A number of the most serious diseases in our society are related to long-term dietary patterns. Atherosclerosis, high blood pressure, obesity, cancer, diabetes, chronic vitamin and mineral deficiencies, certain disorders of the gastrointestinal tract, and abnormalities of bones and teeth all fall into this category. Are you at risk for one or more of these diseases? Probably! Cumulatively, one of each two Americans will be severely affected by one or more of them. Are your chances higher than average? In a few instances the answers may be simple. In most instances, however, the answers are not so clear. They depend on your gender, your race, your ancestry, your lifestyle, your environment, and the diet you have consumed for a long time. Some constituents of ordinary foods can protect us from disease. Others, if consumed in large quantities, can harm us. Our vulnerabilities depend largely on our inheritances and epigenetic events (such as exposure to certain chemicals while we were in our mother's womb).
Let us consider high blood pressure (hypertension). If you are African-American, your risk is higher than if you are white. If you are male, your risk is slightly higher than if you are female. If you have a strong family history of hypertension, your risk increases. If your lifestyle produces constant stress, your risk goes up. If you eat foods that are high in salt, you are more likely to have high blood pressure.
Establishing a precise risk for any individual is nearly impossible. You know without question whether you are male or female and African-American or white. It is much more difficult to ascertain your family history, your lifestyle, or whether you consume a high-salt diet. What constitutes a strong family history? High blood pressure in one distant cousin on your maternal grandmother’s side does not. Certainly, if your mother and father, both sets of grandparents, and all your siblings have high blood pressure, you are genetically at high risk for this condition.
But what about the middle ground? One grandparent and an uncle? Both grandparents on your mother’s side? One grandparent on each side? What is a stressful lifestyle? Policeman, executive, coal miner, fireman? Going through a divorce? Suffering the loss of a loved one? Finally, do you eat a high-salt diet? How high is high? Most of us do not have any idea how much salt we consume. Salt is everywhere. It is introduced into our food supply through all kinds of processing. Canned peas may contain one hundred times as much salt as fresh peas.
It is easy to establish your risk compared with the average person’s. To classify yourself at high, moderate, or low risk, take into account your sex and your race, and carefully assess your family background, your lifestyle, your environment, and your diet.
Perhaps as many as one-half of all American women are depleted to some extent in at least one of the vitamins or minerals. Men (after the adolescent years) are seldom deficient. Why do women find themselves in this predicament? During the reproductive years, women cycle between pregnancy, lactation, and the long periods between. Pregnancy and lactation increase demands for certain nutrients. Without special care, deficiencies will occur. During the interim periods, women lose a significant amount of blood each month. Lost cells must be replaced. Certain nutrients are necessary to make these new cells.
Women are often dieting. In limiting their calories, they limit their intake of certain essential nutrients. Also, many women are regular users of oral contraceptives that may interfere with the absorption and metabolism of certain vitamins. In addition, women are increasing their consumption of alcohol, another agent known to reduce the absorption of several vitamins and minerals. Thus, the modern American woman is taking oral contraceptives, consuming moderate amounts of alcohol, and often crash dieting. She is at particular risk for nutrient deficiencies. Finally, later in life, women undergo certain hormonal changes that constitute the menopause.
Along with the well-known manifestations of menopause are less well-known changes in a woman’s body chemistry. These changes increase her needs for at least one nutrient—calcium. If you are a woman, you are naturally at greater risk for nutrient deficiencies than if you are a man. In addition, cancer of the breast and of the uterus, two very serious diseases, relate to long-term dietary patterns.
From these inferences, it might seem that women are more at risk than men for nutritionally related diseases. But for certain problems, women are; for others, men are. For example, obesity and diabetes (which can lead to atherosclerosis and heart disease), while no more frequent in men than in women, seem to be more serious in men. Which gender is more at risk is not the question.
Simply belonging to a particular racial group can increase our risk for certain nutritionally related diseases. Our racial origins may play a part in hypertension (high blood pressure), which is much more prevalent in African-Americans than in whites. Lactose intolerance (inability to digest milk sugar, affecting older children and adults) is very severe in Orientals, moderately so in African-Americans, and much less so in Caucasians. Thus, your risk for hypertension increases if you are African-American and living in the United States. You must be particularly careful to minimize the other risks for this disease. If you are Oriental or African-American, your risk for lactose intolerance is high. You may have to control the amount of milk and dairy products in your diet. Without dairy products, the typical American diet is low in calcium. Thus, the risk for osteoporosis increases.
We are not sure why these two conditions show racial preferences. For high blood pressure, we are not even certain that its increased incidence in African-Americans is caused entirely by genetic factors. However, it is clear that African-Americans and Orientals must take race into account when determining their risk for these important conditions.
Many of us know the small town where our great-grandparents were born. Some of us even know our great-grandfather’s occupation. How many know how old he was when he died and from what cause? As for our grandparents, few of us could say with any certainty whether Grandmother or Grandfather had high blood pressure. Even those of us who are able to trace our family back many generations, and who can reveal such details about distant relatives as their occupation, education, and religion, know very little about their health problems. Yet this knowledge could be crucial in predicting our own risks for heart attack, high blood pressure, diabetes and other diseases.
The crucial nutritionally related diseases in which family history is important are: atherosclerosis, which may lead to heart attack or coronary artery disease, kidney disease, and senility; hypertension (high blood pressure), which can cause stroke or cerebral vascular accidents (CVA), heart failure and kidney disease; diabetes, which may lead to atherosclerosis and all its complications as well as kidney failure, decreased feeling in fingers and toes (peripheral neuropathy), blindness, and weakness of the extremities; obesity, which is associated with atherosclerosis, hypertension, and diabetes in addition to gall bladder disease; and certain bone diseases, such as osteoporosis, which can cause fractures of the hip and vertebrae in later life.
While we will discuss several other important diseases for which our risks may be lowered by certain dietary modifications, those mentioned above are the most important. The more information we can gather, the better we can build our family “health tree.” For living relatives, the direct approach is often the most productive. Do they have atherosclerosis? Have they ever had a heart attack or heart pains (angina)? What is their blood pressure? Did they ever have a stroke, even a mild one? Were they ever told they had heart failure? Are they short of breath when climbing two flights of stairs? Is it more difficult for them to breathe when lying flat than when propped up with two pillows? Do they take nitroglycerine or digitalis? Do they take blood pressure medication? Have they been told to limit their salt intake? Do they have diabetes? High blood sugar? Sugar in the urine? Do they take insulin or oral hypoglycemic drugs? Are they extremely overweight? Were they overweight in the past? Did the female members of the family become shorter in old age? Did any of them fracture a hip or a wrist? Were they ever told they had osteoporosis? These are the important questions. Be persistent. A family pattern may emerge that will help you determine whether you are at increased risk for one or more of the diet-related diseases.
Below is a checklist containing the most important family health information for tracing your family health tree:
Atherosclerosis: heart attack, angina, blood pressure, stroke, heart failure, shortness of breath, nitroglycerine, digitalis, diuretics, told to limit salt.
Diabetes: insulin, special “diabetic” diet, numbness or loss of power in extremities, kidney disease, and blindness.
Obesity: actual weight of relatives.
Osteoporosis: shorter during old age; fractured hip or wrist.
Hypertension: high blood pressure, rise in blood pressure with age, heart attack, stroke, kidney disease.
Once you have gathered all the information available, you can see whether a pattern emerges.
Lifestyle can be even more significant than gender, race, or family history in determining whether we are at risk for certain nutritionally related diseases. Those of us who live under constant pressure, whether real or imaginary are at increased risk for atherosclerosis and hypertension. Smoking increases our risk for atherosclerosis. Heavy drinking and using a variety of drugs will increase our risk for certain nutrient deficiencies. Constant dieting may limit the intake of important nutrients. When carried to extremes, dieting may result in overt deficiencies. By contrast, moderate amounts of exercise not only will increase the efficiency of our heart and lungs, but may also lower our risk for atherosclerosis and its complications.
It is important that you be extremely honest in examining your lifestyle. Even if it is not possible to change your ingrained living habits, knowing your increased risk for a nutritionally related disease will help you to make informed decisions about your diet.
More than thirty years ago, an association was discovered between a particular set of behavioral characteristics and coronary artery disease. People who exhibited this set of characteristics were called Type A personalities. Type A behavior is a state of mental arousal characterized by a competitive, ambitious, hard-driving existence. Don’t confuse this behavior pattern with simply working hard or achieving success. It more resembles an unrelenting and intensive strive toward accomplishment. Furthermore, it may be more appropriately labeled “Type H personality” because hostility or anger may be the most damaging aspect of this characteristic. There is one theory that the trait is not so harmful unless it is acted out; that if one can just brush off his anger, the body does not respond negatively to it. Type A (or “H”) behavior involves a series of personality features coupled with an environment that brings those traits into a stressful existence.
Are you very hard-driving, constantly under pressure, always harried by deadlines, and does your job exacerbate these traits? Do you act out the hostilities that often accompany these traits? Since it is often difficult to perceive one’s own behavioral traits, it may not be easy to answer that question objectively. Questionnaires can be used to decide whether your behavior pattern constitutes a major, moderate or low-risk pattern. An objective assessment by your spouse or a close friend is often enough. If you fall into the relevant Type A category, then you are at risk for atherosclerosis and hypertension. If the answer is equivocal, the possibility of increased risk must be considered when you calculate your risk for hypertension and atherosclerosis. If the rest of your pattern suggests low risk, probably nothing else needs to be done. If your profile suggests that you are at increased risk for one or both of these disorders, then a change in diet and a change in behavior may make a big difference.
If you smoke cigarettes, you are at increased risk for emphysema (a form of chronic lung disease). But no diet is known to prevent it or lessen its severity. Cigarette smoking is only one of several major causes of atherosclerosis and coronary artery disease. Therefore, if you smoke, it is particularly important to minimize any other risks. If your diet is high in saturated fat, trans-fatty acids and cholesterol, this also increases your risk for atherosclerosis. The two risks (smoking and increased blood-fat levels) are additive. Thus, changing your diet may put you into a lower-risk group, even if you cannot give up smoking.
Heavy alcohol consumption is another part of the lifestyle of many Americans that can affect our risks for nutritionally related diseases. We know that alcohol can be directly toxic to the liver and brain; and it can result in severe (even life-threatening) illnesses, such as cirrhosis or dementia; but we often overlook the high-risk for certain nutritional disorders. The person who consumes three or more “hard drinks” per day over a prolonged period of time is more likely to suffer from a variety of vitamin and mineral deficiencies than the individual who drinks more moderately. Excess alcohol interferes with the body’s absorption of such vitamins as folic acid, thiamin (vitamin B-1), and pyridoxine (vitamin B-6), and with the absorption of such minerals as zinc and magnesium. A deficiency of one or a combination of these nutrients may occur. Heavy drinkers should consume foods high in them.
Over-the-counter drugs and prescription medications further complicate our problems. Their use has become part of the lifestyle of many Americans. Millions of us consume analgesics, tranquilizers, and pills to put us to sleep or keep us awake. Some of these drugs will increase our risk for certain nutritional deficiencies. For example, aspirin can cause gastric irritations and microscopic bleeding, which can lead to iron deficiency. The contraceptive pill can interfere with the absorption of such nutrients as folic acid and vitamin B-6 (pyridoxine). Some women who have been using oral contraceptives for a long time may be at increased risk for deficiency of these two vitamins. Since alcohol interferes with the absorption of folic acid and vitamin B-6, heavy drinkers who are on the pill are at double risk.
Furthermore, our high standard of living has been accompanied by a progressive decline in physical activity. Our society has been slowly transformed from a highly active, physical one to a much more sedentary type. The policeman on the beat, the fire fighter, the construction worker, and the farmer all continue to lead lives full of physical activity. For most of us, life means driving to work, taking the elevator to the office, sitting in a chair most of the day, getting back in the car, driving home, and sitting in front of a TV until bedtime. This reduction in physical activity has placed us at increased risk for obesity, atherosclerosis, hypertension, and osteoporosis.
The realization that fitness can improve the quality of life and sense of well-being, and our longevity, has led to a revolution in physical fitness. Jogging, walking, bicycle riding, swimming, health clubs, aerobic dancing, have become part of the lifestyle of many of us. To the extent that we engage in increased physical activity, this reduces our risk for the diseases mentioned above.
However, exercise is not the answer to all our problems. Obesity, atherosclerosis, hypertension, and osteoporosis are each caused by a few factors acting simultaneously. Lack of exercise is just one. Usually, changes in our lifestyle must be accompanied by changes in our diet. But, don’t try to do it all in one step. Begin gradually, and work your way slowly into a more active lifestyle. If you already suffer from one of above diseases, increase your exercise under professional supervision. Stick with it! Remember that you’re seeking permanent changes in your lifestyle, not a short-term change such as losing five pounds before some important social function.
How do you decide whether you are too sedentary and need to increase your physical activity? Some sophisticated tests employing complicated and expensive measurements can do this very accurately. Sometimes, your doctor will order these tests. You can make a rough determination by answering a few questions. First, does your job involve a lot of physical activity, a moderate amount, or little or none? If the answer is a great deal, increasing your physical activity will probably have little effect on reducing your risk. If your answer is little or none, do you indulge in any form of regular exercise? For example, do you walk or ride a bike to work, jog daily, or play tennis three times a week? If not, you are a person of low physical activity and your risk for the four diseases mentioned above is increased. You can lower that risk by increasing physical activity. Many people’s answers will put them in an intermediate risk level. If you are one of these, you are at somewhat increased risk and will probably benefit by increasing your physical activity. Pick a form of exercise that you enjoy. Don’t jog just because your friends do. There are enough ways to increase physical activity to satisfy everyone. Get into it gradually; and stick with it!
Calorie counting has become an integral part of life for many of us. Diet books are constantly on the best-seller list. For the most part, Americans don’t diet to cure obesity or to prevent it. They diet to achieve an image equated with good health, youth, fitness, sexiness, beauty, and glamour. In other words, Americans diet primarily for cosmetic purposes. Dieting means fewer calories. Fewer calories mandate less food. Less food often means fewer nutrients, which, in certain susceptible groups, can lead to deficiencies. For example, we have seen that iron is a crucial nutrient. If you are consuming fewer than 1,200 calories per day (many diets restrict calories to even lower levels), you will be unable to fulfill your iron requirement from your food alone. Reducing your caloric intake to 1,200 or less will increase your risk for iron, zinc, vitamin B-6, and folic acid deficiencies. This threat would be serious enough if calories were lowered in a way that favors the consumption of foods rich in these nutrients.
Many diets reduce calories by offering “miracle” programs that emphasize one particular food or type of food. The grapefruit diet, the pineapple diet, the diet that allows mainly meat or no meat, and the fruit diet are all so restrictive that nutrient deficiencies do occur. With its amazing resiliency, the human body is usually able to recover; but serious diseases and death may ensue.
If your life is one of constant dieting, ask yourself if you are doing it to treat or prevent obesity. If the answer is yes, then use a balanced reduction in calories that you can sustain for the rest of your life (see Chapter 4). If the answer is no, then stop dieting. If you must diet, use a low-calorie plan that provides the maximum variety of foods. Avoid crash programs that promise instant results. Even if these programs are successful, the price may be too high. As you assess your own risk, you must honestly evaluate your living habits. Do you have a Type A personality? Do you smoke, drink to excess, or use certain kinds of drugs? Is your level of physical activity low? As we discuss each disease, we shall point out which of these practices increases your risk for that affliction and how you can lower that risk by altering your habits and changing your diet.
The dietary pattern we maintain is, in some ways, the most important factor contributing to our risk for nutritionally related diseases. We are not very concerned about what you ate during the past twenty-four hours or seven days. We are most concerned about your pattern or patterns over the years. Before you can make a rational decision about whether you should change your eating habits, it is important to determine the nature of the diet you now consume. Is it high in calories, fat, cholesterol, or salt? Is it low in fiber, calcium, iron, or folic acid?
In each of the following chapters we will review dietary patterns that can lower our risk for certain diseases. When we compare these patterns with the way we eat, for most of us the differences will be great. If you are eating the types of foods that increase risks for the particular disease, changing your diet can lower that risk. Table 1 includes a list of various diseases and the types of diet that increase risks.
Table l. Disease Diet Relationships
Disease Type of diet that increases risk
Atherosclerosis High fat
High saturated fat
High blood pressure High sodium
Cancers of the colon and High fat
breast Alcohol excesses
Diabetes High calorie
Obesity High calorie
Dental caries High refined sugar
Osteoporosis Low calcium
Anemia Low iron
Low folic acid
Low vitamin B12
Diverticulosis Low fiber
In discussions of each disease, foods high or low in the applicable nutrient will be identified. By evaluating your long-term dietary pattern, you should be able to assess whether you are increasing your risk and whether a dietary change will be beneficial for you.
We have considered the major risk factors in the most important nutritionally related diseases. The importance of each risk factor varies with the specific disease. For example, race is important in high blood pressure. It is less important in osteoporosis. By contrast, gender is very important in osteoporosis and much less important in high blood pressure. Family history is important in determining risk for obesity, atherosclerosis, high blood pressure, and diabetes, and not very important in determining our risk for cancer of the colon or diverticulosis. Lifestyle is important in atherosclerosis, hypertension, and vitamin and mineral deficiencies, and of little or no importance in cancer of the breast.
We shall also see how different components of our lifestyle may be particularly important in determining our risk for certain diseases. Smoking is a major risk in atherosclerosis, a minor risk in hypertension, and not a risk in obesity. Type A personality is an important risk in atherosclerosis and hypertension, but not so important in cancer of the breast or colon. Thus, these various components will have a different weight in determining our risk for each disease.
Finally, although dietary pattern is a factor in all these diseases, your pattern may or may not be contributing to your risk for one or more of them. Your traits must be assessed separately for each disease. As you read each chapter you will see that we have assigned a number to each risk for the disease under discussion. The numbers will vary with the disease. Below a certain score, you are at low risk. Above a certain score, you are at high risk. Between these numbers, your risk is moderate. It is also a way of rating any changes that result from your efforts to lower that risk. It is not, however, a precise set of data for calculating your chances of having any specific disease.
Risks are better defined and, therefore, will carry more weight, in some cases than in others. All these considerations will be thoroughly discussed in the following chapters. Once you have estimated your risk for any of the diseases in question, you can decide whether a change in diet is appropriate for you.
After you have determined your status and have decided to alter your diet, it is reasonable to ask: “How do I know I have reduced my risk? Have I made myself immune to atherosclerosis or hypertension or osteoporosis?” There aren’t any tests that can tell you whether or not your risk has dropped from one precise level to another; and no dietary change can make any of us completely immune. Prevention of a nutritional disorder is much more difficult and complicated than prevention of an infectious disease. Every day someone in low-risk categories dies from a heart attack. Conversely, some people in the high-risk categories live to ripe old age and die quietly in bed. By changing our diets, however, we can improve the odds. For some of us, there will be tangible evidence that the odds have changed. The levels of cholesterol and other blood lipids (fats) will change, or our blood pressure will drop slightly; or we will lose some of that excess weight.
In other cases, we may see no change. For example, if you decide to go on a low-fat, high-fiber version of the Prudent Diet to reduce your risk for certain cancers, no direct measurement can confirm whether you have accomplished your goal. We can say only that in populations who have changed their dietary patterns in a similar manner, the incidence of these cancers has dropped. We do know that people have lower incidence of cancer of the colon or of the breast if they consume a low-fat diet.
In the succeeding chapters, we will give you the best available information for making informed choices. A decision to change your diet is a personal one. Only you can decide! For each disease discussed, the amount of accessible data will differ. If you reduce the amount of total fat, saturated fat, and cholesterol in your diet, the level of cholesterol in your blood might drop between 15 and 20 percent. If this happens, we can give you a statistical evaluation of how much that affects your chances for having a heart attack.
Our ability to predict other diseases is much more limited. For example, we know that consuming adequate amounts of calcium in our younger years will offer some protection from osteoporosis and the brittle bones of later years. However, we don’t know how much protection results because we have no way of monitoring the effect of the dietary change. For osteoporosis, your decision to change your diet will have to involve less quantitative data.
Another question is when to change the diet for the maximum benefit? Sometimes, the peak incidence of the disease may be forty to fifty years away. Do you have to change your diet now, or can you wait another ten or twenty years? Although there may be no precise answer, the earlier we modify our diet, the better our chances for reducing risks. The effects of an improper diet are often cumulative. The longer we continue to consume the wrong foods, the harder it will be to overcome our risks.
To those at low risk, we are not advocating complacency or a false sense of security. Even those at lowest risk for a given disease may end up suffering from that disorder. If your profile shows you in this category, your risk is lower than those of someone at higher risk; but you are not guaranteed immunity. If your risk is high, your incentive for modifying your diet should be greater than average.