| Food Composition Data: A User's Perspective (1987) |
|The uses of food composition data|
|Food composition -a key to dietary appraisal and improvement in the United States|
USDA has for decades provided information to help Americans improve their food selections information based on knowledge of human nutritional requirements, food consumption, and food practices . The Dietary Guidelines published jointly by USDA and DHHS in 1980 and revised in 1985  advise Americans to: (a) eat a variety of foods; (b) maintain desirable weight; (c) avoid too much fat, saturated fat, and cholesterol; (d) eat foods with adequate starch and fibre; (e) avoid too much sugar; (f) avoid too much sodium; and (g) if you drink alcoholic beverages, do so in moderation.
Putting these guidelines into practice requires an understanding of the composition of foods. It is important to know the "good" sources of a nutrient - those foods of which a serving provides a substantial part of the day's need - and the "important" sources - those foods that make worthwhile contributions of a nutrient because substantial amounts of the food are consumed . "Important" nutrient sources have been identified by ranking the foods Americans consume by their average contribution of nutrients to the diet.
Eat a Variety of Foods
This is a simple guideline representing a complex food selection technique. What is intended is "Eat the kinds and amounts of foods that will provide the minerals and vitamins your body needs." If Americans are to select diets that provide the recommended amounts of essential nutrients, they must increase their understanding of food composition. To help them, educators must translate complex food composition tables, which were developed for researchers and professionals, into simpler forms .
Maintain Ideal Weight
NHANES estimates that one-fourth of all Americans are overweight . Weight control plans that call for a varied diet made up of low-calorie foods require the use of food composition tables. An USDA pocket calorie guide, Calories and Weight , gives such advice, as does Food 2: A Dieter's Guide .
Avoid Too Much Fat, Saturated Fat, and Cholesterol
Fat intakes over three days from our 1977/78 survey were generally above the 30 to 35 per cent of calories suggested by some authoritative groups . For example, among adults of 35 to 50 years of age, only 13 per cent of the males and 17 per cent of the females had fat intakes that provided less then 35 per cent of total calories . Over one-third of the respondents got 45 per cent or more of their calories from fat.
The amount of saturated fat in diets reported in NFCS has not been estimated. Average cholesterol intakes have been roughly estimated using the limited information available on the types of fats and oils consumed. Intakes are highest for adult males and teenage boys, at 400 to 525 mg per day [ 16].
Efforts to develop guidance that will help Americans avoid too much fat? saturated fat, and cholesterol are complicated by the occurrence of fat and cholesterol in many foods that are important for their contribution of nutrients in US diets. Solutions depend on knowing the fat, cholesterol, and vitamin and mineral content of foods. Food 3: Eating the Moderate Fat and Cholesterol Way addresses this issue .
Eat Foods with Adequate Starch and Fibre
When the fat in the diet is reduced, calories must come from other sources. This guideline stresses that the source should be foods rich in complex carbohydrates. Food composition tables identify these as dry beans and peas, nuts, seeds, vegetables, fruits, and grain products. Increasing the use of foods that are high in complex carbohydrate will also increase the amount of fibre in the diet. Food composition tables in Agriculture Handbook No. 8 have provided crude fibre values for some time; but these values are no longer considered useful. The content of dietary fibre, now believed to be more meaningful, is not known for many foods. To further complicate the matter, available values may not be comparable because of the lack of standard analytical methods. The new data file for the Continuing Survey provides the most up-to-date values for dietary fibre and imputes values where data are missing. However, the values are not sufficient at this time to estimate the dietary fibre content of American diets with any degree of precision.
Avoid Too Much Sugar
Sugar, as intended in this guideline, is not just sucrose but all caloric sweeteners eaten with foods or as ingredients in foods. The few composition tables that attempt to provide data on added sweeteners should be used with caution, since they are useful only for providing rough estimates of the intakes of added sweeteners in diets .
Avoid Too Much Sodium
The sodium content of diets is notably difficult to measure, but there is little doubt that Americans consume more sodium than they need . The amounts of sodium in many commercial products and those added in preparation and at the table are virtually unknown. Sodium Content of Your Food is a bulletin that provides sodium values for commonly used foods. Sodium, Think About It, published by the Food and Drug Administration and FSIS, groups foods by their sodium content for general guidance in following this dietary recommendation.
Food selection guides since the turn of the century have used food composition data as one of several bases. Atwater in 1894 suggested diets for the American male based on content of protein, carbohydrate, fat, and "mineral matter" . Other guides, including the Basic Four in the 1950s  and the Hassle-free Guide , focus on the types of foods that are important sources of vitamins and minerals. The Hassle-free Guide also considered calories, sugar, fat, sodium, and fibre. The dietary guidelines published in 1980  have been interpreted by USDA and DHHS at the federal level, by state extension services, by other local groups, and by the food industry. USDA efforts include consumer bulletins, such as Ideas for Better Eating , Food 2: A Dieter's Guide, Food 3: Eating the Moderate Fat and Cholesterol Way , and Sodium Content of Your Food .
The HNIS staff co-operated with the American Red Cross in developing a six-session nutrition course based on the dietary guidelines and other timely nutrition messages . This course, "Better Eating for Better Health," has been offered by local Red Cross chapters across the country, starting in 1984. Its food guidance system is a food wheel, with suggested servings from several groups of food. The wheel is supplemented with information on food composition and "trade-offs," or food substitutions - all based on food composition data .
The Extension Service - the educational arm of USDA - has nutrition specialists in every state and home economists in almost every county. Their nutrition-related mission is to improve food management skills, the quality of diets, and the nutritional health of the public by transferring research-generated knowledge. They help the public to understand how foods that differ in nutrient content can be combined in diets that are nutritionally sound. Food composition data are fundamental to the development of these educational messages. Many states have developed interactive computer programs for appraising the nutritional quality of diets, and use these programs as educational tools. HNIS and the Extension Service are initiating a joint project for a diet assessment system using data bases that will be updated regularly.