Americans have been eating slightly healthier foods in recent years, but most of that modest improvement is due to consuming less trans fat, according to a study published Monday in the journal JAMA Internal Medicine.
Overall, the dietary quality of Americans remained almost as poor in 2010 as it did a decade earlier, say the Harvard Medical School researchers who conducted the study. Furthermore, the gap in dietary quality between people on the lower and higher ends of the socioeconomic ladder has widened significantly.
Future efforts to improve nutrition must address those disparities, the study’s authors stress.
Change in trans-fats intake
For the study, the Harvard researchers examined 24-hour dietary data collected from 29,124 adults, aged 20 to 85, who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2010. The data was obtained through in-person and telephone interviews.
The researchers then rated those self-reported diets. One of the rating tools they used was the Alternative Healthy Eating Index, which has a scale of 1 to 110. The higher the score, the healthier the diet (more fruits, vegetables, whole grains and healthy fats). A higher score also means a lower risk of obesity and various chronic diseases, including heart disease, type 2 diabetes and certain types of cancer.
Overall, the dietary quality of Americans went from 39.9 in 1999 to 46.8 in 2010 — a change that was definitely heading in the right direction, but half of it can be attributed to people eating less trans fat, a type of saturated fat that has been linked to a variety of medical conditions, particularly heart disease.
The trans fat decline, by the way, can be credited in large part to changes in public health policy. Since 2006, the U.S. Food and Drug Administration (FDA) has required processed food manufacturers to include trans fat on their nutrition labels, and many states and cities have limited its use in restaurants. More recently, the FDA has indicated that it is moving toward banning trans fat in processed foods, where it is mostly found.
(The ban may be necessary, for a study published last week found that 84 percent of food products that are labelled as having “zero” trans fat actually contain some amount of it.)
The rest of the modest improvement in the overall American diet can be attributed to people eating more whole fruit, whole grains, legumes, nuts and polyunsaturated fats. We’re also consuming less (again, slightly less) sugar-sweetened beverages.
Yet we’re not eating more vegetables, the study found. Nor have we decreased our consumption of alcohol or of red and processed meat. And we’ve been gradually increasing our intake of sodium. (This study concurs with the Dietary Guidelines for Americans’ recommendations for red meat and sodium consumption, which are not without controversy.)
Most troubling, however, was the study’s uncovering of a widening gap in dietary quality among socioeconomic groups. People with less than 12 years of school and those at the lower end of the income ladder were significantly more likely to be consuming an unhealthful diet in 2010 than those with more education and more money.
“Nutrition knowledge, which is strongly related to education level, is likely to play a role in adoption of healthful dietary habits,” write the study’s authors, “and better nutrition may be a lower priority for economically disadvantaged groups, who have many other pressing needs.”
Among racial and ethnic groups, non-Hispanic black people had the least healthful diets, and Mexican-Americans had the most healthful. The higher dietary quality of Mexican-Americans is probably the result of culture and traditions, the researchers say, while the lower quality among non-Hispanic blacks is likely due to lower incomes and education.
Women were also found to make significantly healthier food choices than men. The same was true — not surprisingly — of thinner people. People who were not overweight (who had a body mass index of less than 25) had dietary-quality scores that were, on average, almost three points higher than their heavier peers.
Needed: stronger interventions
“The growing chasm in dietary quality by [soecioeconomic status] confront us with the possibility that the governmental efforts to mind this gap have been insufficient,” write two physicians in a commentary that accompanies the new study.
Dr. Takehiro Sugiyama, of the National Center for Global Health and Medicine in Tokyo, Japan, and Dr. Martin F. Shapiro, of the University of California, Los Angeles, then make several suggestions to help narrow that gap. For example, food provided through the Supplemental Nutrition Assistance Program (SNAP), formerly known as the Food Stamp Program), could be restricted to more healthful foods. And programs that offer healthful foods to children and adults in underserved areas, such as the School Breakfast Program and the National School Lunch Program, could be expanded.
“Providing more healthful snacks and fruits for all students after school would discourage them from purchasing unhealthy snacks,” they add.
Expansion of such programs is going to be an uphill battle, however. Earlier this year, Congress cut SNAP funding. And many congressional Republicans also want to cut federal funding for school lunch programs — or, at the very least, to roll back new standards for healthful school lunches.