What's up, Doc?

What's Up, Doc?

What the surgeon general's report means in ordinary terms.

That nutrition and health are closely related has been recognized for many years. The eighteenth-century French political economist Brillat-Savarian said, "The destiny of a people depends on its diet." Five of the 10 leading causes of death in America are related to diet. Another three are associated with alcohol consumption. These eight conditions together accounted for 1.5 million of the 2.1 million total deaths in 1987.

Until as recently as the 1940s the main concern with diet was to provide enough of the various nutrients. Deficiency diseases were the primary consequence of inappropriate dietary intake.

In contrast, much of the concern related to the diet of Americans today is focused on the diseases of abundance. This is not to suggest that poverty and undernutrition do not exist or are not a concern, but the problem of overnutrition has become so large that it must be addressed. The economic cost of premature and preventable illness and death is staggering.

In October 1988, C. Everett Koop, the surgeon general of the United States issued the 750-page Report on Nutrition and Health. He did so, he says, because "of the obligation of the surgeon general to inform the American public of developments in the science base that have widespread implications for human health." This authoritative report is a comprehensive analysis of the relationships between diet and the risk of chronic disease.

Chronic diseases result from many different interactions, but it is clear that diet plays a significant role in their development. The surgeon general's report makes recommendations for changes in diet that can help prevent disease.

The recommendations may sound familiar. They are similar to the Dietary Guidelines for Americans published previously. But the evidence for the recommendations has become so strong and the implications for health so great that they must be stated again with even greater emphasis. The newest report expands the focus and prioritizes the recommendations. It divides the issues into those relevant for "most people" and those relevant to "some people." The conclusions are based on evidence from epidemiological, clinical, laboratory, and animal studies. First priority. The first priority for dietary change for most people is to reduce the intake of fat, especially saturated fat, and cholesterol. Total fat intake is related to obesity and some types of cancers. There is strong evidence that as saturated fat increases in the diet, blood cholesterol levels increase; and as blood cholesterol levels increase, the risk of coronary heart disease increases. On the other hand, decreasing the blood cholesterol levels results in decreasing the risk of death from coronary heart disease.

High intake of saturated fat is the major contributor to high blood cholesterol levels. Dietary cholesterol also raises blood cholesterol levels in most people, but the effect is less than the effect from saturated fat. Further, the blood cholesterol-raising effect of dietary cholesterol is greater when the diet is high in saturated fat. Saturated fats in general also cause more clotting activity in the blood. For these reasons it is important to reduce the amount of saturated fat and cholesterol in the diet.

There is evidence that polyunsaturated fatty acids, such as those found in cooking oils, lower total blood cholesterol. However, they are only half as powerful in lowering serum cholesterol as saturated fats are in raising it. Monounsaturated fat, such as that in olive oil, when substituted for saturated fat also probably lowers blood cholesterol.

The long-chain polyunsaturated fatty acids (omega-3) found in fish oils may also be related to health. Greenland Eskimos who consume large amounts of these oils have lower incidence of coronary heart disease. However, they have increased incidence of strokes. This topic will be discussed in a future issue of VIBRANT LIFE.

Diet is now recognized as the corner-stone of treatment to reduce borderline and high-risk blood cholesterol levels, whether or not drug therapy is eventually used. Is it worth the effort to try to reduce blood cholesterol levels? Yes, indeed. Studies have shown that in men with elevated lipid levels, each 1 percent decrease in total blood cholesterol results in a 1.5 to 2 percent decrease in the risk of heart disease. Decreases in blood cholesterol levels reduce the risk of coronary heart disease, and diet can play an important role in helping to reduce blood cholesterol.

Through the years, scientists have debated whether or not the atherosclerotic disease process can be reversed. Animal studies have not demonstrated that atherosclerotic lesions can actually decrease over time when blood cholesterol levels are reduced. More recently, angiographic studies in humans found atherosclerosis progressed more slowly in those persons who lowered their elevated blood cholesterol levels. The effect was greatest in those with the greatest change in blood lipid levels.

It is important to remember that changes in dietary fat intake should involve both the quantity and quality of the fat. That means there should be less total fat consumed and there should be changes in the type of fat that is eaten. Therefore, dietary changes in fat intake should involve reduction in the total amount, and substitution of oils for some of the solid fats. Simply adding oils to the current intake is not appropriate. Second priority. Dietary fat intake is also related to the second priority: maintain desirable body weight. Fat contains more than twice as many calories as an equal weight of carbohydrate or protein, making it easier to consume excessive calories from high-fat foods. In addition, there is evidence that fat calories are more easily converted to body fat than are an equal number of calories from carbohydrate. We can no longer say a calorie is a calorie is a calorie.

But before we blame fat intake for all our weight problems we must recognize that body weight is the summation of too many calories eaten and too few expended. Most Americans would benefit from more physical exercise. In addition to burning calories, exercise increases the proportion of lean-to-fat body mass. Because lean body tissue uses more energy than does fat tissue, this raises the metabolic rate and in turn helps control weight.

More than a quarter of adult Americans, or about 34 million people, are overweight. People are considered overweight if they weigh more than 120 percent of desirable body weight. Such individuals are at increased risk for diabetes mellitus, high blood pressure and stroke, some types of cancer, and gallbladder disease. Overweight increases blood cholesterol levels and thus is associated with heart disease, but it is also related in other independent ways to coronary heart disease. In addition, there are significant psychosocial consequences related to overweight.

The risk of disease and death increases as excess weight increases. Rates of hypertension and diabetes are nearly tripled in persons 20 percent or more overweight, and elevated blood cholesterol is 50 percent more common in overweight individuals. On the other hand, weight loss can improve the control of non-insulin-dependent (Type II) diabetes and help to decrease blood cholesterol and blood pressure levels. It is estimated that new cases of Type II diabetes could be cut in half if obesity in middle-aged adults were prevented.

Risk of disease is also related to the distribution of body fat. There is greater risk when the fat accumulates around the abdomen and results in an increased waist-to-hip ratio. This is called upper body fat and is found more frequently in men than in women. Lower body fat, accumulating around the hips, buttocks, and extremities, is seen more typically in women. It does not appear to be associated with increased risk. However, women with upper body obesity and a waist-to-hip ratio similar to men are at increased risk just as men are.

The cause of obesity is difficult to determine. As with many other diseases, it is undoubtedly the result of several interacting factors. Although some studies suggest a genetic tendency to obesity, cultural and environmental factors also play important roles in its development.

Clearly, overeating is a prominent contributor to obesity. Yet in some cases the energy imbalance may be more a result of inactivity than simply consumption of too many calories. Thus we return to the need for decreased energy intake to be combined with increased energy output in order to control weight. To decrease energy intake, limit the consumption of foods relatively high in calories, fats, and sugars.

It is important to recognize that weight control is not something to be solved by going "on a diet." Such an attitude suggests that sooner or later you will also go "off the diet." Repeated cycles of weight loss and weight gain may make it more difficult to lose weight with additional attempts.

The most effective weight loss programs are long-term; they incorporate changes in diet and exercise patterns into regular daily living. Weight loss is never simple, but it is more easily achieved if decreased dietary intake is combined with increased physical activity. How about a daily walk? Or why not try jogging, bicycling, or swimming for 20 minutes, at least three times a week? You'll feel better, and you'll be able to control your weight more easily.

Extreme diets are not without risks. Deaths have resulted from extreme low-calories diets (300 or 400 calories per day). Even diets in the range of 800 calories per day need careful medical supervision. (A subsequent issue of VIBRANT LIFE will detail current research relating to obesity and weight loss.) Third priority. The third recommendation, consuming a variety of foods high in complex carbohydrates and fiber, will help to achieve the first two priorities. Such a diet, including whole grains and cereals, dried beans and peas, vegetables and fruits, will by its nature be lower in calories and in fat, especially saturated fat and cholesterol. Low-fat foods high in naturally occurring fiber make you feel full sooner than do foods high in fat and low in fiber. Thus they are helpful in controlling energy intake.

Water-soluble fibers found in oat bran, dry beans, and some fruits help to control blood glucose and blood lipid levels. Foods high in dietary fiber are also helpful in controlling constipation and diverticular disease.

Some studies suggest that increased fiber intake may decrease the risk for colon cancer. In addition, the frequent consumption of fruits and vegetables, especially the dark-green, deep-yellow, and cruciferous vegetables such as broccoli, cabbage, and cauliflower, may lower the risk of a variety of other kinds of cancer. Fourth priority. Fourth on the list of priorities for everyone is to reduce the intake of sodium. High sodium intakes are related to high blood pressure and stroke.

Although sodium is necessary for normal metabolism of the body, Americans consume much more than needed. The current intake of four to six grams per day is far greater than the safe and adequate range of 1.1 to 3.3 grams, and five to ten times more than the amount actually required by the body. Most of the sodium is consumed as salt, which is 40 percent sodium. One gram of sodium is equivalent to about 2.5 grams, or one-half teaspoon, of salt.

Some people maintain normal blood pressure over a wide range of sodium intake. Others appear to be "salt-sensitive." Their blood pressure increases in response to increased sodium intake. Currently there is no practical way of identifying salt-sensitive individuals. That is why it is important for everyone to decrease sodium intake. There is no harm and much to be gained by moderate sodium restriction.

About one third of the sodium in American diets comes from processed foods and another third is added by the consumer. Salt intake may be decreased by using other seasonings such as herbs and by using processed foods less frequently. Fifth priority. The final priority for all persons recommended in the surgeon general's report is that alcohol should be consumed in moderation (less than two drinks per day) if at all. It is the position of this health magazine that alcohol should not be consumed at all. Alcohol is a drug and produces addiction in susceptible persons. It causes birth defects in some children born to women who drink during pregnancy. There is no known safe level for alcohol consumption by the pregnant woman. It impairs judgment and the ability to drive automobiles or operate machinery. It causes adverse reactions when ingested with certain medications. Alcohol abuse can disrupt family functioning and contribute to suicide and homicide.

Alcohol use is the principal cause of liver cirrhosis in the United States. Alcohol acts together with smoking to increase the risk of cancer of the mouth, larynx, and esophagus. A role for alcohol has also been suggested in cancer of the liver, rectum, breast, and pancreas. Studies indicate a direct association between alcohol intake and elevated blood pressure, and with disorders of heart muscle. For all of these reasons, VIBRANT LIFE believes that alcohol should not be consumed.

The surgeon general's report went on to make other recommendations for "some people."

Fluoride.

Community water systems should contain fluoride at optimal levels for the prevention of tooth decay. Water fluoridation is one of the most successful public health efforts ever introduced into the United States. There is overwhelming evidence of its efficacy, safety, and cost-effectiveness in preventing tooth decay.

Sugar.

Consumption and frequency of use of foods high in sugar should be limited in those who are particularly vulnerable to dental cavities. This is especially true of children because erupting teeth are more susceptible to decay than mature teeth.

Although other factors also influence dental health, the major role of sugars in promoting tooth decay is well established. Decreasing the frequency of ingestion and the amount of sugar-rich food will help reduce dental decay. Foods that are sticky and adhere to the teeth are more likely to cause decay than those foods that wash off easily.

Calcium.

Inadequate dietary calcium consumption in the first three to four decades of life may increase the risk for osteoporosis later in life. Bone continues to increase in density even after adult height is reached. Chronically low calcium intake during this time may compromise development of peak bone mass. Higher intakes of calcium during adolescence may increase peak bone mass and delay the onset of bone fractures later in life. Thus, it is important for adolescents and young women to ingest foods rich in calcium. Appropriate levels of physical activity are also helpful in reducing risk of osteoporosis. On the other hand, cigarette smoking increases the risk for osteoporosis. Caffeine and alcohol also may cause a loss of calcium and lower bone density.

The precise relationship of dietary calcium to osteoporosis is not certain; nonetheless, it appears that higher intakes increase bone mass and thus delay the onset of the disease.

Iron.

Children, adolescents, and women of childbearing age should be sure to consume foods that are good sources of iron. The most prevalent form of anemia in the United States is caused by dietary iron deficiency. This disorder has serious consequences. It diminishes the ability of the body to produce hemoglobin, needed to carry oxygen in the blood. It results in reduced work capacity. Depressed immune function, changes in behavior, and impaired intellectual performance may also result. Children from low-income families are at special risk. School performance may be compromised in anemic children.

Diet is important to Americans. Following the recommendations of the surgeon general will help prevent multiple chronic disease conditions and improve health.

Patricia Johnston, Dr. P.H., M.S., R.D., is director of the Doctor of Public Health program, and associate professor of nutrition at Loma Linda University, Loma Linda, California.