Protein Intake and the Risk of Pre-Frailty and Frailty in Norwegian Older Adults. The Tromsø Study 1994–2016

Background Protein intake is suggested as an important dietary factor in the prevention of frailty, however, the influence of lifelong intake remains unclear. Objectives The present study investigated the relationship between daily protein intake and patterns of protein intake over 21 years and the risk of pre-frailty/frailty. Design Prospective cohort study. Setting The population-based Tromsø Study in Tromsø municipality, Norway. Participants In total, 1,906 women and 1,820 men aged ≥45 years in 1994 who participated in both Tromsø4 (1994–95) and Tromsø7 (2015–16). Measurements Frailty status in Tromsø7 was measured according to Fried’s phenotype, classifying participants as “robust” (frailty components present: 0), “pre-frail” (1–2) or “frail” (≥3). Daily intake of protein was estimated from self-reported habitual dietary intake using food frequency questionnaires and assessed as grams per kilogram bodyweight (g/kg BW) and per megajoule energy intake (g/MJ). The protein–frailty association was assessed via longitudinal and cross-sectional multivariable logistic regression analyses. Results The prevalence of pre-frailty and frailty in this study was 27% and 1.0%, respectively. Longitudinal analysis showed that the odds of pre-frailty/frailty decreased by 57% (odds ratio (OR) = 0.43, 95% confidence interval (CI) = 0.31;0.58, p