IOF PRESS RELEASE 21
MAY 13, 2002
Lisboa Congress Center, Portugal
Experts discuss the potential role of vitamin K in the treatment of osteoporosis
Vitamin K plays a pivotal role in bone metabolism and has been identified as a potential target for the treatment of osteoporosis and prevention of bone fractures, according to experts presenting today at a satellite symposium at the IOF World Congress on Osteoporosis, which brought together experts from Japan, the U.S. and France.
Vitamin K is present in natto, a fermented soy product consumed in Japan, as well as in plant oils and some green vegetables such as alfalfa. Several recent observations have led to the theory that vitamin K deficiency may contribute to abnormal bone metabolism and bone fragility. Most significantly, epidemiological studies of Japanese subjects have established an inverse relationship between dietary intake of vitamin K and risk of hip fracture in both men and women. Furthermore, oral administration of vitamin K2 has been shown effective in increasing bone mineral density of patients with osteoporosis.
Researchers at France's INSERM have confirmed the impact of vitamin K deficiency on bone metabolism by measuring serum levels of osteocalcin, a bone-specific protein that contains residues of the vitamin K-dependent amino acid GLA. They showed that levels of undercarboxylated osteocalcin in serum correlated negatively with hip bone marrow density (BMD), and were able to use this measurement to predict the risk of hip fracture in elderly women. Other studies described during the satellite symposium confirmed the relationship between low dietary intake of vitamin K and increased risk of hip fracture, but did not demonstrate a clear association between vitamin K intake and BMD. Furthermore, the putative mechanisms underlying the effects of vitamin K on bone are still unclear. Thus well-designed trials evaluating the effects of dietary vitamin K supplementation on age-related bone loss appear to be called for.
Dr. Masataka Shiraki of the Research Institute and Practice for Involutional Diseases in Japan, reported the results of one such study: an open-label, randomized, prospective study in 362 osteoporotic women who were treated for three years with calcium (200 mg/day), with or without added vitamin K2 (as 45 mg/day menatetrenone). Patients were followed for three years and were assessed for measures of lumbar BMD, bone turnover markers and the incidence of clinical fractures. Lumbar bone mineral density, as measured by dual energy X-ray absorptiometry (DXA), decreased in both groups over the three-year treatment period; the difference was not statistically significant. In spite of this lack of difference in BMD, women in the vitamin K treatment group experienced significantly fewer clinical fractures (33 vertebral and 4 long bone fractures) as compared with those in the control group (54 vertebral and 10 long bone fractures). This suggests that vitamin K2 supplementation is effective in reducing the incidence of clinical fractures in women with osteoporosis, independent of its effects on bone mineral density.
Vitamin K2 has been marketed in Japan since 1995 for the treatment of osteoporosis, but is not available in any other country at this time.
The International Osteoporosis Foundation (IOF) is a worldwide organization dedicated to the fight against osteoporosis around the world. It brings together scientists, physicians, patient societies and corporate partners. Working hand in hand with its 139 member societies in 71 countries and other healthcare-related organizations around the world, IOF encourages awareness and prevention, early detection and improved treatment of osteoporosis.
The IOF World Congress on Osteoporosis is being held May 10-14, 2002 in Lisbon, Portugal. Some 5,000 participants are expected for the congress, expected to be the largest gathering ever of osteoporosis specialists from around the world. Abstracts from the congress are published in a supplementary volume of the journal Osteoporosis International. For more information visit the congress website: www.osteofound.org/wco/2002
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