-fat diet although the increase was greatest in the low P:S group.     

An eight-month controlled study of a low-fat high-fibre diet: effects on blood lipids and blood pressure in healthy young subjects.

The effects on blood lipids and blood pressure of a diet corresponding to present Nordic Nutrition Recommendations, i.e. less than 30% of energy from fat and with a fibre content exceeding 3 g/MJ, were studied in 18 men and 12 women (mean age, 24 years) under strict dietary control over 8 months. Blood sampling, blood pressure and body weight measurement were performed at four occasions on their habitual diet and once a month during the intervention period. An age-matched control group (17 men, 8 women) was followed with monthly measurements parallel to the intervention group. The habitual diets, assessed by 7-day records, showed an average fat content corresponding to 36% of energy. Initial levels of total cholesterol and HDL cholesterol (X +/- SD) were 4.21 +/- 0.61 and 1.23 +/- 0.23 mmol/l for the men in the intervention group; 4.35 +/- 0.79 and 1.21 +/- 0.26 mmol/l for the male controls; 4.61 +/- 0.59 and 1.46 +/- 0.31 mmol/l for the women in the intervention group and 4.48 +/- 0.64 and 1.48 +/- 0.29 mmol/l for the female controls. Significantly decreased levels of total cholesterol and HDL cholesterol throughout the experimental period were seen for both sexes in the intervention group. Total cholesterol fell 0.49 mmol/l (95% CI: 0.41-0.56) in the male subjects and 0.49 mmol/l (95% CI: 0.39-0.59) in the female subjects. The fall in HDL cholesterol was 0.16 mmol/l (95% C: 0.13-0.18) and 0.18 mmol/l (95% CI: 0.12-0.23), respectively. Total cholesterol changes were independent of initial values. All subjects were normotensive at the start of the study with an average blood pressure of 122/68 mmHg for men and 112/68 mmHg for the women. Systolic blood pressure dropped gradually and significantly in the male subjects of the intervention group. A minimum of 6 mmHg below initial values was noted after six months of dietary intervention. No significant changes in dietary intake and blood lipids were observed in the control group. Thus, changes of present dietary habits of young healthy Danish subjects to an intake in accordance with the Nordic Nutrition Recommendations 1989 will favourably affect suggested risk factors for disease.