Despite improvements in America’s diet in recent years, the overall diet quality remains poor and worsens drastically across certain ethnic groups. Researchers from the Harvard School of Public Health (HPSH) analyzed recent diet trends in the United States by looking at people with different socioeconomic backgrounds, and published their findings in the journal JAMA Internal Medicine.

By looking at large bodies of data, researchers were able to see over 10 years of trends caused by changes in nutrition policies, food processing, and dietary quality of the types of foods Americans have been consuming. Evaluating the trends will help improve public health policy, given the current obesity epidemic. “The study provides the most direct evidence to date that the extensive efforts by many groups and individuals to improve U.S. dietary quality are having some payoff, but it also indicates that these efforts need to be expanded,” said the study’s lead author Dong Wang, a doctoral student in the Department of Nutrition at HSPH, in a press release.

The researchers examined the diets of 29,124 adults between the ages 20 to 85 through the National Health and Nutrition Examination Surveys and health eating index, which rates the quality of their diets on a score from 0 to 110. The higher the score, the healthier their diets were ranked between 1999 and 2010. There was a significant decrease in the amount of saturated fats people had been eating, as well as sugar-sweetened drinks. Meanwhile, people were eating more whole fruit, whole grains, nuts, legumes, and polyunsaturated fats. Researchers, however, found an increase in the amount of salt people have in their diets to be “disconcerting,” as excess levels have been known to cause high blood pressure, stroke, heart failure, osteoporosis, stomach cancer, kidney disease, and other ailments, according to the American Heart Association.

Salt is used as a preservative in a lot of processed foods, which unfortunately also tends to be inexpensive; many people with lower education and income levels consume it. Legislation and taxation has helped significantly reduce the amount of trans fat consumed in America, but monetary values still trump a person’s personal behavior changes and diet priorities. The two groups with the lowest diet quality were those who had completed 12 years of school or less and non-Hispanic blacks. Throughout all groups regardless of their income or education, women had the better-quality diets than men

“The overall improvement in diet quality is encouraging, but the widening gap related to income and education presents a serious challenge to our society as a whole,” said Walter Willet, epidemiology and nutrition professor and chair of the Department of Nutrition at HSPH, in a press release.

Source: Wang DD, Leung CW, Li Y, et al. Trends in Dietary Quality Among Adults in the United States, 1999 Through 2010. JAMA Internal Medicine. 2014.