Effects of 12 weeks of Multi-nutrient supplementation on the Immune and Musculoskeletal systems of Older Adults in Aged-Care (The Pomerium Study): Protocol for a Randomised Controlled Trial

Introduction: Immunosenescence leads to increased morbidity and mortality associated with viral infections and weaker vaccine responses. This has been well documented for seasonal influenza and the current pandemic with Sars-Cov2, which disproportionately impact older adults, particularly those in residential aged care facilities. Inadequate nutrient intake associated with impaired immunity, respiratory and muscle function are likely to augment the effects of immunosenescence. In this study, we test whether the effects of inadequate nutrition can be reversed by multi-nutrient supplementation, consequently enhancing vaccine responses, reducing the risk of viral infections, and improving respiratory and muscle function. Methods and analysis: The Pomerium Study is a 12-week, single-blinded, randomised, placebo-controlled trial testing the effects of two daily servings of an oral multi-nutrient supplement (330 kcal, 20g protein, 1.2g CaHMB, 449mg calcium, 520IU vitamin D3, and 25 vitamins and minerals) on the immune system and muscle and respiratory function of older adults in aged-care in Melbourne, Australia. 160 older adults ([≥]75 years old) will be recruited from aged-care facilities and randomised to treatment (multi-nutrient supplement) or control (usual care). Primary outcome is the change in T-cell subsets CD8+ and CD28null counts at 4 and 12 weeks post-intervention. Secondary outcomes measured at baseline and after 12 weeks post-intervention are multiple markers of immunosenescence, body composition (bioimpedance), handgrip strength (dynamometer), physical function (short physical performance battery), respiratory function (spirometry), and quality of life (EQ-5D-3L). Incidence and complications of COVID-19 and/or viral infections (i.e., hospitalisation, complications, or death) will be recorded throughout the trial. Discussion: If the Pomerium Study demonstrates efficacy and safety of a multi-nutrient supplement on immune, muscle and respiratory function, it may be suitable as a strategy to reduce the adverse outcomes from seasonal influenza and viral infections such as COVID-19 in older adults in aged-care.