The Fats of Life: Essential Fatty Acids in Health and Disease

1. The Dietary Fat Doctrine

In the early twentieth century the major concern was whether diets provided sufficient calories and nutrients to ward off infections and disease. When antibiotics were introduced in the 1930s, those with access to these lifesaving drugs had longer and more productive lives. As a result of pushing the average life span ever higher, diseases of aging became commonplace. By the 1930s heart disease had become the leading cause of death in the United States, but the health-care community and the general public had other matters on their minds in the decade leading up to World War II. In the late 1940s fat and cholesterol began to receive an extraordinary amount of attention in terms of funding for studies of the effects of dietary fats on health. A large number of participants were recruited for those studies, and a multitude of scientific publications were generated. It would seem that with all this effort we should now have a grasp of what dietary manipulations are needed to improve our health and longevity. Our understanding of the biochemical and physiological effects of dietary fats has advanced tremendously as a result of this onslaught of research, but where this knowledge leads us, in terms of sound dietary recommendations, is not so clear. Certain fats may improve one health problem but work against another. Saturated fats are resoundingly denounced because they raise total serum cholesterol and low-density lipoprotein (LDL or LDL-cholesterol). There seems to be a consensus that this is bad. On the other hand, polyunsaturated fats lower serum cholesterol and LDL, and consequently are considered good. The stated effects that these two classes of fats have on total serum cholesterol and LDL-cholesterol are accurate, although their classification as bad and good are judgmental and apply primarily to serum cholesterol and LDL. If one looks at the effect these two types of fat have on cancers, the result is often, but not always, reversed. When it comes to arthritis or inflammation, there is a 1 The Dietary Fat Doctrine 3 NUTRITIONAL, CHEMICAL, AND PHYSIOLOGICAL PROPERTIES 4 general consensus that the omega-6 polyunsaturated vegetable oils are bad, whereas omega-3 fish oils are better, and the saturated fats are most favorable. The influence of saturated and polyunsaturated fats on cancers, arthritis, and inflammation are less often mentioned in the popular health media, although the effects of omega-6 versus omega-3 fatty acids on inflammation are beginning to get more recognition. Fats come in many forms: saturated, monounsaturated, polyunsaturated, omega-3, omega-6, partially hydrogenated, and trans fats. These terms are tossed around in health magazines, health sections of newspapers, on television and radio, and in daily conversations, but how well do we understand what it all means? Many people recognize the terms, but they are at a loss to identify which foods contain them. The nutrition facts section of a packaged food label gives the total amount of fat in a standard serving of that food with a breakdown of saturated fat, trans fat, and cholesterol, but is this giving sufficient information to make an informed decision about whether one product is better or worse than another? Labels for foods containing vegetable oils and other forms of fat may give the relative amounts of monounsaturated and polyunsaturated fats, but providing information on these categories is voluntary. Rarely is there an indication of the proportion of omega-3 and omega-6 polyunsaturated fatty acids on a product label. Even if such additional information were provided, would it make the consumer’s decisions any easier? It is easy to understand why there is so much confusion. These fats are not behaving in a consistent way over the full spectrum of all our ailments. This brings to mind the adage Feed a cold and starve a fever—or is it Feed a fever and starve a cold? When the scientific or biological basis for the saying is not understood, it is easy to forget which way it goes. The aim of this book is to inform the reader about how fats are influencing a variety of diseases, disorders, or imbalances so that reasonable dietary decisions can be made. When it comes to fats, such decisions are not as simple as one size fits all. Roles of Fat The physiological ability to store excess energy or caloric intake in the form of fat is a trait that confers numerous advantages across the biological spectrum...