Comparison of monounsaturated fat with carbohydrates as a replacement for saturated fat in subjects with a high metabolic risk profile: studies in the fasting and postprandial states

BACKGROUND: In subjects with a high prevalence of metabolic risk abnormalities, the preferred replacement for saturated fat is unresolved. OBJECTIVE: The objective was to study whether carbohydrate or monounsaturated fat is a preferred replacement for saturated fat. DESIGN: Fifty-two men and 33 women, selected to have any combination of HDL cholesterol < or = 30th percentile, triacylglycerol > or = 70th percentile, or insulin > or = 70th percentile, were enrolled in a 3-period, 7-wk randomized crossover study. The subjects consumed an average American diet (AAD; 36% of energy from fat) and 2 additional diets in which 7% of energy from saturated fat was replaced with either carbohydrate (CHO diet) or monounsaturated fatty acids (MUFA diet). RESULTS: Relative to the AAD, LDL cholesterol was lower with both the CHO (-7.0%) and MUFA (-6.3%) diets, whereas the difference in HDL cholesterol was smaller during the MUFA diet (-4.3%) than during the CHO diet (-7.2%). Plasma triacylglycerols tended to be lower with the MUFA diet, but were significantly higher with the CHO diet. Although dietary lipid responses varied on the basis of baseline lipid profiles, the response to diet did not differ between subjects with or without the metabolic syndrome or with or without insulin resistance. Postprandial triacylglycerol concentrations did not differ significantly between the diets. Lipoprotein(a) concentrations increased with both the CHO (20%) and MUFA (11%) diets relative to the AAD. CONCLUSIONS: In the study population, who were at increased risk of coronary artery disease, MUFA provided a greater reduction in risk as a replacement for saturated fat than did carbohydrate.     

Serum lipoprotein lipid and apoprotein (B and A-I) responses to saturated fat-rich diet in cynomolgus monkeys: effects of carbohydrate type and cholesterol

The effects of carbohydrate type and cholesterol in a high saturated fat diet (40% cal) on serum lipoprotein lipid and apoprotein responses were studied in 12 male cynomolgus monkeys (Macaca fascicularis). For 6 wk each monkey was fed one of four semipurified diets that provided by calorie 49% as starch or sucrose without and with 1 mg/kcal cholesterol. Starch and sucrose diets without added cholesterol resulted in similar levels of serum total cholesterol and apoB; whereas starch produced significantly higher values for these variables than sucrose when cholesterol was added to these diets. Starch diet, irrespective of dietary cholesterol, yielded significantly lower apoA-I levels than sucrose diet. Carbohydrate type did not affect serum triglyceride levels. Cholesterol-enriched starch diet resulted in relatively higher intermediate- and low-density lipoproteins and lower high-density lipoproteins in comparison to similar sucrose diet. Thus, the magnitude of responses of serum lipoproteins can be affected by the type of carbohydrate.     

Synergistic effects of dietary carbohydrate and cholesterol on serum lipids and lipoproteins in squirrel and spider monkeys.

Serum lipid and lipoprotein responses to diets with a high level of simple carbohydrate (69% w/w sucrose) and a low level of saturated fat (5% w/w butter-coconut oil, polyunsaturated/saturated fatty acid ratio 0.03) containing 0, 0.1, and 1.0 mg/kcal added cholesterol was studied in five squirrel (Saimiri sciurea) monkeys. Variations in response produced by altering the nature of dietary carbohydrate (sucrose versus dextrin) and the fat (polyunsaturated/saturated fatty acid ratio, 0.03 versus 1.5) in the above diets were studied in three groups (five per group) of spider monkeys (Ateles sp.). In the absence of exogenous cholesterol, feeding a sucrose-saturated fat diet for 6 weeks produced a consistent increase in serum cholesterol in both species and an increase in serum triglycerides only in squirrel monkeys. Exogenous cholesterol had a remarkable synergistic effect on the high carbohydrate diet in increasing the serum cholesterol and had a suppressing effect on serum triglycerides in both species. Polyunsaturated fat reduced the hypercholesterolemic effect of sucrose with or without exogenous cholesterol. Dextrin diets resulted in lower serum cholesterol responses than sucrose diets when the diets contained 0 or 0.1 mg/kcal added cholesterol. Serum cholesterol response was reflected in beta- and alpha-lipoproteins. These results emphasize the varied response of serum lipids and lipoproteins to dietary changes in carbohydrate, fat, and cholesterol that might have a bearing on experimental atherosclerosis.     

Effects of monounsaturated enriched sunflower oil on CHD risk factors including LDL size and copper-induced LDL oxidation

OBJECTIVE: To compare the effects of a diet high in monounsaturated enriched sunflower oil and a low fat diet on CHD risk factors including in vitro Cu-induced LDL oxidation and LDL size, lipids, lipoproteins, glucose and insulin. DESIGN: A randomized crossover dietary intervention. SETTING: Free living individuals. SUBJECTS: Fourteen healthy males 35 to 55 years of age and 14 healthy postmenopausal women 50 to 60 years of age completed the dietary intervention. Two subjects did not complete the study, and their data were not included. INTERVENTIONS: A low fat, high carbohydrate diet (22% to 25% of energy from total fat, 7% to 8% of energy from monounsaturated fat and 55% to 60% of energy from carbohydrate) was compared to a monounsatutated enriched sunflower oil (MO) diet (40% to 42% of energy from fat, with 26% to 28% from monounsaturated fat and 40% to 45% of energy from carbohydrate) in an isocaloric substitution. Each dietary period was one month. RESULTS: Total cholesterol, LDL cholesterol, triglycerides and glucose were not significantly different between the two diets. HDL cholesterol, HDL3 cholesterol and insulin were significantly higher on the MO diet, mean 7%, 7% and 17% higher respectively. Copper-induced LDL oxidation lag phase was significantly longer (mean 18%) after the MO diet compared to the low fat, high carbohydrate diet. LDL particle size was not significantly different. CONCLUSIONS: The significant increase in LDL oxidation lag phase and the significantly higher HDL cholesterol on the MO diet would be expected to be associated with a decrease in CHD risk.     

Effects of moderate-fat (from monounsaturated fat) and low-fat weight-loss diets on the serum lipid profile in overweight and obese men and women

BACKGROUND: Little evidence of the effects of moderate-fat (from monounsaturated fat) weight-loss diets on risk factors for cardiovascular disease exists because low-fat diets are typically recommended. Previous studies in weight-stable persons showed that a moderate-fat diet results in a more favorable lipid and lipoprotein profile (ie, lower serum triacylglycerol and higher HDL cholesterol) than does a low-fat diet. OBJECTIVE: We evaluated the effects of energy-controlled, low-fat and moderate-fat diets on changes in lipids and lipoproteins during weight loss and subsequent weight maintenance. DESIGN: We conducted a parallel-arm study design in overweight and obese [body mass index (in kg/m(2)): 29.8 +/- 2.4] healthy men and women (n = 53) assigned to consume a low-fat (18% of energy) or moderate-fat (33% of energy) diet for 6 wk to achieve weight loss, which was followed by 4 wk of weight maintenance. All foods were provided and body weight was monitored to ensure equal weight loss between groups. RESULTS: The moderate-fat diet elicited favorable changes in the lipoprotein profile. Compared with baseline, HDL cholesterol was unchanged, whereas triacylglycerol and the ratios of total and non-HDL cholesterol to HDL cholesterol were lower at the end of the weight-maintenance period in the moderate-fat diet group. Despite similar weight loss, triacylglycerol rebounded, HDL cholesterol decreased, and the ratios of total and non-HDL cholesterol to HDL cholesterol did not change during the 10-wk interval in the low-fat diet group. CONCLUSIONS: A moderate-fat weight-loss and weight-maintenance diet improves the cardiovascular disease risk profile on the basis of favorable changes in lipids and lipoproteins. There is merit in recommending a moderate-fat weight-loss diet.     

Fatty acid saturation of the diet and plasma lipid concentrations, lipoprotein particle concentrations, and cholesterol efflux capacity

BACKGROUND: The fatty acid content and saturation degree of the diet can modulate HDL composition and cholesterol efflux. OBJECTIVE: We studied the modifications in plasma lipoprotein particles and serum capacity to stimulate cholesterol efflux induced by different fatty acids. DESIGN: Seventeen women and 24 men followed in the same sequence 4 diets containing 35% of total energy as fat. The saturated fat diet contained 17% palm oil; the monounsaturated fat diet, 20.9% olive oil; the n-6 polyunsaturated fat diet, 12.5% sunflower oil; and the n-3 polyunsaturated fat diet, sunflower oil supplemented with 4-4.5 g fish oil/d. Each phase lasted 4-5 wk. RESULTS: In both sexes, apolipoprotein (apo) A-I concentrations were significantly lower with unsaturated fat diets than with the saturated fat diet, but concentrations of lipoproteins containing only apo A-I (Lp A-I) were lower only in the men. Concentrations of lipoproteins containing both apo A-I and apo A-II (Lp A-I:A-II) were lower with both polyunsaturated fat diets in the women but significantly higher in the men. Lp E concentrations were significantly higher with the 2 polyunsaturated fat diets. Lp E non-B particle concentrations were not modified in the men but were significantly higher in the women in both polyunsaturated fat phases. Lp C-III concentrations were higher with the saturated fat diet only in the men. The serum samples taken after the n-3 polyunsaturated fat phase were the most efficient for extracting cellular cholesterol in both sexes. CONCLUSIONS: The monounsaturated and polyunsaturated fat diets were healthier, producing a better lipid profile. The n-3 polyunsaturated fat diet increased the capacity of serum to promote the efflux of cholesterol from cells in culture.     

Effect of meat replacement by tofu on CHD risk factors including copper induced LDL oxidation

OBJECTIVE: To investigate the effect of replacing lean meat with a soy product, tofu, on coronary heart disease risk factors including serum lipoproteins, lipoprotein (a), factor VII, fibrinogen and in vitro susceptibility of LDL to oxidation. DESIGN: A randomized cross over dietary intervention study. SETTING: Free-living individuals studied at Deakin University. SUBJECTS: Forty-five free-living healthy males aged 35 to 62 years completed the dietary intervention. Three subjects were non-compliant and excluded prior to analysis. INTERVENTIONS: A diet containing 150 grams of lean meat per day was compared to a diet containing 290 grams of tofu per day in an isocaloric and isoprotein substitution. Each dietary period was one month duration. RESULTS: Analysis of the seven-day diet record showed that diets were similar in energy, protein, carbohydrate, total fat, saturated and unsaturated fat, polyunsaturated to saturated fat ratio, alcohol and fiber. Total cholesterol and triglycerides were significantly lower, and in vitro LDL oxidation lag phase was significantly longer on the tofu diet compared to the meat diet. The hemostatic factors, factor VII and fibrinogen, and lipoprotein(a) were not significantly affected by the tofu diet. CONCLUSIONS: The increase in LDL oxidation lag phase would be expected to be associated with a decrease in coronary heart disease risk.     

Separate effects of reduced carbohydrate intake and weight loss on atherogenic dyslipidemia

BACKGROUND: Low-carbohydrate diets have been used to manage obesity and its metabolic consequences. OBJECTIVE: The objective was to study the effects of moderate carbohydrate restriction on atherogenic dyslipidemia before and after weight loss and in conjunction with a low or high dietary saturated fat intake. DESIGN: After 1 wk of consuming a basal diet, 178 men with a mean body mass index (in kg/m(2)) of 29.2 +/- 2.0 were randomly assigned to consume diets with carbohydrate contents of 54% (basal diet), 39%, or 26% of energy and with a low saturated fat content (7-9% of energy); a fourth group consumed a diet with 26% of energy as carbohydrate and 15% as saturated fat. After 3 wk, the mean weight loss (5.12 +/- 1.83 kg) was induced in all diet groups by a reduction of approximately 1000 kcal/d for 5 wk followed by 4 wk of weight stabilization. RESULTS: The 26%-carbohydrate, low-saturated-fat diet reduced triacylglycerol, apolipoprotein B, small LDL mass, and total:HDL cholesterol and increased LDL peak diameter. These changes were significantly different from those with the 54%-carbohydrate diet. After subsequent weight loss, the changes in all these variables were significantly greater and the reduction in LDL cholesterol was significantly greater with the 54%-carbohydrate diet than with the 26%-carbohydrate diet. With the 26%-carbohydrate diet, lipoprotein changes with the higher saturated fat intakes were not significantly different from those with the lower saturated fat intakes, except for LDL cholesterol, which decreased less with the higher saturated fat intake because of an increase in mass of large LDL. CONCLUSIONS: Moderate carbohydrate restriction and weight loss provide equivalent but nonadditive approaches to improving atherogenic dyslipidemia. Moreover, beneficial lipid changes resulting from a reduced carbohydrate intake were not significant after weight loss.     

Interrelated effects of the type of dietary fat and carbohydrate on cholesterol metabolism in rats

Rats were fed semipurified diets, differing in the amount of cholesterol and the sources of fat (corn oil or coconut fat) and carbohydrate (sucrose or starch). After 21 days dietary corn oil had induced higher serum cholesterol concentrations than did coconut fat, except for on diets with a high-cholesterol, high-sucrose background. On high-cholesterol diets containing coconut fat, dietary sucrose increased serum cholesterol, when compared with starch; with corn oil sucrose tended to lower serum cholesterol. Such a tendency was not seen on cholesterol-free diets. Cholesterol feeding caused a dramatic increase in liver cholesterol with all dietary carbohydrate-fat combinations. Liver cholesterol was higher in rats fed corn oil than in those fed coconut fat. The influence of the type of dietary carbohydrate on liver cholesterol was dependent on the type of fat and the amount of cholesterol in the diet. Thus effects of a single dietary component on serum and liver cholesterol in rats are strongly influenced by the background of the diet. This implies that published results of experiments on diet and cholesterol metabolism in rats cannot be compared readily.     

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.     

Diet and coronary heart disease

The controversy over the role of diet in the development of coronary heart disease (CHD) continues. Most studies of dietary involvement have concentrated on the possible nutritional basis of the accepted risk factor - raised serum cholesterol. In animals, although high fat diets, particularly high saturated fatty acid diets, cause raised serum cholesterol levels, myocardial infarction rarely occurs. In human studies initial insight into the importance of dietary fat level and fatty acid composition was gleaned from international studies. Within population studies supported the association of raised serum cholesterol concentration with CHD in males up to 60years of age, and recognised the significance of the type of serum cholesterol, currently thought to be under genetic control. Although intervention studies have shown that high serum cholesterol levels can be reduced by dietary means, there has been no convincing evidence of a reduction in total mortality. An imbalance in the formation of inhibitors and promoters of platelet aggregation from polyunsaturated fatty acids in the diet is postulated as a possible nutritional basis for the formation of a thrombus in the coronary artery.     

Simple Nutrient-Based Rules vs. a Nutritionally Rich Plant-Centered Diet in Prediction of Future Coronary Heart Disease and Stroke: Prospective Observational Study in the US

To better understand nutrition paradigm shift from nutrients to foods and dietary patterns, we compared associations of a nutrient-based blood cholesterol-lowering diet vs. a food-based plant-centered diet with risk of coronary heart disease (CHD) and stroke. Participants were 4701 adults aged 18–30 years and free of cardiovascular disease at baseline, followed for clinical events from 1985 and 86 to 2018. A plant-centered diet was represented by higher A Priori Diet Quality Score (APDQS). A blood cholesterol-lowering diet was represented by lower Keys Score. Proportional hazards regression was used to calculate hazard ratios (HR). Higher APDQS showed a nutrient-dense composition that is low in saturated fat but high in fiber, vitamins and minerals. Keys Score and APDQS changes were each inversely associated with concurrent plasma low-density lipoprotein cholesterol (LDL-C) change. Over follow-up, 116 CHD and 80 stroke events occurred. LDL-C predicted CHD, but not stroke. APDQS, but not Keys Score, predicted lower risk of CHD and of stroke. Adjusted HRs (95% CIs) for each 1-SD higher APDQS were 0.73 (0.55–0.96) for CHD and 0.70 (0.50–0.99) for stroke. Neither low dietary fat nor low dietary carbohydrate predicted these events. Our findings support the ongoing shift in diet messages for cardiovascular prevention.     

Changes in atherogenic dyslipidemia induced by carbohydrate restriction in men are dependent on dietary protein source

Previous studies have shown that multiple features of atherogenic dyslipidemia are improved by replacement of dietary carbohydrate with mixed sources of protein and that these lipid and lipoprotein changes are independent of dietary saturated fat content. Because epidemiological evidence suggests that red meat intake may adversely affect cardiovascular disease risk, we tested the effects of replacing dietary carbohydrate with beef protein in the context of high- vs. low-saturated fat intake in 40 healthy men. After a 3-wk baseline diet [50% daily energy (E) as carbohydrate, 13% E as protein, 15% E as saturated fat], participants consumed for 3 wk each in a randomized crossover design two high-beef diets in which protein replaced carbohydrate (31% E as carbohydrate, 31% E as protein, with 10% E as beef protein). The high-beef diets differed in saturated fat content (8% E vs. 15% E with exchange of saturated for monounsaturated fat). Two-week washout periods were included following the baseline diet period and between the randomized diets periods. Plasma TG concentrations were reduced after the 2 lower carbohydrate dietary periods relative to after the baseline diet period and these reductions were independent of saturated fat intake. Plasma total, LDL, and non-HDL cholesterol as well as apoB concentrations were lower after the low-carbohydrate, low-saturated fat diet period than after the low-carbohydrate, high-saturated fat diet period. Given our previous observations with mixed protein diets, the present findings raise the possibility that dietary protein source may modify the effects of saturated fat on atherogenic lipoproteins.     

Dietary fatty acids affect plasma markers of inflammation in healthy men fed controlled diets: a randomized crossover study

BACKGROUND: The effect of individual dietary fatty acids on emerging risk factors for cardiovascular disease that are associated with subclinical inflammation is unknown. OBJECTIVE: The goal was to evaluate the role of dietary fat and specific fatty acids, especially trans fatty acids, in altering concentrations of markers of inflammation in humans fed controlled diets. DESIGN: In a randomized crossover design, 50 men consumed controlled diets for 5 wk that provided 15% of energy from protein, 39% of energy from fat, and 46% of energy from carbohydrate. Eight percent of fat or fatty acids was replaced across diets with the following: cholesterol, oleic acid, trans fatty acids (TFAs), stearic acid (STE), TFA+STE (4% of energy each), and 12:0-16:0 saturated fatty acids (LMP). RESULTS: Fibrinogen concentrations were higher after consumption of the diet enriched in stearic acid than after consumption of the carbohydrate diet. C-reactive protein concentrations were higher after consumption of the TFA diet than after consumption of the carbohydrate diet, but were not significantly different after consumption of the TFA and TFA+STE diets than after consumption of the LMP diet. Interleukin 6 concentrations were lower after consumption of the oleic acid diet than after consumption of the LMP, TFA, and STE diets. E-selectin concentrations were higher after consumption of the TFA diet than after consumption of the carbohydrate diet. Consumption of the TFA but not the TFA+STE diet resulted in higher E-selectin concentrations than did the LMP diet. CONCLUSIONS: These data provide evidence that dietary fatty acids can modulate markers of inflammation. Although stearic acid minimally affects LDL cholesterol, it does appear to increase fibrinogen concentrations.     

Health benefits of dietary fat reduction by a novel fat replacer: Mimix

The primary goals of this study were to identify any health benefits of the replacement of dietary fat with a novel fat replacer, Mimix, and to assure that the consumption of this fat replacer did not convey any deleterious health effects. Male, weanling, Fischer 344 rats were fed one of six diets containing between 5 and 20% w/w as fat for 8 weeks. These diets included two high fat diets (safflower oil or lard), a low fat diet and three diets where 15% of the fat in the high fat diets was replaced with various amounts of Mimix. When animals were fed a diet rich in saturated fat they consumed significantly more energy than other diet groups. When 15% saturated fat (lard) was replaced with safflower oil animals adjusted their food intake so that no difference in energy intake was observed between the high safflower diet and the low fat and Mimix diets. When the various Mimix fat replacements were compared to animals fed a high fat lard diet there was incomplete compensation of energy intake. Animals fed the high fat lard diet also had higher glucose and total serum cholesterol than their low fat and fat replacement counterparts. Feeding a high fat safflower oil diet to rats resulted in a significantly lower total serum cholesterol and serum triglyceride than all other diets. Replacement of dietary fat with Mimix demonstrated no deleterious effects on the heart, liver and intestinal tract that were all of normal weight, morphology and colour compared to other diet groups. Body composition analysis demonstrated that animals fed high fat diets had higher body fat mass at the expense of lean body mass. This was most obvious for animals fed high fat lard diets who had heavier epididymal fat pads. These data demonstrate that the replacement of dietary fat with the novel fat replacer Mimix can convey a number of health benefits in the absence of any deleterious effects.     

Health benefits of dietary fat reduction by a novel fat replacer: Mimix

The primary goals of this study were to identify any health benefits of the replacement of dietary fat with a novel fat replacer, Mimix, and to assure that the consumption of this fat replacer did not convey any deleterious health effects. Male, weanling, Fischer 344 rats were fed one of six diets containing between 5 and 20% w/w as fat for 8 weeks. These diets included two high fat diets (safflower oil or lard), a low fat diet and three diets where 15% of the fat in the high fat diets was replaced with various amounts of Mimix. When animals were fed a diet rich in saturated fat they consumed significantly more energy than other diet groups. When 15% saturated fat (lard) was replaced with safflower oil animals adjusted their food intake so that no difference in energy intake was observed between the high safflower diet and the low fat and Mimix diets. When the various Mimix fat replacements were compared to animals fed a high fat lard diet there was incomplete compensation of energy intake. Animals fed the high fat lard diet also had higher glucose and total serum cholesterol than their low fat and fat replacement counterparts. Feeding a high fat safflower oil diet to rats resulted in a significantly lower total serum cholesterol and serum triglyceride than all other diets. Replacement of dietary fat with Mimix demonstrated no deleterious effects on the heart, liver and intestinal tract that were all of normal weight, morphology and colour compared to other diet groups. Body composition analysis demonstrated that animals fed high fat diets had higher body fat mass at the expense of lean body mass. This was most obvious for animals fed high fat lard diets who had heavier epididymal fat pads. These data demonstrate that the replacement of dietary fat with the novel fat replacer Mimix can convey a number of health benefits in the absence of any deleterious effects.     

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.     

High-monounsaturated fatty acid diets lower both plasma cholesterol and triacylglycerol concentrations

BACKGROUND: Low-fat diets increase plasma triacylglycerol and decrease HDL-cholesterol concentrations, thereby potentially adversely affecting cardiovascular disease (CVD) risk. High-monounsaturated fatty acid (MUFA), cholesterol-lowering diets do not raise triacylglycerol or lower HDL cholesterol, but little is known about how peanut products, a rich source of MUFAs, affect CVD risk. OBJECTIVE: The present study compared the CVD risk profile of an Average American diet (AAD) with those of 4 cholesterol-lowering diets: an American Heart Association/National Cholesterol Education Program Step II diet and 3 high-MUFA diets [olive oil (OO), peanut oil (PO), and peanuts and peanut butter (PPB)]. DESIGN: A randomized, double-blind, 5-period crossover study design (n = 22) was used to examine the effects of the diets on serum lipids and lipoproteins: AAD [34% fat; 16% saturated fatty acids (SFAs), 11% MUFAs], Step II (25% fat; 7% SFAs, 12% MUFAs), OO (34% fat; 7% SFAs, 21% MUFAs), PO (34% fat; 7% SFAs, 17% MUFAs), and PPB (36% fat; 8% SFAs, 18% MUFAs). RESULTS: The high-MUFA diets lowered total cholesterol by 10% and LDL cholesterol by 14%. This response was comparable with that observed for the Step II diet. Triacylglycerol concentrations were 13% lower in subjects consuming the high-MUFA diets and were 11% higher with the Step II diet than with the AAD. The high-MUFA diets did not lower HDL cholesterol whereas the Step II diet lowered it by 4% compared with the AAD. The OO, PO, and PPB diets decreased CVD risk by an estimated 25%, 16%, and 21%, respectively, whereas the Step II diet lowered CVD risk by 12%. CONCLUSION: A high-MUFA, cholesterol-lowering diet may be preferable to a low-fat diet because of more favorable effects on the CVD risk profile.     

Carbohydrate and fiber recommendations for individuals with diabetes: a quantitative assessment and meta-analysis of the evidence

To review international nutrition recommendations with a special emphasis on carbohydrate and fiber, analyze clinical trial information, and provide an evidence-based recommendation for medical nutrition therapy for individuals with diabetes. Relevant articles were identified by a thorough review of the literature and the data tabulated. Fixed-effects meta-analyses techniques were used to obtain mean estimates of changes in outcome measures in response to diet interventions. Most international organizations recommend that diabetic individuals achieve and maintain a desirable body weight with a body mass index of /=55%; protein, 12-16%; fat, <30%; and monounsaturated fat, 12-15%. The diet should provide 25-50 g/day of dietary fiber (15-25 g/1000 kcal). Glycemic index information should be incorporated into exchanges and teaching material.