In a broad comparison of U.S. dietary standards and real Americans' eating habits, researchers found that people fall short of nutritional recommendations overall, but some groups are worse than others.
Among the findings, researchers said that children and the elderly seemed to eat a healthier diet than younger and middle-aged adults, and women had a better diet than men. Hispanics also tended to have better quality diets than either blacks or whites.
"I think it's a really important piece of science because it demonstrates what many of us suspected for a long time: there are many profound disparities in the American diet," said Gary Bennett, who was not involved with the new work but studies obesity prevention at Duke University in Durham, North Carolina.
For the study, researchers used responses to a large national health survey to compare what 8,272 Americans said they ate in the course of one day to what the U.S. Department of Agriculture (USDA) suggested they should be eating.
Each subset of people was assigned a score between zero and 100 based on the percentage of the USDA recommendation for different food groups, such as fruit, vegetables, grains, milk, meat and beans, they consumed each day.
Overall, the researchers found that children and adults as groups each scored 56, while seniors scored higher with 65, meaning they did a better job meeting the USDA standards than most younger people, but no one came close to a perfect score of 100.
"Regardless of socioeconomic status, age, race and education, the American diet as a whole needs to be improved," said the study's lead author Hazel Hiza, of the USDA's Center for Nutrition Policy and Promotion (CNPP) in Alexandria, Virginia.
Hiza and her colleagues, who published their findings in the Journal of the Academy of Nutrition and Dietetics, did find further differences when they looked at race and income.
Hispanics scored better than African Americans and whites across many different food groups.
Hispanic children, for example, were getting closer to the recommended amounts of fruit and vegetables compared to white children, and closer to the recommended amount of fruit compared to black children.
Bennett cautions, however, that the findings do not mean all Hispanics had better diets than all white and black children.
For kids, family income also made a difference, but not with the result some might expect.
The researchers say that children from poor families were meeting more of the USDA dietary recommendations than wealthy children in several food groups, which is possibly due to the low-income families' participation in the National School Breakfast and Lunch Programs.
Adults, however, did seem to meet more of the USDA recommendations as their incomes increased.
"What we know very clearly is that kids, who are in those lowest poverty groups, are doing OK, but not their parents," said Bennett. "This is a win for some of our policies, but it is also the case that some of these parents are sacrificing their diets for the benefit of their kids."
Overall, Bennett said Americans would benefit from policies that encouraged people to eat more fruit and vegetables.
"Most policy decisions have advanced the production, processing and consumption of inexpensive grains… If we can figure out policy that could do the same for fruit and vegetables, our health would benefit," he said.
Hiza added that Americans should also take into account their physical activity levels, and not just their diets.
Robert Post, deputy director for the USDA CNPP, told Reuters Health that people can find tools and resources to help them meet dietary standards on ChooseMyPlate.gov, including a tool that tracks diet and exercise.