Reduction of plasma cholesterol levels in normal men on an American Heart Association Step 1 diet or a Step 1 diet with added monounsaturated fat

Pecans lower low-density lipoprotein cholesterol in people with normal lipid levels

OBJECTIVE

To compare serum lipid profiles and dietary intakes of people with normal lipid levels who consumed pecans and those who did not consume nuts.

DESIGN

Eight-week, randomized, controlled study of pecan treatment group vs control group.

SUBJECT

Nineteen people with normal lipid levels completed the study; 10 had been randomly assigned to the pecan treatment group (7 women, 3 men, mean age = 45 +/- 10 years) and 9 to the control group (8 women, 1 man, mean age = 37 +/- 12 years).

INTERVENTION

The pecan treatment group consumed 68 g pecans per day for 8 weeks plus self-selected diets. The pecans contributed 459 kcal and 44 g fat daily. The control group avoided nuts and consumed self-selected diets.

MAIN OUTCOME MEASURES

Total serum cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and total triglyceride levels were measured at the time of entrance to the study (baseline), week 4, and week 8. Computer analyses were done on five 3-day food records.

STATISTICAL ANALYSIS

Comparisons were made using analysis of variance or paired t test.

RESULTS

LDL-C was lowered in the pecan treatment group from 2.61 +/- 0.49 mmol/L at baseline to 2.35 +/- 0.49 at week 4 (P < .05) and to 2.46 +/- 0.59 at week 8 (P < .05). At week 8, total cholesterol and HDL-C in the pecan treatment group were significantly lower (P < .05) than in the control group (total cholesterol: 4.22 +/- 0.83 vs 5.02 +/- 0.54 mmol/L; HDL-C: 1.37 +/- 0.23 vs 1.47 +/- 0.34 mmol/L). Dietary fat, monounsaturated fat, polyunsaturated fat, insoluble fiber, magnesium, and energy were significantly higher in the pecan treatment group than in the control group. Body mass indexes and body weights were unchanged in both groups.

APPLICATIONS

Pecans can be included in a healthful diet when energy intake and potential weight gain are addressed.

Effects of dietary modification and treatment of obesity. Emphasis on improving vascular outcomes

This article has considered a vast literature attesting to the efficacy of dietary intervention on risk factors and on vascular outcomes. Rather than rely solely on pharmacotherapy to improve risk factors and vascular outcomes, physicians, nurses, dietitians, pharmacists, and medical providers should emphasize the benefits of a well-balanced, nutritionally sound dietary program. It should be low in SFA; controlled in calories to avoid (or reduce) obesity; and rich in fruits, vegetables, whole-grain products, and good sources of protein. Emphasis on foods rich in n-3 fatty acids shows promise for reducing cardiovascular outcomes. Further studies using these and antioxidants are eagerly awaited.

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.

Macronutrient and energy intakes in young children fed milk products containing different quantities and qualities of fat and protein

BACKGROUND

Milk is the major source of protein and saturated fats in the diet after infancy. In the present study, the effects of different fat and protein quantity as well as fat quality in milk and dairy products on nutrient intake and growth in young children were determined.

METHODS

Thirty-eight healthy children were randomly assigned to one of four feeding groups at 12 months of age: 1) Low-fat milk (1.0 g fat/dl, 3.3 g protein/dl); 2) standard-fat milk (3.5 g fat/dl, 3.3 g protein/dl); 3) partially vegetable fat and protein-reduced milk (3.5 g fat/dl, 50% vegetable; 2.2 g protein/dl); and 4) full-vegetable-fat milk (3.5 g fat/dl, 100% vegetable; 3.0 g protein/dl). Nutrient intake and growth were measured at 12, 15, and 18 months.

RESULTS

The protein intake was significantly reduced with the protein-reduced milks. The intake of saturated fat was significantly lower with low-fat milk (11% of energy) or milks containing vegetable fat (13%) than in standard-fat milk (19.6%). However, the total fat intake was below 30% of energy in low-fat milk, whereas the total fat intake remained more than 30% in the other groups. Energy intake and growth were similar in all groups.

CONCLUSIONS

A modified milk with reduced protein content for young children results in protein intakes closer to recommendations. A modified milk with either 50% or 100% vegetable fat and dairy products with low milk fat and high vegetable fat content results in intakes of total and saturated fats closer to international recommendations, compared with standard or low-fat milk and dairy products.

[Primary nutritional and drug prevention of atherosclerosis]

Atherosclerosis results from a multifactorial process. For that reason, primary prevention of cardiovascular diseases requires several measures that should exhibit antiatherogenic, antithrombotic, antioxidative and antihypertensive properties. Two types of therapeutic strategies can be individualized. Nutritional interventions are the first line measures for population wide primary prevention in subjects at low risk of developing atheroscleric diseases. In high risk individuals who have either one major risk factor (LDL cholesterol above 190 mg/dL) or several additional risk factors, dietary measures must be frequently combined with drug treatments. However, the cost-effectiveness ratio should be weighed prior to any treatment especially with statins. Dietary measures consist to reduce caloric intakes in overweight subjects, or more generally to adopt eating patterns which correspond to the following recommendations: (i) proteins = 15% of total calories; (ii) saturated and polyunsatured fats = 10% each; (iii) carbohydrates plus monounsaturated fats = 65%. Such dietary instructions permit individual dietary changes, just by adjusting the carbohydrates/monounsaturates balance, the sum of both nutrients remaining in all cases equal to two-thirds to total calories. Drug treatments are only indicated after secondary dietary failure. They are generally based on the use of statins since the efficacy of these treatments has been clearly established by such preventive trials as the WOSCOP Study, provided that the therapeutic interventions result in significant reduction of LDL cholesterol levels over several years. Antiplatelet agents (aspirin), antihypertensive therapies, antioxidant supplementations with vitamins E or C are also recommended in some individuals for completing the beneficial effects of the above mentioned measures.

Use of hierarchical models for meta-analysis: experience in the metabolic ward studies of diet and blood cholesterol

Overviews that combine single effect estimates from published studies generally use a summary statistic approach where the effect of interest is first estimated within each study and then averaged across studies in an appropriately weighted manner. Combining multiple regression coefficients from publications is more problematic, particularly when there are differences in study design and inconsistent reporting of effect sizes and standard errors. This paper describes the use of a hierarchical model in such circumstances. Its use is illustrated in a meta-analysis of the metabolic ward studies that have investigated the effect of changes in intake of various dietary lipids on blood cholesterol. These studies all reported average blood cholesterol for groups of individuals who were studied on one or more diets. Thirty-one studies had randomized cross-over designs, 12 had matched parallel group designs, 12 had non-randomized Latin square designs and 16 had other uncontrolled designs. The hierarchical model allowed the different types of comparison (within-group between-diet, between matched group) that were made in the various studies to each contribute to the overall estimates in an appropriately weighted manner by distinguishing between-study variation, within-study between-matched-group variation and within-group between-diet variation. The hierarchical models do not require consistent specification of effect sizes and standard errors and hence have particular utility in combining results from published studies where the relationships between a dependent variable and two or more predictors have been investigated using heterogeneous methods of analysis.

Solid monounsaturated diet lowers LDL unsaturation trait and oxidisability in hypercholesterolemic (type IIb) patients

Lowering high cholesterol concentration decreases the probability of atherosclerotic-related pathology onset. MUFA and PUFA decrease total plasma and LDL cholesterol but PUFA may increase the susceptibility of LDL to undergo oxidative modifications thus becoming more atherogenetic. Olive oil, the predominant fat source in Mediterranean diet, may combine the advantages of both lowering cholesterol level and decreasing LDL susceptibility to oxidation. We studied the effects of feeding MUFA vs PUFA enriched diet on LDL composition and feature in hypercholesterolemic (IIb) patients. Antioxidant values remained constant during the study while LDL fatty acids composition reflected the dietary intake: MUFA concentration increased 11% whereas PUFA decreased 10% after olive oil diet (p < 0.05). PUFA/MUFA ratio and the unsaturation index were lower at the end of MUFA-enriched diet. The challenge, in vitro, of oleate-enriched LDL with Cu2- yielded to lower lag-phase (p < 0.05) in diene conjugated production; the same LDL gave lower lipid hydroperoxide contents after exposition to AAPH. We conclude that oleate-enriched LDL and with lower PUFA content were more resistant to oxidative modifications, as measured by different peroxidation indexes. This feature acquired with the diet may be an useful tool for lowering LDL oxidation and indirectly their atherogenicity.

Effect of wheat bran on serum lipids: influence of particle size and wheat protein

OBJECTIVE

Wheat fiber appears to protect from cardiovascular disease despite its lack of consistent effect on serum lipids. We therefore wished to determine whether reported inconsistencies in the effect of wheat bran resulted from differences in particle size or its high gluten content.

METHODS

Two studies were conducted. In one-month metabolic diets, 24 hyperlipidemic subjects consumed breads providing an additional 19 g/d dietary fiber as medium or ultra-fine wheat bran and extra protein (10% of energy as wheat gluten). In two-week ad libitum diets, 24 predominantly normolipidemic subjects consumed breakfast cereals providing an additional 19 g/d of dietary fiber as coarse or a mixture of ultra-fine and coarse wheat bran with no change in gluten intake. Both studies followed a randomized crossover design with control periods when subjects ate low-fiber breads and cereals respectively with no added gluten. Fasting blood lipids were measured on day zero and at the end of each phase.

RESULTS

Wheat bran had no effect on total, LDL or HDL cholesterol irrespective of particle size or level of gluten in the diet. However, consumption of increased gluten in the metabolic study was associated with a 13+/-4% reduction in serum triglycerides (p = 0.005) which was not seen in the normal-gluten ad libitum study.

CONCLUSIONS

The protective effect of wheat fiber in cardiovascular disease cannot be explained by an effect of wheat bran in reducing serum cholesterol although in hyperlipidemic subjects displacement of carbohydrate by gluten on the high-fiber phases was associated with lower serum triglycerides.

Diet design for a multicenter controlled feeding trial: the DELTA program. Delta Research Group

OBJECTIVE

To describe the process and results of diet standardization, diet validation, and monitoring of diet composition, which were key components of protocol 1 of Dietary Effects on Lipoproteins and Thrombogenic Activity (DELTA-1), the initial protocol in a program of multicenter human feeding studies designed to evaluate the effects of amount and type of fat on lipoproteins and hemostasis parameters in various demographic groups.

DESIGN

DELTA-1 was based on a randomized, blinded, crossover experimental design. Three diets were fed for 8 weeks to 103 healthy men and women aged 22 to 67 years at 4 field centers. Diet A, an average American diet, was designed to provide 37% of energy from fat, 16% of energy from saturated fatty acids (SFAs); diet B (step 1 diet) was designed to provide 30% of energy from fat, 9% of energy from SFA; and diet C (low SFA diet) was designed to provide 26% of energy from fat, 5% of energy from SFA. Key features of diet standardization included central procurement of fat-containing foods, inclusion of standard ingredients, precision weighing of foods--especially sources of fat and cholesterol--and use of standardized written procedures.

SETTING

For menu validation, a set of 12 menus for each diet was prepared in duplicate and chemically assayed. For monitoring of diet composition during the study, an 8-day diet cycle (6 weekday and 2 weekend menus) was sampled by every field center twice during each of 3 feeding periods.

STATISTICAL ANALYSES

Means (+/- standard error) were calculated and compared with target nutrient specifications.

RESULTS

DELTA-1 was able to provide a standardized diet that met nutrient specifications across 4 field centers over 24 weeks of participant feeding spanning a total of 8 months.

APPLICATIONS

Prestudy chemical validation of menus and continuous sampling and assay of diets throughout the study are essential to standardize experimental diets and to ensure that nutrient target goals are met and maintained throughout a controlled multicenter feeding study.

Nuts and plasma lipids: an almond-based diet lowers LDL-C while preserving HDL-C

OBJECTIVE

To compare lipid-altering effects of an almond-based diet with an olive oil-based diet, against a cheese and butter-based control diet.

METHODS

Forty-five free-living hyperlipidemic men (n = 12) and women (n = 33) with a mean plasma total cholesterol (TC) of 251 +/- 30 mg/dL followed one of three diets; almond-based, olive oil-based, or dairy-based for 4 weeks. Total fat in each diet was matched, and the study-provided sources of fat comprised the major portion of fat intake.

RESULTS

Reductions in TC and low-density lipoprotein-cholesterol (LDL-C) between the three groups were significantly different from the almond group (both p < 0.001). Within group analysis revealed that the almond-based diet induced significant reductions in TC (p < 0.05), LDL-C (p < 0.001), and the TC:HDL ratio (p < 0.001), while HDL-C levels were preserved. TC and HDL-C in the control diet were significantly increased from baseline (both p < 0.05), while the olive oil-based diet resulted in no significant changes over the study period. Weight did not change significantly.

CONCLUSION

Results suggest that the more favorable lipid-altering effects induced by the almond group may be due to interactive or additive effects of the numerous bioactive constituents found in almonds.

Diet and cardiovascular disease prevention: what works?

Diet is routinely recommended as the primary strategy for the prevention and treatment of high blood cholesterol. The National Cholesterol Education Program (NCEP), the American Heart Association (AHA), and a host of other health and medical organizations have advocated a diet low in total and saturated fat and cholesterol for reducing risk of cardiovascular disease. What is the evidence supporting these guidelines and the expected efficacy of dietary treatment? There is growing awareness that despite well-documented rationale for the dietary approach, many eligible patients are not routinely prescribed dietary treatment, and among those who are, there is limited response. What are the obstacles in implementing effective dietary intervention for prevention of cardiovascular disease? What are both the theoretical and practical limitations to achieving long-term adherence to diet and what strategies have been shown to be most effective? A review of the data surrounding these diet-lipid relationships is presented along with recently tested and promising behavioral approaches to facilitating patient adherence.

Effects of the ratio of polyunsaturated and monounsaturated fatty acid to saturated fatty acid on rat plasma and liver lipid concentrations

The effects of dietary monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid + MUFA/saturated fatty acid (PUFA + MUFA/SFA) ratio on plasma and liver lipid concentrations were studied. In experiment I, when rats were fed with 40% fat (energy%, PUFA/SFA ratio 1.0) and 1% (w/w) cholesterol (C) diets for 21 d, a large amount of MUFA (28.1 energy%, PUFA + MUFA/SFA = 5.7) in the diet was found to increase the plasma total C, triacylglycerol (TAG), and phospholipid (PL) as compared with the low-MUFA diet (7.0 energy%, PUFA + MUFA/SFA = 1.4). The plasma very low density lipoprotein (VLDL)-C, VLDL-TAG, VLDL-PL, and low density lipoprotein (LDL)-C increased significantly in the high-MUFA diet group, but high density lipoprotein (HDL)-C did not change significantly. The high-MUFA diet resulted in greater accumulation of liver C but lesser accumulation of TAG. In experiment II, when dietary SFA was fixed at a certain level (13.2 energy%; PUFA + MUFA/SFA = 2.0), rats given a larger amount of MUFA (23.1 energy%; PUFA/MUFA = 0.2; MUFA/SFA = 1.8) showed higher plasma and liver C levels than did the low-MUFA diet (7.7 energy%; PUFA/MUFA = 2.5; MUFA/SFA = 0.6). When PUFA was fixed at a certain level (24.4 energy%), there was not a significant difference in the plasma C level between the high- and low-MUFA dietary groups (PUFA + MUFA/SFA = 4.8 and 8.4), but the higher PUFA + MUFA/SFA diet, which was high in MUFA/SFA ratio, significantly decreased the plasma HDL-C and TAG levels. However, when MUFA content was fixed at a certain level (16.4 energy%), no significant difference was observed between the two groups with different PUFA/SFA ratios of 0.2 and 4.1, but liver C level was raised in the higher PUFA/SFA diet. It appears that the PUFA/SFA ratio alone is unsuitable to predict the change of plasma C level, because a large amount of dietary MUFA may lead to an increase of plasma and liver lipids in rats. It seems that the prerequisites for keeping low plasma and liver C are (i) low MUFA/SFA ratio, (ii) high PUFA/MUFA ratio, and (iii) PUFA + MUFA/SFA ratio not to exceed 2.

Effects of reducing dietary saturated fatty acids on plasma lipids and lipoproteins in healthy subjects: the DELTA Study, protocol 1

Few well-controlled diet studies have investigated the effects of reducing dietary saturated fatty acid (SFA) intake in premenopausal and postmenopausal women or in blacks. We conducted a multicenter, randomized, crossover-design trial of the effects of reducing dietary SFA on plasma lipids and lipoproteins in 103 healthy adults 22 to 67 years old. There were 46 men and 57 women, of whom 26 were black, 18 were postmenopausal women, and 16 were men > or =40 years old. All meals and snacks, except Saturday dinner, were prepared and served by the research centers. The study was designed to compare three diets: an average American diet (AAD), a Step 1 diet, and a low-SFA (Low-Sat) diet. Dietary cholesterol was constant. Diet composition was validated and monitored by a central laboratory. Each diet was consumed for 8 weeks, and blood samples were obtained during weeks 5 through 8. The compositions of the three diets were as follows: AAD, 34.3% kcal fat and 15.0% kcal SFA; Step 1, 28.6% kcal fat and 9.0% kcal SFA; and Low-Sat, 25.3% kcal fat and 6.1% kcal SFA. Each diet provided approximately 275 mg cholesterol/d. Compared with AAD, plasma total cholesterol in the whole group fell 5% on Step 1 and 9% on Low-Sat. LDL cholesterol was 7% lower on Step 1 and 11% lower on Low-Sat than on the AAD (both P<.01). Similar responses were seen in each subgroup. HDL cholesterol fell 7% on Step 1 and 11% on Low-Sat (both P<.01). Reductions in HDL cholesterol were seen in all subgroups except blacks and older men. Plasma triglyceride levels increased approximately 9% between AAD and Step 1 but did not increase further from Step 1 to Low-Sat. Changes in triglyceride levels were not significant in most subgroups. Surprisingly, plasma Lp(a) concentrations increased in a stepwise fashion as SFA was reduced. In a well-controlled feeding study, stepwise reductions in SFA resulted in parallel reductions in plasma total and LDL cholesterol levels. Diet effects were remarkably similar in several subgroups of men and women and in blacks. The reductions in total and LDL cholesterol achieved in these different subgroups indicate that diet can have a significant impact on risk for atherosclerotic cardiovascular disease in the total population.

Regulation of plasma lipoprotein levels by dietary triglycerides enriched with different fatty acids

Saturated vegetable oils (coconut, palm, and palm kernel oil) containing predominantly saturated fatty acids, lauric (12:0) or myristic (14:0 and palmitic (16:0), raise plasma total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels in animals and humans, presumably by decreasing LDL receptor activity and/or increasing LDL-C production rate. Although stearic acid (18:0) is chemically a saturated fatty acid, both human and animal studies suggest it is biologically neutral (neither raising nor lowering) blood cholesterol levels. Although earlier studies indicated that medium chain fatty acids (8:0-10:0) were also thought to be neutral, more recent studies in animals and humans suggest otherwise. Unsaturated vegetable oils such as corn, soybean, olive, and canola oil, by virtue of their predominant levels of either linoleic acid (18:2) or oleic acid (18:1), are hypocholesterolemic, probably as a result of their ability to upregulate LDL receptor activity and/or decrease LDL-C production rate. Whether trans fatty acids such as trans oleate (t18:1), in hydrogenated products such as margarine, are hypercholesterolemic remains controversial. Studies in humans suggest that their cholesterol-raising potential falls between the native nonhydrogenated vegetable oil and the more saturated dairy products such as butter. Assessment of the magnitude of the cholesterolemic response of trans 18:1 is difficult because in most diet studies its addition is often at the expense of cholesterol-lowering unsaturated fatty acids, making an independent evaluation almost impossible.

Can dietary interventions change diet and cardiovascular risk factors? A meta-analysis of randomized controlled trials

OBJECTIVES

This study evaluated the effectiveness of dietary advice in primary prevention of chronic disease.

METHODS

A meta-analysis was conducted of 17 randomized controlled trials of dietary behavior interventions of at least 3 months' duration. Results were analyzed as changes in reported dietary fat intakes and biomedical measures (serum cholesterol, urinary sodium, systolic and diastolic blood pressure) in the intervention group minus changes in the control group at 3 to 6 months and 9 to 18 months of follow-up.

RESULTS

After 3 to 6 months, mean net changes in each of the five outcomes favored intervention. For dietary fat as a percentage of food energy, the change was -2.5% (95% confidence interval [CI] = -3.9%, -1.1%). Mean net changes over 9 to 18 months were as follows: serum cholesterol, -0.22 (95% CI = -0.39, -0.05) mmol/L; urinary sodium, -45.0 (95% CI = -57.1, -32.8) mmol/24 hours; systolic blood pressure, -1.9 (95% CI = -3.0, 0.8) mm Hg; and diastolic blood pressure, -1.2 (95% CI = -2.6, 0.2) mm Hg.

CONCLUSIONS

Individual dietary interventions in primary prevention can achieve modest improvements in diet and cardiovascular disease risk status that are maintained for 9 to 18 months.

The effect of dietary fat, antioxidants, and pro-oxidants on blood lipids, lipoproteins, and atherosclerosis

A number of primary and secondary prevention trials, including angiographic studies, have indicated that a decrease in dietary saturated fat and cholesterol produces a decrease in the blood levels of cholesterol and low-density lipoprotein (LDL) cholesterol, leading to a decrease in coronary artery disease (CAD). Increasing evidence indicates that the oxidation of LDL in human beings is atherogenic. Of the three major antioxidants, vitamin E, beta carotene, and vitamin C, the evidence is strongest that vitamin E (at a minimum dose of 100 IU/day) has a strong and independent inverse association with CAD. Selenium and flavonoids also have antioxidant properties, but their association with CAD in human beings is equivocal. Two prooxidants, homocysteine and iron, have been found to be associated with CAD. Blood homocysteine levels can be lowered significantly by an increase in dietary folic acid. Clinical trials are needed to assess expeditiously the effect of antioxidants, particularly vitamin E, and of folic acid on CAD and atherosclerosis. The substitution of monounsaturated fat for saturated fat lowers LDL and makes it less susceptible to oxidation without decreasing high-density lipoprotein (HDL) cholesterol. Studies in transgenic mice indicate that apolipoprotein A-I, the major protein of HDL, may inhibit the oxidation of LDL. Dietary trans fatty acids at the level consumed by many Americans can increase LDL cholesterol and may decrease HDL cholesterol. Individuals who have CAD or have family members who have premature CAD have delayed clearance of dietary fat, as judged by studies of postprandial triglyceride metabolism. The importance of decreasing dietary saturated fat and cholesterol is well established, but a number of other factors appear to influence the risk of CAD significantly and provide important areas for future investigation to improve prevention and treatment through better nutrition.

Effect of a high or a low fat diet on cardiovascular risk factors in male and female runners

Dietary fat may be associated with coronary heart disease (CHD). Studies suggest that restricting fat intake may compromise endurance performance and that increasing fat intake may improve endurance performance. We studied the effects of varying dietary fat intake on CHD risk factors in runners. Twelve male and 13 female runners increased fat from 16% to 30% of daily calories (4 wk each). Of this group, six males and six females increased fat to 42% of daily calories (4 wk). Physiological and lipoprotein risk factors were measured after each diet. Results were analyzed by repeated measures ANOVA. Increasing dietary fat from 16% to 42% of daily calories did not change adiposity, weight, heart rate, blood pressure, serum triglycerides, total cholesterol, LDL cholesterol. Apolipoprotein B, or the Apo A1/Apo B ratio. Compared with those eating higher fat, subjects eating 16% fat had lower HDL cholesterol (50 +/- 3 vs 62 +/- 3 mg.dl-1, P < 0.0001) and Apolipoprotein A1 (111 +/- 6 v. 134 +/- 6 mg/dl, P < 0.0005) and a higher TC/HDL-C ratio (4.05 +/- 0.27 vs 3.42 +/- 0.24, P < 0.0005). Runners who increased fat intake to 42% further raised HDL cholesterol (64 +/- 6 to 69 +/- 5 mg.dl-1, P < 0.04) without adversely affecting other lipoproteins. In conclusion, a 42% fat diet maintained favorable CHD risk factors in female and male runners whereas a 16% fat diet lowered Apo A1 and HDL-C and raised the TC/HDL-C ratio.

Effects of dietary fatty acid composition on plasma cholesterol

It should be clear from the preceding sections that the effects of dietary fatty acids on plasma lipids get more complicated the more we try to simplify them! We have presented one argument as to how different fatty acids may interact to impact human plasma lipids. This is by no means an endorsement that ours is the only argument. Nevertheless, a strong case can be made for 14:0 and 18:2 as being the key players in this scenario. The role of palmitic acid seems to be the most controversial. While clearly certain studies do indeed reveal 16:0 to be hypercholesterolemic relative to 18:1, the data from studies suggesting that it behaves similarly to 18:1 are equally compelling. What is certain is that it is erroneous to assume that 16:0 is the major cholesterol-raising SFA simply because it is the most abundant SFA in the diet. Clearly, 18:0 cannot be considered cholesterol-elevating. One is therefore left with the 12-16C SFA. However, 12:0 and 14:0 are only of concern if diets contain palm-kernel, coconut oil or dairy products as major dietary constituents. Accordingly one is left with 16:0 and its response is highly dependent on the metabolic status as well as the age of the subjects being used. While "elderly" hypercholesterolemic humans clearly benefit from decreased 16:0 (and all SFA) consumption, "younger" normocholesterolemic subjects fail to show such clear-cut effects. Additionally, the concomitant levels of dietary cholesterol and 18:2 also have a major bearing on the cholesterolemic response of 16:0 As far as guidelines for the general public are concerned, clearly for people with TC > 225 and LDL-C > 130 mg/dl and/or those who are overweight (i.e. those percieved to be at high risk), the primary emphasis should clearly be on reducing total fat consumption. Decreasing saturated fat consumption will invariably also lower dietary cholesterol consumption. The latter manouver will generally lower TC and LDL-C. Whether the reduction occurs because of the removal of 14:0, or 16:0 and/or dietary cholesterol is a mute point, since most dietary guidelines advocate curtailing intake of animal and dairy products, which will result in reductions of all the SFA. It remains to be established whether life-long adherence to the above dietary guidelines in those subjects with normal cholesterol levels and an absence of the other conventional risk factors for CHD, will result in a subsequent decrease in CHD risk. In the latest NCEP report 39 million Americans were targeted as those who would benefit from reductions in LDL-C, principally by dietary means. This is indeed a very high number. But that leaves almost 220 million Americans! For them the age old recommendation to consume a moderate fat load, maintain ideal body weight and eat a varied and balanced diet would still appear to be the most powerful advice.

Cholesterol and unsaturated fat diets influence lipid and glucose concentrations in rats

The present study investigated the effects of dietary cholesterol and monounsaturated and polyunsaturated fatty acids on plasma lipids and glucose concentrations. Four groups of ten male Wistar albino rats were fed diets of different fatty acid composition for 40 days. The control group consumed nonpurified diet (containing fat 3.7 g/100 g diet), and cholesterol, olive oil, and safflower oil groups consumed the nonpurified diet enriched with 14 g fat/100 g diet with egg yolk, olive oil, or safflower oil, respectively. Compared with the control, the diet enriched with cholesterol significantly increased fasting plasma cholesterol (P < 0.01), triacylglycerol (P < 0.01), total lipid (P < 0.01) and glucose (P < 0.05) concentrations; in the olive oil group, cholesterol and triacylglycerol levels were significantly increased compared with control group (P < 0.01 in both instances). In safflower oil group, triacylglycerol levels were also significantly increased (P < 0.05) compared with the controls. After comparing diets providing the same amount of fat (cholesterol, olive oil, and safflower oil groups), higher cholesterol, triacylglycerol and total lipid levels were observed in the cholesterol group than in the olive oil group (P < 0.01, P < 0.05 and P < 0.01, respectively), and safflower oil group (P < 0.01 in all instances). High-density lipoprotein-cholesterol concentrations were significantly lower in the cholesterol group than in the olive oil and safflower oil groups (P < 0.05 in both instances) and fasting plasma glucose levels were higher in the cholesterol than in the olive oil (P < 0.05) and safflower oil groups (P < 0.01). Finally, after comparing lipid and glucose levels in the unsaturated fatty acids-enriched diets, higher plasma cholesterol concentrations were observed in the olive oil than in the safflower oil group (P < 0.05). These data suggest that not only the amount but also the type of dietary fat can influence serum lipid levels.

Similar effects of rapeseed oil (canola oil) and olive oil in a lipid-lowering diet for patients with hyperlipoproteinemia

OBJECTIVE

To compare the metabolic effects of a lipid-lowering diet containing either low erucic rapeseed (canola) oil or olive oil.

METHODS

Twenty-two hyperlipidemic patients participated in a cross-over study comprising two consecutive 3.5-week treatment periods. The participants were free-living throughout the study period, visiting the metabolic clinic initially and at the end of each treatment period for weighing and blood sampling. All food was prepared daily and weighed out for each individual appropriate to his/her energy requirement.

RESULTS

Total serum cholesterol, low-density lipoprotein and the ratio between low-density and high-density lipoprotein cholesterol decreased to the same extent on the two diets tested, as did the apolipoproteins B, A-I and Lp(a). After adjustment for body weight changes, most of the reported effects remained virtually unaltered. However, there was a slightly greater decrease in low-density lipoprotein cholesterol with the diet containing rapeseed oil (-17%, p < 0.001) than with the olive oil diet (-13%, p < 0.01) with p < 0.04 for the difference between diets. Also, the intravenous glucose tolerance improved to a similar extent on both diets.

CONCLUSIONS

The results indicate that lipid-lowering diets containing either rapeseed oil or olive oil have similar effects on serum lipoprotein concentration and glucose tolerance in hyperlipidemic subjects.

Polyunsaturated fatty acids result in greater cholesterol lowering and less triacylglycerol elevation than do monounsaturated fatty acids in a dose-response comparison in a multiracial study group

Cholesterol-lowering effects of polyunsaturated and monounsaturated fatty acids were compared as they were varied in a reciprocal dose-dependent fashion in the context of a National Cholesterol Education Program (NCEP) Step 1 diet. The study population comprised 63 moderately hypercholesterolemic African American and white men and women. After a 6-wk baseline diet containing 37% of energy from total fat and 15% from saturated fat, participants consumed four diets for 6 wk each, in random order, containing 10% of energy as saturated fatty acids; 3%, 6%, 10%, and 14% of energy as polyunsaturated fatty acids; and 17%, 14%, 10%, and 6% of energy as monounsaturated fatty acids. Dietary cholesterol, fiber, plant sterol, and squalene contents were constant with all four diets. There was a progressive decrease in total (P = 0.028) and low-density-lipoprotein cholesterol (P = 0.184) across the four diets, with the greatest decrease observed in the diet with the highest content of polyunsaturated fatty acids; a small but significant decrease in high-density-lipoprotein (HDL) cholesterol that did not show a trend between the polyunsaturated and monounsaturated diets; and a trend between the four diets in triacylglycerol elevations (P = 0.029), with the smallest increment occurring in the diets highest in polyunsaturates. The magnitude of the cholesterol-lowering response was greater in those with higher baseline cholesterol and less in those who were more obese. The dietary response was similar in both ethnic groups and in both sexes. In conclusion, in an NCEP Step 1 diet containing 30% total fat, with all other known cholesterol-influencing dietary factors held constant, the substitution of polyunsaturated fatty acid for monounsaturated fatty acid from 3% to 14% resulted in a progressive decline in total cholesterol and less triacylglycerol elevations, without effect on HDL cholesterol.

Frequency of consumption of selected indicator foods and serum cholesterol. GISSI-EFRIM investigators. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto--Epidemiologia dei Fattori di Rischio dell'Infarto Miocardico

The relationship between frequency of consumption of eleven indicator foods (milk, meat, liver, carrots, green vegetables, fruit, eggs, ham, fish, cheese and alcohol) and serum cholesterol was investigated in the comparison group of a case-control study of acute myocardial infarction conducted in Italy. Data were collected on 792 subjects from various Italian regions, admitted to hospital for acute conditions unrelated to any known or potential risk factor for myocardial infarction or to long-term modifications in diet. No statistically or epidemiologically meaningful relationship emerged between serum cholesterol level and frequency of consumption of any of these foods. Cholesterol levels rose according to increasing consumption tertiles for most of the indicator foods considered. Higher values for the higher tertile of consumption were observed for meat, ham and eggs, but also for fruit, carrots and green vegetables. However, correlation coefficients between frequency of consumption of various food items and serum cholesterol level were uniformly low for all food items considered, ranging between -0.09 (for milk) and 0.19 (for ham). Although a more comprehensive diet history may lead to different indications, the present data are not suggestive of any major influence of long-term frequency of consumption of a few selected indicator foods on serum cholesterol levels.

Diets enriched in unsaturated fatty acids enhance apolipoprotein A-I catabolism but do not affect either its production or hepatic mRNA abundance in cynomolgus monkeys

To determine the mechanisms whereby dietary fatty acids influence high density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I concentrations, ten cynomolgus monkeys were fed each of three experimental diets enriched in saturated (SAT), monounsaturated (MONO), or polyunsaturated (POLY) fatty acids in a crossover design consisting of three 13-week periods, with each animal serving as its own control. Each diet contained 30% of energy as fat with 0.22 mg cholesterol/kcal and differed solely by the isocaloric substitution of fatty acids as 18% of total energy calories. The replacement of dietary saturated fatty acids with either monounsaturated or polyunsaturated fatty acids, respectively, resulted in significant reductions of plasma total cholesterol (-17%; -30%), HDL cholesterol (-32%; -41%), and apo A-I (-37%; -44%) concentrations, while no significant differences were noted in plasma lipid or apo A-I concentrations when the MONO and POLY phases were compared. Although the MONO and POLY diets were similar in their effects on plasma lipids and apolipoproteins, the HDL of monkeys fed the POLY diet, as compared with either the SAT or the MONO diets, contained more cholesteryl ester and phospholipid but less total protein, resulting in a significantly lower total lipid to protein constituent ratio. Metabolic experiments revealed that the significantly lower plasma apo A-I concentrations observed during both the MONO and POLY phases relative to SAT were directly attributable to enhanced HDL apo A-I catabolism. Conversely, neither HDL apo A-I production rates nor hepatic apo A-I mRNA concentrations were significantly affected by dietary fatty acid perturbation in this study. Taken together, these data indicate that fractional catabolic rate is the predominant mechanism by which dietary fatty acids differentially modulate circulating concentrations of HDL apo A-I in this species when all other dietary variables are held constant.

Effects of an American Heart Association step I diet and weight loss on lipoprotein lipid levels in obese men with silent myocardial ischemia and reduced high-density lipoprotein cholesterol

Reduced plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are a risk factor for coronary artery disease (CAD). In this study, we examined the sequential effects of an isocaloric American Heart Association (AHA) step I diet and a hypocaloric AHA step I diet (AHA step I diet + weight loss) on lipoprotein lipid levels in 14 middle-aged and older (60 +/- 6 years, mean +/- SD) obese (body mass index [BMI] > 27 kg/m2) nondiabetic men with exercise-induced silent myocardial ischemia (SI) and reduced HDL-C levels (0.85 +/- 0.14 mmol/L). Nine men of comparable age and obesity and with no evidence of exercise-induced ischemia that were evaluated longitudinally served as metabolic controls. In men with SI, after 3 months on the isocaloric AHA step I diet plasma triglyceride (TG) levels decreased by 26% (2.25 +/- 0.66 to 1.67 +/- 0.69 mmol/L, P < .005), cholesterol by 12% (5.24 +/- 0.84 to 4.62 +/- 0.78 mmol/L, P < .01), and low-density lipoprotein cholesterol (LDL-C) by 10% (3.40 +/- 0.69 to 3.05 +/- 0.70 mmol/L, P < .01). However, plasma HDL-C levels also decreased by 7% (0.85 +/- 0.14 to 0.79 +/- 0.13 mmol/L, P < .05). Subsequent weight loss (11 +/- 4 kg) in conjunction with the AHA step I diet resulted in an additional decrease of 24% in TG (P < .005), 10% in cholesterol (P < .05), and 10% in LDL-C (P < .05). Plasma HDL-C levels increased by 8% (P < .01), thereby correcting the decline seen on the AHA step I diet alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Health-related behaviors in the Republic of Karelia, Russia, and North Karelia, Finland

Risk factors and health behaviors related to chronic diseases were studied in a population survey in Pitkäranta District in the Republic of Karelia, Russia, and in North Karelia, Finland, in Spring 1992 (Puska, Matilainen et al., 1993). The random sample of the population (25 to 64 years) was 1,000 in Pitkäranta and 2,000 in North Karelia. Among men there were more current smokers in Pitkäranta than in North Karelia (65% vs. 31%) whereas among women the respective rates were 11% and 16%. Self-reported alcohol consumption was higher in North Karelia. Leisure time physical activity was much less frequent in Pitkäranta both among men and women. Use of vegetables and berries was very infrequent in Pitkäranta. The differences in health behavior can at least partly explain the differences in risk factors and in mortality of chronic diseases.

Short-term consumption of a low-fat diet beneficially affects plasma lipid concentrations only when accompanied by weight loss. Hypercholesterolemia, low-fat diet, and plasma lipids

Study subjects (6 women and 5 men) over the age of 40 years with fasting low-density lipoprotein cholesterol concentrations > 130 mg/dL were studied during three 5-week diet phases and one 10-week phase: baseline (36% fat: 13% saturated fatty acids [SFA], 12% monounsaturated fatty acids [MUFA], 8% polyunsaturated fatty acids [PUFA], and 128 mg cholesterol/1000 kcal); reduced fat (29% fat: 7% SFA, 9% MUFA, 11% PUFA, and 85 mg cholesterol/1000 kcal); and two low fat (15% fat: 5% SFA, 5% MUFA, 3% PUFA, and 73 mg cholesterol/1000 kcal). Body weight was maintained during the first three 5-week phases (baseline, reduced fat, and low fat [-->energy]) and decreased during the last 10-week phase when the low-fat diet was provided such that the subjects determined, in part, their caloric intake (low fat [decreases energy]). Mean body weight declined by 0.62 +/- 0.47 kg/wk during the first 5 weeks and 0.43 +/- 0.43 kg/wk during the second 5 weeks of the 10-week low-fat (decreases energy) period. Relative to the baseline diet, plasma cholesterol concentrations decreased from 226 +/- 33 to 195 +/- 19 (-13%), 208 +/- 22 (-7%), and 190 +/- 19 (-15%) mg/dL when the subjects consumed the reduced-fat, low-fat (--> energy), and low-fat (decreases energy) diets, respectively. Low-density lipoprotein cholesterol concentrations decreased from 158 +/- 28 to 128 +/- 16 (-18%), 134 +/- 17 (-14%), and 119 +/- 15 (-23%) mg/dL when the subjects consumed the reduced-fat, low-fat (--> energy), and low-fat (decreases energy) diets, respectively. High-density lipoprotein cholesterol concentrations decreased from 48 +/- 11 to 42 +/- 9 (-10%), 35 +/- 7 (-25%), and 38 +/- 8 (-18%) mg/dL when the subjects consumed the reduced-fat, low-fat (--> energy), and low-fat (decreases energy) diets, respectively. Triglyceride concentrations increased from 110 +/- 32 to 115 +/- 31 (8%), 188 +/- 76 (75%), and 130 +/- 32 (22%) mg/dL when the subjects consumed the reduced-fat, low-fat (--> energy), and low-fat (decreases energy) diets, respectively. Maximal changes in plasma lipid concentrations were observed after the first 5 weeks of the low-fat (decreases energy) diet phase despite continued weight loss throughout the entire 10-week diet period.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of increasing dietary polyunsaturated fatty acids within the guidelines of the AHA step 1 diet on plasma lipid and lipoprotein levels in normal males

We attempted to ascertain the effects of polyunsaturated fatty acids by conducting two studies in normal young men, in which monounsaturated fats were replaced by polyunsaturated fats within the guidelines of the American Heart Association step 1 diet. Study A employed a randomized parallel design in which subjects first consumed an average American diet (AAD) containing 37% of calories as fat (saturated fat, 16% calories; monounsaturated fat, 14% calories; and polyunsaturated fat, 7% calories). After 3 weeks, one third of the subjects continued with the AAD, one third switched to a step 1 diet in which total fat calories were reduced to 30% by replacing saturated fat with carbohydrate, and one third switched to a polyunsaturated fat-enriched (Poly) diet with the same 30% fat calories and a reduction of monounsaturated fat from 14% to 8% and an increase of polyunsaturated fat from 7% to 13% of calories. The randomized period lasted 6 weeks. Total and low-density lipoprotein (LDL) cholesterol levels on the step 1 and Poly diets were reduced compared with levels on the AAD (P < .001). Total and LDL cholesterol did not differ between the step 1 and Poly diets, although comparison between the two diets is limited by the small study groups. Serum apolipoprotein (apo) B levels fell on the Poly diet compared with the AAD. Total high-density lipoprotein (HDL), HDL2, and HDL3 cholesterol levels were not significantly affected by the diets. Postprandial lipid and lipoprotein concentrations did not significantly differ either. In study B, a randomized crossover design was used in which all subjects ate the step 1 and Poly diets for 5 weeks each with a 4-day break between diets. In the eight subjects studied, the values for fasting plasma total, LDL, and HDL cholesterol; triglycerides; apoB; and apoA-I were essentially identical at the end of each diet period. Postprandial triglyceride areas obtained after ingestion of a large, standard fat load were also the same. Finally, LDL apoB and HDL apoA-I turnovers were unaffected by replacement of monounsaturates with polyunsaturates. In summary our results indicate that modest exchanges of monounsaturated for polyunsaturated fats do not significantly affect LDL or HDL levels or metabolism, which supports the view that reducing saturated fats is the key to lowering total and LDL cholesterol.

Diet and health: what should we eat?

Many recent studies have implicated dietary factors in the cause and prevention of important diseases, including cancer, coronary heart disease, birth defects, and cataracts. There is strong evidence that vegetables and fruits protect against these diseases; however, the active constituents are incompletely identified. Whether fat per se is a major cause of disease is a question still under debate, although saturated and partially hydrogenated fats probably increase the risk of coronary heart disease. One clear conclusion from existing epidemiologic evidence is that many individuals in the United States have suboptimal diets and that the potential for disease prevention by improved nutrition is substantial.

Effect of dietary fat selection on plasma cholesterol synthesis in older, moderately hypercholesterolemic humans

To study factors controlling plasma cholesterol levels, the effect of dietary fat type on cholesterol synthesis was examined in 15 hypercholesterolemic subjects (low-density lipoprotein [LDL] cholesterol > 130 mg.dL-1) consuming over a period of 32 days (1) a baseline diet (36% kcal as fat: 15% saturated, 15% monounsaturated, and 6% polyunsaturated fat; 180 mg cholesterol.1000 kcal-1) and diets meeting National Cholesterol Education Program step 2 criteria (30% kcal as fat, < or = 7% saturated fat, 80 to 85 mg cholesterol/Mcal), where two thirds of the fat was either (2) olive, (3) corn, or (4) canola oil. Plasma total, LDL, and high-density lipoprotein (HDL) cholesterol and triglyceride levels were determined at the end of each period. Cholesterol fractional synthesis rate (FSR) was also measured as the deuterium (D) incorporation into plasma total cholesterol relative to body D2O level (1.2 g D2O.kg-1 estimated body water) over 24 hours. Absolute synthesis rates (ASRs) were determined as the product of FSR and rapid turnover cholesterol pool size. Plasma total and LDL cholesterol levels declined significantly (P < .005) on all plant-oil diets compared with the baseline diet; however, triglyceride levels were not different. FSRs were higher (P < .05) for the corn oil (0.0665 +/- 0.0097 pool.d-1) compared with baseline (0.0412 +/- 0.0060 pool.d-1) and olive oil (0.0409 +/- 0.0052 pool.d-1) but not canola oil (0.0492 +/- 0.0072 pool.d-1) diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Long term metabolic effects of two dietary methods of treating hyperlipidaemia

OBJECTIVES

To compare the long term metabolic effects of two diets for treating hyperlipidaemia.

DESIGN

Randomised controlled study: after three weeks of normal (control) diet, subjects were randomly allocated to one of two test diets and followed up for six months.

SETTING

Lipid clinic of tertiary referral centre in Naples.

SUBJECTS

63 subjects with primary type IIa and IIb hyperlipoproteinaemia entered the study, and 44 completed it. Exclusion criteria were taking drugs known to influence lipid metabolism, evidence of cardiovascular disease, homozygous familial hypercholesterolaemia, and body mass index over 30.

INTERVENTIONS

Two test diets with reduced saturated fat (8%) and cholesterol (approximately 200 mg/day): one was also low in total fat and rich in carbohydrate and fibre, and the other was low in carbohydrate and fibre and rich in polyunsaturated and monounsaturated fats.

MAIN OUTCOME MEASURES

Fasting plasma lipid and lipoprotein concentrations; blood glucose, insulin, and triglyceride concentrations before and after a test meal.

RESULTS

In comparison with the control diet, both test diets induced significant and similar decreases in low density lipoprotein cholesterol concentrations (by a mean of 0.72 (SE 0.15) mmol/l, P < 0.001, for low total fat diet; by 0.49 (0.18) mmol/l, P < 0.05, for high unsaturated fat diet) and plasma triglyceride concentrations (by 0.21 (0.09) mmol/l, P < 0.05, for low total fat diet; by 0.39 (0.15) mmol/l, P < 0.05, for high unsaturated fat diet), while high density lipoprotein cholesterol concentrations after fasting and plasma glucose and insulin concentrations during test meals were not modified by either diet.

CONCLUSIONS

Both test diets are suitable (alone or in combination) for treatment of hypercholesterolaemia.

Long-term effects of three fat-modified diets in hypercholesterolemic subjects

Altogether 160 free living subjects (aged 30-60 years) most of whom had moderate hypercholesterolemia were randomised into the following diet groups to find out long-term effects of different fat-modified diets: (1) control diet 35/14:10:4 (energy percents from fat/saturated:monounsaturated:polyunsaturated fatty acids in actual diets); (2) AHA type diet 32/10:8:8; (3) monoene-enriched diet 34/11:11:5; (4) reduced-fat diet 30/12:8:3. LDL cholesterol fell equally with the AHA type diet (4.54 +/- 0.97 vs. 4.21 +/- 0.89 mmol/l (mean +/- S.D., 0 vs. 6 months), P = 0.001) and with the monoene-enriched diet (4.55 +/- 0.95 vs. 4.25 +/- 0.95 mmol/l, P = 0.004) during the 6-month study. Moderate amounts of polyenes or monoenes as part of natural diets did not decrease HDL cholesterol level in the long term. Serum lipid values remained unchanged with the reduced-fat diet. Analysis by apolipoprotein E phenotypes showed a decrease in LDL cholesterol only in subjects with phenotype 3/3 in the monoene-enriched group (-8.6 +/- 8.7 vs. +1.3 +/- 15.4, percent change in LDL cholesterol E 3/3 vs. E 4/3 + 4/4), but in the AHA type group LDL cholesterol decreased similarly in phenotypes E 3/3 and E 4/3 + 4/4 (-6.9 +/- 10.1 vs -6.9 +/- 16.5).

Effects of canola, corn, and olive oils on fasting and postprandial plasma lipoproteins in humans as part of a National Cholesterol Education Program Step 2 diet

The most stringent dietary recommendations of the National Cholesterol Education Program (NCEP) are to limit fat intake to < 30% of calories, saturated fat intake to < 7% of calories, and cholesterol intake to < 200 mg/d (Step 2 diet). There is debate as to whether the remaining fat in the diet should be relatively high in monounsaturated or polyunsaturated fatty acids. We examined this issue by testing the effects of diets meeting the aforementioned guidelines that were enriched in three different vegetable oils on plasma lipids in the fasting and postprandial states in a clinically relevant population. Female and male subjects (n = 15, mean age, 61 years) with low-density lipoprotein cholesterol (LDL-C) concentrations > 130 mg/dL were studied under strictly controlled conditions. Subjects were first placed on a diet similar to that currently consumed in the United States to stabilize plasma lipids with respect to identical fat and cholesterol intakes. The subjects then received diets meeting NCEP Step 2 criteria in which two thirds of the fat calories were given either as canola, corn, or olive oil in a randomized, double-blinded fashion for 32 days each. Plasma cholesterol concentrations declined after consumption of diets enriched in all the test oils; however, the declines were significantly greater for the canola (12%) and corn (13%) than for the olive (7%) oil-enriched diet. Mean plasma LDL-C concentrations declined after consumption of diets enriched in all the test oils (16%, 17%, and 13% for canola, corn, and olive oil, respectively), and the magnitude of the declines was statistically indistinguishable among the test oils. Mean plasma high-density lipoprotein cholesterol (HDL-C) concentrations declined after consumption of the baseline diet, and these declines were significant for the canola (7%) and corn (9%) oil-enriched diets. Changes in LDL apolipoprotein (apo)B concentrations paralleled those of LDL-C. Switching from the baseline to the vegetable oil--enriched diets had no significant effect on plasma triglyceride, apoA-I, and lipoprotein(a) concentrations or the total cholesterol to HDL-C ratio. LDL apoB to apoA-I ratios were significantly reduced when the subjects consumed the vegetable oil--enriched diets. Differences similar to those observed in the fasting state were observed in the postprandial state.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect on blood lipids of very high intakes of fiber in diets low in saturated fat and cholesterol

BACKGROUND

It is known that soluble fiber in the diet can lower blood lipid levels. It is less certain, however, that eating foods with soluble fiber will further lower blood lipids when the intake of saturated fat and cholesterol has already been reduced to very low levels. Furthermore, the mechanism of the lipid-lowering effect of fiber has not been elucidated.

METHODS

To address these questions, we studied 43 volunteers with hyperlipidemia in a crossover study involving two four-month dietary periods. The two metabolic diets contained foods high in either soluble or insoluble fiber and were separated by a two-month National Cholesterol Education Program Step 2 diet. The metabolic diets were low in saturated fat (< 4 percent of total calories) and cholesterol (< 25 mg per 1000 kcal), high in carbohydrate (> or = 60 percent of total calories), and very high in fiber (> 24 g per 1000 kcal).

RESULTS

Blood lipids fell to their lowest levels by week 4 of both study diets. When the soluble-fiber period was compared with the insoluble-fiber period, the subjects' total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol levels were found to be lower by a mean (+/- SE) of 4.9 +/- 0.9 percent (P < 0.001), 4.8 +/- 1.3 percent (P < 0.001), and 3.4 +/- 1.3 percent (P = 0.014), respectively. In contrast, the ratio of total to HDL cholesterol was not significantly different during the two dietary periods. The loss of fecal bile acids was 83 +/- 14 percent greater during the soluble-fiber period than during the insoluble-fiber period (P < 0.001) and was related to the differences in total and LDL cholesterol and apolipoprotein B levels (r = 0.42, P = 0.005; r = 0.49, P < 0.001; and r = 0.33, P = 0.035, respectively). The difference in serum cholesterol levels between the two dietary periods was greater among the men (7.5 +/- 1.2 percent, P < 0.001) than among the women (3.4 +/- 1.2 percent, P = 0.008).

CONCLUSIONS

Very high intakes of foods rich in soluble fiber lower blood cholesterol levels even when the main dietary modifiers of blood lipids--namely, saturated fat and cholesterol--are greatly reduced.

Dietary changes in Swedish adolescents

A school-based dietary survey, using seven-day records, was performed in two cohorts of Swedish adolescents; 14- and 17-year-olds. The study comprised 366 boys and 365 girls. When compared to previous studies in Sweden, a striking finding was a decrease in dietary fat intake and an increase in carbohydrate intake. However, the relative intake of saturated fat had not changed (15% of total energy). The dietary change was mainly due to an increased consumption of cereal products. There were no major differences in dietary habits or nutrient density of the food between the two age groups, or between boys and girls. The mean intakes of protein, fat and carbohydrate, expressed as a percentage of the total energy intake, were 15, 33 and 52%, respectively. The mean intakes of vitamins and minerals were low only for selenium. The boys had a high iron intake (1.5 and 1.7 times the recommended intake for 14- and 17-year-olds, respectively) while the mean iron intake for girls was 0.9 times the recommended dietary allowances in both age groups. The intake of dietary salt was higher in boys than in girls (7.7 g and 9.0 g per day in 14- and 17-year-old boys, respectively, and 5.8 g per day in both 14- and 17-year-old girls). In a long-term health perspective, this positive change in nutrient intake in adolescents may contribute to a reduction in the incidence of diet-related diseases in Sweden.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol screening in the adolescent

Guidelines for screening populations for hypercholesterolemia are controversial. In pediatric patients, screening has been targeted to those with a family history of hypercholesterolemia or early myocardial infarction. Because specific guidelines for adolescents have not been developed, we undertook a study of cholesterol screening in 224 consecutive patients (mean age, 14.8 +/- 2.2 years; range, 11-20 years). In this study, 33 (14.7%) adolescents had levels above 185 mg/dL; 71 (32.7%) of the patients reported a positive family history for early myocardial infarction or elevated lipids. A positive family history obtained from the adolescent patient had a 36% sensitivity, 69% specificity, 17% positive predictive value, and an 87% negative predictive value compared with elevated cholesterol level. A positive history reported by the parent had a 65% sensitivity, 46% specificity, 16% positive predictive value, and an 89% negative predictive value. A positive family history obtained from either parent or adolescent had a 45% sensitivity, 69% specificity, 19% positive predicative value, and 89% negative predictive value. Family history by the adolescent was significantly different from parental history (p < 0.001). Family history is a poor predictor for cholesterol level in adolescents.