Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk

Kaneki, Masao; Hedges, Stephen J.; Hosoi, Takayuki; Fujiwara, Saeko; Lyons, Anthony; Crean, St.John; Ishida, Nobuhiko; Nakagawa, Mamoru; Takechi, Masahiro; Sano, Yoshihisa; Mizuno, Yuzo; Hoshino, Shinjiro; Miyao, Mariko; Inoue, Satoshi; Horiki, Kiyomi; Shiraki, Masataka; Ouchi, Yasuyoshi; Orimo, Hajime

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Volume 17, Issue 4 , Pages 315-321, April 2001

Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2:

possible implications for hip-fracture risk

Masao Kaneki, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Stephen J. Hedges, PhD
- Department of Human Metabolism and Clinical Biochemistry, Clinical Science Center, Northern General Hospital, University of Sheffield, Sheffield, UK
Takayuki Hosoi, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Saeko Fujiwara, MD
- Department of Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan
Anthony Lyons, FRCSEd
- Department of Orthopaedic and Accident Surgery, University Hospital, Queen’s Medical Centre, Nottingham, UK
St.John Crean, MBBS, FDSRCS
- Department of Oral and Maxillofacial Surgery, Eastman Dental Institute, London, UK
Nobuhiko Ishida, MD
- Umezono Hospital, Tokyo, Japan
Mamoru Nakagawa, BA
- Sekisui Chemical Co., Ltd., Osaka, Japan
Masahiro Takechi, BA
- Sekisui Chemical Co., Ltd., Osaka, Japan
Yoshihisa Sano, PhD
- Drug Metabolism & Pharmacokinetcs, Eisai Co., Ltd., Ibaraki, Japan
Yuzo Mizuno, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Shinjiro Hoshino, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Mariko Miyao, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Satoshi Inoue, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Kiyomi Horiki, MSc
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Masataka Shiraki, MD
- Research Institute and Practice for Involutional Diseases, Nagano, Japan
Yasuyoshi Ouchi, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
Hajime Orimo, MD
- Department of Geriatric Medicine, University of Tokyo Graduate School of Medicine, Tokyo, Japan
- Correspondence to: Takayuki Hosoi, MD, PhD, Endocrinology Section, Tokyo Metropolitan Geriatric Center, 35-2, Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan

Accepted 16 October 2000.

Abstract

Increasing evidence indicates a significant role for vitamin K in bone metabolism and osteoporosis. In this study, we found a large geographic difference in serum vitamin K2 (menaquinone-7; MK-7) levels in postmenopausal women. Serum MK-7 concentrations were 5.26 ± 6.13 ng/mL (mean ± SD) in Japanese women in Tokyo, 1.22 ± 1.85 in Japanese women in Hiroshima, and 0.37 ± 0.20 in British women. We investigated the effect of Japanese fermented soybean food, natto, on serum vitamin K levels. Natto contains a large amount of MK-7 and is eaten frequently in eastern (Tokyo) but seldom in western (Hiroshima) Japan. Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration. We analyzed the relation between the regional difference in natto intake and fracture incidence. A statistically significant inverse correlation was found between incidence of hip fractures in women and natto consumption in each prefecture throughout Japan. These findings indicate that the large geographic difference in MK-7 levels may be ascribed, at least in part, to natto intake and suggest the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.

Keywords: vitamin K, osteoporosis, hip fracture, natto, fermented soybean food, geographic comparison