Saturated and unsaturated bone marrow lipids have distinct effects on bone density and fracture risk in older adults

Woods, Gina N.; Ewing, Susan K.; Schafer, Anne L.; Gudnason, Vilmundur; Sigurdsson, Sigurdur; Lang, Thomas; Hue, Trisha F.; Kado, Deborah M.; Vittinghoff, Eric; Rosen, Clifford; Li, Xiaojuan; Schwartz, Ann V.

Affiliations

¹Department of Medicine, UC San Diego, La Jolla, CA, USA

²Department of Medicine, VA San Diego Healthcare System, San Diego, CA, USA

³Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA

⁴Department of Medicine, University of California, San Francisco, CA, USA

⁵Endocrine Research Unit, San Francisco Veterans Affairs Health Care System, San Francisco, CA, USA

⁶Icelandic Heart Association Research Institute, Reykjavik, Iceland

⁷Faculty of Medicine, University of Iceland, Reykjavik, Iceland

⁸Department of Radiology, University of California, San Francisco, CA, USA

⁹Department of Medicine, Stanford University, Palo Alto, CA, USA

¹⁰Department of Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA

¹¹Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, ME, USA

¹²Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA

Abstract and keywords

Greater bone marrow adiposity (BMAT) is associated with lower bone mineral density (BMD) and vertebral fractures; less is known about BMAT composition and bone. We studied BMAT composition and bone outcomes in 465 participants from the Age Gene/Environment Susceptibility (AGES)-Reykjavik study. BMAT saturation and unsaturation, measured with magnetic resonance spectroscopy, were defined as the ratio of saturated (1.3 ppm peak) or unsaturated (5.3 ppm peak) lipid to total marrow contents, respectively. At baseline and follow-up visits, spine and hip BMD were assessed with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) and vertebral fractures were identified with DXA. Incident clinical fractures were identified through medical records for up to 8.8 years of follow-up. Associations between BMAT composition and BMD, bone loss, and fractures were evaluated in adjusted regression models. At baseline, mean ± standard deviation (SD) participant age was 81.7 ± 4.3 years, mean BMAT unsaturation was 3.5% ± 1.0%, and mean saturation was 46.3% ± 7.2% in the full cohort (47.7% women). Each SD increase in BMAT saturation was associated with lower trabecular BMD: −23.6% (spine) and −13.0% (total hip) (all p < 0.0001). Conversely, BMAT unsaturation (per SD increase) was associated with higher trabecular BMD: +17.5% (spine) and +11.5% (total hip) (all p < 0.001). BMAT saturation (per SD increase) was associated with greater risk for prevalent (odds ratio [OR] 1.46; 95% confidence interval [CI], 1.11–1.92) and incident (OR 1.55; 95% CI, 1.03–2.34) vertebral fracture. BMAT unsaturation (per SD increase) was associated with lower risk for incident vertebral fracture (OR 0.58; 95% CI, 0.38–0.89). In gender stratified analyses, BMAT saturation and unsaturation had opposite associations with incident clinical fracture among men. In general, saturated marrow lipids were associated with worse skeletal outcomes, whereas unsaturated lipids were associated with better outcomes. We recommend that future studies of marrow fat and skeletal health report measurements of saturated and unsaturated marrow lipids, rather than total marrow fat content alone.

Keywords: OSTEOPOROSIS; GENERAL POPULATION STUDIES; BONE-FAT INTERACTION

Links

DOI: 10.1002/jbmr.4504

PubMed: 35038186

WoS: 000748717800001

History

Received: 2021-04-18

Revised: 2021-12-13

Accepted: 2022-0101

Cited Works (6)

Year	Entry
2020	Woods GN, Ewing SK, Sigurdsson S, Kado DM, Eiriksdottir G, Gudnason V, Hue TF, Lang TF, Vittinghoff E, Harris TB, Rosen C, Xu K, Li X, Schwartz AV. Greater bone marrow adiposity predicts bone loss in older women. J Bone Miner Res. February 2020;35(2):326-332.
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Cited By (2)

Year	Entry
2023	Wu P-h, Joseph G, Saeed I, Pirmoazen AM, Kenny K, Kim TY, Schafer AL, Schwartz AV, Li X, Link TM, Kazakia GJ. Bone marrow adiposity alterations in Type 2 diabetes are sex-specific and associated with serum lipid levels. J Bone Miner Res. December 2023;38(12):1877-1884.
2023	Bermudez B. Effects of Unsaturated Fatty Acids on Bone Strength, Accrual, and Nutrient Trafficking [PhD thesis]. University of Colorado Denver; 2023.