Fermented dairy intake and markers of musculoskeletal ageing on the island of Ireland: insights from the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA) and The Irish Longitudinal Study on Ageing (TILDA)

Abstract Purpose Fermented dairy foods may support healthy musculoskeletal ageing via high-quality protein and gut-muscle axis modulation. Epidemiological evidence linking fermented dairy foods with physical function in older adults is limited. We examined associations between fermented dairy intake and physical function in older adults in Ireland using two independent population-based cohorts, to assess the consistency of associations across differing dietary assessment approaches. Methods Cross-sectional analyses of data from the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA; n = 2791; mean age 64 ± 9 years) and The Irish Longitudinal Study on Ageing (TILDA; n = 3999; mean age 66 ± 9 years) was performed. Fermented dairy intake was calculated from cohort-specific food frequency questionnaires (FFQs) with outcomes including muscle strength, frailty and functional limitations. Multivariable linear and logistic regression models were applied, adjusting for demographic and health-related covariates. Results In NICOLA, fermented dairy intake was not associated with physical function outcomes after confounder adjustment. Associations observed in crude models were attenuated after adjustment, with no dose–response relationships. In TILDA, participants in the highest tertile of fermented dairy intake had higher odds of low grip strength compared with those in the lowest tertile (OR = 2.71; 95% CI: 1.12, 6.88; p = 0.030). However, analysis of individual fermented dairy foods indicated that this association was driven by yoghurt intake and was attenuated after covariate adjustment. Conclusions Across two independently analysed cohorts, fermented dairy intake was not consistently associated with physical function after confounder adjustment. There is a need for longitudinal and interventional studies to better determine the role of fermented dairy foods in musculoskeletal ageing.