Diet Quality, Physical Activity, and Epigenetic Aging in the Finnish Working-Age Population.

<h4>Background</h4>The role of diet in epigenetic aging over long follow-up periods and the possible moderating role of physical activity have remained unclear.<h4>Objectives</h4>We examined: 1) whether dietary habits over follow-ups of 17-32 y are associated with the level or change of epigenetic aging over a 7-y follow-up, and 2) whether physical activity moderates these associations.<h4>Methods</h4>The prospective population-based Young Finns Study data (n = 1039) were used. Epigenetic aging was measured in 2011 and 2018 using PhenoAge and GrimAge age deviation (AgeDev_Pheno, AgeDev_Grim) and Dunedin pace of aging computed from the epigenome (DunedinPACE). Food Frequency Questionnaires were used in 2001, 2007, 2011, and 2018 to calculate 5 diet indices: Mediterranean Diet Index, Findiet Index, Alternative Healthy Eating Index (AHEI) Dietscore (additionally used in 1986), and Baltic Sea Diet Index. The applied physical activity index included, e.g., frequency and intensity of exercise. Covariates included cardiovascular and metabolic factors, other health behaviors, and socioeconomic factors.<h4>Results</h4>More favorable scores in: 1) all diet indices except Dietscore were associated with decelerated AgeDev_Grim cross-sectionally (β = -0.08 to -0.06, P = 0.003-0.022), 2) the means of all diet indices over follow-ups of 17-32 y were associated with slower epigenetic aging in all 3 epigenetic clocks (β = -0.01 to -0.23, P = 2e-5-0.042), and 3) AHEI and Findiet Index were most consistently associated with a decelerated change in AgeDev_Grim and AgeDev_Pheno over a 7-y follow-up. Modest interaction effects were also observed: among those with high physical activity, epigenetic aging was approximately similar irrespective of diet healthiness, whereas among those with low physical activity, more favorable diet index scores were associated with less accelerated epigenetic aging.<h4>Conclusions</h4>Healthier eating over the follow-up was associated with decelerated epigenetic changes across different diet indices. In terms of biological aging, having a healthy diet may be especially crucial for those with low levels of physical activity.