Obesity is a concern for bone health with aging

Abstract

Accumulating evidence supports a complex relationship between adiposity and osteoporosis in overweight/obese individuals, with local interactions and endocrine regulation by adipose tissue on bone metabolism and fracture risk in elderly populations. This review was conducted to summarize existing evidence to test the hypothesis that obesity is a risk factor for bone health in aging individuals. Mechanisms by which obesity adversely affects bone health are believed to be multiple, such as an alteration of bone-regulating hormones, inflammation, oxidative stress, the endocannabinoid system, that affect bone cell metabolism are discussed. In addition, evidence on the effect of fat mass and distribution on bone mass and quality is reviewed together with findings relating energy and fat intake with bone health. In summary, studies indicate that the positive effects of body weight on bone mineral density cannot counteract the detrimental effects of obesity on bone quality. However, the exact mechanism underlying bone deterioration in the obese is not clear yet and further research is required to elucidate the effect of adipose depots on bone and fracture risk in the obese population.

Keywords: Bone marrow fat; Fracture; Inflammation; Obesity; Osteoporosis.

Figure 1. Mechanisms responsible for bone cell metabolism that contribute to osteoporotic fractures in obesity

Bone loss attributed to an imbalance of bone cell metabolism (osteoclast vs. osteoblast) that can contribute to osteoporotic fracture in obese individuals. In particular, factors such as high saturated fat (SFA) intake, low dietary calcium, hyperparathyroidism (PTH), and elevated oxidative stress, and inflammation will favor osteoclastogenesis and bone resorption. In contrast, dietary intake of polyunsaturated fatty acids (PUFA), protein, and supplemental vitamin D, high growth hormone (GH) and fibroblast factor 23 (FGF23) may enhance osteoblastogenesis and bone formation. Additionally, lack of physical mobility, a body composition that is high in adiposity and low in muscle mass, and compromised bone quality (Ct, cortical BMD), will also increase the risk of fracture. Factors are shown that have positive (+) and negative (−) actions on osteoporotic fractions in obesity.