Fruits and dietary phytochemicals in bone protection

Osteoporosis is a disease of bone characterized by loss of bone matrix and deterioration of bone microstructure that leads to an increased risk of fracture. Cross-sectional studies have shown a positive association between higher fruit intake and higher bone mineral density. In this review, we evaluated animal and cellular studies of dried plum and citrus and berry fruits and bioactive compounds including lycopene, phenolics, favonoids, resveratrol, phloridzin, and pectin derived from tomato, grapes, apples, and citrus fruits. In addition, human studies of dried plum and lycopene were reviewed. Animal studies strongly suggest that commonly consumed antioxidant-rich fruits have a pronounced effect on bone, as shown by higher bone mass, trabecular bone volume, number, and thickness, and lower trabecular separation through enhancing bone formation and suppressing bone resorption, resulting in greater bone strength. Such osteoprotective effects seem to be mediated via antioxidant or anti-inflammatory pathways and their downstream signaling mechanisms, leading to osteoblast mineralization and osteoclast inactivation. In future studies, randomized controlled trials are warranted to extend the bone-protective activity of fruits and their bioactive compounds. Mechanistic studies are needed to differentiate the roles of phytochemicals and other constitutes in bone protection offered by the fruits. Advanced imaging technology will determine the effective doses of phytochemicals and their metabolites in improving bone mass, microarchitecture integrity, and bone strength, which is a critical step in translating the benefits of fruit consumption on osteoporosis into clinical data.