Association of habitual diet with skeletal muscle composition in a cross-sectional, population-based imaging study

Skeletal muscle health influences overall health and functionality. Nutrition is an important contributor to muscle health, however there is insufficient research on the relation between nutrition and muscle composition, i.e. mass and fatty infiltration, on a population-based level.

We aimed to investigate the association of habitual dietary intake of energy-providing nutrients (carbohydrates, fat, protein and alcohol) and of essential amino acids with skeletal muscle fat and muscle area derived by magnetic resonance imaging (MRI) in a sample of middle-aged individuals from a population-based cohort.

We analyzed N = 294 individuals (45% women, mean age 56.5 years) from the KORA-MRI study, Southern Germany. Muscle fat (%) and muscle area (cm²) were assessed by a multi-echo Dixon sequence on whole-body MRI. Habitual dietary intake was calculated based on repeated 24 h recalls and a food frequency questionnaire. Correlation analyses and adjusted regression models were calculated.

Alcohol intake was associated with increased skeletal muscle fat, particularly in men (β = 0.28%, 95% confidence interval [0.10%,0.45%]; p = 0.002) per percent of total energy intake). Protein intake was tentatively associated with lower muscle fat (β=-0.33% [-0.68%,0.01%]; p = 0.052). Accounting for overall protein and energy, specific essential amino acids were tentatively associated with lower muscle fat, e.g. leucine (β=-0.63%, [-1.27%,0.01%]; p = 0.054).

In middle-aged adults, habitual alcohol and protein intake are associated with fatty infiltration of skeletal muscle. Individualized diet adaptations might improve muscle composition and function.