New 30-year study links dietary patterns to healthy ageing, with AHEI leading

Ageing comes for all of us, yet for some people it arrives sooner - and with a heavier toll - than for others.

How we grow older is shaped in part by things we cannot change, including genetics and exposure to pollution. Even so, evidence indicates we still have meaningful influence, particularly through day-to-day behaviours such as sleep, physical activity, and diet.

Healthy ageing and the 30-year study

In a new 30-year study, scientists explored in detail how eating patterns relate to healthy ageing. They defined healthy ageing as reaching age 70 without major chronic disease and without declines in cognitive, physical, or mental health.

The work is among the first to compare several dietary patterns in midlife against overall healthy ageing, says co-author Frank Hu, an epidemiologist at Harvard University.

"Studies have previously investigated dietary patterns in the context of specific diseases or how long people live," Hu says. "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?'"

To do this, Hu and colleagues drew on long-running data from 105,000 adults aged 39 to 69 (average age 53), collected from 1986 to 2016 through the Nurses' Health Study and the Health Professionals Follow-Up Study.

Over the 30-year period, participants repeatedly completed dietary questionnaires. The research team then scored each person’s diet according to adherence to eight established dietary patterns, aiming to identify which one was most strongly linked with healthy ageing.

Eight dietary patterns assessed (AHEI, aMED, DASH, MIND, and more)

The eight dietary patterns were: the Alternative Healthy Eating Index (AHEI), the Alternative Mediterranean Index (aMED), the Dietary Approaches to Stop Hypertension (DASH), the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), the healthful plant-based diet (hPDI), the Planetary Health Diet Index (PHDI), the empirically inflammatory dietary pattern (EDIP), and the empirical dietary index for hyperinsulinemia (EDIH).

The researchers note that these patterns overlap in several ways, including an emphasis on whole, plant-forward foods and healthier fats.

Alongside those eight patterns, the study also looked at participants’ intake of ultra-processed foods - industrial products typically made with many ingredients and often high in sugar, salt, and less healthy fats.

AHEI and the odds of healthy ageing at 70

Using their definition, 9,771 participants qualified as healthy agers, equal to 9.3 percent of the overall sample.

Across the board, higher adherence to any of the eight dietary patterns was linked with healthy ageing, meaning any one of them was associated with better odds of staying well at 70.

This points to a more nuanced picture, the researchers say: there is not a single universally “best” diet for everyone. Even so, one pattern emerged as the strongest overall.

According to the results, the AHEI performed best for healthy ageing. The researchers describe it as similar to the older Healthy Eating Index, but with a stronger focus on preventing chronic disease.

People in the highest AHEI quintile were 86 percent more likely to reach healthy ageing at 70 than those in the lowest quintile. When the threshold was set at age 75, the highest quintile was 2.24 times more likely to age healthily.

The AHEI prioritises plant-based foods such as fruit, vegetables, whole grains, nuts, and legumes, while limiting red and processed meat, sugar-sweetened drinks, sodium, and refined grains.

"Since staying active and independent is a priority for both individuals and public health, research on healthy aging is essential," says co-author Marta Guasch-Ferré, a Harvard nutritionist.

"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," she adds.

Although AHEI led the field, the researchers report that several other patterns were close behind, including aMED, DASH, PHDI, and MIND.

Beyond its strongest association with overall healthy ageing, AHEI also showed the strongest relationship with preserving physical function and mental health. PHDI, meanwhile, was most strongly linked to maintaining cognitive health and surviving to age 70.

Ultra-processed foods and lower likelihood of healthy ageing

By contrast, eating more ultra-processed foods was associated with reduced odds of healthy ageing.

"Our findings also show that there is no one-size-fits-all diet. Healthy diets can be adapted to fit individual needs and preferences," says lead author Anne-Julie Tessier, a nutritionist at the University of Montreal.

The study was published in Nature Medicine.