Poster Topical Area: Aging and Chronic Disease
Poster Board Number: 18
Objectives: Long-chain polyunsaturated fatty acids (LCPUFA) have been shown to benefit musculoskeletal health in adults. However, LCPUFA status could be altered in obesity, and little is known regarding influences of LCPUFA on bone growth in children with obesity. This study examined the relationship between LCPUFA status and bone mass during childhood obesity.
Methods: Fatty acid profile was measured in red blood cells (RBC) using gas chromatography (Varian CP-3800) in overweight and obese children (n=108, 9.0 ± 0.2 y, body mass index (BMI)-for-age and -sex z-score 3.08 ± 0.10) using baseline samples from two trials (#NCT01290016). Non-dominant forearm was assessed for bone mass using dual-energy x-ray absorptiometry (Hologic Discovery A). Bone geometry and muscle-fat were also measured at the 38% and 66% radius using peripheral quantitative computed tomography (Stratec XCT-2000). Fasting blood glucose and insulin were measured using autoanalyzers (Beckman Access and Beckman DxC600), and the homeostasis model of assessment estimate of insulin resistance (HOMA-IR) was calculated. Children were divided into three groups based on RBC arachidonic acid (AA, C20:4 n-6) status with stratification for Tanner stage, and compared using a mixed model ANOVA with post-hoc Tukey Kramer comparison.
Results: Higher AA status negatively associated with forearm bone mass and geometry. Projected bone area and bone mineral content (BMC) were 5-13% greater in children in the first AA tertile relative to the third. Similarly, children in the second tertile had the highest total bone cross-sectional area (CSA), strength-strain index and estimated fracture load at the 66% radius, which is suggestive of a larger and possibly stronger bone. The differences in bone size and BMC could in part be related to forearm muscle mass, as muscle CSA decreased across AA tertiles (0.21 ± 0.02 m2 vs 0.17 ± 0.03 m2 in 1st and 3rd tertile, p=0.03). Moreover, fasting insulin concentrations and HOMA-IR were increased by 27.4% and 31.5% respectively in children in the third tertile compared to tertiles 1 and 2.
Conclusion: AA is a potential suppressor of forearm bone size and BMC in overweight and obese children, which may be attributed to the alterations in glucose homeostasis and muscle mass growth.
Trial registration: ClinicalTrials.gov: NCT01290016; Supported by a contribution from the Dairy Research Cluster Initiative (Dairy Farmers of Canada, Agriculture and Agri-Food Canada, the Canadian Dairy Network and the Canadian Dairy Commission). H.W. is supported by Canada Foundation for Innovation, and Canada Research Chairs Program. I.M is supported by the Natural Sciences and Engineering Research Council of Canada Postgraduate Scholarships-Doctoral Program.
Ste-anne-de-bellevue, Quebec, Canada