US Diet Improves, but Gap Widens Between Rich and Poor

Larry Hand

September 02, 2014

Diet quality in the United States improved during a recent 12-year period, reflecting positive changes in consumers' food choices and food processing, according to a new article published online September 1 in JAMA Internal Medicine.

The overall quality of the diet remains poor, however, continuing to leave people at risk of chronic diseases, including type 2 diabetes — and an existing gap widened further between high- and low-socioeconomic-status (SES) individuals, the researchers write.

Dong D. Wang, MD, MSc, of the department of nutrition, Harvard School of Public Health, Boston, Massachusetts, and colleagues analyzed data on a nationally representative sample of 29,124 adults aged 20 to 85 years collected through the National Health and Nutrition Examination Survey (NHANES) for the years 1999 to 2010.

"Overall, this is encouraging news for clinicians because there has been kind of a misperception that the population cannot change their dietary habits," coauthor Frank B. Hu, MD, PhD, professor of nutrition and epidemiology at Harvard School of Public Health, told Medscape Medical News in a telephone interview.

"There has been an improvement in diet quality, and professionals can play a major role in improving the diet quality of their patients and their families, [who are] more inclined to follow the advice of their doctor," he continued. "Clinicians and professionals can play a major role in educating the patient, helping them make healthier choices."

Gap Between Rich and Poor Widens

The researchers collected dietary data during in-person and telephone interviews conducted as part of NHANES surveys. They assessed nutrient intake using US Department of Agriculture (USDA) databases. They also categorized data by groups according to income, education level, age, race/ethnicity, and body mass index (BMI).

And they benchmarked the data according to the Alternate Healthy Eating Index (AHEI-2010) and the US Department of Agriculture's MyPyramid Equivalents Database (MPED), assessing diet quality according to an AHEI-2010 score range of 0 to 110. A higher AHEI-2010 score indicated a more healthful diet. "For fruits, vegetables, whole grains, nuts and legumes, long-chain (omega-3) fats, and polyunsaturated fatty acids, a higher score corresponded to higher intake. For trans fats, sugar-sweetened beverages and fruit juices, red and/or processed meat, and sodium, a higher score corresponded to lower intake," the authors note.

The analysis shows that the energy-adjusted mean AHEI-2010 overall score increased from 39.9 during 1999–2000 to 46.8 during 2009–2010 (linear trend P < 0.001).

A reduction in consumption of trans fats accounted for more than 50% of the increased score.

As to individual components:

  • Sugar-sweetened beverages increased by 0.9 points, reflecting a decline in consumption.

  • Whole fruit increased by 0.7 points, reflecting an increase in consumption.

  • Whole grains increased by 0.5 points.

  • Polyunsaturated fatty acids increased by 0.5 points.

  • Nuts and legumes increased by 0.4 points.

  • Sodium significantly decreased by 0.5 points (reflecting an increase in consumption).

Diet quality scores for high-SES groups, based on income and education level, were consistently higher than for low-SES groups, and the gap widened over time.

For the high-SES group, scores increased from 3.9 during 1999–2000 to 7.8 during 2009–2010. The researchers observed no significant temporal trend for the low-SES group.

Among other categories:

  • •Women's scores were significantly higher than men's.

  • •Mexican Americans scored higher than non-Hispanic whites.

  • •Lower BMI was associated with better diet quality scores.

Overall Picture: Some Good News but Much Room for Improvement

The authors say public-policy changes regarding trans fat, including labeling requirements, efforts by some cities and other governments to limit use of trans fat, as well as some manufacturers' reformulation of food processes, have likely played a role in overall improvements.

"Science-based nutrition policies can make a huge difference in improving the nutrition quality of the population," Dr. Hu said.

"Diet quality in the general population has been improving moderately but steadily. One of the most important changes has been reduction in consumption of soft drinks or sugar-sweetened beverages," he noted.

"But consumption is still high, and there's still a lot of room to improve. Some areas haven't changed that much. One area that is going in the wrong direction is the consumption of sodium, which has increased in the population, which may reflect increasing consumption of processed food. Most sodium, or salt, comes from highly processed food."

"The most disconcerting finding is the gap between the poor and the rich widened over time in terms of diet quality. This may explain the increasing disparity in chronic disease between people in the high-SES and the low-SES groups," he added.

In order to effect change, Dr. Hu says, "The environment has to be improved so that healthy foods become more affordable and more accessible to people in the low-SES groups. Federal nutrition programs may need to pay more attention to diet quality and food qualities, not just quantities or the total amount of calories."

Food "Deserts": Poorer People Need Policies to Help Them

In accompanying invited commentary, Takehiro Suglyama, MD, PhD, of the National Center for Global Health and Medicine, Tokyo, Japan, and Martin F. Shapiro, MD, of the University of Tokyo, agree. They write that people of lower SES tend to have less access to healthy food; "food deserts" denote poorer communities where residents may have difficulty getting nutritious food.

Higher prices also keep poorer people from buying more healthful food, they say, and lower-SES individuals also may have limited knowledge about the effect of an unhealthy diet on their health.

They conclude, "We urgently need to support multipronged initiatives to improve diet quality for persons of lower SES."

Neither the authors nor the commentators have reported any relevant financial relationships.

JAMA Intern Med. Published online September 1, 2014. Abstract, Commentary

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