People whose eating habits matched any of ten dietary patterns regarded as healthy, from the Mediterranean and Nordic diets to DASH and plant-based eating, showed slower biological aging on three epigenetic clocks, according to an analysis of about 7,500 adults from two German cohorts led by the German Center for Neurodegenerative Diseases (DZNE). No single diet stood out: the differences between patterns were modest, the authors report in Nature Communications.
The peer-reviewed, open-access paper was published Aug. 29 and publicized by DZNE in September; the release was carried by ScienceDaily on Oct. 20. The discovery analysis used baseline data from 6,470 participants in DZNE’s Rhineland Study in Bonn. Key results were then replicated in 1,034 participants of the EPIC-Potsdam Study run by the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE). The study is cross-sectional: diet and blood samples were assessed at one point in time.
Rather than assign each person to one diet, the researchers scored everyone’s food frequency questionnaire against ten diet-quality indices: the Mediterranean Diet Score, DASH, MIND, the Alternate Healthy Eating Index 2010, a Nordic diet score, the EAT-Lancet diet, overall, healthful and unhealthful plant-based diet indices, and the Dietary Inflammatory Index. Biological aging was read from DNA methylation in blood, measured at about 850,000 sites with the Illumina MethylationEPIC array, using three clocks: GrimAge acceleration, PhenoAge acceleration and DunedinPACE, which estimates the pace of aging.
The effects were small but consistent. For each standard deviation higher score on the DASH diet, for example, DunedinPACE was 0.10 standard deviations lower (95% confidence interval -0.12 to -0.08), while GrimAge and PhenoAge acceleration were each 0.03 standard deviations lower. The Nordic score showed a similar pattern. A higher Dietary Inflammatory Index, which denotes a more pro-inflammatory diet, ran the other way, with DunedinPACE 0.07 standard deviations higher per standard deviation of score.
“The effects are not massive, but they are measurable and relevant for prevention,” said Monique Breteler, director of population health sciences at DZNE and head of the Rhineland Study, in the release. “Importantly, there is probably no single ‘correct’ diet.”
Few people scored well on every index at once. “According to our data, hardly anyone counts as a healthy eater by every standard at once,” said lead author Juliana Tavares, a doctoral researcher at DZNE. Although each diet was associated with different methylation sites, the biological pathways those sites mapped to overlapped heavily. “More than 70 percent of the affected biological pathways were shared across all diets,” Tavares said, naming cell structure, cell signaling and metabolism. A few pathways were diet-specific: heart-related pathways for DASH and pathways related to cognition and memory for MIND.
One unexpected finding was that the association between diet quality and slower aging was strongest among current smokers, even though smokers did not eat better than non-smokers. In the replication cohort, the smoker-specific associations held for GrimAge but not PhenoAge after correction for multiple testing. The authors do not have a confirmed explanation; Tavares suggested “there is just more health benefit to gain for smokers by eating healthy.”
Why it matters
Dietary guidance often presents competing “best” diets. This study suggests that, at least by the yardstick of epigenetic aging, the shared features of healthy patterns matter more than the differences between them. Breteler said that is encouraging because “it leaves room to tailor healthy eating to personal and cultural preferences.”
The authors frame the result as relevant to prevention. “By slowing the aging process, the risk of age-related diseases such as dementia or cardiovascular disorders can be reduced,” Breteler said, though this study measured epigenetic clocks rather than disease. “You don’t need a perfect diet — that may be the most practical message here,” Tavares said, adding that the diet-specific pathways point toward future research on targeted dietary interventions.
The caveats
The analysis is cross-sectional, so it shows association, not that changing diet slows the clocks. Participants were predominantly German and of European ancestry, so the findings may not generalize to other populations. Food frequency questionnaires carry measurement error and may miss less common foods, and residual confounding cannot be excluded. EPIC-Potsdam’s dietary data were collected in the 1990s, and only three aging metrics, each based on a subset of methylation sites, were examined. The study did not measure disease outcomes. The work was funded by DZNE, Germany’s Federal Ministry of Education and Research, the German Research Foundation, the Helmholtz Association and other public bodies; the authors declare no competing interests.
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