Radavelli-Bagatini S, Zhu K, Lewis JR, Prince RL. - 45092 N - J Bone Miner Res 2014 ; in press.
Previous studies suggest that dairy intake may associate with reduced bone and muscle loss with ageing, but there are limited data in the very old. We evaluated the association between intake of dairy foods and peripheral bone structure and muscle mass in 564 elderly women aged 80-92 (mean 84.7) years, who were participants of the CAIFOS/CARES cohort and attended the 10-year follow-up. Assessments included dairy consumption (milk, yoghurt and cheese) by a validated food frequency questionnaire, 15% tibia bone mass, area and volumetric BMD (vBMD) by pQCT (peripheral Quantitative Computed Tomography), and appendicular bone and skeletal muscle mass by DXA (dual-energy x-ray absorptiometry). Women were categorized according to tertiles of dairy intake: first tertile (</=1.5 servings/day), second tertile (1.5-2.2 servings/day) and third tertile (>/=2.2 servings/day). Controlling for confounding factors, pQCT assessment at the 15% tibia showed that compared to those in the first tertile of dairy intake, women in the third tertile had 5.7% greater total bone mass (P = 0.005), principally due to an increase in cortical and subcortical bone mass (5.9%, P = 0.050), resulting in a 6.2% increase in total vBMD (P = 0.013). Trabecular but not cortical and subcortical vBMD was also higher (7.8%, P = 0.044). DXA assessment showed that women in the third tertile of dairy intake had greater appendicular bone mass (7.1%, P = 0.007) and skeletal muscle mass (3.3%, P = 0.014) compared to tertile 1. The associations with bone measures were dependent on dairy protein and calcium intakes, whereas the association with appendicular muscle mass was not totally dependent on dairy protein intake. Our results suggest a positive association of dairy intake with appendicular bone mineralization and muscle mass in elderly women. Because many fractures in this age group are of the appendicular skeleton often associated with falls, dairy intake may be a modifiable lifestyle factor contributing to healthy ageing. (c) 2014 American Society for Bone and Mineral Research.