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.     

Effects of soy as tofu vs meat on lipoprotein concentrations

OBJECTIVES: To investigate the effect of replacing lean meat with a soy product, tofu, on serum lipoprotein concentrations. STUDY AND DESIGN: Randomized cross-over dietary intervention study. SUBJECTS: Forty-two free-living healthy males aged 35-62 y completed the dietary intervention. Three additional subjects were non-compliant and excluded prior to analysis. INTERVENTIONS: A diet containing lean meat (150 g/d) was compared with one with 290 g/d tofu in an isocaloric and isoprotein substitution. Both diet periods were 1 month, and fat intake was carefully controlled. RESULTS: Seven-day diet records showed the two diets were similar in energy, macronutrients and fibre. Total cholesterol (mean difference 0.23 mmol/l, 95% CI 0.02, 0.43; P=0.03) and triglycerides (mean difference 0.15 mmol/l, 95% CI 0.02, 0.31; P=0.017) were significantly lower on the tofu diet than the lean meat diet. However, HDL-C was also significantly lower on the tofu diet (mean difference 0.08 mmol/l, 95% CI 0.02, 0.14; P=0.01) although the LDL-C:HDL-C ratio was similar. CONCLUSION: The effect on HDL-C and the small LDL-C reduction differ from some other studies, where fat was often less controlled, and the comparison was of soy as textured protein or soymilk against casein. This suggests a differential effect of the various proteins compared to the soy may influence the findings. In practice, the replacement of meat with tofu would usually be associated with a decrease in saturated fat and an increase in polyunsaturated fat and this should enhance any small benefits due to the soy protein. SPONSOR: Deakin University with some contribution from a Commonwealth Department of Veterans Affairs research grant. European Journal of Clinical Nutrition (2000) 54, 14-19     

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.     

Dietary fat and cardiovascular disease risk: quantity or quality?

When considering dietary fat quantity, there are two main factors to consider, impact on body weight and plasma lipoprotein profiles. Data supporting a major role of dietary fat quantity in determining body weight are weak and may be confounded by differences in energy density, dietary fiber, and dietary protein. With respect to plasma lipoprotein profiles, relatively consistent evidence indicates that under isoweight conditions, decreasing the total fat content of the diet causes an increase in triglyceride and decrease in high-density lipoprotein (HDL) cholesterol levels. When considering dietary fat quality, current evidence suggests that saturated fatty acids tend to increase low-density lipoprotein (LDL) cholesterol levels, whereas monounsaturated and polyunsaturated fatty acids tend to decrease LDL cholesterol levels. Long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) (20:5n-3) and docosahexaenoic acid (DHA) (22:6n-3), are associated with decreased triglyceride levels in hypertriglyceridemic patients and decreased risk of developing coronary heart disease (CHD). Dietary trans-fatty acids are associated with increased LDL cholesterol levels. Hence, a diet low in saturated and trans-fatty acids, with adequate amounts of monounsaturated and polyunsaturated fatty acids, especially long-chain omega-3 fatty acids, would be recommended to reduce the risk of developing CHD. Additionally, the current data suggest it is necessary to go beyond dietary fat, regardless of whether the emphasis is on quantity or quality, and consider lifestyle. This would include encouraging abstinence from smoking, habitual physical activity, avoidance of weight gain with age, and responsible limited alcohol intake (one drink for females and two drinks for males per day).     

Dietary habits affect the susceptibility of low-density lipoprotein to oxidation

OBJECTIVE: To study, if there are differences in the fatty acid composition of low-density lipoprotein (LDL) in people eating three different long-standing habitual diets: vegetarian, high fish intake, or high saturated fat (milk fat) diet as a control group, and to study if these differences influence the oxidation susceptibility of LDL. DESIGN: Cross-sectional study using blood samples and a validated dietary frequency questionnaire with illustrations. Setting: Helsinki University Central Hospital, Finland. SUBJECTS: The effect of three different types of long-standing diets of different fatty acid content (a strict vegetarian diet, n=11; a high fish intake diet, n=9; and a high saturated fat (milk fat) diet, controls, n=7) on the serum and LDL fatty acid content, and on the susceptibility of LDL to oxidation in vitro, was studied in healthy normocholesterolemic volunteers who had been on these diets for years. Oxidation of LDL was carried out by using CuSO4 as a pro-oxidant. RESULTS: There were no statistically significant differences in the serum lipids or lipoproteins, though the vegetarian group exhibited lowest mean values of total, high-density lipoprotein (HDL) and LDL cholesterol levels. Both the serum and LDL eicosapentaenoic, docosapentaenoic and docosahexaenoic acid proportions were highest in the fish and lowest in the vegetarian groups. Linoleic acid was highest among the vegetarians. In the fish group, the vitamin A concentration in serum was higher than in vegetarians and controls and beta-carotene lower than in controls, but in alpha-tocopherol, or lycopene concentrations there were no statistically significant differences. The lag phase of LDL oxidation was shortest (116 min) in the fish group and longest (165 min) in the vegetarian group, and the control group was between them (129 min). The mean oxidation percentage after 2.5 h of copper-induced oxidation was highest (44%) in the fish group and lowest (22%) in the vegetarian group and intermediate (31%) in the control group. CONCLUSION: Long-term dietary habits predict the fatty acid composition of serum and LDL, and influence the susceptibility of LDL to oxidation. In the fish group with the highest content of omega-3 fatty acids in LDL, the oxidation susceptibility of LDL was highest. In the vegetarian group with less omega-3 fatty acids in LDL, the LDL was more resistant to oxidation. SPONSORSHIP: Helsinki University Central Hospital.     

Environmental influences on hemostasis and thrombosis. Diet and smoking.

High levels of factor VII coagulant activity (VIIc) and fibrinogen concentration are independently associated with an increased risk of acute coronary heart disease in middle-aged men. Studies have, therefore, been undertaken to determine the responsiveness of these hemostatic factors to changes in diet and smoking habit. Plasma VIIc increases acutely with an increase in total fat intake, but fibrinogen is unaffected. In the general community, men who have a high total fat intake for their body size tend to have a high VIIc level. Changes in the dietary ratio of saturated to polyunsaturated fat of up to 14 days' duration have no effect on factor VIIc or fibrinogen (there are conflicting reports on the influence of dietary very-long-chain polyunsaturated fatty acids on fibrinogen concentration). Cigarette smokers have a higher fibrinogen concentration than do nonsmokers, but their levels slowly revert toward those of nonsmokers when the habit is relinquished.     

Comparative effects of lean- and high-fat meat or cereal diets on plasma lipids in the pig

Adult male pigs were maintained either on a commercial pelleted cereal diet (P/S ratio 1.0; 8% of energy as fat) or on one of two diets based on animal protein (red meat) and respectively high (P/S ratio 0.3; 46% of energy) or low (P/S ratio 1.6; 13% of energy) in fat. The diets were fed isocalorically so that there were no differences in body weight or in plasma triacylglycerols or insulin. Plasma total and high density lipoprotein cholesterol concentrations did not differ in pigs fed the cereal diet or the low fat meat diet, but were significantly higher in animals fed the high fat meat diet. Plasma low density and very low density lipoprotein cholesterol concentrations were also raised with increased consumption of saturated fat. The data show that the source of dietary protein had little influence on plasma lipids at low levels of fat intake and that the major factor affecting the plasma cholesterol concentration during meat consumption was dietary fat both in absolute terms and P/S ratio. Plasma cholesterol levels were no higher with a diet containing lean meat and plant products than with a diet consisting almost entirely of cereal grains.     

Dietary polyunsaturated fat intake is associated with low-density lipoprotein size, but not with susceptibility to oxidation in subjects with impaired glucose metabolism and type II diabetes: the Hoorn study

OBJECTIVE: A high monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) intake is associated with lower plasma low-density lipoprotein (LDL)-cholesterol. However, PUFA may increase the susceptibility of LDL to undergo oxidative modifications. The aim of this study was to analyze the association of habitual dietary fat intake with LDL size and oxidizability. DESIGN: Cross-sectional. SETTING: Cohort study. SUBJECTS: Seven hundred and fifty-eight subjects with normal, impaired glucose metabolism and type II diabetes. INTERVENTIONS: Mean LDL size was measured by high-performance gel-filtration chromatography. In vitro oxidizability of LDL was determined by measuring lag time, reflecting the resistance of LDL to copper-induced oxidation. Information about dietary fat intake was obtained by a validated food frequency questionnaire. RESULTS: PUFA intake (energy percent) was significantly and negatively associated with LDL size in subjects with type II diabetes (standardized beta (95% confidence interval) -0.17 (-0.28;-0.06)) and impaired glucose metabolism - although not statistically significant - (-0.09 (-0.24;0.05)), but not in subjects with normal glucose metabolism (0.01 (-0.10;0.12)) (P-value for interaction=0.02). No significant associations were observed for total, saturated fat and MUFA intake with LDL size. Intake of fat was associated with lag time; however, the small magnitude of the associations suggested that the composition of dietary fat is not a major factor affecting lag time. The same association with lag time was observed in all three glucose metabolism categories. CONCLUSIONS: In individuals with abnormal glucose metabolism, higher PUFA intake is associated with smaller LDL particle size, but does not alter the susceptibility of LDL to in vitro oxidation. SPONSORSHIP: Dutch Diabetes Research Foundation, and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO).     

Dietary modulators of lipid metabolism in the Indian diet-heart study (I.D.H.S.).

Of the 621 adults (25 to 65 years of age, 531 males) with either risk factors or with coronary heart disease (CHD) 310 subjects were given a cardiovasoprotective (CVP) diet (group A) and 311 subjects a normal diet (group B) in a randomized, single blind and controlled fashion. Risk factors and incidence of CHD were comparable between the two groups. The intervention group received a significantly higher percentage of calories in relation to complex carbohydrates, vegetable proteins, polyunsaturated fatty acids and high P:S ratio diet as compared to the control group. The control group received higher saturated fat and cholesterol. Compliance was assessed by dietary questionnaire during the follow-up. After 8 weeks of dietary trial, there was a significant decrease in mean serum total cholesterol (8.2 vs 2.1%), low density lipoprotein (LDL) cholesterol (9.8 vs. 2.7%) and triglyceride (11.2 vs 5.8%) in the intervention group compared to baseline levels and changes in control subjects. Body weight and physical activity at the entry to study and during the trial were similar in both groups. The decrease in mean HDL cholesterol were insignificant both in the intervention (4.3%) and control group (5.0%). There were no adverse effects of diet during the 8 weeks of trial. It is possible that a diet with 27.5% energy from total fat including 10.1% energy from monounsaturated fatty acids, P:S ratio 1.38, 120 mg dietary cholesterol, 26.0 g dietary fibre per 1000 kcal would modulate the lipid metabolism resulting in a significant reduction in serum total cholesterol, LDL cholesterol and triglyceride with no reduction in HDL cholesterol. This diet may be capable of reducing CHD incidence and mortality in the long term Indian diet-heart study (IDHS).     

Lean meat and heart health

The general health message to the public about meat consumption is both confusing and misleading. It is stated that meat is not good for health because meat is rich in fat and cholesterol and high intakes are associated with increased blood cholesterol levels and coronary heart disease (CHD). This paper reviewed 54 studies from the literature in relation to red meat consumption and CHD risk factors. Substantial evidence from recent studies shows that lean red meat trimmed of visible fat does not raise total blood cholesterol and LDL-cholesterol levels. Dietary intake of total and saturated fat mainly comes from fast foods, snack foods, oils, spreads, other processed foods and the visible fat of meat, rather than lean meat. In fact, lean red meat is low in saturated fat, and if consumed in a diet low in SFA is associated with reductions in LDL-cholesterol in both healthy and hypercholesterolemia subjects. Lean red meat consumption has no effect on in vivo and ex vivo production of thromboxane and prostacyclin or the activity of haemostatic factors. Lean red meat is also a good source of protein, omega-3 fatty acids, vitamin B12, niacin, zinc and iron. In conclusion, lean red meat, trimmed of visible fat, which is consumed in a diet low in saturated fat does not increase cardiovascular risk factors (plasma cholesterol levels or thrombotic risk factors).     

Apolipoprotein E gene promoter -219G->T polymorphism increases LDL-cholesterol concentrations and susceptibility to oxidation in response to a diet rich in saturated fat

BACKGROUND: The apolipoprotein E (APOE) gene promoter polymorphism (-219G-->T) has been associated with increased risk of myocardial infarction, premature coronary artery disease, and decreased plasma apolipoprotein E concentrations. OBJECTIVE: We aimed to determine in healthy subjects whether this polymorphism modifies the susceptibility of LDL to oxidation and the lipid response to the content and quality of dietary fat. DESIGN: Fifty-five healthy men with the APOE3/E3 genotype (7 GG, 38 GT, and 10 TT) completed 3 dietary periods, each lasting 4 wk. The first was a saturated fatty acid (SFA)-rich diet [38% fat-20% SFA and 12% monounsaturated fatty acid (MUFA)-and 47% carbohydrates (CHO)], which was followed by a CHO-rich diet (30% fat-<10% SFA and 12% MUFA-and 55% CHO) or a MUFA-rich diet (38% fat-<10% SFA and 22% MUFA-and 47% CHO) in a randomized crossover design. At the end of each dietary period, LDL oxidation susceptibility, lipids, and lipoproteins were measured. RESULTS: Compared with carriers of the G allele, TT subjects had a significantly (P < 0.05) shorter lag time after the SFA diet. The replacement of the SFA diet by the CHO or MUFA diet induced a greater increase (P < 0.05) in lag time in the TT subjects than in the GG or GT subjects. Carriers of the T allele had higher LDL-cholesterol (P < 0.05) and apolipoprotein B (P < 0.05) plasma concentrations after the SFA diet than did GG subjects. Compared with GG subjects, carriers of the T allele had a significantly (P < 0.05) greater decrease in LDL cholesterol and apolipoprotein B when they changed from the SFA to the CHO diet. CONCLUSION: The -219G-->T polymorphism may partially explain differences in individual responses to diet.     

Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males

A randomised crossover dietary intervention study was performed to evaluate the effects of replacing meat protein in the diet with a soyabean product, tofu, on blood concentrations of testosterone, dihydrotestosterone, androstanediol glucuronide, oestradiol, sex hormone-binding globulin (SHBG), and the free androgen index (total testosterone concentration/SHBG concentration x 100; FAI). Forty-two healthy adult males aged 35-62 years were studied. Diets were isoenergetic, with either 150 g lean meat or 290 g tofu daily providing an equivalent amount of macronutrients, with only the source of protein differing between the two diets. Each diet lasted for 4 weeks, with a 2-week interval between interventions. Fasting blood samples were taken between 07.00 and 09.30 hours. Urinary excretion of genistein and daidzein was significantly higher after the tofu diet (P < 0.001). Blood concentrations of sex hormones did not differ after the two diets, but the mean testosterone:oestradiol value was 10% higher (P = 0.06) after the meat diet. SHBG was 3% higher (P = 0.07), whereas the FAI was 7% lower (P = 0.06), after the tofu diet compared with the meat diet. There was a significant correlation between the difference in SHBG and testosterone:oestradiol and weight change. Adjusting for weight change revealed SHBG to be 8.8% higher on the tofu diet (mean difference 3 (95% CI 0.7, 5.2) nmol/l; P = 0.01) and testosterone:oestradiol to be significantly lower, P = 0.049). Thus, replacement of meat protein with soyabean protein, as tofu, may have a minor effect on biologically-active sex hormones, which could influence prostate cancer risk. However, other factors or mechanisms may also be responsible for the different incidence rates in men on different diets.     

Atherosclerosis--epidemiological studies on the health effects of a Mediterranean diet

Mediterranean diets are characterized by olive oil, as the dominant fat source and a high to moderate consumption of fruit and vegetables, cereal products, fish, legumes, in combination with little meat and wine with meals. The "reference" Mediterranean diet seems to differ according to country, but is associated with good health and a long life expectancy. From the Seven Countries Studies, it has been shown that especially the traditional Cretan diet was associated with very low 25-year mortality rates for coronary heart disease, cancer and all-causes. In terms of nutrients and bioactive compounds the "reference" Mediterranean diet is low in saturated fat and high in monounsaturated fatty acids, high in antioxidants especially vitamin C and E, and high in fiber and folic acid. Several epidemiological studies have investigated these dietary components either separately or in combination in other than Mediterranean populations. In general, also in other populations beneficial effects on the coronary risk profile have been observed, which gives further support to the positive health effects of the Mediterranean diet. Intervention studies in East Finland and Southern Italy have convincingly shown that the coronary risk profile (lower LDL cholesterol and blood pressure levels) is improved by a Mediterranean diet. Moreover, the Cretan diet was tested in cardiac patients and showed a 70 % lower cardiac and all-causes mortality compared to the control diet. In conclusion, epidemiological studies and intervention trials suggest that the Cretan Mediterranean diet lowers the risk of coronary heart disease.     

A diet rich in high-oleic-acid sunflower oil favorably alters low-density lipoprotein cholesterol, triglycerides, and factor VII coagulant activity

OBJECTIVE: To compare concentrations of factor VII coagulant activity (factor VIIc), fibrinogen, plasminogen activator inhibitor-1, and blood lipids on a saturated fat-rich diet with one rich in monounsaturated fat. DESIGN: Subjects were randomly allocated to two groups. The study design was an ABB/BAA extra-period crossover. One group consumed a diet rich in saturated fatty acid (SFA) with fat making up 20.8% of total energy, for 5 weeks and then one rich in monounsaturated fatty acid (MUFA), with fat making up 20.3% of total energy for 10 weeks. The other group consumed the MUFA diet for 5 weeks followed by the SFA diet for 10 weeks. SUBJECTS/SETTING: Men and women aged 35 to 69 years who were nonsmokers with no chronic illness and not on any medication were recruited to participate. Eighteen subjects were recruited and 15 (5 men, 10 women) completed the community-based study. INTERVENTION: Blood was sampled at the beginning and end point of each 5-week diet period for analysis of coagulation and fibrinolysis factors and blood lipids. Subjects kept 3-day food diaries twice during each of the three diet periods and were weighed on each visit for blood collection. Analysis of plasma fatty acids was used to indicate dietary compliance. MAIN OUTCOME MEASURES: Differences in fasting factor VIIc, fibrinogen, plasminogen activator inhibitor-1, insulin, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, apolipoproteins A-1 and B, and plasma oleic acid levels while receiving the SFA diet vs MUFA diet. STATISTICAL ANALYSIS: A general linear model allowing for the ABB/BAA extra-period crossover, was used for each of the outcome measures. RESULTS: Factor VIIc was lower on the MUFA diet ( P <.05) but fibrinogen and insulin concentrations and plasminogen activator inhibitor-1 activity did not differ between diets. Low-density lipoprotein cholesterol ( P <.001) and triglyceride ( P <.01) levels were lower on the MUFA diet compared with the SFA diet. A significant increase in both plasma phospholipid and neutral lipid oleic acid (P <.0001) occurred on the MUFA diet. CONCLUSIONS: Substitution of foods rich in saturated fat with foods rich in high-oleic-acid sunflower oil and margarine has favorable outcomes on blood lipids and factor VIIc. This oil presents another useful source of MUFA for diets aimed at prevention of heart disease.     

Lowering dietary saturated fat and total fat reduces the oxidative susceptibility of LDL in healthy men and women

The present study examined the effects of reducing dietary total fat and saturated fat (SFA) on LDL oxidative susceptibility in 27 healthy men and women (age 24-65 y). Each subject consumed each of three diets for 8 wk: an average American diet (AAD, 34% energy from fat, 15% from SFA), a Step-1 diet (29% fat, 9% SFA) and a very low SFA diet (Low-Sat, 25% fat, 6% SFA). In vitro LDL oxidation was assessed by copper-mediated oxidation, as measured by the kinetics of conjugated diene formation and lipid peroxide formation. Compared with the AAD, plasma LDL-cholesterol (LDL-C) and HDL cholesterol levels were 8% lower (P: = 0.16 and P: = 0.11, respectively), in subjects when they consumed the Step-1 diet and 11% (P: < 0.03) and 14% (P: < 0.057) lower, respectively, when they consumed the Low-Sat diet. Conjugated diene production and oxidation rate were 7% (P: < 0. 05) and 9% (P: < 0.05) lower, respectively. The reduction of lipid peroxide formation was 9% (P: < 0.05) in subjects when they consumed the Low-Sat diet vs. the AAD. In addition, lipid peroxide and conjugated diene formation were positively correlated with plasma total and LDL-C and apolipoprotein B (apo B) levels (r = 0.5-0.6, P: < 0.001), suggesting that quantity of LDL is an important determinant of oxidative modification. Furthermore, at the same level of apo B or LDL-C, LDL from subjects when they consumed either Step-1 or Low-Sat diets was less susceptible (P: < 0.05) to oxidation than those when they consumed the AAD, suggesting that qualitative changes also affect LDL oxidative susceptibility. Therefore, the benefits of lowering dietary SFA may extend beyond decreasing LDL-C levels and include favorable qualitative changes in LDL that further decrease risk of coronary heart disease.     

Unscrambling the research: Eggs, serum cholesterol and coronary heart disease

The role of dietary cholesterol in raising plasma cholesterol levels has been debated over the past 25 years. Consequently, eggs, as a food high in dietary cholesterol, have been targeted as a food to limit when advising patients on a diet to lower serum cholesterol levels. The aim of the present review was to evaluate the literature to address the effects of dietary cholesterol from eggs on serum cholesterol levels and risk of coronary heart disease. An increase in dietary cholesterol from eggs by 100 mg daily, equivalent to half a medium egg or three to four eggs a week, results in an increase of approximately 0.05 mmol/L in LDL cholesterol. Adding 100 mg of cholesterol per day (equivalent to three to four eggs a week) to a high saturated fat diet caused an increase in LDL cholesterol of 0.061 ± 0.006 mmol/L, whereas adding the same quantity of cholesterol to a low saturated fat diet caused an increase in LDL cholesterol of only 0.036 ± 0.004 mmol/L (P = 0.03). Despite the small increase in LDL‐cholesterol levels with increasing egg intake, most epidemiological studies have shown little or no association between egg intake and risk of coronary heart disease. However, the impact of dietary cholesterol for people with type 2 diabetes has been poorly studied. In conclusion, in a healthy Western population, there is insufficient evidence to excessively restrict egg intake as part of a healthy diet. Eggs should be considered in a similar way as other protein‐rich foods and selected as part of a varied diet that is low in saturated fat and contains a variety of cardio‐protective foods such as fish, wholegrains, fruits, vegetables, legumes and nuts.     

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.     

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.     

Incorporation of lean red meat into a National Cholesterol Education Program Step I diet: a long-term, randomized clinical trial in free-living persons with hypercholesterolemia

OBJECTIVE: Clinicians often recommend that intake of all meat, particularly red meat, be reduced in conjunction with a low-fat, low-cholesterol diet to reduce low-density lipoprotein (LDL) cholesterol. This study was designed to determine the long-term effects of lean red meat (beef, veal and pork) compared to lean white meat (poultry and fish) consumption on lipoprotein concentrations in free-living hypercholesterolemic subjects consuming a National Cholesterol Education Program (NCEP) Step I diet. METHODS: A randomized, crossover design was utilized. Hypercholesterolemic men and women (LDL cholesterol between 3.37 and 4.92 mmol/L) (triglycerides <3.96 mmol/L) (n = 145) were counseled to consume > or =80% of their 170 g/d meat intake as either lean red meat or lean white meat for two 36-week phases, separated by a four-week washout period of free meat selection. Subjects were instructed to follow an NCEP Step I diet throughout the study. RESULTS: There were no significant differences in lipid concentrations between the lean red meat and lean white meat phases. LDL cholesterol was 4.02+/-0.04 (SEM) and 4.01+/-0.04 mmol/L in the white and red phases, respectively; this represented a decrease of approximately 2% from baseline concentrations (p < 0.01). Total cholesterol also declined by 1% from baseline (p < 0.05), and high-density lipoprotein (HDL) cholesterol rose over the study period by approximately 2% to approximately 3% from baseline to reach concentrations of 1.37+/-0.03 mmol/L and 1.38+/-0.03 mmol/L in the white and red phases, respectively (p < 0.001). Triglycerides were not altered by treatment. CONCLUSIONS: Consumption of lean red meat or lean white meat, as part of an NCEP Step I diet, is similarly effective for reducing LDL cholesterol and elevating HDL cholesterol concentrations in free-living persons with hypercholesterolemia.     

Regulation of cholesterol and lipoprotein metabolism in guinea pigs mediated by dietary fat quality and quantity.

The effects of dietary fat quality and quantity on regulation of cholesterol and lipoprotein metabolism were measured in guinea pigs. The animals were fed 7.5 or 15% (wt/wt) fat diets containing either polyunsaturated corn oil (CO), monounsaturated olive oil (OL) or saturated lard as the fat source. Dietary fat quality had a number of significant effects: animals fed the CO-based diet had lower plasma LDL levels and LDL particles of higher density with decreased ratios of core-to-surface components. Apoprotein B/E receptor-mediated binding of LDL to hepatic membranes was twofold higher for animals fed the CO-based diet. Animals fed the OL-based diet had lower hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity and increased levels of hepatic cholesterol. Hepatic cholesteryl ester levels were lowest for animals fed the lard-based diet. Increasing dietary fat quantity resulted in increased plasma LDL levels and hepatic cholesterol, HMG-CoA reductase activity and receptor affinity for LDL. No changes were observed in LDL binding. These data demonstrate that, independent of dietary fat quantity, CO-based diets lower plasma LDL levels, modify LDL composition and increase hepatic apoprotein B/E receptor number.