Mediterranean Diet Linked to Slightly Younger DNA-Based Aging Readings in Study

This is an observational study in people, not a trial. Researchers analysed 928 participants from the Airwave Health Monitoring Study, a cohort of British police employees. The average age was 41, and 59% were men. The analysis is cross-sectional, meaning it looks at one point in time. It can show links. It cannot show that diet or smoking caused the differences.

The tests are called epigenetic clocks. They read chemical tags on DNA, taken here from blood, to estimate biological age. Early clocks were built to predict calendar age. Later ones also draw on physical function or mortality risk. The team compared eleven clocks. The question was whether they pick up both a harmful habit and a protective one.

Diet was measured with a 7-day food diary. Each person got a Mediterranean Diet Score from 0 to 10. Points were given for higher intake of fruit, vegetables, legumes, fish, nuts and whole grains, and for lower intake of red and processed meat and dairy. Moderate alcohol and a higher ratio of monounsaturated to saturated fat, a proxy for olive oil, also scored. Smoking was assessed by self-report and by blood cotinine, a marker of recent nicotine exposure.

A higher diet score was linked to lower "age acceleration", meaning a biological age older than expected for calendar age, on two clocks: GrimAge and Bernabeu. The differences were small. For GrimAge it was −0.07 standard deviations (95% CI −0.13 to −0.01). For Bernabeu it was −0.08 (−0.14 to −0.02). A standard deviation is a measure of how widely people vary on a clock. These results held after statistical correction for testing many clocks. The models also adjusted for factors including income, education, alcohol, weight, physical activity and anxiety.

The smoking signal was far larger. Smoking was strongly linked to higher age acceleration, particularly on GrimAge, Bernabeu and DunedinPACE. Among current smokers, the GrimAge difference was 1.79 standard deviations (95% CI 1.54 to 2.04) in those with lower diet adherence. It was 1.35 (1.01 to 1.68) in those with higher adherence. So the smoking signal was smaller in better eaters.

The authors are clear about what this does not mean. In their words, the results do not suggest "that diet neutralises the risks of tobacco". Even the better-eating smokers had a much higher reading than non-smokers.

There are other limits. Diet and clock readings were taken together, so the order of events is unknown. Diaries can be inaccurate. The data could not reconstruct lifetime smoking, such as pack-years, so past heavy smokers may be grouped with lighter ones. The group is also a single workplace cohort. The study does not show that any person's clock reading predicts their own health.

For you

For readers, the point is practical but modest. Several clocks respond to lifestyle, and smoking dominates the picture. A better diet shows only a faint, clock-specific association. Only two of the eleven clocks showed it after correction.

What to watch next

Studies that follow people over time, to test whether changing diet or quitting smoking actually moves these clocks.

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