Usual dietary intake of fermented soybeans (Natto) is associated with bone mineral density in premenopausal women.
ABSTRACT Fermented soybeans (Natto), a traditional Japanese food, contain more than 100 times as much vitamin K2 as various cheeses and are considered to promote gamma-carboxylation. Thus it is conceivable that Natto may play a preventive role in the development of osteoporosis. In this study, the relationships between the bone stiffness index measured by ultrasound, bone turnover markers, and lifestyle factors, including Natto intake, were examined in relation to vitamin D receptor (VDR) polymorphism. Among 117 premenopausal volunteers, approximately 75% were bb homozygotes, 20% were Bb heterozygotes, and only 5% were BB homozygotes. The B allele group and the bb group were subdivided according to Natto intake. In a monovariate analysis, no significant differences in indices for dietary intake, including Ca and vitamin D intake, were observed. The stiffness index in the B allele group, however, was slightly lower than in the bb groups when there was no Natto intake. There were no significant differences in serum ALP and Gla-osteocalcin, bone formation markers, or NTx and Ca in urine, bone resorption markers. A logistic regression test, including the interactional effect of Natto intake and VDR RFLP, indicated that the B allele group was a risk factor of bone mineral loss and that Natto was effective in maintaining bone stiffness in this group. Although the present study was cross sectional and requires longitudinal investigation, Natto may improve the bone health of people who have a low affinity receptor for vitamin D.
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ABSTRACT: A protective role for vitamin K in bone health has been suggested based on its role as an enzymatic cofactor. In observational studies, vitamin K insufficiency is generally associated with lower bone mass and increased hip fracture risk. However, these findings are not supported in randomized controlled trials (RCT) of phylloquinone (vitamin K(1)) supplementation and bone loss at the hip in the elderly. This suggests that increased vegetable and legume intakes may simultaneously improve measures of vitamin K status and skeletal health, even though the mechanisms underlying these improvements may be independent of each other. Menaquinone-4 (vitamin K(2)), when given at pharmacological doses, appears to protect against fracture risk and bone loss at the spine. However, there are emerging data that suggest the efficacy of vitamin K supplementation on bone loss is inconclusive.Nutrition Reviews 11/2008; 66(10):549-57. · 4.47 Impact Factor
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ABSTRACT: Vitamin K is a nutrient that was originally identified as an essential factor for blood coagulation. Recently, vitamin K has emerged as a potential protector against osteoporosis, atherosclerosis, and hepatocarcinoma. Accumulated evidence indicates that subclinical non-hemostatic vitamin K deficiency in extrahepatic tissues, particularly in bone and possibly in vasculature, exists widely in the otherwise healthy adult population. Vitamins K1 and K2 have been shown to exert protective effects against osteoporosis, although it is important that the beneficial effects will be further confirmed by large-scale, randomized, clinical trials. Increasing evidence implicates a role for vitamin K in calcification of arteries and atherogenesis. Moreover, the therapeutic potential of vitamin K2 as an antihepatoma drug has recently been highlighted. Most of the new biological functions of vitamin K in bone, vasculature, and hepatoma cells are considered attributable to promotion of gamma-carboxylation of glutamic acid residues in vitamin K-dependent proteins, which is shared by vitamins K1 and K2. In contrast, vitamin K2-specific, gamma-carboxylation-unrelated functions have also been demonstrated. Thus, biological differences between vitamins K1 and K2 and potential involvement of gamma-carboxylation-independent actions in the new roles of vitamin K remain open issues. Molecular bases of coagulation-unrelated pleiotropic actions of vitamin K and its implications in human health deserve further investigations.Nutrition 22(7-8):845-52. · 3.03 Impact Factor