advised daily to modify our diets in order to

advised daily to modify our diets in order to avoid these major diseases. It is difficult to reconcile such claims with the statement of the Surgeon General. It is a strange kind of epidemic that is associated with declining infant mortality, greater growth of children, lower death rates at all ages, and a higher proportion of Americans living to old age than ever before.

Can diet cause chronic

diseases ?

Chronic and degenerative diseases, nonetheless, are our major medical problems. Almost 65 percent of Americans will die from heart disease, stroke or cancer. These diseases are associated with aging. Mortality from them has risen steadily as the proportion of elderly people in the population has increased. When w-e take into account the increased numbers of elderly, however, we find that death rates from heart disease and stroke have been declining since the 1940s. Also, mortality from most cancers has remained unchanged or gone down.

Since more than half of us live beyond age 75, many of us must be resistant to these diseases. Those who die at an early age must be particularly susceptible. This great variability in resistance is largely hereditary; it cannot be explained bydifferences in diet. Diet is only one of more than 20 risk factors that have been identified for heart disease. Efforts to prevent these diseases by dietary methods have not been highly successful. They are complex diseases; their basic causes are not known. Most of those who are susceptible to them require comprehensive medical care and drug treatment.

When people differ so greatly in susceptibility to chronic and degenerative diseases, can general dietaryguidelines for the entire population be effective in preventing them? Let us examine the situation with hypertension.

Restricting salt intake to 5 grams per day has been proposed as a guideline for the entire population for preventing this disorder. Most of us can consume much more than this without ill effect. About 15 percent of Americans, largely from families with a history of high blood pressure, will develop hypertension. Of these, only- about half benefit from reducing their intake of salt but usually it must be to well below 5 grams per day. Some respond to other dietary modifications. Many w-ho are overweight find that their blood pressure falls if they lose weight. Most of those with severe hypertension require treatment with drugs. With a problem this complex, is a general dietary guideline likely to be an effective preventive measure? It would seem necessary to identify those who are susceptible and to encourage them to seek the comprehensive care thev need.

Moderation, variety

and balance

Other guidelines we hear about frequently are: “avoid too much fat, saturated fat, cholesterol and sugar,” and “consume adequate amounts of starch and fiber.” Fat is a major source of energy - calories. Moderation in fat intake is a guideline for maintaining appropriate body weight. Poly-unsaturated fatty acids are essential nutrients. In order to maintain appropriate balance in our diets among the various types of fatty acids, the guideline for variety should also apply to fats. People with elevated blood cholesterol levels need more stringent therapeutic guidelines for controlling the fat and cholesterol content of their diets. General guidelines for the public, however, should not be replaced w-ith therapeutic guidelines. Infants and growing children have high energy needs; the caloric content of their diets should not be restricted.

Guidelines to eat adequate amounts of starch and not too much sugar are, in reality, guidelines for variety in carbohydrate consumption. Eating an adequate amount of fiber is important for maintaining a healthy digestive tract. The recommendation for variety in food selection - four servings of cereal grain products and four of fruits and vegetables daily - should assure appropriate balance for all of these.