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Member Research and Reports

Member Research and Reports

Harvard Finds Quality of U.S. Diet Shows Modest Improvement, but Overall Remains Poor

Dietary quality in the U.S. has improved steadily in recent years—spurred in large part by reduced trans fat intake—but overall dietary quality remains poor and disparities continue to widen among socioeconomic and racial/ethnic groups, according to a new study from Harvard School of Public Health (HSPH).

The study appears online September 1 in JAMA Internal Medicine.

Given changes in the economy, in policies related to nutrition, and in food processing since the turn of the century, the researchers decided to investigate recent trends in dietary quality in the U.S. They also investigated trends within different socioeconomic subgroups because differences in diet can contribute to variation in the burden of chronic diseases such as heart disease, diabetes, and cancer.

Data came from a nationally representative sample of 29,124 adults aged 20-85 from the U.S. 1999-2010 National Health and Nutrition Examination Surveys. The scientists evaluated dietary quality over time using the Alternate Healthy Eating Index 2010 (AHEI-2010), which rates dietary quality on a score of 0 to 110 (with higher scores indicating healthier diets), and which strongly predicts major chronic disease. They also used another dietary quality index, the Healthy Eating Index 2010.

The researchers noted a significant reduction in trans fat consumption suggests that collective actions, such as legislation and taxation, are more effective in supporting people’s healthy choices than actions that depend solely on individual, voluntary behavior change.

Other changes in eating habits also played a significant role in boosting dietary quality. People are eating more whole fruit, whole grains, nuts, legumes, and polyunsaturated fats, and they’re drinking fewer sugar-sweetened beverages, the study found. On the other hand, people did not eat more vegetables or less red and/or processed meat. And their salt intake increased—which the researchers found “disconcerting.”

The results showed that people with higher socioeconomic status had healthier diets than people with lower socioeconomic status and that gap increased from 1999 to 2010.

Among racial and ethnic groups, Mexican Americans had the best dietary quality, while non-Hispanic Blacks had the poorest. The lower diet quality among non-Hispanic Blacks was explained by lower income and education. The authors speculated that Mexican Americans’ better-quality diets may be due to dietary traditions or culture. Among all groups, women generally had better quality diets than men. Read more