This systematic review suggests that supplementation with phytonadione and menaquinone-4 reduces bone loss .
In the case of the latter , there is a strong effect on incident fractures among Japanese patients
BACKGROUND Observational and some experimental data suggest that low intake of vitamin K may be associated with an increased risk of fracture .
OBJECTIVE To assess whether oral vitamin K ( phytonadione and menaquinone ) supplementation can reduce  bone loss  and prevent fractures .
Factors Affecting Bone Loss in Female Endurance Athletes
Background : Low bone mass leading to stress fractures is a well-known and yet unsolved problem among female athletes . Purpose : To quantify the rate of bone loss in healthy female athletes and investigate the effects of estrogen and vitamin K supplementation on bone loss . Study Design : Prospect i ve cohort study . Methods : We classified 115 female endurance athletes into amenorrheic , eumenorrheic , or estrogen-supplemented groups and r and omized them to receive either placebo or vitamin K1 . The bone mineral densities of the subjects ' femoral neck and lumbar spine were measured at baseline and after 2 years . Results : Bone mineral density in the lumbar spine remained constant , but bone density in the femoral neck had decreased significantly after 2 years in all three subgroups . The decrease was higher in amenorrheic ( —6.5 % ± 4.0 % ) than in eumenorrheic ( —3.2 % ± 4.1 % ) and estrogen-supplemented athletes ( —3.9 % ± 3.1 % ) . Supplementation with vitamin K did not affect the rate of bone loss . Conclusions : The rate of bone loss in all three subgroups of female athletes was unexpectedly high ; neither estrogen nor vitamin K supplementation prevented bone loss . Clinical Relevance : High-intensity training maintained over several years must be regarded in women as a risk factor for osteoporosis , and protocol s for optimal treatment should be developed
This systematic review suggests that supplementation with phytonadione and menaquinone-4 reduces bone loss .
In the case of the latter , there is a strong effect on incident fractures among Japanese patients
BACKGROUND Observational and some experimental data suggest that low intake of vitamin K may be associated with an increased risk of fracture .
OBJECTIVE To assess whether oral vitamin K ( phytonadione and menaquinone ) supplementation can reduce  bone loss  and prevent fractures .