• Posted March 25, 2025

This Diet Is Best For Healthy Aging

How should a person eat in middle age to protect their health as they grow older?

One diet came out a clear winner in a 30-year study involving more than 105,000 men and women and eight diets, researchers reported in the journal Nature Medicine.

People whose dietary pattern more closely stuck to the Alternative Healthy Eating Index (AHEI) in middle-age had the greatest likelihood of good health in their 70s, researchers say.

Those with the highest AHEI score had 86% better odds of healthy aging at 70, and were 2.2 times more likely to be healthy at 75, results show.

The AHEI centers on a diet rich in fruits, vegetables, whole grains, nuts, legumes and healthy fats, and low in red and processed meats, sugary drinks, sodium and refined grains, researchers said.

“Our findings suggest that dietary patterns rich in plant-based foods, with moderate inclusion of healthy animal-based foods, may promote overall healthy aging and help shape future dietary guidelines,” co-senior researcher Marta Guasch-Ferré, an associate professor of public health at the University of Copenhagen and adjunct associate professor of nutrition at the Harvard T.H. Chan School of Public Health, said in a news release.

Harvard researchers created the AHEI in 2002 as an alternative to the U.S. Department of Agriculture’s Healthy Eating Index, which measures how well people’s diets stick to the federal Dietary Guidelines for Americans.

Both indexes are similar, but the AHEI is more oriented toward reducing risk of chronic disease, Harvard says.

For the new study, researchers analyzed diet questionnaires regularly filled out by health professionals participating in two long-term medical studies.

The team scored how well the participants followed eight healthy diets: the AHEI, the Alternative Mediterranean Index, the Dietary Approaches to Stop Hypertension (DASH), the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), the Healthful Plant-Based Diet, the Planetary Health Diet Index, the Empirically Inflammatory Dietary Pattern, and the Empirical Dietary Index for Hyperinsulinemia.

“Studies have previously investigated dietary patterns in the context of specific diseases or how long people live,” co-senior researcher Frank Hu, chair of nutrition at the Harvard T.H. Chan School of Public Health, said in a news release.

“Ours takes a multifaceted view, asking, how does diet impact people’s ability to live independently and enjoy a good quality of life as they age?” Hu added. 

During 30 years of follow-up, nearly 9,800 participants – more than 9% -- aged in a healthy manner, researchers said. They reached age 70 free of major chronic diseases and with their cognitive, physical and mental health intact.

Adhering to any one of the healthy diet patterns was linked to overall healthy aging, including maintaining better cognitive, physical and mental health, researchers found.

But the AHEI proved the leading healthy diet, followed by the Planetary Health Diet Index. That diet considers both human and environmental health by emphasizing plant-based foods and minimizing animal products, researchers said.

Specifically, the AHEI had the strongest association with better physical and mental health in old age, while the PHDI had the strongest association with better cognitive health, the study says.

Higher intake of ultra-processed foods -- particularly processed meat and sugary or diet drinks -- was associated with lower chances of healthy aging, results show.

“Our findings also show that there is no one-size-fits-all diet. Healthy diets can be adapted to fit individual needs and preferences,” lead author Anne-Julie Tessier, assistant professor of nutrition at the University of Montreal, said in a news release.

On its website, Harvard recommends that people following the AHEI eat:

• About five servings of vegetables a day, including extra helpings of green leafy veggies that can reduce the risk of diabetes. Skip potatoes and fries.

• About four servings a day of fruit, which can protect against heart disease and some cancers.

• Around five to six servings a day of whole grains, which can ward off heart disease, diabetes and colon cancer.

• A daily serving of nuts, legumes or tofu, which adds protein to the diet and might help protect against diabetes and heart disease.

• At least one serving of fish per week, which provides fatty acids that are good for the brain and body.

• Healthy unsaturated fats like olive oil, canola oil, peanut oil or safflower oil in cooking, swapping them whenever possible for saturated fats like butter or lard.

More information

Harvard Medical School has more on the Alternative Healthy Eating Index.

SOURCE: Harvard T.H. Chan School of Public Health, news release, March 24, 2025