Elucidating the role of selenium in musculoskeletal ageing using different study designs

Abstract

Introduction: There is limited information on the role of selenium in MSK ageing and function. The overall aim of this PhD thesis was to elucidate the role of selenium in human MSK ageing using different study designs. Methods: The Newcastle 85+ Study was used to assess biomarkers of selenium status (serum selenium, GPx3 activity, SePP) in 757 participants. The associations between these biomarkers and MSK function, and its rate of change up to 5 years was assessed using linear correlations and linear mixed models. The PRECISE Study was used to explore the effects of long-term selenium supplementation on bone turnover markers (BTMs) (OC, PINP, CTX, BALP) measured in non-fasted samples at baseline, 6 months and 5 years. Data were analysed using ANCOVA to investigate the shape of the dose response relationships. Results: In The Newcastle 85+ Study 82 %, 30 % and 83 % of the population had suboptimal selenium status when using selected cut-offs for serum selenium, GPx3 activity and SePP respectively. Low (tertile 1) and medium (tertile 2) selenium concentrations, compared to high (tertile 3) were associated with a greater rate of change in TUG performance, and severe sarcopenia respectively, and low (tertile 1) SePP concentrations, compared to high (tertile 3) were associated with a higher prevalence of disability. In The PRECISE Study, using a 70 µg/L selenium cut-off, 12 % of participants were classified as having suboptimal selenium concentrations. Plasma selenium concentrations increased in a dose-dependent manner with selenium supplementation after 6 months and remained elevated at 5 years. There was no significant effect of selenium supplementation on any of the BTMs. Discussion: This PhD thesis shows that that while very old adults have suboptimal selenium status which may be associated with muscle health, there was no impact of selenium supplementation on BTMs.