The role of nutrition and diet in reducing the risk of certain chronic diseases, such as cardiovascular disease, diabetes mellitus, and some forms of cancer, has been well documented. The Dietary Guidelines and Food Guide Pyramid recommend the selection of foods from a variety of food groups, the choice of a diet that is low in fat, saturated fat, and cholesterol, and moderate use of salt and sodium.
The average American diet does not meet these recommendations. The American diet is high in total fat and saturated fat and low in fiber and complex carbohydrates. In addition, there has been no regular reporting of how well Americans have been doing in improving consumption patterns. Thus, USDA developed the Healthy Eating Index to provide a single summary measure of dietary quality. Prior to this, some instruments had been developed which evaluated specific diet components such as fat and cholesterol. Few instruments have been developed, however, which assess overall dietary quality.
In an effort to measure how well American diets conform to recommended healthy eating patterns, the U.S. Department of Agriculture (USDA) has developed an index, called the Healthy Eating Index. Based on different aspects of a healthful diet, the Index is designed to provide a measure of overall dietary quality. The Index provides a picture of foods people are eating, the amount of variety in the diet and compliance with specific dietary guidelines recommendations. Ten dietary components have been identified and are shown here.
The overall Index has a total possible score ranging from zero to 100. Each of the 10 dietary components has a scoring range of zero to 10. Individuals with an intake at the recommended level received a maximum score of 10 points. A score of zero was assigned when no foods in a particular group were eaten. Intermediate scores were calculated proportionately.
The Healthy Eating Index was applied to the 1989 and 1990 USDA data from the Continuing Survey of Food Intake by Individuals. The data are based on representative samples of 3,997 individuals in 1989 and 3,466 individuals in 1990.
The higher the score on the Healthy Eating Index, the better the diet conformed to the Dietary Guidelines for Americans and the Food Guide Pyramid.
The scores in the individual component categories of the Healthy Eating Index varied. Out of a possible score of 10, the average scores were as follows:
ITEM AVERAGE SCORE Grains.....................6.1 Vegetables.................6.1 Fruits.....................4.0 Milk.......................6.7 Meat.......................7.5 Total.Fat..................6.3 Saturated.Fat..............5.0 Cholesterol................7.9 Sodium.....................7.0 Variety....................7.0
Not only were a number of the average scores on the various components of the Healthy Eating Index low, but the percent of people meeting the recommended levels in any given category was also low. As shown in the table here:
There is an association between the Healthy Eating Index and a number of economic and demographic parameters:
Only 12 percent of Americans had scores on the Healthy Eating Index that were 80 or above. The average scores for the 2 years studied were similar at 63.8 and 63.9. One-third or less of the people surveyed consumed the suggested number of servings from the 5 major food groups. People were most likely to underconsume in the fruit, vegetable and grain groups. In addition, variety in the diet was limited and intakes of total fat and saturated fat were above recommended levels for more than 80 percent of the individuals studied.
Although the average Healthy Eating Index score for most people needs improvement, some individuals are at a higher risk of a low Index. Persons from low-income households, individuals with less education, and persons in the 15 to 39 years of age category were most likely to have lower average scores on the Healthy Eating Index.
Based on the most current scientific information available, including the Dietary Guidelines for Americans published by USDA and DHHS, and the Food Guide Pyramid, the Index was developed to provide a single summary measure of dietary quality. The Index is based on the five major food groups from the Food Guide Pyramid and the Dietary Guidelines. The Index is a practical standard for assessing dietary quality.
The Index correlates well with other conventional measures of diet quality. Comparisons with RDA levels confirm a positive correlation between the Index and individual nutrient intake levels. Higher Index scores are associated with improved nutrient intakes.
Ten dietary components comprise the Index. All 10 components contribute evenly to the overall Index score. Doing well on one component does not ensure a high score on the overall Index. Overall dietary quality is reflected in the total Index score and is not determined based on any individual component score. Using one component score, such as percent of calories from fat, as an indicator of dietary quality can result in misclassifications.
There is significant variation in average scores among the individual Index components. Fruits and saturated fat have the lowest average component scores, indicating that consumers are doing the poorest in these areas. Of all individuals, less than 20 percent achieved recommended levels in the grains, fruits, vegetables, total fat, and saturated fat components. Only in the cholesterol component did greater than 50 percent of individuals achieve a perfect score.
Practical applications of the Healthy Eating Index results are identified below.
Results of the Index provide insights into the types of dietary changes needed to improve American eating patterns. A two-tiered approach is warranted. First, nutrition promotion activities are required to address the nutritional needs of all Americans. To that end, USDA is proposing a general nutrition education and nutrition promotion initiative for all Americans as part of the 1995 Farm Bill. In addition, the recently implemented Schools Meals Initiative for Healthy Children ensures that the nutrition standards for school meals meet the dietary guidelines. This is complemented by Team Nutrition which focuses on empowering children to make food choices for healthful diets.
Targeted strategies for nutrition promotion are also needed. Results from this research suggest that individuals from low-income households and less-educated people are more likely to score lower on the Healthy Eating Index. Therefore, efforts are already underway within USDA to integrate nutrition into all of the food assistance programs.
In this study, the Index was applied to the 1989 and 1990 CSFII data to evaluate the overall quality of American diets. Average scores for the overall Index for both years are approximately 64 percent, a score judged as "Needs Improvement." HEI values are similar for both years, indicating that dietary intake does not vary greatly from year to year. USDA intends to use the Index as one method to monitor changes in dietary patterns in the United States population over time. The Index will be periodically published as nationally representative dietary survey data become available.
The Healthy Eating Index provides one instrument that will be useful in monitoring trends in U.S. consumption patterns over time. This will provide policymakers with the capability of revising and fine-tuning specific programs in a more timely manner to be responsive to the changing nutrition profile of the population.
In addition, a self-assessment instrument would be of use to the American consumer in that it would provide a standard against which an individual could evaluate the quality of his/her own diet. In addition, a self-assessment instrument could serve as a useful guide to consumers in helping them select the types and amounts of foods needed to achieve recommended intakes. The Index would provide a basis for the development of such an instrument.
It is the intention of the USDA Center for Nutrition Policy and Promotion to begin developing a consumer-oriented, self-assessment guide following the public release of the Healthy Eating Index.