Association of habitual diet and bone marrow adipose tissue - magnetic resonance imaging in a population-based sample.

backgroundBone marrow adipose tissue (BMAT) is a metabolically active fat depot that may influence bone and hematopoietic function, yet its relationship with habitual diet remains largely unexplored at the population level. As diet represents an easily modifiable factor, a better understanding of its role in bone health and potential sex-specific differences is needed.

objectiveWe examined how habitual intake of energy-providing nutrients (fat, carbohydrates, protein, alcohol) and micronutrients (calcium, phosphorus, vitamin D) relates to imaging-derived measures of BMAT.

methodsIn a sample from a population-based cohort, habitual diet was assessed based on a food frequency questionnaire and repeated 24 h recalls. Using magnetic resonance imaging (MRI) with a 2-point T1-weighted Dixon sequence, fat fraction of BMAT was quantified at vertebrae L1 and L2 in N = 297 participants (44% women, mean age 56.1 years, mean BMI 28.0 kg/m²) and at left and right femur in N = 163 participants (67% women, mean age 57.5 years, mean BMI 27.1 kg/m²) with available dietary data. Associations between habitual diet and BMAT were assessed using correlation analyses and linear regression models in the overall study population and stratified by sex, adjusting for age, BMI, physical activity, and diabetes status.

resultsMean vertebral and femoral BMAT were 54.8% and 86.5% in women, and 54.6% and 89.8% in men, respectively. Vertebral and femoral BMAT were positively correlated in women (ρ = 0.54, p < 0.001) and men (ρ = 0.36, p = 0.0096). Associations between habitual intake of energy-providing nutrients or micronutrients and BMAT were mostly non-significant across anatomical sites and sexes. Only in women, protein intake was positively associated with vertebral BMAT (β = 1.03, 95%CI [0.2, 1.9], p = 0.020, per percent of total energy intake). In men, an opposite effect direction was observed, which was not significant (β =-0.73, 95%CI [-1.6, 0.1], p = 0.096). For femoral BMAT, all associations were non-significant in either sex.

conclusionIn this population-based sample, habitual dietary intake of energy-providing nutrients and micronutrients showed no consistently significant association with vertebral or femoral BMAT in women and men. Opposite effect directions in men and women, as well as one significant association between protein intake and vertebral BMAT in women were observed in exploratory analyses. This may indicate potential site- and sex-specific differences, underlining the distinct biological properties of this adipose tissue depot.