Scientists tested 10 healthy diets against DNA aging clocks in 7,500 people, and the people who gained the most from eating well were not who you would expect

Mediterranean, Nordic, plant-based, DASH: there is no shortage of diets that claim to be the healthiest. Researchers at the German Center for Neurodegenerative Diseases compared 10 of them in roughly 7,500 adults in Germany. Instead of tracking weight or cholesterol, they read each person’s biological age from chemical marks on their DNA, using about 850,000 measurement sites per person. They then compared how closely people followed each diet with how fast their bodies seemed to be aging.

Every one of the 10 diets was linked to slower biological aging. People who followed any of them more closely tended to look younger on epigenetic clocks, the tools that estimate the body’s age from DNA. Some diets showed stronger links than others, but the differences between them were modest.

“Importantly, there is probably no single ‘correct’ diet,” said Monique Breteler, head of the Rhineland Study at DZNE. “That is an encouraging finding, because it leaves room to tailor healthy eating to personal and cultural preferences, budget and taste.”

The diets also turned out to describe different people. Someone who scored high on one healthy eating pattern often scored low on another. “Hardly anyone counts as a healthy eater by every standard at once,” said lead author Juliana Tavares. Yet whichever standard people met, the link with slower aging showed up.

That fits a larger picture. A 2025 study in Nature Medicine followed more than 100,000 people for up to 30 years and found that several healthy diets were all linked to better odds of healthy aging, with the Alternative Healthy Eating Index showing the strongest link. And in a small 2021 trial in the journal Aging, an eight-week program of diet and lifestyle changes was linked to a drop in epigenetic age, suggesting these clocks can move.

The researchers used three different epigenetic clocks and confirmed what they found in the first group, 6,470 people from the Rhineland Study in Bonn, in a second group of 1,034 people from the EPIC-Potsdam study.

The second finding is the one nobody predicted. The link between healthy eating and slower aging was stronger in smokers than in nonsmokers, even though smokers did not generally eat better. The researchers do not yet know why. One possibility is that smoking does so much damage that there is more room for diet to make a measurable difference.

“Smoking is very harmful to health,” Tavares said, stressing that the finding is no reason to think diet can cancel out tobacco.

Under the surface, the diets worked through largely the same biology. More than 70% of the biological pathways linked to the diets were shared across all 10, covering cell structure, cell signaling and metabolism. A few were specific: the DASH diet, designed to lower blood pressure, was tied to heart-related pathways, and the MIND diet, designed for brain health, to pathways involved in memory.

For anyone overwhelmed by competing diet advice, the takeaway is reassuring. Picking a healthy pattern you can actually stick to, and that suits your culture, budget and taste, may matter more than finding the perfect one. What you eat matters in many small ways, from which ultra-processed foods you choose to what goes into your coffee.

There are limits to what this shows. The study is observational, so it shows links, not proof that diet slows aging. Diet was self-reported at one point in time, and people who eat well may differ in other ways, such as exercise or income. Epigenetic clocks are estimates, and how well they predict real health outcomes is still being studied. The participants were German adults, and the effects, as the researchers say, are measurable but not large.

Source

Tavares JF, Liu D, Talevi V, et al. “Associations between diet quality, epigenetic aging and epigenome in two population-based cohorts.” Nature Communications, 2026.
DOI: 10.1038/s41467-026-77064-4

Also cited

Tessier AJ, Wang F, Korat AA, et al. “Optimal dietary patterns for healthy aging.” Nature Medicine, 2025.
DOI: 10.1038/s41591-025-03570-5

Fitzgerald KN, Hodges R, Hanes D, et al. “Potential reversal of epigenetic age using a diet and lifestyle intervention: a pilot randomized clinical trial.” Aging, 2021.
DOI: 10.18632/aging.202913