The Role of AOPP in Age-Related Bone Loss and the Potential Benefits of Berry Anthocyanins

Age-related bone loss is a major factor in osteoporosis and osteoporotic fractures among the elderly. Because bone homeostasis involves a balance between bone formation and resorption, multiple mechanisms may induce age-dependent changes in bone. Oxidative stress is one such factor that contributes to the pathology of aging-associated osteoporosis (AAO). Advanced oxidation protein products (AOPP) are a biomarker of oxidant-mediated protein damage, and can also act to increase the production of reactive oxygen species (ROS), thereby perpetuating oxidative damage. AOPP is a relatively novel marker of oxidative stress, and its role in bone aging has not been fully elucidated. Furthermore, it has been theorized that dietary antioxidants may decrease AOPP levels, thereby reducing AAO risk, but a limited number of studies have been specifically targeted at addressing this hypothesis. Therefore, the objective of this review is to examine the findings of existing research on the role of AOPP in age-related bone loss, and the potential use of dietary antioxidants to mitigate the effects of AAOP on age-related bone loss. Cross-sectional studies have delivered mixed results, showing that AOPP levels are inconsistently associated with bone loss and aging. However, in vitro studies have documented multiple mechanisms by which AOPP may lead to bone loss, including upregulation of the JNK/p38 MAPK signaling pathways as well as increasing expression of sclerostin and of receptor activator of NFκB ligand (RANKL). Studies also indicate that antioxidants-especially berry anthocyanins-may be an effective dietary agent to prevent aging-associated bone deterioration by inhibiting the formation of AOPP and ROS. However, the understanding of these pathways in AAO has largely been based on in vitro studies, and should be examined in further animal and human studies in order to inform recommendations regarding dietary anthocyanin use for the prevention of AAO.