According to a new study published Monday in Health Affairs, Americans are eating healthier now than they were at the turn of the millennium. Better still, these changes in diet have likely prevented more than a million premature deaths in that time frame, as well as reduced the incidence of chronic conditions like cancer and heart disease.

Despite the good news, however, the study authors caution that our overall diets remain poor and that the gaps in dietary quality among different socioeconomic groups such as African-Americans have only increased over time.

A Soda Too Far

To track the changes in our diets, the study authors turned to data obtained from the National Health and Nutrition Examination Survey, an annual “population-based survey designed to collect information on the health and nutrition of the U.S. household population,” conducted by the Centers for Disease Control and Prevention (CDC). Ultimately focusing on 33,825 adults from 1999 to 2012, they used a measure known as the Alternate Healthy Eating Index (2010 version) to determine the quality of their diets on a scale from 1 to 110. In that time span, the average index score rose from 39.9 to 48.2.

To determine how these scores may have translated to better health outcomes, the authors then referenced data from two other separate cohort studies, the Nurses' Health Study and the Health Professionals Follow-Up Study, which altogether comprised more than 170,000 people. This allowed them to calculate that the improvements in diet from 1999 to 2012 have prevented roughly 1.1 million premature deaths and led to 8.6 percent fewer cases of cardiovascular disease, 1.3 percent fewer cancer cases, and 12.6 percent fewer type 2 diabetes cases.

Though encouraging, it should be noted that these changes in diet weren’t necessarily implemented out of the goodness of our hearts. The largest gains came from the reduction of trans fats and the lowered intake of sugary beverages, both food items that have come under scrutiny by public health experts as well as governmental regulation during the same time frame.

Earlier this June, the Food and Drug Administration announced that it was formally going forward with a near-complete ban on artificial trans fats (one that will take three years to complete) in the food supply — the end result of a process that saw trans fat consumption plummet drastically in the past decade. And though many states have failed to pass so-called “soda taxes” in the last few years, the public perception of soft drinks has likewise eroded. The consumption of full-calorie sodas by the average American has dropped by 25 percent since the late 1990s, for instance, according to research cited by The New York Times.

The authors’ findings suggest then that lawmakers and health professionals alike have a crucial role to play in influencing our dieting choices, particularly for especially vulnerable populations. African-Americans’ diets were the poorest, a trend that has only expanded when compared to other ethnic groups in the following years.

"Our findings provide further justification for promoting healthful diets as a national priority for chronic disease prevention, as well as for legislative and regulatory actions to improve the food supply more broadly," said lead author Dong Wang, doctoral candidate in the Departments of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, in a statement.

Source: Wang D, Li Y, Chiuve S, et al. Improvements In US Diet Helped Reduce Disease Burden And Lower Premature Deaths, 1999–2012; Overall Diet Remains Poor. Health Affairs. 2015.