WHAT IS THE EFFECT OF DIETARY INFLAMMATORY INDEX (DII) ON THE INCIDENCE OF SARCOPENIA AND FUNCTIONAL DISABILITY AMONG OLDER ADULTS?

Abstract

Introduction: The low-grade inflammatory process related to ageing, named inflammaging, has been associated with both sarcopenia and functional disability. It is widely known that nutrition plays a fundamental role in inflammation. However, the inflammatory potential of the diet measured by the Dietary Inflammatory Index (DII) has been scarcely explored in relation to the incidence of sarcopenia, especially in Western populations, characterized by diets associated with higher levels of inflammatory cytokines. There is also a gap as to whether this inflammatory potential measured by DII increases the risk of incidence of functional disability for basic activities of daily living (BADLs) among older people. Objectives: Therefore, the present study has three objectives: 1) Verify whether the dietary inflammatory index is a risk factor for the incidence of sarcopenia in individuals aged 60 years or over; 2) Verify whether the dietary inflammatory index is a risk factor for the incidence of disability in basic activities of daily living in individuals aged 50 years or over; and 3) Verify whether the dietary inflammatory index is a risk factor for the incidence of disability in instrumental activities of daily living (IADLs) in individuals aged 50 years or over. Methods: Two longitudinal incidence studies will be carried out with data from the English Longitudinal Study of Aging (ELSA Study). For both studies, the exposure studied will be the inflammatory potential of the diet measured by the DII, with the score divided into tertiles. The outcomes will be the incidence of sarcopenia and the incidence of disability for BADLs and IADLs. For all studies, the baseline will be composed of data collected in wave 9 (2018) of the ELSA Study. Those who present any state of sarcopenia (probable sarcopenia, sarcopenia or severe sarcopenia) according to EWGSOP2 will be excluded at the baseline of the first study. Those who present any difficulty with BADL (adapted Katz scale) or IADL (adapted Lawton index) will be excluded from the baseline of the second study. Outcomes will be measured in wave 10 (2020), after two years of follow-up. To analyse the incidence of sarcopenia, multinomial logistic regression models will be used and to analyse the incidence of disability for BADL and IADL, Poisson regression models will be used. The models will be controlled by sociodemographic variables, lifestyle habits and health conditions. Results: The incidence of sarcopenia and disability in BADLs and IADLs is expected to be higher in individuals with greater dietary inflammatory potential according to the dietary inflammatory index.