A large-scale epidemiological study published Thursday in a leading nutrition journal has found that people who consumed the highest amounts of ultra-processed foods — a category that includes packaged snacks, ready meals, soft drinks, and reconstituted meat products — showed biological age markers that were, on average, 2.7 years older than their chronological age compared to those who ate the least processed food. The study followed participants for a median of nine years and controlled for smoking, physical activity, sleep, and body mass index.
The researchers used an epigenetic clock — a tool that measures chemical modifications to DNA that accumulate with aging — to assess biological age independent of the number on a birth certificate. This method has grown increasingly standard in longevity research because it appears to reflect an individual's physiological condition more accurately than chronological age alone. Participants in the highest quartile of ultra-processed food consumption showed consistently accelerated epigenetic aging across multiple clock measurements.
"What's notable here is not just the association, but its robustness across different ways of measuring biological age," said the study's senior author. "You can quibble with any single epigenetic clock, but when you see the same direction of effect across five independent measures, that's telling you something real about the biology."
"When you see the same direction of effect across five independent measures of biological age, that's telling you something real about the biology."
— Senior author, nutritional epidemiology study
The mechanisms by which ultra-processed foods might accelerate biological aging are not yet fully understood, but researchers have proposed several pathways. Highly processed foods tend to be low in dietary fiber, which is critical for gut microbiome diversity. They often contain additives, emulsifiers, and artificial flavors whose long-term biological effects are still being studied. They are also typically high in refined sugars and unhealthy fats, which promote chronic inflammation — a well-established accelerator of cellular aging.
Several independent scientists not involved in the study praised its methodology while noting that it cannot establish causation. "This is a strong observational study, not a randomized controlled trial," said one nutritional epidemiologist. "We don't yet know whether changing your diet would reverse these aging markers, though there's good reason to think it might." Public health advocates, however, said the accumulating evidence is strong enough to justify updating dietary guidelines and food labeling requirements without waiting for definitive causal proof.