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

Replacement of dietary fat with palm oil: effect on human serum lipids, lipoproteins and apolipoproteins

Thirty-eight male volunteers participated in a double-blind cross-over trial evaluating the effect of replacing the usual sources of saturated fat in the Dutch diet (animal fats and hydrogenated oils) by palm oil, which is virtually free of cholesterol and trans-fatty acids, on serum lipids, lipoproteins and apolipoproteins. Maximum (about 70%) replacement had no significant effect on serum total cholesterol or most lipoprotein fractions, but resulted in an 11% increase in serum high-density-lipoprotein (HDL)2-cholesterol relative to the control (P2 = 0.01). The palm-oil diet also caused an 8% decrease in low-density-lipoprotein (LDL):HDL2 + HDL3-cholesterol ratio (P2 = 0.02) as well as a 9% decrease in triacylglycerols in the low-density-lipoprotein fractions (P2 = 0.01). Palm oil consumption resulted in a 4% increase in serum apolipoprotein AI (P2 = 0.008) and a 4% decrease in apolipoprotein B (P2 = 0.01) relative to the control diet; the B:AI apolipoprotein ratio was decreased by 8% (P2 < 0.0001). These results were not significantly affected by the different lipoprotein E phenotypes of the volunteers. Although the observed differences were relatively modest, the present study, nonetheless, indicates that dietary palm oil, when replacing a major part of the normal fat content in a Dutch diet, may slightly reduce the lipoprotein- and apolipoprotein-associated cardiovascular risk profiles.

Plasma lipid levels and platelet and neutrophil function in patients with vascular disease following fish oil and olive oil supplementation

This double-blind study was designed to examine and compare the effects of supplementing the existing diet with fish oil or olive oil on lipids and cell function in patients with peripheral vascular disease. Thirty-two patients with symptomatic and angiographically demonstrated peripheral vascular disease were screened, matched, and randomly allocated to take either 15 g/d fish oil or olive oil for 4 weeks. Fish oil reduced serum triglyceride levels by 26%, but increased total cholesterol levels due to a significant increase in both low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein-2 cholesterol (HDL2-C). There was a nonsignificant decrease in HDL3-C levels. Olive oil reduced total cholesterol levels, accountable to a significantly decrease in LDL-C levels. Serum thromboxane B2 (TXB2) levels remained unchanged following fish oil, but were significantly increased by olive oil. Urinary excretion of TXB2 and 6-keto-PGF1 alpha was unaffected by either oil supplement. Platelet aggregation, which was measured in platelet-rich plasma in response to two doses of collagen or platelet-activating factor (PAF), was significantly reduced after fish oil, but was increased by olive oil. Following fish oil, there was a significant increase in eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) levels and a decrease in arachidonic acid content of platelet phospholipids. The platelet fatty acid composition after olive oil was unchanged. Fish oil decreased neutrophil leukotriene B4 (LTB4) generation following calcium ionophore stimulation by 33%, while leukotriene B5 levels increased significantly. Neutrophil PAF production and plasma lyso-PAF were unaffected by either oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Case report: survival of an infant with a birthweight of 345 grams

Infant survival with ever-decreasing birthweights is attainable with recent advances in maternal-fetal medicine and enhanced neonatal intensive care. We report a gestation complicated by severe chronic hypertension and fetal distress necessitating delivery at 26 1/7 weeks. The growth-retarded newborn weighted 345 g (12 oz) and survived with minimal sequelae despite a protracted and complicated neonatal course.

Cholesterol absorption, elimination, and synthesis related to LDL kinetics during varying fat intake in men with different apoprotein E phenotypes

Cholesterol absorption, fecal elimination, and synthesis and low density lipoprotein (LDL) metabolism were measured in 29 middle-aged men while on their normal diet and a diet low in fat and cholesterol, and the obtained values were related to apoprotein (apo) E phenotypes. Basal cholesterol absorption efficiency was positively related to production rate (PR) for LDL apo B and negatively to cholesterol synthesis (measured by fecal steroids and dietary cholesterol), which in turn was negatively associated with the LDL level and positively with the fractional removal (FCR) of LDL apo B. The apo E subscript (e.g., E2/2 = 1, E2/3 = 2, etc.) was positively associated with cholesterol absorption and the LDL apo B and cholesterol levels and negatively with cholesterol synthesis and FCR for LDL apo B. Effective bile acid and cholesterol synthesis, fecal elimination of cholesterol, removal of LDL apo B, and low cholesterol absorption characterized men with the epsilon 2 allele. Reduction of dietary fat and cholesterol intakes lowered LDL cholesterol levels and cholesterol absorption but increased cholesterol synthesis proportionally to the apo E subscript; the FCR and PR for LDL apo B were significantly increased and decreased, respectively. The decrease in absorption was related to enhanced removal of LDL apo B and synthesis of cholesterol. During the modified diet, cholesterol metabolism was poorly related to LDL, apo E phenotypes, and LDL apo B kinetics. A positive correlation of cholesterol absorption with dietary fat intake in combined studies suggests that a dietary fat reduction-associated decrease in LDL cholesterol is at least partly caused by reduced cholesterol absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary fatty acids on serum lipids and lipoproteins. A meta-analysis of 27 trials

To calculate the effect of changes in carbohydrate and fatty acid intake on serum lipid and lipoprotein levels, we reviewed 27 controlled trials published between 1970 and 1991 that met specific inclusion criteria. These studies yielded 65 data points, which were analyzed by multiple regression analysis using isocaloric exchanges of saturated (sat), monounsaturated (mono), and polyunsaturated (poly) fatty acids versus carbohydrates (carb) as the independent variables. For high density lipoprotein (HDL) we found the following equation: delta HDL cholesterol (mmol/l) = 0.012 x (carb----sat) + 0.009 x (carb----mono) + 0.007 x (carb---- poly) or, in milligrams per deciliter, 0.47 x (carb----sat) + 0.34 x (carb----mono) + 0.28 x (carb----poly). Expressions in parentheses denote the percentage of daily energy intake from carbohydrates that is replaced by saturated, cis-monounsaturated, or polyunsaturated fatty acids. All fatty acids elevated HDL cholesterol when substituted for carbohydrates, but the effect diminished with increasing unsaturation of the fatty acids. For low density lipoprotein (LDL) the equation was delta LDL cholesterol (mmol/l) = 0.033 x (carb----sat) - 0.006 x (carb----mono) - 0.014 x (carb----poly) or, in milligrams per deciliter, 1.28 x (carb----sat) - 0.24 x (carb----mono) - 0.55 x (carb---- poly). The coefficient for polyunsaturates was significantly different from zero, but that for monounsaturates was not. For triglycerides the equation was delta triglycerides (mmol/l) = -0.025 x (carb----sat) - 0.022 x (carb----mono) - 0.028 x (carb---- poly) or, in milligrams per deciliter, -2.22 x (carb----sat) - 1.99 x (carb----mono) - 2.47 x (carb----poly).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a monounsaturated rapeseed oil and a polyunsaturated sunflower oil diet on lipoprotein levels in humans

The effects of high oleic acid rapeseed oil compared with polyunsaturated fats on serum lipoprotein levels are largely unknown. Therefore, we fed 30 women and 29 men a baseline diet rich in saturated fat, which was followed by a diet rich in high oleic and low erucic acid rapeseed oil (total energy content of fat, 38%; saturates, 12.4%; monounsaturates, 16%; n-6 polyunsaturates, 6%; and n-3 polyunsaturates, 2%) and one rich in sunflower oil (total energy content of fat, 38%; saturates, 12.7%; monounsaturates, 10%; n-6 polyunsaturates, 13%; and n-3 polyunsaturates, 0%). The oils were incorporated into mixed natural diets that were dispensed in a random order for 3.5 weeks each in a blinded crossover design. The diet composition was confirmed by analysis of duplicate diets. Both test diets reduced serum total cholesterol (TC) and low density lipoprotein (LDL) cholesterol levels from baseline, the monounsaturated rapeseed oil diet more than the polyunsaturated sunflower oil diet (TC: -15% versus -12%, p less than 0.01; LDL cholesterol: -23% versus -17%, p less than 0.01). Very low density lipoprotein (VLDL) cholesterol and total, VLDL, and LDL triglyceride levels were lower during the sunflower oil diet compared with the rapeseed oil diet. Total high density lipoprotein (HDL) cholesterol levels remained unchanged by both diets. The consumption of rapeseed oil resulted in a more favorable HDL2 to LDL cholesterol ratio (0.43 +/- 0.19 versus 0.39 +/- 0.18, p less than 0.01) and an apolipoprotein A-I to B ratio (3.0 +/- 1.4 versus 2.4 +/- 1.6, p less than 0.001) than did the sunflower oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary fatty acids, lipoproteins, and cardiovascular disease

Dietary fat quality and quantity significantly affect the metabolism of all the plasma lipoproteins and probably constitute the most significant dietary determinants of plasma lipoprotein levels. Since the major role of the plasma lipoproteins is the transport of exogenous and endogenous fat, this would be expected of a highly regulated, metabolically homeostatic system. The data clearly show that dietary fat saturation affects all aspects of lipoprotein metabolism, from synthesis to intravascular remodeling and exchanges to receptor-mediated and nonspecific catabolism. The experimental data regarding dietary fatty acid effects on lipoprotein metabolism are complicated and at times contradictory due to the large degree of metabolic heterogeneity in the population, which, when coupled with the known abnormalities of lipoprotein metabolism associated with certain types of hyperlipoproteinemia, can present responses from A to Z. It is clear that the same dietary pattern has different effects in different individuals and that complicating factors of individuality raise some concerns regarding generalized dietary recommendations. As new knowledge of the role of dietary factors and CVD risk develops, and our abilities to characterize the individual patient's response to dietary interventions become more refined, it may be possible to specify dietary fat intervention from a patient-oriented concept rather than a single all-purpose diet approach. Thus it would be possible to design dietary interventions to match patient needs and gain both efficacy and compliance. With the spectrum of approaches possible--low fat, moderate fat with MUFA, n-3 PUFA, etc.--we should be able to approach dietary interventions to reduce CVD risk at both a population-based level and a patient-specific level. There remains much to learn regarding the effects of dietary fatty acids on the synthesis, intravascular modifications, and eventual catabolism of the plasma lipoproteins. The area of lipoprotein metabolism in health and disease, of its modifications by diets and drugs, and of the contributions of genetic heterogeneity to these processes is one of notable advances over the past two decades and continues to be an area of intense investigation.

Potential for enhancing the nutritional properties of milk fat

Milk fat has been identified as a hypercholesterolemic fat because it contains cholesterol and is primarily saturated. However, different types of dietary saturated fats do not have equivalent effects on plasma cholesterol levels relevant to ingestion of polyunsaturated fats. Research suggests that the hypercholesterolemic effect of saturated fats in human diets is largely due to 12, 14, and 16 carbon chain length fatty acids. Evidence also suggests that stearic acid (C18:0) is as effective as oleic acid (C18:ln-9) in lowering plasma cholesterol levels when either replaces palmitic acid (C16:0) in the diet of men. Milk fat has a unique fatty acid profile with approximately 10% short- and medium-chain length saturated fatty acids (less than 12 carbons) and 35% of total fatty acids from stearic and oleic acids. The contribution of milk products to fat and cholesterol intake in the typical American diet is less than that provided by other animal products. This paper will review the recommendations of the National Cholesterol Education Program, the effects of milk fat ingestion on blood cholesterol, and the rationale and feasibility of three approaches to modifying the lipid composition of milk fat.

Food use and health effects of soybean and sunflower oils

This review provides a scientific assessment of current knowledge of health effects of soybean oil (SBO) and sunflower oil (SFO). SBO and SFO both contain high levels of polyunsaturated fatty acids (PUFA) (60.8 and 69%, respectively), with a PUFA:saturated fat ratio of 4.0 for SBO and 6.4 for SFO. SFO contains 69% C18:2n-6 and less than 0.1% C18:3n-3, while SBO contains 54% C18:2n-6 and 7.2% C18:3n-3. Thus, SFO and SBO each provide adequate amounts of C18:2n-6, but of the two, SBO provides C18:3n-3 with a C18:2n-6:C18:3n-3 ratio of 7.1. Epidemiological evidence has suggested an inverse relationship between the consumption of diets high in vegetable fat and blood pressure, although clinical findings have been inconclusive. Recent dietary guidelines suggest the desirability of decreasing consumption of total and saturated fat and cholesterol, an objective that can be achieved by substituting such oils as SFO and SBO for animal fats. Such changes have consistently resulted in decreased total and low-density-lipoprotein cholesterol, which is thought to be favorable with respect to decreasing risk of cardiovascular disease. Also, decreases in high-density-lipoprotein cholesterol have raised some concern. Use of vegetable oils such as SFO and SBO increases C18:2n-6, decreases C20:4n-6, and slightly elevated C20:5n-3 and C22:6n-3 in platelets, changes that slightly inhibit platelet generation of thromboxane and ex vivo aggregation. Whether chronic use of these oils will effectively block thrombosis at sites of vascular injury, inhibit pathologic platelet vascular interactions associated with atherosclerosis, or reduce the incidence of acute vascular occlusion in the coronary or cerebral circulation is uncertain. Linoleic acid is needed for normal immune response, and essential fatty acid (EFA) deficiency impairs B and T cell-mediated responses. SBO and SFO can provide adequate linoleic acid for maintenance of the immune response. Excess linoleic acid has supported tumor growth in animals, an effect not verified by data from diverse human studies of risk, incidence, or progression of cancers of the breast and colon. Areas yet to be investigated include the differential effects of n-6- and n-3-containing oil on tumor development in humans and whether shorter-chain n-3 PUFA of plant origin such as found in SBO will modulate these actions of linoleic acid, as has been shown for the longer-chain n-3 PUFA of marine oils.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of canola oil on serum lipids in humans

Previous work in this laboratory had shown in a pilot study that canola oil could lower blood pressure and serum cholesterol levels. Attempting to extend this work to a larger cohort over a longer period, a 4-month study using a 30 ml/day addendum of canola oil as the replacement of the edible oils in the usual diet was undertaken in 36 hypercholesterolemic and/or hypertriglyceridemic subjects. Serum low-density-lipoprotein cholesterol (LDL-C) decreased from 173 +/- 9.0 to 160 +/- 10.0 mg/dl, p less than 0.025. Blood pressure, total cholesterol, and high-density-lipoprotein cholesterol (HDL-C) did not change significantly even though the HDL subfractions did, HDL2 decreasing and HDL3 increasing.

Relationships of dietary fat consumption to serum total and low-density lipoprotein cholesterol in hispanic preschool children

BACKGROUND

Studies of the relationship between dietary fat intake and serum lipids in young children have yielded inconclusive results. We studied this relationship in 108 Hispanic children ages 4-5 years.

METHODS

Four 24-hr recalls approximately 3 months apart and two Willett semiquantitative food frequency questionnaires approximately 6 months apart were obtained by interviewing the children's mothers. Diet measures were averaged for the multiple administrations of each of these instruments.

RESULTS

Based on the 24-hr recalls, children in the highest tertile of total fat consumption (36.2% of total calories) compared with the lowest tertile (30.2% of total calories) had mean total serum cholesterol of 4.32 mmol/liter (167 mg/dl) vs 3.91 mmol/liter (151 mg/d) (test for linear trend across tertiles, P less than 0.05) and mean low-density lipoprotein cholesterol of 2.74 mmol/liter (106 mg/dl) vs 2.29 mmol/liter (89 mg/dl) (test for linear trend, P less than 0.01). Children in the highest tertile of saturated fat consumption (14.6% of total calories) compared with the lowest tertile (11.2% of total calories) had mean total serum cholesterol of 4.39 mmol/liter (170 mg/dl) vs 3.97 mmol/liter (154 mg/dl) (test for linear trend, P less than 0.05) and mean low-density lipoprotein cholesterol of 2.80 mmol/liter (108 mg/dl) vs 2.35 mmol/liter (91 mg/dl) (test for linear trend, P less than 0.01). These relationships remained significant when calorie-adjusted nutrient intakes were examined and after adjustment in multiple linear regression models for age, sex, and body mass index, with the exception of the association of calorie-adjusted total fat with total serum cholesterol level (P = 0.07). Similar results were obtained using the Willett questionnaires.

CONCLUSIONS

These findings indicate that dietary fat, particularly saturated fat consumption, is an important correlate of blood lipid levels in preschool children. These are also the first reported data indicating that the Willett questionnaire, as a method for measuring the atherogenic components of diet, has criterion-related validity in young children.

Polyunsaturated fatty acids and coronary heart disease

Polyunsaturated fatty acids can be used to replace saturated fatty acids in the diet in order to decrease plasma cholesterol concentrations. Intakes of up to 12% of the energy intake as linoleic do not decrease HDL cholesterol. Animal studies show a decreased incidence of atherosclerosis in animals fed polyunsaturated fats compared with saturated fats. Linoleic acid is required for the synthesis of eicosanoids, which are important in the regulation of platelet aggregation, blood pressure and coronary flow. Small amounts of linoleic acid are required for normal eicosanoid synthesis but larger intakes may lead to overproduction of eicosanoids. Dietary eicosapentaenoic and docosahexaenoic acids, which are provided by fish oils, have a protective effect on experimental myocardial infarction. Epidemiological evidence and secondary prevention trials suggest that these marine-derived polyunsaturates offer protection from CHD. Current advice on fat intake needs to be revised to take into account the neutrality of monounsaturated fatty acids and the need to balance the different types of polyunsaturated fatty acids.

Effects of an ethyl ester preparation of fish oils (Himega) on lipids and lipoproteins in hyperlipidaemia

Clinical trials were conducted to assess the utility of HimegaR in the management of hyperlipidaemia. Himega is an ethyl ester concentrate from fish oil containing at least 50% n-3 fatty acid and minimal cholesterol. In Study 1, 13 subjects with primary hypertriglyceridaemia consumed Himega or a triglyceride-based fish oil in a randomised, double-blind crossover study for 12 weeks. Nine subjects took 2 g/day of n-3 fatty acid but four subjects with marked hypertriglyceridaemia took 4 g/day. Plasma triglycerides were reduced by approximately 50% with either product. There was a very similar effect on all lipid and lipoprotein parameters, including an 18% increase in LDL cholesterol and 23% increase in serum apolipoprotein B. In Study 2, nine subjects with primary hypercholesterolaemia took 2 g/day of n-3 fatty acid (Himega) or placebo (olive oil) in a randomised, double-blind crossover study for nine weeks. Plasma cholesterol was reduced by 6%, without significant change in LDL cholesterol. Fish oils in the form of ethyl esters or triglyceride are assimilated to a similar degree and lead to equivalent triglyceride-lowering in hypertriglyceridaemia, while simultaneously increasing LDL particle numbers. Himega does not reduce LDL levels in hypercholesteraemia, despite being a product with minimal cholesterol content.

Fatty acid content of marine oil capsules

The use of dietary omega 3 fatty acid capsules has been associated with a decrease in plasma triglyceride levels. In addition, populations consuming diets rich in fish appear to have a decreased incidence of cardiovascular disease. Eicosapentaenoic acid (EPA, 20:5 omega 3) and docosahexaenoic acid (DHA, 22:6 omega 3) are major fatty acids in fish oils. It is believed that fish oils exert their biologic effect through these fatty acids. Many individuals are currently taking fish oil capsules to lower lipids, increase bleeding time, and possibly decrease cardiovascular risk. These capsules also have been classified as food additives with less stringent controls on content. We assessed the fatty acid, cholesterol, and vitamin A and E content of eight commercially available capsules along with cod liver oil. The content of EPA was found to range from 8.7-26.4% (wt %) with a mean of 17.3% (82.4% of labeled content), and that of DHA from 8.9-17.4% with a mean of 11.5% (90.0% of labeled content) as assessed by capillary column gas-liquid chromatography. The mean content of the polyunsaturated omega 3 fatty acids was 31.9%, and that of the omega 6 fatty acids was 1.4%. The content of saturated fatty acids was 32.0%, and that of monounsaturated fatty acids was 25.1%. Cholesterol content was low, with a range of 0.7-8.3 mg/g, the alpha-tocopherol range was 0.62-2.24 mg/g, and the range of retinyl esters was 0.4-298.4 micrograms/g. Cod liver oil had substantially more retinyl esters (2450.1 micrograms/g) than did fish oil capsules.(ABSTRACT TRUNCATED AT 250 WORDS)