Table of Contents - Click to go to a topic
Coronary heart disease can be explained through a three stage process. The first stage in the onset of this disease is due to an overload of cholesterol. This overload, termed hypercholesterolemia, can be due either to one's intake of fat in the diet or to genetic factors. When the body encounters levels of fat and cholesterol which are in excess of its needs and its capacity to metabolize, the plasma cholesterol and low-density lipoprotein then increase. On average, hypercholesterolemia occurs when the body's levels reach 180 mg per day (Connor and Bristow, 1985).
After the development of hypercholesterolemia and its presence for a considerable amount of time, stage two in the development of coronary heart disease (atherosclerosis) becomes noticable. Atherosclerosis produces lesions on the arteries which first appear as fatty streaks, then appear as fibrous plaque, and then develop into very complicated lesions. Various risk factors can increase one's chance to evolve from stage two into the final stage of coronary heart disease. The most crucial of these risk factors include obesity, hypertension, cigarette smoking, stress, and lack of physical exercise.
The third stage, coronary heart disease, usually is announced by one of three major manifestations : angina pectoris, myocardial infarction, or sudden cardiac death. While angina pectoris is the most common chronic problem, often induced by exercise, sudden cardiac death has become a major problem in this country, and has attracted a great deal of public attention. These three stages which explain the development of coronary heart disease clearly illustrate the method by which this disease develops.
Fats are an essential part of the human diet, supplying energy and an insulating layer of protection around body organs. Fatty acids are the building blocks of fat and they are comprised of saturated, unsaturated, and poly-unsaturated fats. While unsaturated fats do not influence cholesterol levels within the body, and may, in fact, even lower them, saturated fats directly increase the amount of cholesterol ( a member of the sterol group of fats) in the body (Connor and Bristow, 1985).
High levels of cholesterol in the body as the direct result of a continued overdoes of saturated fats in the diet can lead to heart disease. As described in the previous exlanation of coronary heart disease, high levels of cholesterol, or hypercholesterolemia, are the preliminary factors for the development of coronary heart disease. An overload of cholesterol leasd to the formation of a fibrous plaque on the artery walls, which is termed atherosclerosis. The degenerative process of atherosclerosis can begin early in life if one's diet is continuously high in saturated fats, and the process could continue for many years into adulthood. This process progresses until one or multipe arteries narrow due to the build-up on the walls, and the supply of blood and oxygen to the heart is blocked. At this point, a heart attack occurs.
Therefore, coronary heart disease, which develops as a result of hypercholesterolemia,
could be directly related to the amount of saturated fat ingested by an
individual over a lifetime.
As previously explained, hypercholesterolemia is important because it is the basis for the development and progression of atherosclerosis, which can then lead to coronary heart disease. Essentially, if an individual does not develop hypercholesterolemia, this person will then not be at risk for developing heart disease. Because diet plays such an important role in the onset of a cholesterol overload, monitoring one's fat intake could prevent the development of this disease.
If an individual considers the major dietary factors of cholesterol and total fat (saturated fat, monounsaturated fat, and polyunsaturated fat, s/he is less likely to encounter heart disease dueing the course of a lifetime. By monitoring the intake of these crucial gactors, one can, in part, determine the prevalence of heart disease during life. A low allowance of both cholesterol and saturated fat in the diet can, in a sense, prevent the onset of coronary heart disease (Gold, 1992). This idea has been supported by a number of epidemiological studies (Connor and Connor, 1972). Populations consuming a low cholesterol, low fat diet have very little coronary heart disease; Japan is a classic example of a country with a high standard of living and modern technology, but a low incidence of coronary heart disease due to their nutritional habits. However, populations in the Western world, such as the United States, where the diet is primarily concentrated upon aimal foods high in saturated fat and cholesterol, have a comparatively high incidence of coronary heart disease. The native diets of these countries have served to either prevent heart disease or cause it, showing that monitoring one's diet can serve as a preventive method for contracting coronary heart disease.
The detection of heart disease most frequently occurs following a heart attack or the discovery of high levels of cholesterol in the body. While treatment may involve surgery and the inclusion of an exercise regimen in one's lifestyle, a change in diet can also help treat coronary heart disease by maintaining low levels of cholesterol in the body in order to prevent a heart attack in the future.
By monitorig the intake of cholesterol and saturated fat, one can treat
heart disease just as one would prevent it. By maintaining low cholesterol
levels and including an exercise regimen in one's daily life, the effects
of atherosclerosis may recede and the heart can begin to mend itself if
damage to it has occurred as the result of a heart attack (Gold, 1992).
A number of studies have shown that the fat found in a vegetarian's
diet does put him/her at significantly lower risk for heart disease (Mann,
1993). Saturated fat, which leads to an increase in cholesterol levels,
is derived from an animal origin, while unsaturated fat originates from
vegetables. Therefore, cholesterol can be obtained almost only from animal
foods. Although cholesterol is needed for various bodily functions, the
body produces all that is needed, suggesting that no cholesterol is needed
in our diet. While most saturated fats which lead to cholesterol are found
in animal products, such as meat and dairy foods, saturated fatty acids
found in vegetable matter are at least 25% lower. Vegetarians have been
found, on average, to have a 10% lower blood cholesterol level than those
who eat animal products, because they do not consume the saturated fat
present in these products (http://www.vegorg/Orgs/VegSocUK/Research/heart/html).
The American Heart Association has set a number of guidelines and nutritional values which should be followed in order to maintain a healthy heart (http://www.concentric.net/~wavmed/cholesterol.htm). The food and drug administration requires that all food products supply a listing of their nutritional information on the pckages of the products, which would make it quite easy to chart one's daily intake of nutrients for the day.
Total fat intake or the day should always be less than 30 % of calories. The three components of total fat (saturated, polyunsaturated, and monounsaturated fatty acids) should comprise this total percentage as follows : less than 10% of the daily fat intake should be from saturated fatty acids, no more than 10% of the daily intake should be from polyunsaturated fatty acid, and the remaining 10-15% of fat should be comprised of monounsaturated fatty acid. Also, to reduce this risk of heart disease, less then 300 mg of cholesterol a day should be ingested. To control sodium levels, no more than 3000 mg a day should be consumed (Connor and Bristow, 1985)
By regulating these three aspects of one's diet, heart disease can be
avoided to some extent. Following these nutritional guidelines, suggested
by the American Heart Association, one can control daily fat intake and
minimize the risk of developing coronary artery disease.
As well as providing guidelines, the American Heart Association has developed an eating plan designed to help protect the heart (http://www.concentric.net/~wavmed/cholesterol.htm). This plan consists mostly of tips on how to prepare food and measure daily serving sizes.
The plan is quite elaborate and lengthy, but it includes many useful ideas. The first eight ideas are as follows. A person should allow for less than six ounces per day of cooked lean meat, fish, or poultry. Main dishes with pasta, rice, beans, or vegetables instead of or as well as a small portion of mean provide a great deal of nutrients and sustenance, without added fat. The five to eight teaspoons of fat allowed per day may be used for cooking or baking. Healthy cooking methods for main courses include baking, broiling, steaming, roasting, and using the microwave. These methods require no added fat while cooking, like certain other methods such as deep frying. Before cooking food, trim off all visible fat, and then drain fat during or after cooking. The three to four egg yolks which are allowed per week may be used for cooking or baking. Organ mean (liver, kidney, brains, gizzard, heart) should be severely limited as it is exremely high in saturated fat. Whole fat milk or cheese should be substituted with skim or 1% milk and low or non fat cheese.
This eating plan provides a few tips to lower to fat and cholesterol
in your diet. A number of low-fat, low cholesterol cookbooks now exist,
including one by the American Heart Association. These books can guide
you to a healthy lifestyle and a reduced risk of coronary heart disease.
Connor, W.E., and Bristow, J.D. (1985). Coronary Heart Disease: Prevention, Complications, and Treatment. Philadelphia: J.B. Lippincott Company.
Connor, W.E., and Connor, S.L. (1972). The key role of nutritional factors in the prevention of coronary heart disease. Prev. Med, 1, 49-83.
Gold, P. (1992). Cholesterol and Coronary Heart Disease. New Jersey: The Parthenon Publishing Group Inc.
Mann, G.V. (1993). Coronary Heart Disease: The Dietary Sense and Nonsense. London: Janus Publishing Company.
Psychology DepartmentThe Health Psychology Home Page is produced and maintained by David Schlundt, PhD.
Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical
|Return to the Health Psychology Home Page|
|Send E-mail comments or questions to Dr. Schlundt|