Scientific rationale:
Sarcopenia and functional decline drive disability and healthcare use in ageing. Dietary fat is modifiable, but evidence on how fat amount and quality affect muscle mass, strength and metabolism is mixed. UK Biobank’s scale and deep phenotyping enable robust estimates, mechanistic insight and identification of subgroups for targeted prevention.
Research questions:
How are total fat and fat subtypes (saturated, mono! and polyunsaturated, omega!3) related to grip strength, physical performance and body composition in older adults?
Do associations vary by sex, adiposity, physical activity, diabetes status or socioeconomic position?
Are links mediated by circulating lipid profiles, fatty!acid composition or inflammatory markers?
Do dietary fat patterns predict incident outcomes: sarcopenia!related codes, falls, fractures and disability?
Objectives:
Quantify cross!sectional and longitudinal associations between dietary fat (FFQ and repeated 24!h recalls) and muscle phenotypes (grip strength, activity/accelerometry, DXA; MRI muscle/IMAT where available).
Identify pathways using NMR metabolomics, routine biochemistry and inflammatory markers as mediators.
Strengthen causal inference with genetic instruments for fatty acids/lipids (e.g., FADS) in Mendelian randomization.
Define risk strata and actionable thresholds to inform guidance and future trials.
Approach:
We will analyse participants aged !60 with diet data and follow!up. Multivariable regression, mixed models and Cox/competing!risk analyses will adjust for age, sex, BMI, energy intake, activity, comorbidity and lifestyle. We will test mediation and interactions, and explore non!linear dose-response with splines. Results will be aggregate only, within UK Biobank governance and data!security requirements.