a1 Department of Community Preventive Medicine, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Niigata City 951-8510, Japan
a2 Department of Health and Nutrition, Niigata University of Health and Welfare, 1398 Shimami-cho, Niigata City 951-3198, Japan
a3 Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Asahimachi-dori, Niigata City 951-8514, Japan
a4 Department of Physical Therapy, Niigata University of Health and Welfare, 1398 Shimami-cho, Niigata City 951-3198, Japan
a5 Department of Nursing, Niigata University of Health and Welfare, 1398 Shimami-cho, Niigata City 951-3198, Japan
a6 Department of Nursing, School of Health Sciences, Niigata University Faculty of Medicine, 2-746 Asahimachi-dori, Niigata City 951-8518, Japan
a7 Department of Hygienic Sciences, Kobe Pharmaceutical University, 4-19-1 Motoyamakita-cho, Higashinada-ku, Kobe City 658-8558, Japan
Objective Low Ca intake is common among Japanese women, but its effect on bone metabolism has not been fully elucidated. The aim of the present study was to determine the relationship between Ca intake and serum markers of bone turnover in postmenopausal Japanese women.
Design A cross-sectional study.
Setting A community setting.
Subjects Subjects were 595 home-dwelling postmenopausal Japanese women. Ca intake was assessed by a validated FFQ. Serum type I collagen cross-linked N-telopeptides (NTX) and osteocalcin were measured as markers of bone turnover. The relationships between demographic characteristics, lifestyles, serum Ca, vitamin D and intact serum parathyroid hormone and bone turnover were also assessed.
Results The average age of the subjects was 64·5 (sd 5·8) years and the mean Ca intake was 527 (sd 160) mg/d. Ca intake was significantly associated with serum NTX (P = 0·0104), but not with serum osteocalcin. Mean serum NTX concentration in the lowest quartile of Ca intake (<417 mg/d) was significantly higher than in the fourth, referent quartile. Among these Japanese postmenopausal women, very low Ca intake (less than ∼400 mg/d) was associated with increased bone resorption but not bone formation.
Conclusions Increased bone resorption may be one mechanism by which this Ca-depleted population normalizes bone metabolism and prevents osteoporosis.
(Received July 08 2008)
(Accepted January 07 2009)
(Online publication March 12 2009)