Ten healthy diets, one payoff: slower ageing, study of 7,500 shows

Ten different healthy dietary patterns, from Mediterranean to Nordic to plant-based diets, were all associated with slower biological ageing, suggesting there is no single correct way to eat for healthy longevity, according to research from the German Centre for Neurodegenerative Diseases (DZNE), SciTechDaily reported.

The findings, published in Nature Communications, drew on blood samples and dietary information from around 7,500 people, with results first identified among 6,470 participants in DZNE's Rhineland Study in Bonn and independently confirmed using data from 1,034 participants in the EPIC-Potsdam Study run by the German Institute of Human Nutrition Potsdam-Rehbrücke.

Rather than sorting participants into a single diet category, researchers scored everyone's eating habits against the recommendations of all ten dietary patterns studied, including the blood-pressure-focused DASH diet, and assessed biological ageing through chemical changes to DNA that accumulate over a person's lifetime.

Juliana Tavares, a DZNE doctoral researcher and the study's lead author, said the same person could score highly on one diet and poorly on another, meaning people who ate healthily by one standard were often not the same people who ate healthily by another, and that almost no one counted as a healthy eater by every measure simultaneously.

Despite this, higher scores on any of the ten patterns were associated with slower biological ageing. Professor Monique Breteler, director of Population Health Sciences at DZNE and head of the Rhineland Study, said the findings suggested there was probably no single “correct” diet, leaving room to tailor healthy eating to personal taste, culture and budget.

The association between diet quality and slower ageing was strongest among smokers, even though they did not eat more healthily than non-smokers; researchers do not yet know the biological explanation, though Tavares suggested smokers may simply have more health benefit available to gain from a healthy diet given the scale of harm caused by smoking.

To measure biological ageing, researchers analysed DNA methylation – chemical modifications to DNA that change systematically with age – across roughly 850,000 sites in the genome, using three different “epigenetic clock” methods, about twice the coverage of most previous studies.

While each dietary pattern was linked to a distinct set of methylation sites, more than 70% of the underlying biological pathways were shared across all ten diets, involving cell structure, cell signalling and metabolism – processes central to ageing and chronic disease – which Tavares said helped explain why all the diets examined were linked to slower biological ageing, with differences between diets modest in absolute terms.

The study establishes an association rather than proof of causation; it does not by itself show that any of the diets caused ageing to slow or reduced disease risk.

Breteler placed the findings within the broader context of disease prevention, saying the observed effects, while not massive, were measurable and relevant, given that slowing biological ageing could help reduce the risk of age-related diseases such as dementia and cardiovascular disorders.

The researchers also identified diet-specific pathways matching each pattern's particular focus – heart-related pathways unique to the DASH diet, and pathways related to cognition and memory unique to the MIND diet, which is designed to support brain health – which Tavares said could help guide future research into more targeted dietary interventions, even as the study's broader