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 infuence 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 crosssectional 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% confdence interval (CI) = 0.31;0.58, p