Research has shown that people who eat healthy diets tend to live longer, healthier lives—but a new study has good news for the rest of us: People who made small improvements to a less healthy diet significantly cut their risk of death over time.
For the study, published in the New England Journal of Medicine, researchers at Harvard T.H. Chan School of Public Health looked at data from two separate, ongoing Harvard studies: the Nurses' Health Study and the Health Professionals' Follow-Up Study. For the studies, participants answered questions at the start and then again every two years for lifestyle and health, and every four years for diet.
Using data from those studies, researchers were able to track the eating habits of nearly 74,000 adults over a 12-year period from 1986 to 1998 and their mortality risk over the following 12 years, from 1998 to 2010. Specifically, the researchers compared the quality of participants' diets against three scoring methods: the 2010 Alternate Healthy Eating Index, the Mediterranean Diet, and the Dietary Approaches to Stop Hypertension, or DASH, diet.
The researchers found that people who made improvements to their diet over a 12-year period has a reduced risk of death over the subsequent 12 years.
According to the researchers, the food groups that most improved overall diet quality were whole grains, fruits, vegetables, and fish. And even modest improvements made a difference, the researchers found: A 20 percent improvement in diet quality—the sort of increase accomplished by swapping out just one serving of red or processed meat for a serving of legumes or nuts—was associated with an 8 to 17 percent reduction in mortality risk, depending on the overall diet score.
But the researchers also found out the opposite held true. Participants who reported a diet that worsened by 20 percent had a 6 to 12 percent increase in mortality risk over the next 12 years.
According to STAT News, the findings held even when researchers accounted for changes to lifestyle and health, such as stopping or starting smoking. That said, the researchers acknowledged the study was limited in that the cohort was primarily white and comprised entirely of health care professionals (Muanya, The Guardian, 7/18; Park, TIME, 7/12; Sheridan, STAT News, 7/12).
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