Appraisal of dietary fat as a causative factor in atherogenesis

Doing Nutrition Differently

This conversation is part of a special issue on “Critical Nutrition” in which multiple authors weigh in on various themes related to the origins, character, and consequences of contemporary American nutrition discourses and practices, as well as how nutrition might be known and done differently. In this section, authors reflect on the limits of standard nutrition in understanding the relationship between food and human health. They also focus on how nutrition practitioners are or could be creating different practices for how nutritional information is made available, shared, and absorbed. Among the different frameworks under discussion are individualized nutrition, ecological nutrition, critical dietary literacy, feminist nutrition, and technologies of humility.

Coronary heart disease, hypercholesterolemia, and atherosclerosis. I. False premises

Lipid-rich caseous debris of advanced lesions stimulated interest in the role of cholesterol and lipids in atherosclerosis. Lipid-containing arterial lesions in cholesterol-overfed animals (cholesterolosis) and xanthomatous vascular lesions in subjects with familial hypercholesterolemia were then misrepresented as being atherosclerotic and led to the development of the hypercholesterolemic/lipid hypothesis. It is untenable that cholesterol, an essential multifunctional metabolite, is pathogenic at all blood levels and hypercholesterolemia is not prerequisite for human or experimental atherosclerosis. Serum cholesterol levels display a poor correlation with atherosclerosis at autopsy and with unreliable national coronary heart disease (CHD) mortality in each sex. Atherosclerosis topography and its iatrogenic production in humans and experimentally in herbivores by hemodynamic means both support a biomechanical causation and preclude causality by any circulating humoral factor. CHD, not a specific disease, is a nonspecific complication of many diseases including atherosclerosis and cannot be equated with coronary atherosclerosis due to differences in pathology and pathogenesis. Thus, extrapolations from CHD risk factors or correlations with fallacious vital statistics to atherosclerosis are invalid. It follows that the hypercholesterolemic/lipid hypothesis evolving from false premises, misuse of CHD, scientific misrepresentation, and fallacious data has no legitimate basis.

Heated fat, vitamin E and vascular eicosanoids

A semisynthetic diet containing adequate amounts of vitamin E and 10% (w/w) of a mixture of polyunsaturated oils subjected to heating and characterized by elevated indexes of thermal alteration (polar component, dimer triglyceride, altered triglyceride contents and reduced alpha-tocopherol levels) was fed to growing male rats for a period of eight weeks. It resulted in a selective alteration of the production of vascular eicosanoids (elevation of platelet thromboxane formation and decrease of vascular prostacyclin release) compared to the values found in rats fed a diet containing a fresh mixture of polyunsaturated oils. Major nutritional parameters, plasma lipids and the fatty acid profiles of plasma, liver and heart lipids were not different in the two groups of animals. Supplementation of an excess vitamin E (300 mg/kg) to the diet containing heated fat neutralized the adverse effects of heated fat on vascular eicosanoid production.

The advisability of the prudent diet in adolescence

Risk factor status for cardiovascular disease is affected by life style. Adolescence is a time during which long term life-style habits, including dietary habits, are established. Physicians who treat adolescent patients have a responsibility to be aware of the scientific evidence on the diet-heart question so that they can provide their patients with sound dietary advice. The American Heart Association has recommended that Americans consume a "prudent diet" in which daily consumption of cholesterol is no more than 300 mg with up to 30-35% of calories derived from fat, and less than 10% of calories derived from saturated fat and less than 10% from polyunsaturated fat. This paper reviews this recommendation with particular reference to studies of adolescents. This review centers around four main issues: 1) the estimated effect on serum cholesterol levels of a switch from the usual American diet to the prudent diet; 2) the effect of a predicted decrease in serum cholesterol on the risk of developing cardiovascular disease; 3) evaluation of the evidence of possible adverse effects of the prudent diet; 4) feasibility of the prudent diet. Based on a review of these four issues, the authors feel that the American Heart Association's prudent diet should be strongly recommended for all healthy adolescents.

Changes in the dietary habits of male workers in Warsaw plants over a period of four years

At the Polish Trial on Ischaemic Heart Disease Prevention begun in 1976-77 the dietary habits of 5,484 male workers aged 40-59 years working in 14 Warsaw plants were assessed by 24-hour recall. After two and four years of follow-up in 1978-79 and 1980-81 this study was repeated in random samples of the previously screened population still in employment in these plants i.e., 652 men (response rate after two years=70.4%) and 574 men (response rate after four years=65.0%). In the initial screening the mean energy value of the reported daily food ration was 2,700 kcal/11,296 kJ. This energy derived 13.6% from protein, 37.1% from fat, and 49.3% from carbohydrate. After two years the mean energy value of the daily food ration as well as the amounts of the daily consumed fat and carbohydrate and vitamin B1 had decreased significantly. The amounts of the remaining nutrients were not significantly changed. After four years only the mean daily consumption of vitamin C was decreased significantly. The mean values of the total energy value of the food ration as well as of the amounts of nutrients were not significantly different. On the other hand, differences were found in the amount of food products--the reported consumption of cereals and bread as well as animal fat increased significantly, while the consumption of meat and meat products, vegetable fats, fruits and sugar decreased.

Dietary lipids, sugar, fiber and mortality from coronary heart disease. Bivariate analysis of international data

Univariate analyses with data for the years 1954-1969 from 20 economically advanced countries showed that a combined dietary lipid score based on per capita consumption of saturated fat, cholesterol, and polyunsaturated fat (equation of Keys, et al.) and the consumption of refined and processed sugars were both highly correlated with age-standardized coronary heart disease (CHD) mortality rates for the years 1969-1973 for both men and women aged 35-74 years (r values of 0.54 to 0.72). Fiber intake, estimated as the sum of calories available from vegetables, fruits, grains, and legumes, yielded a significant inverse correlation with CHD mortality rates (r = -0.49 to -0.68). These three dietary variables are highly intercorrelated. With bivariate analyses (2 X 2 cross-classification and analysis of variance), lipid score, but neither that of sucrose or fiber, was consistently and significantly related to CHD mortality. However, with both higher and lower lipid scores, CHD mortality rates tended to be slightly (nonsignificantly) higher with higher sugar values and with lower fiber values.

Epidemiology as a guide to clinical decisions. The association between triglyceride and coronary heart disease

The hypothesis that triglyceride is a cause of coronary heart disease, although unconfirmed and never universally accepted, has nonetheless strongly influenced the practice of preventive medicine. We have examined the epidemiologic association between triglyceride and coronary heart disease to evaluate the validity of inferring that there is a causal relation between the two. Neither the evidence from published studies nor an analysis of data from the Western Collaborative Group Study provides strong support for the causal hypothesis. Information from other scientific disciplines is also meager, contrasting with the coherence of diverse evidence supporting the hypothesis that cholesterol is a cause of coronary heart disease. These arguments fall short of disproving the belief that lowering triglyceride will prevent coronary heart disease, especially since triglyceride and cholesterol are inextricably associated through mutual lipoprotein carriers. But we propose that the ethics of preventive medicine place the burden of proof on the proponents of intervention. We therefore recommend that widespread screening and treatment of healthy persons for hypertriglyceridemia be abandoned until more persuasive evidence becomes available.