Summary and Recommendations This Report addresses the substantial impact of daily dietary patterns on the health of Americans. Good health does not always come easily. It is the product of complex interactions among environmental, behavioral. social, and genetic factors. Some of these are, for practical purposes, beyond personal control. But there are many ways in which each of us can influ- ence our chances for.good health through the daily choices we make. In recent years, scientific investigations have produced abundant informa- tion `on the ways personal behavior affects health. This information can help us decide whether to smoke, when and how much to drink, how far to walk or climb stairs, whether to wear seat belts. and how or whether to engage in any other activity that might alter the risk of incurring disease or disability. For the two out of three adult Americans who do not smoke and do not drink excessively, one personal choice seems to influence long-term health prospects more than any other: what we eat. Food sustains us. it can be a source of considerable pleasure, it is a reflection of our rich social fabric and cultural heritage, it adds valued dimensions to our lives. Yet what we eat may affect our risk for severai of the leading causes of death for Americans, notably, coronary heart disease, stroke, atherosclerosis, diabetes, and some types of cancer. These disor- ders together now account for more than two-thirds of all deaths in the United States.' Undeinutrition remains a problem in several parts of the world, as well as for certain Americans. But for most of us the more likely problem has become one of overeating--too many calories for our activity levels and an imbalance in the nutrients consumed along with them. Although much is still uncertain about how dietary patterns protect or injure human health, enough has been learned about the overall health impact of the dietary patterns now prevalent in our society to recommend significant changes in those patterns. This first Surgeon General's Report on Nutrition and Health offers com- prehensive documentation of the scientific basis for the recommended dietary changes. Through the extensive review contained in its chapters, the Report examines in detail current knowledge about the relationships among specific dietary practices and specific disease conditions and sum- 1 O Nutrition and Health marizes the implications of this information for individual food choices, public health policy initiatives, and further research. The Report's main conclusion is that overconsumption of certain dietary components is now a major concern for Americans. While many food factors are involved, chief among them is the disproportionate consumption of foods high in fats, often at the expense of foods high in complex carbohydrates and fiber that may be more conducive to health. A list of the key recommendations based on the evidence presented in the Report is provided in Table 1. Magnitude of the Problem Diet has always htid a vital influence on health. Until as recently as the 1940's, diseases such as rickets, pellagra, scurvy;beriberi. xerophthalmia, and goiter (caused by lack of adequate dietary vitamih D, niacin, vitamin C, thiamin, vitamin A, and iodine, respectively) were prevalent in this country and throughout the world. Today, thanks to an abundant food supply, fortification of some foods with critical trace nutrients, and better methods for determining and improving the nutrient content of foods, such "defi- ciency" diseases have been virtually eliminated in developed countries. For example, the introduction of iodized salt in the 1920's contributed greatly to eliminating iodine-deficiency goiter as a public health problem in the United States. Similarly, pellagra disappeared subsequent to the dis- covery of the dietary causes of this disease. Nutrient deficiencies are reported rarely in the United States, and the few cases of protein-energy malnutrition that are listed annually as causes of death generally occur as a secondary result of severe illness or injury, child neglect, the problems of the house-bound aged, premature birth, alcoholism, or some combination of these factors. As the diseases of nutritional deficiency have diminished, they have been replaced by diseases of dietary excess and imbalance-problems that now rank among the leading causes of illness and death in the United States, touch the lives of most Americans, and generate substantial health care costs. Table 2, for example, lists the 10 leading causes of death in the United States in 1987. In addition to the five of these causes that scientific studies have associated with diet (coronary heart disease, some types of cancer, stroke, diabetes mellitus, and atherosclerosis), another three-cirrhosis of the liver, acci- dents, and suicides--have been associated with excessive alcohol intake. 2 Summary and Recommendations O Table 1 Recommendations Issues for Most People: o FLUS and cholesterol: Reduce consumption of fat (especially saturated fat) and cholesterol. Choose foods relatively o?? in these substances, such as vegeta- bles, fruits, whole grain foods, fish, poultry, lean meats. and low-fat dairy products. Use food preparation methods that add little or no fat. o Energy and weight control: Achieve and maintain a desirable body weight. To do so. choose a dietary pattern in which energy (caloric) intake is consistent with energy expenditure. To reduce energy intake, limit consumption of foods relatively high in calories, fats, and sugars, and minimize alcohol consumption. Increase energy expenditure through regular and sustained physical activity. o Complex carbohydrates andjiber: Increase consumption of whole grain foods and cereal products, vegetables (including dried beans and peas). and fruits. o Sodium: Reduce intake of sodium by choosing foods relatively low in sodium and limiting the amount of salt added in food preparation and at the table. o Alcohol: To reduce the risk for chronic disease, take alcohol only in modera- tion (no more than two drinks a day), if at all. Avoid drinking any alcohol be-. fore or while driving, operating machinery, taking medications. or engaging in any other activity requiring judgment. Avoid drinking alcohol while pregnant. Other Issues for Some People: o Fluoride: Community water systems should contain fluoride at optimal levels for prevention'of tooth decay. If such water is not available, use other appro- priate sources of fluoride. o Sugars: Those who are particularly vulnerable to dental caries (cavities), espe- cially children, should limit their consumption and frequency of use of foods high in sugars. o Calcium: Adolescent girls and adult women should increase consumption of foods high in calcium, including low-fat dairy products. 0 Iron: Children, adolescents, and women of childbearing age should be sure to consume foods that are good sources of iron, such as lean meats, fish, certain beans, and iron-enriched cereals and whole grain products. This issue is of sbecial concern for low-income families. 0 Nut&ion and Health Table 2 Estimated Total Deaths and Percent of Total Deaths for the 10 Leading Causes of Death: United States, 1987 Rank Cause of Death la Heart diseases (Coronary heart disease) (Other heart disease) 28 Cancers 3a Strokes 4b Unintentional injuries (Motor vehicle) (All others) ,5 Chronic obstructive lung diseases 6 Pneumonia and influenza 7a Diabetes mellitus 8" Suicide 9b Chronic liver disease and cirrhosis IOa Atherosclerosis Percent of Total Number Deaths 759.400 35.7 (5 11,700) (24.1) (747.700) (11.6) 476.700 22.4 148,700 7.0 92.500 4.4 (46.800) (2.2) (45.700) (2.2) 78.000 3.7 68.600 3,.2 37,800 1.8 29.600 1.4 26.000 I' 23.100 I:i . . . All causes 2,125,lOO 100.0 aCauses of death in which diet plays a part. Kauses of death in which excessive alcohol consumption plays a part. Source: National Center for Health Statistics, Monthly Vital Statistics Report, vol. 37, no. 1, April 25, 1988. Although the precise proportion attributable to diet is uncertain, these eight conditions accounted for nearly 1.5 million of the 2.1 million total deaths in 1887. Dietary excesses or imbalances also contribute to other problems such as high blood pressure, obesity, dental diseases, os- teoporosis, and gastrointestinal diseases. Together, these diet-related con- d&ions inflict a substantial burden of illness on Americans. For example: o Coronary Heart Disease. Despite the recent sharp decline in the death rate from this condition, coronary heart disease still accounts for the largest number of deaths in the United States. More than 1.25 million heart attacks occur each year (two-thirds of them in men), and more than 500,000 people die as a result. In 1985, illness and deaths from coronary heart disease cost Americans an estimated $49 billion in direct health care expenditures and lost productivity. o Stroke. Strokes occur in about 500,000 persons per year in the United States, resulting in nearly 150,000 deaths in 1987 and long-term dis- ability for many individuals. Approximately 2 million living Americans suffer from stroke-related disabilities, at an estimated annual cost of more than $11 billion. 4 Summary and Recommendations O o Higlz Blood Pressure. High blood pressure (hypertension) is a major risk factor for both heart disease and stroke. Almost 58 million people in the United States have hypertension, including 39 million who are under age 65. The occurrence of hypertension increases with age and is higher for black Americans (of which 38 percent are hypertensive) than for white Americans (29 percent). o Cancer. More than 475,000 persons died of cancer in the United States in 1987, making it the second leading cause of death in this country. During the same period, more than 900,000 new cases of cancer occurred. The costs of cancer for 1985 have been estimated to be $22 billion for direct health care; $9 billion in lost productivity due to treatment or disability, and $41 billion in lost productivity due to premature mortality, for a total cost of $72 billion. a Diabetes Mel&us. Approximately 11 million Americans have diabe- tes, but almost half of them have not been diagnosed. In addition to the nearly 38,000 deaths in 1987 attributed directly to this condition, diabetes also contributes to an estimated 95,000 deaths per year from associated cardiovascular and kidney complications. In 1985, diabetes was estimated to cost $13.8 billion per year. or about 3.6 percent of total health care expenses. o Obesity. Obesity affects approximately 34 million adults ages 20 to 74 years in the United States, with the highest rates observed among the poor and minority groups. Obesity is a risk factor for coronary heart disease, high blood pressure, diabetes, and possibly some types of cancer as well as other chronic diseases. o Osteoporosis. Approximately 15 to 20 million Americans are affected by osteoporosis, which contributes to some I .3 million bone fractures per year in persons 45 years and older. One-third of women 65 years and older have vertebral fractures. On the basis of x-ray evidence, by age 90 one-third of women and one-sixth of men will have suffered hip fractures, leading to death in 12 to 20 percent of those cases and to long-term nursing care for many who survive. The total costs of osteoporosis to the U.S. economy were estimated to be $7 to $10 billion in 1983. o Dental Diseases. Dental caries and periodontal disease continue to affect a large proportion of Americans and cause substantial pain, restriction of activity, and work loss. Although dental caries among children, as well as some forms of adult periodontal disease, appear to be declining, the overall prevalence of these conditions imposes a substantial burden on Americans. The costs of dental care were esti- mated at $21.3 billion in 1985. O Nutrition and Health o Diverricular Disease. Because most persons with diverticular disease do not have symptoms, the true prevalence of this condition is un- known. Frequency increases with age. and up to 70 percent of people between the ages of 40 and 70 may be affected. In 1980, diverticulosis was accountable for some 2OO;OOO hospitalizations. In assessing the role that diet might play in prevention of these conditions, it must be understood that they are caused by a combination (and interac- tion) of multiple environmental, behavioral, social. and genetic factors. The exact proportion that can be attributed directly to diet is uncertain. Although some experts have suggested that dietary factors overall are responsible for perhaps a third or more of a11 cases of cancer, and similar estimates have been made for coronary heart disease, such suggestions are based on interpretations of research studies that cannot completely dis- tinguish dietary from genetic, behavioral, or environmental causes. We know, for example, that cigarette smoking exerts a powerful influence on the occurrence of both coronary heart disease and some types of cancer. We also know that some people are genetically predisposed to coronary heart disease, stroke, and diabetes and that the interaction of genetic predisposition with dietary patterns is an important determinant of individ- ual risk. For these reasons, it is not yet possible to determine the proportion of chronic diseases that could be reduced by dietary changes. Nonetheless, it is now clear that diet contributes in substantial ways to the development of these diseases and that modification of diet can contribute to their prevention. The magnitude of the health and economic cost of diet-related disease suggests the importance of the dietary changes suggested. This Report reviews these issues in detail. Nature of the Evidence Whereas centuries of clinical observations and decades of basic and clinical research prove that dietary deficiencies of single, identifiable nutrients can cause disease, research on the relationship of dietary excesses and imbal- ances to chronic disease yields results that rarely provide such direct proof of causality. Instead, investigators must piece together various kinds of information from several kinds of sources. Nevertheless, the quantity of current animal, laboratory, clinical, and epidemiologic evidence that as- sociates dietary excesses and imbalances with chronic disease is substan- tial and, when evaluated according to established principles, compelling. Scientists must often draw inferences about the relationships between dietary factors and disease from laboratory animal studies or human meta- 6 Summary and Recommendations O bolic and population studies that approach the issues indirectly. Data sources for'such human studies include clinical and laboratory measure- ments of physiologic indicators of nutritional status or risk factors, as well as dietary intake data estimated for populations or individuals. Epi- demiologic studies using these data compare dietary intake and disease rates in different countries or in defined groups within the same country. Interpretations of animal studies are limited by uncertainties about their applicability to people. Clinical, laboratory, and dietary intake studies can provide useful information, but each has limitations. Currently available clinical and laboratory measurements reveal only a small part of the com- plex physiological responses to diet, and they may reflect past rather than current nutritional status. Dietary surveys depend on accurate recall of the types and portion sizes of consumed foods as well as on the assumption that the food intake during any one period represents typical intake. Reported intake, however,' is not always accurate, and intake reported for a given period may differ significantly from that typical of longer time periods. Dietary intake data provide useful indicators for populations. but even when an association or correlation between a dietary factor and a disease is observed, it is often difftcult to prove that the dietary factor is an actual or sole cause of that disease. This difference between association and causation is basic to understand- ing the scientific evidence that links diet to chronic disease. Uncertainties in the ability to determine causation have sometimes made it difftcult to achieve consensus on appropriate public health nutrition policies. Estab- lished principles require evaluation of the supporting evidence for a given association between a dietary factor and a disease on the basis of its consistency, strength, specificity, and biological plausibility. The evidence showing that dietary intake of saturated fat raises blood cholesterol, which in turn increases the chance of coronary heart disease, illustrates this point. The similarity in results from laboratory, clinical, and epidemiologic research, the apparent relationship between dose and effect in these stud- ies, the observations that the increase in blood cholesterol level is specific to saturated fatty acids but not to other types, and the biological plausibility of explanations for the observations, when taken together, provide consid- erable support for concluding that the association is causal, at least for some individuals. For some of the other diseases reviewed in this Report, the available evidence is less complete and less consistent. Nevertheless, much evi- dence supports credible associations between a dietary pattern of excesses 7 O Nutrition and Health and imbalances and several important chronic diseases. These associa- tions, in turn, suggest that the overall health of Americans could be im- proved by a few specific but fundamental dietary changes. Key Findings and Recommendations Even though the results of various indivjdual studies may be inconclusive, the preponderance of the evidence presented in the Report's comprehen- sive scientific review substantiates an association between dietary factors and rates of chronic diseases. In particular. the evidence suggests strongly that a dietary pattern that contains excessive intake of foods high in calories, fat (especially saturated fat), cholesterol. and sodium, but that is low in complex carbohydrates and fiber, is one thaf contributes signifi- cantly to the high rates of major chronic diseases among Americans. It alsd suggests that reversing such dietary patterns should lead to a reduced incidence of thkse chronic diseases. This Surgeon General's Report on Nutrition and Health provides a com- prehensive review of the most important scientific evidence in support of current Federal nutrition policy as stated in the Dietary Grridelines for Americans. These Guidelines, issued jointly by the Department of Agri- culture and the Department of Health and Human Services, recommend: o Eat a variety of foods. o Maintain desirable weight. o Avoid too much fat, saturated fat. and cholesterol. o Eat foods with adequate starch and fiber. o Avoid too much sugar. o Avoid too much sodium. o If you drink alcoholic beverages, do so in moderation. Evidence presented in this Report expands the focus of these seven guide- lines and provides considerable insight into priorities. Clearly emerging as the primary priority for dietary change is the recommendation to reduce intake of total fats, especially saturated fat, because of their relationship to development of several important chronic disease conditions. Because excess body weight is a risk factor for several chronic diseases. mainte- nance of desirable weight is also an important public health priority. Evi- dence further supports the recommendation to consume a dietary pattern that contains a variety of foods, provided that these foods are generally low in calories, fat, saturated fat, cholesterol, and sodium. 8 Summary and Recommendations O Taken together, the recommendations in this Report promote a dietary pattern that emphasizes consumption of vegetables, fruits, and whole grain prdducts-foods that are rich in complex carbohydrates and fiber and relatively low in calories-and of fish, poultry prepared without skin. lean meats, and low-fat dairy products selected to minimize consumption of total fat, saturated fat. and cholesterol. The evidence presented in this Report suggests that such overall dietary changes will lead to substantial improvements in the nutritional quality of the American diet. Consuming a higher proportion of calories from fruits, vegetables, and grains may lead to a modest reduction in protein intake for some people, but this reduction is unlikely to impair nutritional status. Average levels of protein consumption in the United States. 60 grams per day for women and 90 grams per day for men. are well above the National Research Council's recommendations of 44 and 56 grams per day, respec- tively. The evidence also suggests that most Americans generally need not con- sume nutrient supplements. An estimated 40 percent of Americans con- sume supplemental vitamins, minerals, or other dietary components at an annual cost of more than $2.7 billion. Although nutrient supplements are usually safe in amounts corresponding to the Recommended Dietary Al- lowances (and such Allowances are set to ensure that the nutrient needs of practically all the population are met), there are no known advantages to healthy people consuming excess amounts of any nutrient, and amounts greatly exceeding recommended levels can be harmful. For example, some nutrients such as selenium have a narrow range of safe level of intake. Toxicity has been reported for most minerals and trace elements, as well as some vitamins, indicating that excessive supplementation with these sub- stances' can be hazardous. Finally, some recommendations for dietary change apply broadly to the general public whereas others apply only to specific population groups. These major findings and recommendations of The Swgeon General's Report on Nutrition and Health are noted below. Issues for Most People o Fats and cholesterol: Reduce consumption of fat (especially saturated fat) and cholesterol. Choose foods relatively low in these substances, such as vegetables, fruits, whole grain foods, fish, poultry, lean meats, and low- fat dairy products. Use food preparation methods that add little or no fat. 9 O Nutrition and Health High intake of total dietary fat is associated with increased risk for obesity, some types of cancer, and possibly gallbladder disease. Epidemiologic. clinical, and animal studies provide strong and consistent evidence for the relationship between saturated fat intake, high blood cholesterol, and increased risk for coronary heart -disease. Conversely, reducing blood cholesterol levels reduces the risk for death from coronary heart disease. .Excessive saturated fat consumption is the major dietary contributor to total blood cholesterol levels. Dietary cholesterol raises blood cholesterol levels, but the effect is less pronounced than that of saturated fat. While polyunsaturated fatty acid consumption, and probably monounsaturated fatty acid consumption, lowers total blood cholesterol, the precise effects of specific fatty acids are not well defined. Dietary fat contributes more than twice as many calories as equal quanti- ties (by weight) of either protein or carbohydrate, and some studies indicate that diets high in total fat are associated with higher obesity rates. In addition, there is substantial, although not yet conclusive, epidemiologic and animal evidence in support of an association between dietary fat intake and increased risk for cancer, especially breast and colon cancer. Similarly, epidemiologic studies suggest an association between gallbladder disease, excess caloric intake, high dietary fat, and obesity. More precise conclu- sions about the role of dietary fat await the development of improved methods to distinguish among the contributions of the high-calorie, high- fat, and low-fiber components of current American dietary patterns. At present, dietary fat accounts for about 37 percent of the total energy intake of Americans-well above the upper limit of 30 percent recom- mended by the' American Heart Association and the American Cancer Society, and above the percent consumed by many societies, such as Mediterranean countries, Japan, and China, for example, where coronary heart disease rates are much lower than those observed in the United States. Consumption of saturated fat and cholesterol is also substantially higher among many Americans than levels recommended by several expert groups. The major dietary sources of fat in the American diet are meat, poultry, fish, dairy products, and fats and oils. Animal products tend to be higher in both total and saturated fats than most plant sources. Although some plant fats such as coconut and palm kernel oils also contain high proportions of saturated fatty acids, these make minor contributions to total intake of saturated fats in the United States. Dietary cholesterol is found only in foods of animal origin, such as eggs, meat, poultry, fish, and dairy prod- 10 Summary and Recommendations O ucts. To help reduce consumption of total fat. especially saturated fat and cholesterol, food choices should emphasize intake of fruits. vegetables. and whole grain products and cereals. They should also emphasize con- sumption of fish, poultry prepared without skin, lean meats, and low-fat dairy products. Among vegetable fats, those that are more unsaturated are better choices. o Energy and weight control: Achieve and maintain a desirable body weight. To do so, choose a dietary pattern in which energy (caloric) intake is consistent with energy expenditure. To reduce energy intake, limit consumption of foods relatively high in calories, fats, and sugars and minimize alcohol consumption. Increase energy expenditure through regular and sustained physical activity. People are considered overweight if their body mass index, or BMI (a ratio of weight to height described in the Report), exceeds the 85th percentile for young American adults (approximately 120 percent of desirable body weight); they are considered severely overweight if their BMI exceeds the 95th percentile (approximately 140 percent of desirable body weight). Overweight individuals are at increased risk for diabetes mellitus. high blood pressure and stroke, coronary heart disease, some types of cancer, and gallbladder disease. Epidemiologic and animal studies have shown consistently that overall risk for death is increased with excess weight, with risk increasing as severity of obesity increases. Type II (noninsulin-dependent) diabetes mellitus accounts for approxi- mately 90 percent of all cases of diabetes and is strongly associated with obesity. Clinical studies indicate that weight loss can improve control of Type II diabetes. Obesity increases the risk for high blood pressure, and consequently for stroke; it also increases blood cholesterol levels associated with coronary heart disease. In addition, it appears to be an independent risk factor for coronary heart disease. Weight reduction has been shown to reduce high blood pressure and high blood cholesterol. Most obese individuals who achieve a more desirable body weight improve their cholesterol profile, achieving a decrease in both total blood cholesterol and LDL (low density lipoprotein) cholesterol. Some studies have found an association between overweight and increased risk for several cancers, especially cancer of the uterus and breast. In addition, overweight increases the risk for gallbladder disease. 11 Ll Nutrition and Health More than a. quarter of American adults are overweight. Black women age 4.5 and above have the highest prevalence, about 60 percent. Although evidence suggests a genetic component to the tendency of many people to become overweight, patterns of dietary caloric intake and energy expendi- ture play a key role. Sustained and Iang- term efforts to reduce body weight can best be achieved as a result of improving energy balance by reducing energy consumption and raising energy expenditure through physical ac- iivity arid exercise. Maintenance of desirable body weight throughout the lifespan requires a balance between energy (calorie) intake and expenditure. Weight control may be facilitated by decreasing energy intake, especially by choosing foods relatively low in calories, fats, and sugars, and by minimizing alcohol consumption. Energy expenditure can be enhanced thrbugh regular phys- ical activities such as daily walks or by jogging, bicycling, or swimming at least three times a week for at least 20 minutes. o Complex carbohydrates andfiber: Increase consumption of whole grain foods and cereal products, vegetables (including dried beans and peas), and fruits. Dietary patterns emphasizing foods high in complex carbohydrates and fiber are associated with lower rates of diverticulosis and some types of cancer. The association shown in epidemiologic and animal studies be- tween diets high in complex carbohydrates and reduced risk for coronary heart disease and diabetes mellitus is, however, difficult to interpret. The fact that such diets tend also to be lower in energy and fats, especially saturated fat and cholesterol, clearly contributes to this difficulty. Some evidence from clinical studies also suggests that water-soluble fibers from foods such as oat bran, beans, or certain fruits are associated with lower blood glucose and blood lipid levels. Consuming foods with dietary fiber is usually beneficial in the management of constipation and diverticuiar dis- ease. While inconclusive, some evidence also suggests that an overall increase in intake of foods high in fiber might decrease the risk for colon cancer. Among several unresolved issues is the role of the various types of fiber, which differ in their effects on water-holding capacity, viscosity, bacterial fermentation. and intestinal transit time. Other food components associated with decreased cancer risk are com- monly found in diets high in whole grain cereal products containing com- plex carbohydrates and fiber. In addition, some epidemiologic evidence 12 Summary and Recommendations O suggests that frequent consumption of vegetables and fruits, particularly dark green and deep yellow vegetables and cruciferous vegetables (such as cabbage and broccoli), may lower risk for cancers of the lung and bladder as well as some cancers of the alimentary tract. However, the specific compo- nents in these foods that may have protective effects have not yet been established. Current evidence suggests the prudence of increasing con- sumption of whole grain foods and cereals, vegetables (including dried beans and peas), and fruits. 0 Sodium: Reduce intake of sodium by choosing foods relatively low in sodium and limiting the amount of salt added in food preparation and at the table. Studies indicate a relationship between a high sodium intake and the occurrence of high blood pressure and stroke. Salt contains about 40 percent sodium by weight and is used widely in the preservation, process- ing, and preparation of foods. Although sodium is necessary for normal metabolic function, it is consumed in the United States at levels far beyond the 1.1 to 3.3 grams per day found to be as safe and adequate for adults by the National Research Council. Average current sodium intake for adults in the United States is in the range of 4 to 6 grams per day. Blacks and persons with a family history of high blood pressure are at greater risk for this condition. While some people maintain normal blood pressure levels over a wide range of sodium intake, others appear to be "salt sensitive" and display increased blood pressure in response to high sodium intakes. Although not ail individuals are equally susceptible to the effects of so- dium, several observations suggest that it would be prudent for most Americans to reduce sodium intake. These include the lack of a practical biological marker for individual sodium sensitivity, the benefit to persons whose blood pressures do rise with sodium intake, and the lack of harm from moderate sodium restriction. Processed foods provide about a third or more of dietary sodium. Because about another third of the sodium consumed by Americans is added by the consumer, much can be done to reduce sodium consumption by using less salt at the table and substituting alternative flavoring such as herbs, spices, and lemon juice in the preparation of foods. In addition, choices can be made of foods modified to lower sodium content and less frequent choices could be made of foods to which sodium is added in processing and preservation. 13 O Nutrition and. Health o Alcohol:' To reduce the risk for chronic disease, take alcohol only in moderation (no more than two drinks a day), if at all. Avoid drinking any alcohol before or while driving, operating machinery, taking medica- tions, or engaging in any other activity requiring judgment. Avoid drink- ing alcohol while pregnant. Alcohol is a drug that can produce addiction in susceptible individuals, birth defects in some children born to mothers who drink alcohol during pregnancy, impaired judgment, impaired ability to drive automobiles or operate machinery, and adverse reactions in people taking certain medica- tions. In addition, alcohol abuse has been associated with disrupted family functioning, suicides, and homicides. Excessive use of alcohol is also associated with liver disease, some types of cancer, high blood pressure, stroke, and disorders of the heart muscle. Extensive epidemiologic and clinical evidence has identified alcohol con- sumption as the @-incipal cause of liver cirrhosis in the United States, at least in part as a result of the direct toxic effects of alcohol on the liver. Smoking and alcohol appear to act synergistically to increase the risk for cancers of the mouth, larynx, and esophagus. Less conclusive and some- what conflicting evidence suggests a role of alcohol in other types of cancers such as those of the liver, rectum, breast, and pancreas. Studies indicate a direct association between increased blood pressure and the consumption of alcohol at levels beyond about two drinks? daily. Extremely excessive alcohol consumption is associated with cardiomyop- athy. Alcohol consumption by the mother during pregnancy has also been associated with fetal malformations. Although consumption of up to two drinks per day has not been associated with disease among healthy men and nonpregnant women, surveys suggest that at least 9 percent of the total population consumes two or more drinks per day and those in this group need to reduce their alcohol consumption. A threshold level of safety for alcohol intake during pregnancy has not been established. Thus, pregnant women and women who may become pregnant should avoid drinking alcohol. aOne drink is defined as a 12 ounce beer, a5 ounce glass of wine, or 1 `/z fluid ounces (one jigger) of distilled spirits, each of which contains about I ounce of alcohol. 14 Summary and Recommendations O Other Issues for Some People o Fluoride: Community water systems should contain fluoride at optimal levels for prevention of tooth decay. If such water is not available, use other appropriate sources of fluoride. The most efficient means of making fluoride available to the general public to reduce dental disease is through drinking water. Numerous epidemiolog- ic and clinical studies have attested to the efficacy, safety and cost-effec- tiveness of systemic fluoride in the prevention of tooth decay. Lifetime use of water containing an optimal fluoride concentration of approximately 1 part per million has been shown to reduce the prevalence of dental caries by more than 50 percent. Water fluoridation is considered one of the most successful public health efforts introduced in the United States. For children living in areas with inadequate concentrations of fluoride in the water, supplementary fluoride sources should be used at dosages that depend on the fluoride content of the local water supply and the age of the child. The effectiveness of prenatal fluoride administration, however, is uncertain because clinical studies of its effects on subsequent caries inci- dence have been equivocal. Excessive fluoride should be avoided because it may cause mottling of developing teeth. o Sugars: Those who are particularly vulnerable to dental caries (cavities), especially children, should limit their consumption and frequency of use of foods high in sugars. Although genetic, behavioral, and other dietary factors also influence dental health, the major role of sugars in promotion of tooth decay is well established from animal, epidemiologic, clinical, and biochemical studies. Newly erupting teeth are generally more vulnerable to decay than mature teeth. Research has shown that three conditions must exist for the formation of dental caries: the presence of fermentable carbohydrate, acid-producing bacteria, and a susceptible tooth. Caries-producing bacteria metabolize a range of sugars (glucose, fructose, maltose, lactose, and sucrose) to acids that demineralize teeth. The unique role of sucrose (common table sugar) in dental caries is related to its special ability to be converted by these bacteria into long, complex molecules that adhere firmly to teeth and form plaque. 15 0 Nutrition and Health The most important diet-related interventions are fluoridation of drinking water, or the use of other means of fluoride administration, and control of intake of sugars. While fluoride is the most important factor overall in dental caries prevention, reduction in the frequency of consumption and in the quantity of sugar-rich foods in the diet will also help reduce decay. Sticky sweet foods that adhere to the teeth are more cariogenic than those that wash-off quickly. The longer cariogenic foods remain in the mouth, the more they .are likely to increase the initiation and progression of tooth decay. o Calcium: Adolescent girts and adult women should increase consumption of foods high in calcium, including low-fat dairy products. Inadequate dietary calcium consumption in the first thre'e to four decades of life may be associated with increased risk for osteoporosis in later life. Osteoporosis, a chronic disease characterized by progressive loss of bone mass with aging, &curs in both women and men, although postmenopausal women are twice as likely as men to have severe osteoporosis with conse- quent bone fractures. Evidence shows that chronically low calcium intake, especially during adolescence and early adulthood, may compromise de- velopment of peak bone mass. In postmenopausal women, the group at highest risk for osteoporosis, estrogen replacement therapy under medical supervision is the most effective means to reduce the rate of bone loss and risk for fractures. Maintenance of adequate levels of physical activity and cessation of cigarette smoking have also been associated with reduced osteoporosis risk. Although the precise relationship of dietary calcium to osteoporosis has not been elucidated, `it appears that higher intakes of dietary calcium could increase peak bone mass during adolescence and delay the onset of bone fractures'later in life. Thus, increased consumption of foods rich in calcium may be especially beneficial for adolescents and young women. Food sources of calcium consistent with other dietary recommendations in this Report include low-fat dairy products, some canned fish, certain vegeta- bles, and some Calcium-enriched grain products. 0 Iron: Children, adolescents, and women of childbearing age should be sure to consume foods that are good sources of iron, such as lean meats, fish, certain beans, and iron-enriched cereals and whole grain products. This issue is of special concern for low-income families. Dietary iron deficiency is responsible for the most prevalent form of anemia in the United States. Iron deficiency hampers the body's ability to produce hemoglobin, a substance needed to carry oxygen in the blood. A 16 Summary and Recommendations O principal, consequence of iron deficiency is reduced work capacity, al- though depressed immune function, changes in behavior, and impaired intellectual performance may also result. Because of the serious conse- quences of iron deficiency, continual monitoring of the iron status of individuals at high risk-particularly children from low-income families, adolescents, and women of childbearing age-is vital. as is treatment of those identified to be iron deficient. Proper infant feeding-preferably breastfeeding, otherwise use of iron- fortified formula-is the most important safeguard against iron deficiency in infants. Among adolescents and adults, iron intake can be improved by increasing consumption of iron-rich foods such as lean meats, fish, certain kinds of beans, and iron-enriched cereals and whole grain products. Also, consuming foods that contain vitamin C increases the likelihood that iron will be absorbed efftciently. Policy Implications Dietary Guidance General Public Educating the public about the dietary choices most conducive to preven- tion and control of certain chronic diseases is essential. Educational efforts should begin in primary school and continue throughout the secondary grades, and should focus on the dietary principles outlined in this Report- the potential health benefits of eating a diet that is lower in fat (especially saturated fat) and rich in complex carbohydrates and fiber. The importance of ade.quate physical activity should also be stressed. Efforts should con- tinue throughout each stage of life to promote the principles outlined in the Dietary Guidelines for Americans. Special Populations A disproportionate burden of diet-related disease is borne by subgroups in our population. Black Americans, for example, have higher rates of high blood pressure, strokes, diabetes, and other diseases associated with obesity (but lower rates of osteoporosis) than the general population. Some groups of Native Americans exhibit the highest rates of diabetes in the world. Pregnant and lactating women also have special nutritional needs. Particular effort should be made to identify and remove the barriers to optimal health and nutritional status in such high-risk groups, using meth- ods that take into consideration their diverse cultural backgrounds. 17 tl Nutritioil and Health Many older persons suffer from chronic diseases that can reduce functional independence; many take multiple medications that may adversely interact with'nutrients. Sound public education directed toward this group-and professional education directed toward individuals who care for older Americans-should focus on dietary .means to reduce risk factors for chronic disease, to promote functional independence, and to prevent ad- verse consequences of use of medications. Health Professionals Improved nutrition training of physicians and other health professionals is needed, Training should emphasize basic principles of nutrition, the role of diet in health promotion and disease prevention, nutrition assessment methodologies and their interpretation, therapeutic aspeAs of dietary in- tervention, behavioral aspects of dietary counseling, and the role of dieti- tians and nutritionists in dietary counseling of patients. Programs and Services Food Labels -Food labeling offers opportunities to inform people about the nutrient content of foods so as to facilitate dietary choices most conducive to health. Food manufacturers should be encouraged to make full use of nutrition labels. Labels of processed foods should state the content of calories, protein, carbohydrate, fats, cholesterol, sodium, and vitamins and miner- als. To the extent permitted by analytical methods, manufacturers should disclose information where appropriate on the content of saturated and unsaturated fatty acids and total fiber in foods that normally contain them. Descriptiye terms such as "low calorie" and "sodium reduced" in compli- ance with the-Food and Drug Administration's regulations for food labeling may also be helpful, and the expanded use of these terms should be encouraged. Nutrition Services Health care programs for individuals of all ages should include nutrition services such as, when appropriate, nutrition counseling for individuals or groups, interpretation and implementation of prescribed therapeutic diets tailored to individual food preferences and lifestyle, referral to appropriate community services and food assistance programs, monitoring of prog- ress, and appropriate followup. These services should routinely incorpo- rate assessment of nutritional status and needs based on established criteria 18 Summary and Recommendations O to identify individuals with nutritional risk factors who would profit from preventive measures and those with nutritional disorders who need re- medial care. Food Services Lack of access to an appropriate diet should not be a health problem for any American. Wherever food is served to people or provided through food assistance programs, it should reflect the principles of good nutrition stated in this Report. Whether served in hospitals, schools, military installations, soup kitchens, day care.centers, or nursing homes, or whether delivered to homes, food service programs offer important opportunities for improving health and providing dietary education. Such programs should pay special attention to the nutritional needs of older people, pregnant women, and children, especially those of low income or other special dietary needs. Because a large proportion of the population takes meals in restaurants and convenience `food facilities, improvements in the overall nutritional bal- ance of the meals served in such places can be expected to contribute to health benefits. Food service programs should also take particular care to ensure that special diets lower in fat, especially saturated fat, are provided to people with elevated blood cholesterol, heart disease, or diabetes; that diets low in sodium are provided to individuals with high blood pressure: and that protein-restricted diets are made available to people with end-stage kidney disease. Food Prodycts The public would benefit from increased availability of foods and food products low in calories, total fat, saturated fat, cholesterol, sodium, and sugars, but high in a variety of natural forms of fiber and, perhaps, certain minerals and vitamins. Food manufacturers can contribute to improving the quality of the American diet by increasing the availability of palatable, easily prepared food products that will help people to follow the dietary principles outlined here. Because the public is becoming increasingly conscious of the role of nutrition in health, development of such products should also benefit the food industry. Research and Surveillance Impressive evidence already links nutrition to chronic disease. However, much more information is needed to continue to identify changes in the 19 0 Nutrition and Health national diet that will lead to better health for the Nation. Gaps in our knowledge of nutrition suggest future research and surveillance needs. Examples are: o The role of specific dietary factors in the etiology and prevention of chronic diseases. o The childhood dietary pattern that will best prevent later development of chronic diseases. o The effects of maternal nutrition on the health of the developing fetus. o The nutrient and energy requirements of older adults. o How nutrient requirements translate into healthful dietary patterns. o The development of biochemical markers of dietary intake to monitor better the effects of dietary intervention. o The identification of effective educational methods to translate dietary recommendations into appropriate food choices. o The establishment of a nutrition surveillance system that will enhance the monitoring of population-specific and State-specific trends in the occurrence of nutrition-related risk factors and conditions. Specific research recommendations are listed at the end of each chapter of the full Report and in Appendix D of this volume. 20 Appendix A Selected Events in the History of Nutritional Science to 1950 c. 1500 B.C. c. 400 B.C. c. 300 B.C. c. 200 A.D. Papyrus Ebers contains prescription believed to refer to diabetes. Hippocrates wrote of relationship of diet to health. Beriberi described in ancient Chinese texts. Arataeus gave the name diabetes to the condition of "too much passing of urine." 1250 Joinville described scurvy among troops of Louis IX at the siege of Cairo. 1614 1650 1730 1747 Sanctorius published studies relating body weight to food intake. Glisson described rickets in De Rachitide. Casal described pellagra, calling it "ma1 de la rosa." Lind proved that citrus fruits cure scurvy in first controlled human dietary experiment. Menghini established presence of iron in blood. 1752 1780 Reaumur published experiments on digestion in birds. Spallanzani produced evidence that digestion was the chemical action of gastric juices. 1789 Lavoisier and Seguin make first measurements relating oxygen consumption to human energy metabolism. Cod liver oil used as treatment for rickets. 1796 Lemon juice officially introduced in British Navy to prevent SCUNY. 1807 Davy isolated sodium, potassium, calcium, magnesium, sulphur. and boron.. 1810-23 1810 1816 1827 1833 Chevreul studied chemistry of animal fats. Wollaston isolated cystic oxide (later named cystine) from urine- first amino acid discovered. Magendie identified dietary nitrogen requirements in dogs. Prom classified food constituents as saccharine, oily, and albuminous (sugar, fat, and protein). Beaumont reported observations and experiments on digestion in his patient St. Martin. 1838 Mulder introduced the term "protein." 21 0 Nutrition and Health 1839 1840 1843 1848 1849-57 1850 1850-52 1866-81 1867 1877 1885 1896 1897 1902 1909-28 1912 1914 1916 1918 1919-22 1921-24 1922 1928 1929 193 l-37 1932 Boussingault conducts first nitrogen balance studies in animals. Liebig published Animal Cherni.srv. stating basic principles of metabolism. Chossat studied the effect of starvation on the body using pigeons. Addison described pernicious anemia. Bernard elucidated digestive action of pancreatic juices and glycogenic function of liver. Livingstone described xerophthalmia (due to vitamin A deficiency) in Africa. Chatin in France used iodine to prevent goiter. Voit and Pettenkofer explained protein metabolism. Boussingault recognized iron as essential nutrient. Pavlov began classic studies on digestion in dogs. Takaki demonstrated in controlled dietary experiments with Japanese Navy sailors that beriberi could be prevented. Atwater and Bryant introduced their basic reference, Chemical Composition of American Food Materiuls. Eijkman published his work on causes of beriberi. Rubner showed that food components increased metabolism by different amounts. Osborne and Mendel studied the nutritive value of protein. Funk coined the term "vitamine." Goldberger established dietary cause of pellagra. M.cCollum and Davis and Osborne and Mendel discovered accessory dietary factors "fat-soluble A" and "water-soluble B." Mellanby showed that experimental rickets in dogs is due to lack of fat-soluble vitamin. Water-soluble B factor shown to be more than one factor. Blindness in children shown to be result of lack of vitamin A. McCollum identified vitamin D in cod liver oil. Goldberger identified pellagra-preventing factor in yeast. Role of intrinsic and extrinsic factors in pernicious anemia discovered. Fluoride content of drinking water identified as cause of mottled enamel of teeth and prevention of tooth decay. Vitamin C isolated from lemon juice. Warburg and Christian identified riboflavin and defined its molecular function. 22 Summary and Recommendations O 1933 1938 1941 Williams identified kwashiorkor as a nutritional disease. Rose classified amino acids as essential and nonessential. Evidence provided for the influence of prenatal diet on the health of the newborn infant. 1944-46 Keys and coworkers studied effects on young men of experimentally induced semistarvation and methods of dietary rehabilitation. 1945 194w9 Grand Rapids, Michigan, becomes the first city in the world to fluoridate its drinking water to prevent tooth decay. Crystalline vitamin B,2 isolated from liver extract and shown to contain cobalt. 1949 Framingham Study of coronary heart disease risk factors begins. 23 Appendix B Selected Federal Domestic Nutrition Policy Initiatives, 1862-1988 1862 1867 1887 1889 1893 1906 1914 1916 1917 1921-29 1924 1927 1930 1933 U.S. Department of Agriculture (USDA) created. Merrill Act establishes land grant colleges. Office of Education established with responsibilities for nutrition education within public schools. Hatch Act establishes agricultural experiment stations. Federal research laboratory established at Staten -Island. Name is changed to the National Institute of Health in 1930. U.S. Public Health Service Commissioned Corps authorized for duty on communicable, nutritional, and other diseases. USDA authorized by Congress to conduct research on agriculture and human nutrition. The Pure Food and Drug (Wiley) Act prohibits interstate commerce and misbranded and adulterated foods, drinks, and drugs. Federal Meat Inspection Act passed. Cooperative Extension Service created as part of USDA. USDA publishes Food for Young Children, first dietary guidance pamphlet. U.S. Food Administration established to supervise World War I food supply. First dietary recommendations issued by USDA-Five Food Groups. Maternity and Infancy Act enabled State health departments to employ nutritionists. Addition of iodine to salt to prevent goiter is first U.S. food fortification program. Food, Drug, and Insecticide Administration established. Name is changed to Food and Drug Administration (FDA) in 1932. USDA and Federal Emergency Relief Administration buy and distribute surplus agricultural commodities as food relief. Public Health Service Hygienic Laboratory designated as National Institute of Health (later changes to National Institutes of Health). Agricultural Act amendments permit purchase of surplus commodities for donation to child nutrition and school lunch programs. 25