.BETA.-Cryptoxanthin and Bone Metabolism: The Preventive Role in Osteoporosis

Abstract

Bone loss with aging induces osteoporosis. The most dramatic expression of the disease is represented by fractures of the proximal femur. Pharmacologic and nutritional factors may play a role in the prevention of bone loss with aging. β-Cryptoxanthin, a kind of carotenoid, is abundant in Satsuma mandarin orange (Citrus unshiu MARC.). Amoung various carotenoids including β-cryptoxanthin, lutein, lycopene, β-carotene, astaxanthin, and rutin, β-cryptoxanthin has been found to have a unique anabolic effect on bone calcification in vitro. Hesperidin, which is contained in Satsuma mandarin orange, did not have an anabolic effect on bone calcification in vitro. β-Cryptoxanthin has stimulatory effects on osteoblastic bone formation and inhibitory effects on osteoclastic bone resorption in vitro, thereby increasing bone mass. β-Cryptoxanthin has an effect on the gene expression of various proteins which are related to osteoblastic bone formation andmineralization in vitro. β-Cryptoxanthin has inhibitory effects on enzyme activity which is related to osteoclastic bone resororption, and the carotenoid induces apoptosis of mature osteoclastic cells in vitro. Oral administration of β-cryptoxanthin has been shown to have the anabolic effects on bone components in young and aged rats, and the administration has the preventive effects on bone loss in streptozotocin-diabetic rats and ovariectomized rats in vivo. Moreover, the intake of β-cryptoxanthin-reinforced juice for longer periods has been shown to have both stimulatory effects on bone formation and inhibitory effects on bone resorption in healthy human or postmenopausal women in evaluating with serum biochemical markers of bone metabolism in vivo. Thus the intake of dietary β-cryptoxanthin may have a preventive effect on osteoporosis due to stimulating bone formation and due to inhibiting bone resorption. Moreover, epidemiological studies suggest the potential role of β-cryptoxanthin as a sustainable nutritional approach to improving bone health of human subjects. β-Cryptoxanthin is an important food factor in maintaining bone healthy and in preventing osteoporosis.