Dietary calcium and vitamin K are associated with osteoporotic fracture risk in middle-aged and elderly Japanese women, but not men: the Murakami Cohort Study.

Affiliation

Platonova K(1), Kitamura K(1), Watanabe Y(1), Takachi R(2), Saito T(3), Kabasawa K(4), Takahashi A(5), Kobayashi R(5), Oshiki R(5), Solovev A(1)(6), Iki M(7), Tsugane S(8), Sasaki A(9), Yamazaki O(10), Watanabe K(11), Nakamura K(1).
Author information:
(1)Division of Preventive Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
(2)Department of Food Science and Nutrition, Nara Women's University Graduate School of Humanities and Sciences, Nara, Japan.
(3)Department of Health and Nutrition, Niigata University of Health and Welfare, Niigata, Japan.
(4)Department of Health Promotion Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
(5)Department of Rehabilitation, Niigata University of Rehabilitation, Niigata, Japan.
(6)Department of Public Health and Health, Pacific State Medical University, Vladivostok, Russia.
(7)Department of Public Health, Kindai University Faculty of Medicine, Osaka, Japan.
(8)Center for Public Health Sciences, National Cancer Center, Tokyo, Japan.
(9)Murakami Public Health Center, 10-15 Sakanamachi, Niigata, Japan.
(10)Niigata Prefectural Office, Niigata, Japan.
(11)Department of Orthopaedic Surgery, Niigata University Hospital, Niigata, Japan.

Abstract

Although dietary Ca, vitamin D and vitamin K are nutritional factors associated with osteoporosis, little is known about their effects on incident osteoporotic fractures in East Asian populations. This study aimed to determine whether intakes of these nutrients predict incident osteoporotic fractures. We adopted a cohort study design with a 5-year follow-up. Subjects were 12 794 community-dwelling individuals (6301 men and 6493 women) aged 40-74 years. Dietary intakes of Ca, vitamin D and vitamin K were assessed with a validated FFQ. Covariates were demographic and lifestyle factors. All incident cases of major osteoporotic limb fractures, including those of the distal forearm, neck of humerus, neck or trochanter of femur and lumbar or thoracic spine were collected. Hazard ratios (HR) for energy-adjusted Ca, vitamin D and vitamin K were calculated with the residual method. Mean age was 58·8 (sd 9·3) years. Lower energy-adjusted intakes of Ca and vitamin K in women were associated with higher adjusted HR of total fractures (Pfor trend = 0·005 and 0·08, respectively). When vertebral fracture was the outcome, Pfor trend values for Ca and vitamin K were 0·03 and 0·006, respectively, and HR of the lowest and highest (reference) intake groups were 2·03 (95 % CI 1·08, 3·82) and 2·26 (95 % CI 1·19, 4·26), respectively. In men, there were null associations between incident fractures and each of the three nutrient intakes. Lower intakes of dietary Ca and vitamin K were independent lifestyle-related risk factors for osteoporotic fracture in women but not men. These associations were robust for vertebral fractures, but not for limb fractures.