Cholesterol-lowering effect of a low-fat diet containing lean beef is reversed by the addition of beef fat

The whole food beef matrix is more than the sum of its parts

Foods are not simply a delivery vehicle for nutrients; they consist of a matrix in which nutrients and non-nutrient compounds are presented that induce physiologic effects different from isolated nutrients. Dietary guidance is often based on effects of single nutrients that are considered unhealthy, such as saturated fat in beef. The purpose of this paper is to propose a working definition of the whole food beef matrix whose consumption has health effects distinct from those of isolated nutrients. The beef matrix can be defined as: the collective nutritive and non-nutritive components of the beef food structure and their unique chemical and physical interactions that may be important for human health which are distinguishable from those of the single components in isolation. Background information supporting this approach is summarized on multiple components provided by beef, temporal changes in beef consumption, dietary guidance that restricts beef, and how the background diet determines healthfulness rather than a single food. Examples of research are provided on other whole foods that differ from their constitutive nutrients and lay the groundwork for studies of beef as part of a healthy dietary pattern.

Producing high-oleic acid beef and the impact of ground beef consumption on risk factors for cardiovascular disease: A review

This review summarizes the effects of high-oleic acid oil and high-oleic acid ground beef interventions on risk factors for cardiovascular disease (CVD) in human trials, and also summarizes studies designed to increase the amount of oleic acid (18:1n-9) in beef. In three human trials, high-oleic acid oils and high-oleic acid ground beef increased plasma high-density lipoprotein cholesterol over baseline values or over high-carbohydrate diets. Neither low-oleic acid nor high-oleic acid ground beef increased risk factors for CVD, confirming earlier studies that used high-oleic acid oils. High-oleic acid beef can be obtained from cattle fed a corn-based finishing diet to USDA Grade of USDA Choice or greater; from beef from cattle with Japanese genetics; and from the brisket. Beef from grass-fed cattle contains more n-3 fatty acids than beef from conventionally-fed cattle, but also contains greater amounts of saturated and trans-fatty acids.

A brief history of meat in the human diet and current health implications

Anthropological investigations have confirmed many times over, through multiple fields of research the critical role of consumption of animal source foods (ASF) including meat in the evolution of our species. As early as four million years ago, our early bipedal hominin ancestors were scavenging ASFs as evidenced by cut marks on animal bone remains, stable isotope composition of these hominin remains and numerous other lines of evidence from physiological and paleo-anthropological domains. This ASF intake marked a transition from a largely forest dwelling frugivorous lifestyle to a more open rangeland existence and resulted in numerous adaptations, including a rapidly increasing brain size and altered gut structure. Details of the various fields of anthropological evidence are discussed, followed by a summary of the health implications of meat consumption in the modern world, including issues around saturated fat and omega-3 fatty acid intake and discussion of the critical nutrients ASFs supply, with particular emphasis on brain function.

Human evolution and diet: a modern conundrum of health versus meat consumption, or is it?

Despite negative press reports on the effect of meat and other animal-source foods (ASFs) on human health and a vocal minority who contend that humans evolved as vegetarians, scientific evidence contradicts these views. For several million years before the development of agriculture, our ancestors were heavily reliant on ASFs as a source of energy and critical substrates such as protein and long-chain omega-3 fatty acids. Numerous lines of evidence in the anthropological literature have confirmed this scenario. Studies on ASF composition and clinical trials on ASF consumption have provided clear evidence of a requirement for meat in the diet to provide nutrients essential to health, such as Vitamin B12, long-chain omega-3 fatty acids and bioavailable forms of iron and zinc. Other studies have demonstrated that lean ASFs have a role in cholesterol-lowering diets and are important for mental function. Finally, it is possible and desirable to produce meat of a lean nature that mimics the many healthy attributes of wild-game meats and, by emphasising pasture feeding over grain feeding, this can be achieved to a large extent in Australia.

Consumption of a plant sterol-based spread derived from rice bran oil is effective at reducing plasma lipid levels in mildly hypercholesterolaemic individuals

To establish the effectiveness of a new phytosterol-containing spread derived from rice bran oil (RBO), a randomised, double-blind, cross-over human clinical trial was conducted over 12 weeks. A total of eighty mildly hypercholesterolaemic (total blood cholesterol level ≥ 5 and ≤ 7·5 mmol/l with a serum TAG level of ≤ 4·5 mmol/l) individuals were randomised into two groups (n 40). Group 1 consumed spread only daily for 4 weeks. They were randomised to consume 20 g RBO spread (RBOS), 20 g standard spread (SS) or 20 g phytosterol-enriched spread (PS). After a 4-week period, individuals changed to the next randomised treatment until all three treatments had been consumed. Group 2 consumed spread plus oil daily for 4 weeks. They consumed 20 g RBOS plus 30 ml RBO, 20 g SS plus 30 ml sunflower oil or 20 g RBOS. Blood samples were collected for the analysis of lipid parameters, and 3 d diet records were collected. Compared with SS, RBOS significantly reduced total cholesterol by 2·2 % (P = 0·045), total cholesterol:HDL by 4·1 % (P = 0·005) and LDL-cholesterol by 3·5 % (P = 0·016), but was not as effective overall as PS, which reduced total cholesterol by 4·4 % (P = 0·001), total cholesterol:HDL by 3·4 % (P = 0·014) and LDL-cholesterol by 5·6 % (P = 0·001). In group 2, the addition of RBO to the RBOS produced no differences in cholesterol levels. These results confirm that RBOS is effective in lowering serum cholesterol when consumed as part of a normal diet.

Lean beef contributes significant amounts of key nutrients to the diets of US adults: National Health and Nutrition Examination Survey 1999-2004

Consumption of lean meat is a valuable addition to a healthy diet because it provides complete protein and is a rich source of vitamin B(12), iron, and zinc. The objective of this study was to examine the nutritional contribution of total beef and lean beef (LB) to the American diet using the USDA definition of LB as defined in MyPyramid. Twenty-four-hour dietary recall data from adults 19 to 50 years of age (n = 7049) and 51+ years (n = 6243) participating in the National Health and Nutrition Examination Survey 1999-2004 were assessed. Lean beef was defined as beef with <9.28 g fat per 100 g (excess was discretionary fat). Fifty percent of adults 19 to 50 years and 41% of adults 51+ years consumed beef on the day of the dietary recall. Total beef consumed among adults 19 to 50 and 51+ years was 49.3 +/- 1.4 g (1.74 oz/d) and 37.1 +/- 1.2 g (1.31 oz/d), respectively. In adults 19 to 50 and 51+ years, LB contributed 3.9% and 3.7% to total energy; 4.5% and 4.1% to total fat, 3.8% and 3.6% to saturated fatty acids; 13% and 11% to cholesterol intake; 15% and 14% to protein; 25% and 20% to vitamin B(12); 23% and 20% to zinc; and 8% and 7% to iron, respectively. Beef was also an important food source of many other nutrients, including niacin, vitamin B(6), phosphorus, and potassium. In addition, beef provided only 1% of total sodium intake. Consumption of beef contributed significantly to intake of protein and other key nutrients by US adults.

Nutrient contribution of total and lean beef in diets of US children and adolescents: National Health and Nutrition Examination Survey 1999-2004

This study examined the nutritional contribution of total beef and lean beef (LB) to the diet of US children and adolescents using the US Department of Agriculture definition of LB as defined in MyPyramid. Twenty-four hour dietary recall data from children 4-8 years of age [y] (n=2474), 9-13 y (n=3273), and adolescents 14-18 y (n=4044) participating in the NHANES 1999-2004 were assessed. LB was defined as beef with ≤9.28 grams [g] fat/100 g (excess was discretionary fat). Means and standard errors were determined using appropriate sample weights. Consumption of LB contributed significantly to intake of protein and many key nutrients such as vitamins B6 and B12, zinc, iron, niacin, phosphorus, and potassium by US children and adolescents without providing significantly to intakes of total fat, saturated fatty acids, or sodium.

Fat in animal products: facts and perceptions

Early research in man at the end of the fifties and beginning of the sixties indicated that the composition of dietary fat influenced plasma cholesterol levels. In effect this research showed that plasma cholesterol was raised by saturated fatty acids (SFA), was lowered by polyunsaturated fatty acids (PUFA) and was not influenced by monounsaturated fatty acids (MUFA). Within the SFA it was also observed that the greater the chain length, the lesser the cholesterol raising effect. A quantitative relationship between the change in blood cholesterol (ΔC) resultant from changes in the percentage energy from SFA (ΔS) and PUFA (ΔP) was established as ΔC = 1.3 (2ΔS − ΔP). For the ensuing tivo decades this association dominated nutrition education programmes with the message that ‘saturates or animal fats raise blood cholesterol and polyunsaturates or vegetable oils lower blood cholesterol’.

In the 1980s it became evident that the two main fractions of blood cholesterol yielded different risks for coronary heart disease. Low-density lipoprotein (LDL) cholesterol raised the risk and high-density lipoprotein (HDL) cholesterol lowered the risk. Earlier work on the qualitative effect of dietary fat was now repeated to examine the direction of change of the LDL and HDL subfractions of plasma cholesterol. Broadly speaking these data showed that SFA raised LDL cholesterol and had little effect on HDL cholesterol. PUFA lowered LDL cholesterol but when the intake was high, also lowered HDL cholesterol. Whilst this summarizes events leading up to current thinking on dietary fats and blood cholesterol, it is likely in the near future to be linked to another area of research involving the antioxidant vitamins and pro-vitamins (vitamin E, vitamin C and β-carotene). A growing body of data in the literature indicates a protective effect of antioxidant vitamins in epidemiological trials.

Notwithstanding these findings, it is likely that dietary advice will continue to seek a lowering of SFA intake. PUFA intake will be capped and MUFA intake will be a more acceptable alternative. However, with increasing emphasis on antioxidant vitamin status, such advice is likely to be coupled with advice on increased consumption of fruit and vegetables.

Red meat from animals offered a grass diet increases plasma and plateletn-3 PUFA in healthy consumers

Red meat from grass-fed animals, compared with concentrate-fed animals, contains increased concentrations of long-chain (LC)n-3 PUFA. However, the effects of red meat consumption from grass-fed animals on consumer blood concentrations of LCn-3 PUFA are unknown. The aim of the present study was to compare the effects on plasma and platelet LCn-3 PUFA status of consuming red meat produced from either grass-fed animals or concentrate-fed animals. A randomised, double-blinded, dietary intervention study was carried out for 4 weeks on healthy subjects who replaced their habitual red meat intake with three portions per week of red meat (beef and lamb) from animals offered a finishing diet of either grass or concentrate (n20 consumers). Plasma and platelet fatty acid composition, dietary intake, blood pressure, and serum lipids and lipoproteins were analysed at baseline and post-intervention. Dietary intakes of totaln-3 PUFA, as well as plasma and platelet concentrations of LCn-3 PUFA, were significantly higher in those subjects who consumed red meat from grass-fed animals compared with those who consumed red meat from concentrate-fed animals (P < 0·05). No significant differences in concentrations of serum cholesterol, TAG or blood pressure were observed between groups. Consuming red meat from grass-fed animals compared with concentrate-fed animals as part of the habitual diet can significantly increase consumer plasma and platelet LCn-3 PUFA status. As a result, red meat from grass-fed animals may contribute to dietary intakes of LCn-3 PUFA in populations where red meat is habitually consumed.

A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef

Growing consumer interest in grass-fed beef products has raised a number of questions with regard to the perceived differences in nutritional quality between grass-fed and grain-fed cattle. Research spanning three decades suggests that grass-based diets can significantly improve the fatty acid (FA) composition and antioxidant content of beef, albeit with variable impacts on overall palatability. Grass-based diets have been shown to enhance total conjugated linoleic acid (CLA) (C18:2) isomers, trans vaccenic acid (TVA) (C18:1 t11), a precursor to CLA, and omega-3 (n-3) FAs on a g/g fat basis. While the overall concentration of total SFAs is not different between feeding regimens, grass-finished beef tends toward a higher proportion of cholesterol neutral stearic FA (C18:0), and less cholesterol-elevating SFAs such as myristic (C14:0) and palmitic (C16:0) FAs. Several studies suggest that grass-based diets elevate precursors for Vitamin A and E, as well as cancer fighting antioxidants such as glutathione (GT) and superoxide dismutase (SOD) activity as compared to grain-fed contemporaries. Fat conscious consumers will also prefer the overall lower fat content of a grass-fed beef product. However, consumers should be aware that the differences in FA content will also give grass-fed beef a distinct grass flavor and unique cooking qualities that should be considered when making the transition from grain-fed beef. In addition, the fat from grass-finished beef may have a yellowish appearance from the elevated carotenoid content (precursor to Vitamin A). It is also noted that grain-fed beef consumers may achieve similar intakes of both n-3 and CLA through the consumption of higher fat grain-fed portions.

Hamburger high in total, saturated and trans-fatty acids decreases HDL cholesterol and LDL particle diameter, and increases TAG, in mildly hypercholesterolaemic men

The consumption of high-fat hamburger enriched with SFA and trans-fatty acids may increase risk factors for coronary vascular disease, whereas hamburger enriched with MUFA may have the opposite effect. Ten mildly hypercholesterolaemic men consumed five, 114 g hamburger patties per week for two consecutive phases. Participants consumed high-SFA hamburger (MUFA:SFA = 0·95; produced from pasture-fed cattle) for 5 weeks, consumed their habitual diets for 3 weeks and then consumed high-MUFA hamburger (MUFA:SFA = 1·31; produced from grain-fed cattle) for 5 weeks. These MUFA:SFA ratios were typical of ranges observed for retail ground beef. Relative to habitual levels and levels during the high-MUFA phase, the high-SFA hamburger: increased plasma palmitic acid, palmitoleic acid and TAG (P < 0·01); decreased HDL cholesterol (HDL-C) and LDL particle diameter percentile distributions (P < 0·05); and had no effect on LDL cholesterol or plasma glucose (P>0·10). Plasma palmitoleic acid was positively correlated with TAG (r 0·90), VLDL cholesterol (r 0·73) and the LDL:HDL ratio (r 0·45), and was negatively correlated with plasma HDL-C (r − 0·58), whereas plasma palmitic, stearic and oleic acids were negatively correlated with LDL particle diameter (all P ≤ 0·05). Because plasma palmitoleic acid was derived from Δ9 desaturation of palmitic acid in liver, we conclude that alterations in hepatic stearoyl-CoA desaturase activity may have been responsible the variation in HDL-C and TAG caused by the high-SFA and high-MUFA hamburgers.

Lipid-lowering and anti-inflammatory effects of tetradecylthioacetic acid in HIV-infected patients on highly active antiretroviral therapy

BACKGROUND

Highly active antiretroviral therapy (HAART) often leads to a dramatic improvement in clinical, viral and immunologic parameters in HIV-infected individuals. However, the emergence of long-term side-effects of HAART and in particular dylipidaemia is increasingly reported. Based on the potential lipid-lowering and immunomodulatory properties of tetradecylthioacetic acid (TTA) we examined whether TTA in combination with dietary intervention could modify lipid levels in peripheral blood in HIV-infected patients on HAART.

MATERIALS AND METHODS

Ten HIV-infected patients on protease inhibitor-based HAART with hyperlipidaemia followed a cholesterol-lowering diet throughout the study period (8 weeks). During the last 4 weeks of the study all patients received TTA (1 g qd) in addition to the cholesterol-lowering diet.

RESULTS

Our main and novel findings were: (i) TTA in combination with dietary intervention reduces total cholesterol, LDL cholesterol, triglycerides and LDL/HDL cholesterol in these patients, and a particularly suppressing effect was observed during the TTA phase regarding total cholesterol. (ii) During the TTA phase, the cholesterol-lowering effect was accompanied by a significant reduction in plasma levels of tumour necrosis factor alpha. (iii) Our studies in peripheral blood mononuclear cells from these patients and in the liver from wild-type mice receiving TTA suggest that the hypolipidaemic effects of TTA may involve up-regulation of scavenger and LDL-receptor expression.

CONCLUSIONS

Although few patients were studied, the present pilot study suggests that TTA combined with dietary intervention could be an interesting therapeutic approach in HIV-infected patients on HAART, potentially resulting in both hypolipidaemic and anti-inflammatory effects.

Cardiovascular disease resulting from a diet and lifestyle at odds with our Paleolithic genome: how to become a 21st-century hunter-gatherer

Our genetic make-up, shaped through millions of years of evolution, determines our nutritional and activity needs. Although the human genome has remained primarily unchanged since the agricultural revolution 10,000 years ago, our diet and lifestyle have become progressively more divergent from those of our ancient ancestors. Accumulating evidence suggests that this mismatch between our modern diet and lifestyle and our Paleolithic genome is playing a substantial role in the ongoing epidemics of obesity, hypertension, diabetes, and atherosclerotic cardiovascular disease. Until 500 generations ago, all humans consumed only wild and unprocessed food foraged and hunted from their environment. These circumstances provided a diet high in lean protein, polyunsaturated fats (especially omega-3 [omega-3] fatty acids), monounsaturated fats, fiber, vitamins, minerals, antioxidants, and other beneficial phytochemicals. Historical and anthropological studies show hunter-gatherers generally to be healthy, fit, and largely free of the degenerative cardiovascular diseases common in modern societies. This review outlines the essence of our hunter-gatherer genetic legacy and suggests practical steps to re-align our modern milieu with our ancient genome in an effort to improve cardiovascular health.

Increased beef consumption increases apolipoprotein A-I but not serum cholesterol of mildly hypercholesterolemic men with different levels of habitual beef intake

The objective of this research was to compare the effects of a lean beef enriched in oleic acid to a beef that is typical of the commercial beef consumed in the United States. Ten mildly hypercholesterolemic men, ages 34-58 years old, were selected from the Texas A&M University faculty and staff. Subjects were randomly assigned to one of two diets for a 6-week duration followed by a crossover after a 4-week habitual diet washout period. Diets were consumed daily for a 6-week study period. Participants substituted lean beef obtained from Wagyu bullocks or commercial beef for the meat typically consumed. Total cholesterol, apolipoproteins A-I and B, triacylglycerols, and low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol were measured in serum samples collected weekly. Beef type had no effect on any measured variable. There were no significant differences between baseline HDL or LDL cholesterol concentrations after the consumption of the beef test diets. Apolipoprotein A-I, serum glucose, and uric acid concentrations were elevated by the additional dietary beef. Analysis of records of customary diets indicated that one group consumed 160 g of beef daily, whereas the other group consumed only 26 g of beef daily. Therefore, post hoc analyses tested the habitual beef intake x treatment time interaction. LDL cholesterol concentration was markedly higher in the group with low habitual beef intake (180 vs 144 mg/dl), and HDL cholesterol was slightly higher (44 vs 40 mg/dl; post-test values) than for the group with high habitual beef intake, but there were no habitual intake x time interactions for LDL or HDL cholesterol. Creatinine and blood urea nitrogen concentrations also were greater in the individuals habitually consuming less beef. This study had three important findings: i) a lean beef source enriched with oleic acid was no different from commercial beef in its effect on lipoprotein fractions; ii) neither previous level of beef intake nor baseline LDL cholesterol concentration influenced the serum cholesterol response to added dietary beef, which was negative; and iii) apolipoprotein A-I, but not HDL or LDL cholesterol, was sensitive to the additional dietary beef.

Fatty acid analysis of wild ruminant tissues: evolutionary implications for reducing diet-related chronic disease

HYPOTHESES

Consumption of wild ruminant fat represented the primary lipid source for pre-agricultural humans. Hence, the lipid composition of these animals' tissues may provide insight into dietary requirements that offer protection from chronic disease in modern humans.

METHOD

We examined the lipid composition of muscle, brain, marrow and subcutaneous adipose tissue (AT) from 17 elk (Cervus elaphus), 15 mule deer (Odocoileus hemionus), and 17 antelope (Antilicapra americana) and contrasted them to wild African ruminants and pasture and grain-fed cattle.

RESULTS

Muscle fatty acid (FA) was similar among North American species with polyunsaturated fatty acids/saturated fatty acids (P/S) values from 0.80 to 1.09 and n-6/n-3 FA from 2.32 to 2.60. Marrow FA was similar among North American species with high levels (59.3-67.0%) of monounsaturated FA; a low P/S (0.24-0.33), and an n-6/n-3 of 2.24-2.88. Brain had the lowest n-6/n-3 (1.20-1.29), the highest concentration of 22:6 n-3 (elk, 8.90%; deer, 9.62%; antelope, 9.25%) and a P/S of 0.69. AT had the lowest P/S (0.05-0.09) and n-6/n-3 (2.25-2.96). Conjugated linoleic acid (CLA) isomers were found in marrow of antelope (1.5%), elk (1.0%) and deer (1.0%), in AT (deer, 0.3%; antelope, 0.3%) in muscle (antelope, 0.4%; elk, trace), but not in brain.

CONCLUSIONS

Literature comparisons showed tissue lipids of North American and African ruminants were similar to pasture-fed cattle, but dissimilar to grain-fed cattle. The lipid composition of wild ruminant tissues may serve as a model for dietary lipid recommendations in treating and preventing chronic disease.

The effect of replacing dietary saturated fat with polyunsaturated or monounsaturated fat on plasma lipids in free-living young adults

OBJECTIVE

To examine, in free-living adults eating self-selected diets, the effects on plasma cholesterol of substituting saturated fat rich foods with either n-6 polyunsaturated or monounsaturated fat rich foods while at the same time adhering to a total fat intake of 30-33% of dietary energy.

DESIGN

Two randomised crossover trials.

SETTING

General community.

SUBJECTS

Volunteer sample of healthy free-living nutrition students at the University of Otago. Trial I, n=29; and trial II, n=42.

INTERVENTIONS

In trials I and II participants were asked to follow for 2(1/2) weeks a diet high in saturated fat yet with a total fat content that conformed to nutrition recommendations (30-33% energy). During the 2(1/2) week comparison diet, saturated fat rich foods were replaced with foods rich in n-6 polyunsaturated fats (trial I) whereas in trial II the replacement foods were rich in monounsaturated fats. Participants were asked to maintain a total fat intake of 30-33% of energy on all diets.

MAIN OUTCOME MEASURES

Energy and nutrient intakes, plasma triglyceride fatty acids, and plasma cholesterol.

RESULTS

When replacing saturated fat with either n-6 polyunsaturated fat or monounsaturated fat, total fat intakes decreased by 2.9% energy and 5.1% energy, respectively. Replacing saturated fat with n-6 polyunsaturated fat (trial I) lowered plasma total cholesterol by 19% [from 4.87 (0.88) to 3.94 (0.92) mmol/l, mean (s.d.)], low density lipoprotein cholesterol by 22% [from 2.87 (0.75) to 2.24 (0.67) mmol/l], and high density lipoprotein cholesterol by 14% [from 1.39 (0.36) to 1.19 (0.34) mmol/l], whereas replacing saturated fat with monounsaturated fat (trial II) decreased total cholesterol by 12%, low density lipoprotein cholesterol by 15%, and high density lipoprotein cholesterol by 4%, respectively. The change in the ratio of total to high density lipoprotein cholesterol was similar during trial I and trial II.

CONCLUSIONS

Young adults are very responsive to dietary-induced changes in plasma cholesterol even when an isocaloric replacement of saturated fat with n-6 polyunsaturated or monounsaturated fat is not achieved. Replacing saturated fat with either n-6 polyunsaturated or monounsaturated fat is equally efficacious at reducing the total to high density lipoprotein cholesterol ratio.

SPONSORSHIP

University of Otago, Meadow Lea Ltd.

Effects of a prudent diet containing either lean beef and mutton or fish and skinless chicken on the plasma lipoproteins and fatty acid composition of triacylglycerol and cholesteryl ester of hypercholesterolemic subjects11This study was sponsored by the Meat Board of South Africa

In this two-phase crossover study, 39 hypercholesterolemic subjects followed a prudent diet with either lean red meat or fish and skinless chicken (treatment groups), and 13 subjects (reference group) followed their habitual diet. Fasting blood samples were analyzed for plasma total cholesterol, triacylglycerol (TAG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein one- and two-cholesterol, apolipoprotein-B, very low density lipoprotein cholesterol, and very low density lipoprotein TAG, and fatty acid composition of plasma TAG and cholesteryl ester (CE). Body mass and blood pressure were determined. Seven-day dietary records were kept once at baseline and twice during the treatment periods. Significant differences were observed in dietary intake between the baseline and treatment diets and between the two treatment diets. HDL-C (P < 0.05) and diastolic blood pressure (P < 0.01) were higher in patients on the red meat diet than in those on the chicken-fish diet. No other significant differences in lipoproteins were observed between the effects of the two treatment diets. The linoleic acid (%), eicosapentaenoic acid (%), and the eicosapentaenoic acid/arachidonic acid ratios in TAG and CE were higher (P < 0.01) in subjects on the chicken-fish diet than in those on the red meat diet. In conclusion, this study showed that the effect of two lipid-lowering diets containing either lean red meat or skinless chicken and fish on the atherogenic lipoproteins did not differ significantly. A prudent diet with skinless chicken and fish, however, had a more favorable effect on the fatty acid composition of the plasma TAG and the CE than did the lean red meat diet.

Balanced intakes of natural triglycerides for optimum nutrition: an evolutionary and phytochemical perspective

Natural whole foods contain fats as structural components, and have a balance of polyunsaturated fat, monounsaturated fat, and saturated fat. Since we are still a Paleolithic species, adapted to eating only wild foods, it is difficult to justify the consumption of anything other than an overall balance of triglyceride/phospholipid types in an evolutionary sense. No natural fats are intrinsically good or bad--it is the proportions that matter. Variety is recommended in dietary lipid structure, degree of saturation, and chain length. Pathological n-3/n-6 polyunsaturated fat imbalance, obesity, and progressive glucose intolerance are consequences of adopting cereal grain based diets by both humans and livestock. Food processing and refining amplify these problems. Excessive concerns regarding polyunsaturated fat peroxidation in vivo are not warranted when trigylcerides are balanced and normal diets are consumed. Numerous phytochemicals present in unrefined oils, fruits, vegetables, and herbs afford significant protection from lipid peroxidation and chronic disease.

A low-fat diet supplemented with monounsaturated fat results in less HDL-C lowering than a very-low-fat diet

OBJECTIVE

The purpose of this study was to compare the effects of a very-low-fat diet with a low-fat diet supplemented with monounsaturated oil on plasma lipid levels in subjects with hypercholesterolemia.

DESIGN

The 8-week study was divided into one 2-week baseline diet and two 3-week intervention periods in a randomized crossover design.

SETTING

The study was conducted in an outpatient setting at the Deakin Institute of Human Nutrition, Deakin University, Geelong, Australia.

SUBJECTS

Twenty-four free-living subjects with hypercholesterolemia participated in and completed the study.

INTERVENTION

After a 2-week baseline period of a self-selected diet, subjects were assigned to one of two dietary interventions: a very-low-fat (10% of energy from fat), high-carbohydrate diet or a low-fat (26% of energy from fat) diet supplemented with olive oil and an olive oil-based margarine.

MAIN OUTCOME MEASURES

Lipid measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations. Plasma cholesteryl esters were measured to monitor compliance.

STATISTICAL ANALYSES

A paired t test was used to assess differences between treatment periods for each subject. The dependence of the difference between treatment periods on the covariates of age, sex, initial cholesterol concentration, and energy intake was analyzed using repeated measures and analysis of covariance.

RESULTS

The low-fat diet supplemented with monounsaturated fat resulted in significantly less high-density lipoprotein cholesterol lowering than the very-low-fat diet (P=.005). Both interventions resulted in significant reductions in both low-density lipoprotein cholesterol and total cholesterol compared with the baseline diet.

APPLICATIONS

This study suggests that a low-fat diet enriched with olive oil provides advantages over a very-low-fat diet in the control of serum lipoproteins among persons with hypercholesterolemia.

Impact of meat consumption on nutritional quality and cardiovascular risk factors in young adults: the Bogalusa Heart Study

OBJECTIVE

To document the contribution of meat consumption to the overall nutritional quality of the diet and assess its impact on cardiovascular risk factors in young adults.

DESIGN AND SETTING

A cross-sectional survey of young adults in Bogalusa, La.

SUBJECTS

We collected 24-hour dietary recalls from 504 19- to 28-year-olds from 1988 through 1991.

STATISTICAL ANALYSES

We examined dietary composition by meat consumption quartiles. Analysis of variance and Newman-Keuls range tests were performed.

RESULTS

Young adults consume an average of 6.5 oz meat daily; whites most often consumed beef and blacks most often consumed pork and poultry. Persons in the < 25th percentile for meat consumption consumed a diet closest to recommended levels--with 11% of energy from protein, 55% from carbohydrate, 32% from fat, 11% from saturated fatty acids, and 264 mg dietary cholesterol. In contrast, persons in the > 75th percentile for meat consumption consumed a diet with 18% of energy from protein, 40% from carbohydrate, 41% from fat, 13% from saturated fatty acids, and 372 mg dietary cholesterol. Intakes of heme iron and phosphorus were lower and calcium intake higher in persons in the < 25th percentile compared with those in the > 75th percentile for meat consumption. The percent of persons meeting two thirds of the Recommended Dietary Allowances for vitamin B-12, niacin, and zinc was greater in the > 75th percentile for meat consumption compared with the < 25th percentile for meat consumption. We noted no differences across meat consumption quartiles in blood lipids and lipoproteins, anthropometric measurements, and hemoglobin levels.

APPLICATIONS/CONCLUSIONS

Consumption of moderate amounts of lean meat, along with healthier choices in other food groups, may be necessary to meet the current dietary recommendations.

Hábitos alimentares aterogênicos de grupos populacionais em área metropolitana da região sudeste do Brasil

Em amostra representativa da população de duas áreas de estudo (568 indivíduos), Município de Cotia, SP, Brasil, foi realizado inquérito alimentar, baseado na história alimentar do indivíduo. Os objetivos foram: identificar o potencial aterogênico de dietas de diferentes agrupamentos humanos, estratificados em classes sociais e analisar diferenciais de consumo de alguns nutrientes, que conferem aterogenicidade à dieta entre esses agrupamentos. Foram analisados diferenciais de consumo, entre homens e mulheres, segundo classes sociais e tomando-se como referência o percentil 50 (P50) da amostra, dos seguintes constituintes da dieta: energia, proteínas totais, proteínas de origem animal, percentagem de calorias protéicas (P%), ácidos graxos, gorduras, carboidratos. Seguindo esse critério, foram analisados perfis de dieta em relação às recomendações do National Cholesterol Education Program (NEP) no que diz respeito às calorias fornecidas pelas gorduras (G >30%), ac. graxos saturados (AGS> 10%), carboidratos (HC>60%) e colesterol (>300mg/dia). Os resultados mostraram que os diferenciais de consumo foram mais pronunciados entre os homens do que entre as mulheres. As classes sociais, entre os homens, que apresentaram maiores percentuais acima do P50 da amostra, no que diz respeito à energia , proteínas totais, gorduras e carboidratos, foram as representadas pelos trabalhadores não qualificados, que se dedicam a trabalhos braçais com alto consumo energético e a dos pequenos proprietários e comerciantes. A classe de maior poder aquisitivo e nível educacional apresentou consumo moderado desses constituintes. O consumo de proteínas de origem animal, acima do P50, entre homens e mulheres, guardou relação direta com o nível socioeconômico da classe . A participação calórica das gorduras (G%) e proteínas (P%) foi diretamente proporcional ao poder aquisitivo da classe, ao passo que a dos carboidratos (HC%) guardou relação inversa. Por outro lado, o consumo de colesterol acima de 300mg/dia situou-se nas faixas de 37 a 50% e de 20 a 32% para os homens e mulheres, respectivamente. A percentagem de dietas com calorias provenientes das gorduras (G%) acima de 30% variou de 25 a 40%, para os homens e de 45 a 50% para as mulheres. A participação dos ácidos graxos saturados (AGS%) em proporções maiores ou iguais a 10 foi relativamente baixa para ambos os sexos: de 5 a 17% para os homens e menos de 10% para as mulheres. Os percentuais de casos em que a relação ácidos graxos saturados e insaturados (AGS/AGI) guardou valores menores ou iguais a 1, também foi baixa para a população em geral; situou-se entre 7 e 22% para os homens e em proporções abaixo de 10%, para as mulheres. Concluiu-se que a dieta se apresenta como provável fator de risco de doenças cardiovasculares, dislipidemias, obesidade e hipertensão, para grande parte da população.

Diets rich in lean beef increase arachidonic acid and long-chain omega 3 polyunsaturated fatty acid levels in plasma phospholipids

Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20:4 omega 6) content in people in Westernized societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long-chain polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long-chain PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long-chain PUFA in plasma phospholipids (PL). First, we examined the effect of grilling (5-15 min) and frying (10 min) different cuts of fat-trimmed lean beef on the long-chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight) for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very low-fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20:3 omega 6), 20:4 omega 6, eicosapentaenoic acid (20:5 omega 3), docosapentaenoic acid (22:5 omega 3) and docosahexaenoic acid (22:6 omega 3).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dietary fat level and quality on plasma lipoprotein lipids and plasma fatty acids in normocholesterolemic subjects

This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing froma typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6 women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The VLF diet reduced both the low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol levels; addition of the monounsaturated fats and PUFA increased the HDL-cholesterol levels, whereas butter increased the cholesterol levels in both the LDL- and HDL-fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18:2 omega 6) and eicosapentaenoic acid (20:5 omega 3) and to increases in palmitoleic (16:1), eicosatrienoic (20:3 omega 6) and arachidonic acids (20:4 omega 6) in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception of 16:1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18:1 and significant decreases in all omega 3 PUFA except 22:6 compared with the usual diet. The addition of safflower oil resulted in significant increases in 18:2 and 20:4 omega 6 and significant decreases in 18:1, 20:5 omega 3 and 22:5 omega 3. These results indicate that the reduction of saturated fat content of the diet (< 6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects. Although the VLF vegetarian diet reduced both LDL- and HDL-cholesterol levels, the long-term effects of VLF diets are unlikely to be deleterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon eicosanoid precursor fatty acids in the plasma.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect on serum lipids of addition of safflower oil or olive oil to very-low-fat diets rich in lean beef

The cholesterol-lowering effect of very-low-fat diets rich in lean beef has previously been shown to be reversed with the addition of beef fat. The aim of this study was to determine the effect on serum lipid levels of the addition of safflower oil or olive oil to a very-low-fat diet rich in lean beef. Subjects were assigned to either the safflower oil or the olive oil group. In the first week the subjects ate their usual diet; in the second and third weeks all subjects ate a very-low-fat (9% of energy) diet rich in lean beef. In the fourth and fifth weeks the fat content of the diet was increased in a stepwise fashion to 20% and 30% of energy, respectively, by substituting safflower oil or olive oil for carbohydrate. Low-density lipoprotein cholesterol (LDL-C) concentrations decreased by 13% to 14%, and high-density lipoprotein cholesterol (HDL-C) concentrations decreased by 20% to 25% in subjects after 2 weeks of the very-low-fat, lean-beef diet. The LDL-C concentrations remained low after the addition of safflower oil or olive oil to the very-low-fat diet. These results indicate that a reduction in saturated fat, not total fat, is required to reduce serum total cholesterol and LDL-C levels. Provided that the total diet is low in saturated fat, these serum lipid responses can be achieved even when the diet is rich in fat-trimmed lean beef.

Humans, lipids and evolution

The genetically ordered physiology of contemporary humans was selected over eons of evolutionary experience for a nutritional pattern affording much less fat, particularly less saturated fat. Current dietary recommendations do not accord exactly with those generated by an understanding of prior hominoid/hominid evolution. Similarly, widely advocated standards for serum cholesterol values fail to match those observed in recently studied hunter-gatherers, whose experience represents the closest living approximation of "natural" human lipid metabolism. The evolutionary paradigm suggests that fats should comprise 20-25% of total energy intake, that the ratio of polyunsaturated to saturated fat should exceed 1.0, and that total serum cholesterol levels should be below 150 mg/dL (approximately 4 mM/L).