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Member Research & Reports

Member Research & Reports

Harvard: Improvements in U.S. Diet Lower Premature Deaths

Two new studies from Harvard T.H. Chan School of Public Health shed light on critical dietary issues facing Americans. One study showed that while recent improvements in the U.S. diet have helped reduce disease and premature death, the overall American diet is still poor. Another, which analyzed interventions to reduce childhood obesity, found three that would save more in health care costs than they would cost to implement.

Both studies were published November 2, 2015 in the November issue of Health Affairs.

In the U.S. diet study, researchers analyzed how changes in dietary quality from 1999-2012 impacted disease and premature death. They examined dietary quality among 33,885 U.S. adults who participated in the National Health and Nutrition Examination Survey, using a measure called the Alternate Healthy Eating Index 2010. To see how this dietary quality would impact disease and mortality, they used information from two long-running studies, the Nurses’ Health Study and Health Professionals Follow-Up Study, involving roughly 173,000 people.

They found that healthier eating habits cumulatively prevented 1.1 million premature deaths over the 14 years, and the difference in dietary quality between 1999 and 2012 resulted in 12.6% fewer type 2 diabetes cases, 8.6 percent fewer cardiovascular disease cases, and 1.3 percent fewer cancer cases.

Notably, the researchers found that it only took small improvements in dietary quality to substantially reduce disease burden, which is a measure of both fatal and non-fatal loss of health due to disease.

Despite steady improvement, however, the authors said that overall dietary quality in the U.S. is far from optimal. They found that the study participants’ average healthy eating score — on a scale ranging from 0-110, with 110 being the healthiest — never reached 50.

In addition, disparities across different socioeconomic groups actually increased during the study period; African Americans had the poorest dietary quality, and this was accounted for by differences in income and education. The researchers also found that, except for significant reductions in trans fat and sugar-sweetened beverages, most key components of healthful diets showed only modest or no improvements.

Noting that the drop in trans fat intake was driven largely by regulatory actions, such as the FDA’s recent ban on its use, the authors suggested that additional policies — such as expanding taxation on sugary beverages or mandating less salt in food — could help maintain and accelerate improvements in the national diet. Read more