The University Network

Want To Live Longer? New Harvard University Study Shows Improving Diet Over Time Reduces Risk Of Death

New research from the Harvard T.H. Chan School of Public Health shows that it is possible to reduce the risk of premature death by improving our diet over a span of 12 years.

According to the study, we could live longer by eating healthier — more whole grains, vegetables, fruits, nuts, and fish  — over time. Red meat, processed meats and sugary drinks, on the other hand, are not as healthy, so we should eat less of it.

The research is published in the New England Journal of Medicine.

The lead author of the study is Mercedes Sotos-Prieto, who was a postdoctoral fellow in the Harvard T.H. Chan School of Public Health’s Department of Nutrition at the time of the study and is currently an assistant professor of nutrition at Ohio University.

The researchers used three diet quality indices — the 2010 Alternate Healthy Eating Index, the Alternate Mediterranean Diet score, and the Dietary Approaches to Stop Hypertension (DASH) diet score — in their analyses and found the results broadly consistent. These three indices, while distinct, are consistent in that they assign higher scores to healthier foods and lower scores to less healthy foods.

“Overall, our findings underscore the benefits of healthy eating patterns including the Mediterranean diet and the DASH diet,” Sotos-Prieto said in a statement.

“Our study indicates that even modest improvements in diet quality could meaningfully influence mortality risk and conversely, worsening diet quality may increase the risk.”

The Study

The research team used data from two long-term studies involving nearly 74,000 adults over a span of 12 years that stretched from 1986 to 1998. Participants in the study provided information about their diets every four years and about their lifestyle and health every two years.

The researchers analyzed the data for links between changes in diet over the 12-year study period and the participants’ risk of dying in the 12 years that followed, from 1998 to 2010, and found that, irrespective of the diet quality index used, participants with improved diet quality over a 12-year period reduced their risk of death in the subsequent 12 years.

A small improvement in the diet, which could be achieved by simply substituting one serving of red or processed meat each day by a daily serving of nuts or legumes, reduced risk of death by 8 percent to 17 percent, depending on the diet score. On the other hand, worsening diet quality increased risk of death by 6 percent to 12 percent.

Those who had relatively healthy diets for 12 years reduced their risk of death from any cause by 9 percent to 14 percent.

But what about people who had relatively unhealthy diets at the beginning of the study but whose diet scores improved the most?

“As compared with participants who had consistently low diet scores over time, those with the poorest score at baseline but the largest improvements 12 years later had a 15 to 18 percent lower risk of death from any cause depending on the score,” Sotos-Prieto told TUN.

When TUN asked Sotos-Prieto if there is a particular diet she would recommend, this was her response:

“Overall, our findings support the recommendations of the 2015-2020 dietary guidelines which recommend several healthy eating patterns. It is not necessary to conform to a single dietary plans to achieve a healthy eating pattern. These three dietary patterns, although different in description and composition, capture the essential elements of a healthy diet. Common food groups in each score that contributed most to improvements were whole grains, fruits, vegetables, and fish or n-3 fatty acids.”

The research team also included Frank Hu, Frederick John Stare Professor of Epidemiology and Nutrition and chair of the Department of Nutrition, Shilpa Bhupathiraju, Josiemer Mattei, Teresa Fung, Yanping Li, Walter Willett, and Eric Rimm.


The study shows how important it is to eat healthy over time and gives hope to those whose diet may not be healthy but can still reap the benefit if they improve their diet quality.

“A main take-home message is that it is never too late to improve diet quality for reducing mortality risk and improving longevity,” Sotos-Prieto said.

“Our results underscore the concept that modest improvements in diet quality over time could meaningfully influence mortality risk, and conversely, worsening diet quality may increase the risk.”