Person who weight 10 kgs. or more above their ideal body weight have an increased risk of both high blood pressure and coronary artery disease occurring together. If obesity occurs in conjunction with an elevated blood sugar, or a high serum cholesterol, it also significantly increase the risk of developing coronary heart disease. Thus, obesity itself may not be an independent risk factor, but it is importantly related to the development of coronary heart disease. Weight reduction often results in a decrease in blood pressure, improved sugar tolerance, and lower serum lipid levels, reducing several of these known coronary risk factors. In patients who have experienced a heart attack, or who have coronary artery disease with chest pain, obesity has detrimental effects by placing an additional strain on the heart. Obesity can also increase symptoms in patients with valvular heart disease by increasing the workload of the heart.
LOW-CHOLESTEROL, LOW-FAT DIETS. The current epidemic of atherosclerosis has forced attention upon the nature of our diet. There is now considerable evidence that excessive ingestion of fatty foods can increase the blood fats or lipids and that the atherogenic diet consumed by millions of Americans may be responsible in part for the finding that about 30 percent of American males over age thirty and under age forty-five have cholesterol levels in excess of 260 milligrams per 100 milliliters of plasma. Although factors other than diet also are important, the fact remains that the risk of developing coronary heart disease is about 3 times as great in men who have cholesterol levels above 260 milligrams per 100 milliliters as in men with levels under 180 miligrams per 100 milliliters. It is egually clear that weight reduction and diet can lower blood lipid levels.
What is this atherogenic diet ? It consists mainly of eating hundreds of milligrams of cholesterol contained in meats, certain shellfish, and dairy products, and large quantities of fats, primarily of the saturated type rather than the polyunsaturated variety. It is now well-established that in many individuals diets high in cholesterol and saturated fats can lead to elevated blood cholesterol levels. Diets high in carbohydrates can lead to increased blood triglyceride levels by stimulating triglyceride production in the body). Beef, lamb, and pork are particularly high in saturated fats and cholesterol; and eggs, shellfish, and organ meats contribute greatly to a high intake of cholesterol. The increasing use of packaged foods, such as frankfurters and luncheon meats, has added to the high intake of saturated- fats, and saturated- fat shortenings often are used in packaged bakery goods. Concentrated sweets and other carbohydrates, including alcohol, contribute to elevations of the triglycerides.
The question of whether or not diminishing the blood lipids will prevent the development of atherosclerosis in young individuals, or reverse the disease when it is already established, is clearly an important one. The answer is not yet available, but the circumstantial evidence that diet is important is sufficiently compelling to lead us to believe that a special diet should be used by individuals with elevated lipids, whether or not they have recognized coronary heart disease.
Recent research indicates that different patterns of lipid elevations in the bloodstream may require different types of treatment. Thus, a specific diet useful for one type of hyperlipidemia may be inappropriate for another.
OTHER FAD DIETS. Many other diets have been proposed to correct supposed endocrine disorders, or to induce a desirable spiritual state, as well as to cause weight reduction.
The hypoglycemic diet is a low-carbohydrate, high-protein diet, frequently without calorie restriction, which is recommended bu its advocates for relieving a variety of nonspecific symptoms which they attribute to be low blood sugar. In the great majority of instances, however, the blood-sugar level is not low, and such symptoms are not caused by hypoglycemia. The most common cause of a temporary low blood sugar is so-called reactive hypoglycemia, which occurs after a meal; this can occur in mild diabetics, for example. In most cases this does not require treatment, although occasionally, when it is troublesome, frequent feedings and a relatively low-carbohydrate, high-protein diet may be used. In some instances injections of adrenal cortical extract also are given to increase the blood sugar, but they are of no value for this purpose.
One diet popular for nearly twenty years consists of a 500-calorie diet plus injections of the hormone, human chorionic gonadotropin. However, claims for the use of HCG in the treatment of obesity have not been substantiated, and the diet does not provide an adequate range and quantity of nutrients.
A vegetarian diet provides adequate nutrition as long as it contains an adequate quantity of protein and essential amino acids. These can be obtained by adding skim milk, cottage cheese, and several eggs per week to the basic diet.
“SPECIAL ” WEIGHT-REDUCING DIETS. In recent years a large number of best-selling books have appeared on how to lose weight in the hurry. Unfortunately, many of these diets present special problems, and do not contain an adequate amount of all required nutrients.
One type of popular weight-reducing diet consists of severely restricting carbohydrate intake, while obtaining most of the daily calories from foods high in protein and fat. On such a diet, person burn their own fat as a source of calories for energy, and weight loss is produced. However, this process produces acidic ketone bodies which, although they may depress the apetite, can also cause other problems, such as dehydration, elevated blood uric acid, or the development of kidney stones. Moreover, such a high-fat diet can serve to increase blood cholesterol levels, particularly in individuals in whom these levels tend to be high on a normal diet. Finally, certain nutrients such as calcium and iron are deficient in this diet. For these reasons, an individual who wishes to reduce his weight should consult his physician before beginning a diet that requires severe carbohydrate restriction.
Other popular reducing diets with serious nutritional deficiencies include the high protein-high water diet, the gelatin diet, and the skim milk and bananas diet. These, and the low-carbohydrate diets mentioned above, are low in milk and bread and cereal foods, and do not promote sound eating habits.
LOW-SALT DIETS. Patients with a persistently elevated blood pressure and patients with congestive heart failure usually require a diet that is low in sodium. In patients with high blood pressure, a reduction in the sodium intake is frequently associated with a reduction in the blood pressure, and some of the drugs which are successful for treating hypertension increase the excretion of salt and water by the kidney. In patients with heart failure, the kidneys retain salt and water abnormally, leading to fluid accumulation in the lungs, in other organs such as the liver, and in the legs. In order to prevent this accumulation of fluid, it is necessary to limit the sodium intake. This is done by restricting the intake of foods rich in sodium, such as milk breads, and soup, and by limiting the amount of salt used for seasoning. Salt substitutes , which contain little or no sodium, may be used as condiments to make food palatable.
VITAMIN E. Although vitamin E deficiency in sheep, cattle, and rabbits may result in conspicuous abnormalities of the muscle, vitamin E deficiency in primates does not affect the heart even when other organs are involved. No heart disease in man has ever been clearly related to a vitamin E deficiency. The use of vitamin E in doses 10 to 50 times the daily requirement was recommended nearly thirty years ago for the treatment of a variety of heart disorders, including angina pectoris, heart attack, and heart failure, but no convincing evidence of its effectiveness has been forthcoming in the intervening years.
A number of studies have related the incidence and severity of coronary heart disease to differences in occupational activity. Men in sedentary occupations have been reported to have fatal heart attacks at a younger age than those whose occupations involved vigorous activity, and there is increasing evidence that regular physical activity may help prevent or delay the development of symptoms due to coronary artery disease. An occupational situation also could foster or diminish the development of coronary heart disease by altering a coronary risk factor, such as diet. However, comparative studies of population group with similar dietary intake appear to show a greater incidence of coronary artery disease and heart attack in sedentary than in physically active worker. In a prospective study of 667 middle-aged London men, clinical symptoms of coronary heart disease occurred more commonly among bus drivers than among the more-active conductors on double deck buses; in another study, symptoms were more common among postal clerks, telephone operators, and executives than among the mail-carrying postmen. Although it is possible that no difference exist in the incidence of coronary artery narrowing by atherosclerosis in such studies, the incidence of clinical symptoms due to coronary artery disease in physically active individuals appears to be less than that for more sedentary persons.
Progressive exercise training may be of considerable benefit in preventing or delaying the onset of symptomatic coronary artery disease in normal individuals, and in reducing the severity of symptoms and mortality in patients who have clinical evidence of coronary artery disease. The question as to whether daily physical exercise results in the formation of new coronary arteries in patients with coronary artery disease is unresolved. However, exercise training does reduce several of the risk factors which make an individual more phone to develop coronary artery disease, such as obesity and elevated blood lipids. Furthermore, the heart rate and blood pressure are reduced at any level of exercise in the well-trained individual, resulting in a decrease in the demands of heart muscle for oxygen at that degree of exertion. After a graded program of exercise training many patients with coronary heart disease show an improvement in angina pectoris, so that more exercise can be undertaken before chest pain develops.
Studies performed in Israel comparing the survival rate in patients with a prior heart attack who then underwent a program of progressive exercise rehabilitation, to that in similar patients who led a sedentary existence, showed a fivefold increase in mortality rate in the individuals who did not undergo daily physical exercise during a ten-year period of follow-up.
currently there is considerable enthusiasm for daily exercise, such as walking, jogging, or swimming, as a measure in the prevention of symptomatic coronary artery disease. However, it is important to emphasize that exercise is not free of danger, both to the musculoskeletal and the cardiovascular systems. This is especially true for middle-aged individuals who may have unsuspected coronary artery disease, particularly those with coronary risk factors, and who suddenly undertake vigorous exercise after years of minimal physical activity. such individuals should seek a physicians guidance before beginning a graded program of exercise training.
Exercise rehabilitation of patients with angina pectoris and a previous heart attack is being recommended by many physicians, In several cities, cardiac rehabilitation centers have been organised where patients with known coronary artery disease are monitored for electrocardiographic changes, alterations in blood pressure, rhythm disorders, and symptoms during programs of progressively increasing exercise. Individuals exercise training programs at home are prescribed for each patient based on information obtained during this period of observed exercise. In many of these centers the patient undergoes electrocardiographic monitoring during his daily exercise, and he is retested at given time intervals, any change in his exercise program being related to his improved work performance.
However, the majority of patients with symptomatic coronary artery disease who undertake a period of exercise rehabilitation attempt to improve their exercise tolerance gradually, while under a physicians care, but not under direct supervision during exercise. Unfortunately, self-motivated exercise training generally has been less successful than formal, supervised exercise programs. Patients are cautioned to avoid sudden strenuous activity and to perform graded physical activity to an extent slightly less than that which brings on symptoms of chest pain, fatigue, or shortness of breath. Physical activity which produces slow progressive increases in heart rate, blood pressure, and cardiac output is less likely to produce symptoms than exercise which rapidly increases those factors which determine the oxygen demand of the heart muscle, For example, walking, jogging, swimming, and bicycling are less likely to produce chest pain than handball, volleyball, and tennis. Isometric exercise, such as sustained hand grip or lifting a heavy object, is to be avoided since this type of exertion is associated with a rapid increase in heart rate, blood pressure, and the oxygen demands of heart muscle.