| Food Composition Data: A User's Perspective (1987) |
|The uses of food composition data|
|Using food composition data to communicate nutrition to the consumer|
Interrelationships of nutrition education and food composition data
The NUTREDFO data base was specifically designed for use by professionals as a tool for nutrition guidance research, and for the development of nutrition guidance information and other technical nutrition information. Throughout the world the means by which we have communicated nutrition generally to the population has been a food grouping system . In the United States, the Department of Agriculture has traditionally developed food guides for the purpose of translating dietary allowances into a form which the consuming public can use to improve the nutritional balance of their diets. USDA food guides have evolved over time as a result of an increased understanding of human nutrient needs, food composition, and the relationship of diet to health . All the guides have emphasized that maintenance of good health depends upon consuming a varied diet that will provide adequate amounts of energy and essential nutrients.
The Basic Four Food Groups system, which is currently used in the United States , is based upon the balance concept, which assumes that an appropriate mixture of food items from each group will form the foundation of an adequate diet with respect to protein and certain vitamins and minerals for which dietary standards and adequate food composition data were available at the time of the plan's inception. Nutritionists designed the guide to provide approximately 1,200 kcal and at least 80 per cent of the eight nutrients which had Recommended Dietary Allowances (RDA) published in 1953 . These nutrients were protein, vitamin A, thiamine, riboflavin, niacin, vitamin C, calcium, and iron. Because of dietary inadequacies in calcium and vitamins A and C in the American population at that time, the food sources of these nutrients were emphasized - thus the formation of dairy and fruit and vegetable groups. Protein was also cited for specific attention in the meat group because diets containing animal protein sources were expected to contribute micro-nutrients that were difficult to obtain in sufficient amounts from other foods.
This food grouping system assumed that if the need for the key or "leader" nutrients (the basis of the four food groups) were met, then it was likely that requirements for other nutrients such as vitamins B6, B12. magnesium, zinc, folic acid, and pantothenic acid would also be satisfied . As new findings are reported on the functions of these other nutrients; as methodologies improve for quantifying these nutrients in foods and biological tissues; and as we examine current food consumption practices, and evaluate and develop diets and menus based on new data, indications are that the assumption behind food commodity groupings and so-called leader nutrients may no longer be valid.
In addition, diseases caused by deficiencies of leader nutrients are currently not the major nutritional concerns in the United States. Other diseases such as cancer, diabetes, hypertension, and heart disease have developed despite the widespread use of the food-group concept in nutrition education. The recent addition by the USDA of a fat, sugar, and alcohol group to the Basic Four addresses these concerns by helping the public become more aware of the dietary levels of nutrients that have been linked to public health problems.
In 1980, USDA and the Department of Health, Education and Welfare (now Health and Human Services) jointly issued recommendations entitled Dietary Guidelines for Americans . As with other dietary guidance materials, the guidelines are designed to help consumers make informed choices about foods. The object is to obtain the correct balance of vitamins, minerals, and dietary fibre, without overconsuming salt or calories, especially calories from fat, sugar, and alcohol.
An important companion publication to the Dietary Guidelines is Ideas for Better Eating: Menus and Recipes to Make Use of the Dietary Guidelines . The menus are designed for healthy adults. There are two versions of each day's menus, one providing 1,600 kcal and the other 2,400 kcal, reflecting the average amounts of energy from foods that women and men, respectively, reported consuming in recent food consumption surveys . Thus, these menus are designed not for weight reduction, but to reflect as closely as possible the recommendations in the Dietary Guidelines and RDA. The menus on average contain less than 35 per cent of calories as fat (as suggested in the text of the 1980 RDA), 50 per cent or more calories from carbohydrates, an average cholesterol content lower than the current average consumption, and sodium content within the 1,100 to 3,300 milligrams range recommended in the 1980 RDA publication.
The NUTREDFO data-base system was developed to analyse the menus in Ideas for Better Eating. A careful analysis of these menus indicated a number of problems. The protein content, and most vitamin and mineral content, varied between menus, but on average met or exceeded the 1980 RDA for adults. The exceptions were vitamin B6, folacin, iron, and zinc on the 1,600 kcal diet. Even though these values were low in the menus, they were not as low as usual consumption levels reported at a comparable level of calories in national surveys.
The advances that have been made in improving analytical data for a greater number of nutrients have identified new nutritional problems which, it seems, current nutritional guidance is not addressing or the food supply adequately providing. Nutritional guidelines must reflect current dietary concerns, which in part result from advances in food composition research. The question for nutrition education is, should we change the configuration of the food grouping system to emphasize the nutrients that are now of concern?
During the past few years, several articles have criticized commodity-based food grouping systems [7, 27, 35, 50]. Critics argue that food groups fail to assure nutritional adequacy and are of little relevance to current nutritional thinking. Some have suggested replacing commodity-based systems with nutrient-based systems, thus assuring individuals of a closer approximation to dietary standards .
However, commodity food groups have long been used as a basis for nutrition education; they are natural and easily recognized by people with little technical background in nutrition [1, 36]. Nevertheless, the variability of nutrient compositions within a commodity group can lead to inaccurate or misleading nutritional information. A summary of food composition that is based on both commodity groups and similarity in nutrient attributes can be very useful in understanding and explaining the nutritional structure of the food supply.