A review published in the June 26, 2006 issue of the American Medical Association journal Archives of Internal Medicine concluded that supplementing with either of the commonly available forms of vitamin K is associated with a reduction in bone loss. Vitamin K is synthesized by plants and bacteria, and is available in supplements in the synthetic forms of phytonadione (vitamin K1) or menaquinone-4 (vitamin K2). The authors, from the University Of York, the University of Surrey, and St Thomas Hospital in London, England analyzed 13 clinical trials involving oral phytonadione and menaquinone supplementation which provided data on bone loss. Seven of the trials, conducted in Japan using menaquinone, also included fracture data. The researchers found that all of the trials except one demonstrated a benefit for phytonadione and menaquinone in reducing bone loss as determined by bone mineral density. A separate analysis of the seven trials that included the vitamin's effect on fractures demonstrated that menaquinone supplementation was associated with a 60 percent reduction in vertebral fracture risk, a 77 percent reduction in hip fracture risk and an 81 percent reduction in all nonvertebral fracture risk compared to participants who did not receive the vitamin. In their discussion, the authors observe that there are at least three proteins in bone and cartilage that are dependent upon vitamin K: osteocalcin, matrix gamma-carboxyglutamic acid protein, and protein S. In addition, previous research has found that patients with osteoporosis have low vitamin K blood levels. Based on the findings of the current review, the authors suggest that individuals at risk of fracture be encouraged to consume a vitamin K rich diet. Bone Health FREE AIR MAIL SHIPPING IN THE UNITED STATES! The statements made here have not been evaluated by the FDA. The foregoing statements are based upon sound and reliable studies, and are meant for informational purposes. Consult with your medical practitioner to determine the underlying cause of your symptoms. Copyright 1997-2010 Life Extension Vitamin Supplies and Life Extension Institute, Inc. All rights reserved.