A comparison of dietary trends among racial and socioeconomic groups in the United States.

BACKGROUND: There may be dietary differences among racial and socioeconomic groups in the United States.
METHODS: Using data from a representative sample of adults, we compared dietary trends among blacks and whites of varying socioeconomic status. We developed comparable measures of diet and of the consumption of macronutrients and food groups for 6061 participants in the 1965 Nationwide Food Consumption Surveys, 16,425 in the 1977-1978 Nationwide Food Consumption Surveys, and 9920 in the 1989-1991 Continuing Survey of Food Intake by Individuals (all conducted by the U.S. Department of Agriculture). The primary outcome was the score (range, 0 to 16) on the Diet Quality Index, a composite of eight food-and-nutrient-based recommendations from the National Academy of Sciences. A score of 4 or less was considered to indicate a relatively more healthful diet, and a value of 10 or more a relatively less healthful diet.
RESULTS: Overall dietary quality improved in all groups, from a mean Diet Quality Index score of 7.4 in 1965 to 6.4 in 1989-1991. In 1965, blacks of low socioeconomic status and, to a lesser extent, whites of low socioeconomic status had better diets than whites of high socioeconomic status. By the 1989-1991 survey, the differences among racial and socioeconomic groups had narrowed. In 1965, 9.3 percent of whites of low socioeconomic status, 16.4 percent of blacks of low socioeconomic status, and 4.7 percent of whites of high socioeconomic status had mean scores of 4 or less. In the 1989-1991 survey the respective percentages were 19.9, 23.5, and 20.0. Fat consumption decreased in all groups. The consumption of fruits and vegetables varied little over time, except for an increase among blacks of medium and high socioeconomic status. The consumption of grains and legumes increased over time among whites of medium and high socioeconomic status and declined among blacks of low socioeconomic status.
CONCLUSIONS: In 1965, there were large differences among groups in dietary quality, with whites of high socioeconomic status eating the least healthful diet, as measured by the index, and blacks of low socioeconomic status the most healthful. By the 1989-1991 survey, the diets of all groups had improved and were relatively similar.