Dietary factors and chronic low-grade systemic inflammation in relation to bone health

Chronic low-grade systemic inflammation, which has been categorized by a two- to fourfold age-related increase in circulating inflammatory cytokines and acute phase reactants, has been implicated in the pathophysiology of a range of musculoskeletal-related disorders, including osteoporosis, sarcopenia, and fragility fractures. While the precise mechanism(s) underlying this age-related increase in inflammation (termed "inflammaging") are yet to be determined, genetic factors, pathological conditions and various hormonal, environmental, and lifestyle factors have all been shown to play a role. Over the past decade, there has been considerable interest into whether dietary interventions, including weight loss and caloric restriction alone or with exercise, and various dietary patterns, foods and nutrients, can modulate the inflammatory response within the body, particularly in people with diseases known to have a strong inflammatory pathogenesis (e.g., type 2 diabetes, cardiovascular disease, and cancer). Of the key dietary factors known to be important for bone and muscle health which have been investigated in terms of whether they exhibit anti-inflammatory properties, there have been mixed findings with regard to dietary and supplemental calcium and vitamin D, dairy products, dietary protein, vitamin K, magnesium and omega-3 fatty acids or their combination. Based on the available data, there is no consistent evidence that these dietary factors modulate inflammation in apparently healthy adults. However, a limited number of intervention trials have demonstrated that calcium and vitamin D supplementation, high dairy diets, increased dietary protein, vitamin K, and omega-3 fatty acids can produce modest reductions in circulating inflammatory biomarkers in people with osteoporosis, sarcopenia or the presence of another chronic disease(s). Whether a reduction in these inflammatory markers translates into beneficial effects on skeletal health or a reduction in fracture risk, is not known. Given the emerging clinical evidence linking low-grade systemic inflammation to osteoporosis, sarcopenia and fractures in the elderly, further intervention trials are warranted to evaluate the long-term efficacy of different nutrients or their combination on markers of inflammation and their putative effect on modulating musculoskeletal health outcomes.