Osteoporosis and osteoarthritis are two sides of the same coin paid for obesity.

Obesity is characterized by adipose tissue expansion and chronic low-grade inflammation. Among the inflammatory mediators related to obesity development are the adipokines. These cytokines are released from fatty tissues and act in an autocrine, paracrine, or endocrine manner. Adipocytes influence the comorbidities of obesity such as osteoporosis (OP) and osteoarthritis (OA). It is still controversial as to whether OP is associated with either a low or high body mass index, but it is quite clear that the latter condition increases the risk for OA development. Bone marrow adipocytes (BMAs) have the same precursors of osteoblasts, which are the primary cells involved in bone formation, and the amount of BMAs appears to be inversely related to bone mineral density. Although adipokines released by these adipocytes influence bone loss progress, their exact role remains controversial. Differently, the infrapatellar fat pad (IPFP) is indicated to protect the function of joint regarding OA. However, there is relatively limited information about the secretion of adipokines and other inflammatory mediators by the IPFP. Despite some inconsistencies, nutritional interventions targeting obesity may also benefit patients with OP and OA. The association among obesity, OP, and OA is quite complex, and many factors need to be explored that are mainly related to the role of adipokines derived locally rather than from visceral and subcutaneous adipose tissue. Also, nutritional intervention may affect fatty tissue mass and secretion of inflammatory mediators that may, at least in part, influence other tissues in the organism such as bone and articular cartilage. The aim of this review was to present the latest knowledge about the interrelationship between obesity and OA or OP and to discuss whether a dietary intervention for obesity will hold promise for patients with OA or OP.

Nutrition, osteoarthritis and cartilage metabolism.

BACKGROUND: Osteoarthritis (OA) is a degenerative joint disease and a leading cause of adult disability. There is no cure for OA and there is no effective treatment to stop its progression. Current pharmacologic treatments such as analgesics and non-steroidal anti-inflammatory drugs may improve the pain and offer some relief but they do not affect the progression of the disease. The chronic intake of these drugs may result in severe adverse events. The aim of this review is to revise the effects of nutrition on cartilage metabolism and OA progression. METHODS: A systematic literature search was performed including those related to macro- and micro-nutrients' actions on cartilage and OA outcome. We selected peer-reviewed articles reporting the results of human clinical trials. RESULTS: Glucosamine and chondroitin sulfate have shown to delay OA knee progression in several clinical trials. The effectiveness of some products considered nutraceuticals has been widely reviewed in the literature. This article presents a general description of the effectiveness and mechanism of action of nutrients, vitamins, antioxidants and other natural components considered as part of the normal diet. Many in vitro studies indicate the efficacy of specific nutrients in cartilage metabolism and its involvement in OA. However, rigorous clinical studies needed to evaluate the efficacy of these compounds in humans are still missing. The influence of nutrients and diet on the metabolism of cartilage and OA could represent a long-term coadjuvant alternative in the management of patients with OA. Effects of diet modifications on lipid and cholesterol profiles, adequate vitamin levels and weight reduction in obese patients could influence the course of the disease. CONCLUSION: This review demonstrates that nutrition can improve the symptoms of OA. Glucosamine and chondroitin sulfate have shown robustly to delay the progression of knee OA in several well-designed studies, however more controlled clinical trials are needed to conclude that nutritional changes slow down the progression of the disease.