Role of nutritional factor menaquinone-7 in bone homeostasis and osteoporosis prevention

Abstract

Bone homeostasis is mainly regulated by osteoblasts, osteocytes and osteoclasts. Osteoblasts promote bone formation and osteoclasts stimulate bone resorption. Bone loss with aging is due to decreased osteoblastic bone formation and increased osteoclastic bone resorption. Bone loss with various pathophysiologic states leads to osteoporosis. Nutrition and functional food factors may play a role in the prevention of bone loss. Menaquinone-7 (MK-7), a kind of vitamin K 2 , has been shown to reveal stimulatory effects on osteoblastic bone formation and suppressive effects on osteoclastic bone resorption in vitro. MK-7 stimulates protein synthesis (including osteocalcin and other protein molecules) in osteoblastic cells. MK-7 regulates the gene expression of various proteins, which are related to cellular functions in osteblastic and osteoclastic cells. MK-7 suppresses activation of NF-κB signaling pathways in osteoblasts and osteoclasts. Moreover, dietary intake of MK-7 has been shown to reveal potential preventive effects on bone loss in osteoporosis animal models and postmenopausal women. This review will discuss the role of dietary MK-7 in the prevention of osteoporosis.