Marrow fat and bone: review of clinical findings

Abstract

With growing interest in the connection between fat and bone, there has been increased investigation of the relationship with marrow fat in particular. Clinical research has been facilitated by the development of non-invasive methods to measure bone marrow fat content and composition. Studies in different populations using different measurement techniques have established that higher marrow fat is associated with lower bone density and prevalent vertebral fracture. The degree of unsaturation in marrow fat may also affect bone health. Although other fat depots tend to be strongly correlated, marrow fat has a distinct pattern, suggesting separate mechanisms of control. Longitudinal studies are limited, but are crucial to understand the direct and indirect roles of marrow fat as an influence on skeletal health. With greater appreciation of the links between bone and energy metabolism, there has been growing interest in understanding the relationship between marrow fat and bone. It is well established that levels of marrow fat are higher in older adults with osteoporosis, defined by either low bone density or vertebral fracture. However, the reasons for and implications of this association are not clear. This review focuses on clinical studies of marrow fat and its relationship to bone.

Keywords: bone marrow fat; bone marrow fat composition; bone marrow lipids; magnetic resonance spectroscopy; osteoporosis.

Figure 1

Measurement of vertebral bone marrow fat using magnetic resonance spectroscopy. (A) Positioning of box in the middle of the vertebral body (L3 as example). (B) Example spectrum in vertebral bone marrow (3 T). Four peaks were well resolved: olefinic, double bond –CH =CH– protons at 5.31 ppm, water protons at 4.65 ppm, the CH₂ methylene protons α to a double bond (–CH =CHCH₂–), at 2.03 ppm, and the bulk CH₂ methylene protons at 1.3 ppm. Adapted with permission from Ref. (18).