Nutritional covariates of dietary calcium in elderly Japanese women: results of a study using the duplicate portion sampling method.
OBJECTIVE
The purposes of this study were to determine the intake of nutrients related to bone health, including calcium (Ca), phosphorus (P), sodium (Na), potassium (K), protein, and vitamin D, in elderly Japanese women and to examine possible intercorrelations between Ca intake and other nutrients.


METHODS
Fifty-three elderly women in a rural community in Japan participated by supplying duplicate meal samples of everything they ate during a 24-h period. Dietary Ca, P, Na, K, protein, and vitamin D intakes were examined. The mean (standard deviation) age of the 53 women was 68.2 y (6.4 y).


RESULTS
The mean (standard deviation) intakes of dietary Ca, P, Na, K, protein, and vitamin D were 670 (219) mg/d, 1019 (267) mg/d, 4203 (1341) mg/d, 2752 (844) mg/d, 65.2 (18.3) g/d, and 9.90 (8,89) microg/d, respectively. Dietary Ca was significantly correlated with dietary P (r = 0.732, P < 0.0001), Na (r = 0.336, P = 0.0140), K (r = 0.571, P < 0.0001), and protein (r = 0.563, P < 0.0001), but not with vitamin D. After adjusting the data to reflect the total dry weight, dietary Ca was still correlated with P (r = 0.696, P < 0.0001), K (r = 0.423, P = 0.0018), and protein (r = 0.405, P = 0.0029).


CONCLUSIONS
The intake of dietary nutrients relevant to bone health in ambulatory Japanese elderly women was examined and documented. The potential confounding effects of these nutrients, especially P, K, and protein, should be taken into account when evaluating the effects of dietary Ca on bone health in observational studies.
Nakamura
Kazutoshi
K
Department of Community Preventive Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. kazun@med.niigata-u.ac.jp
Hori
Yasushi
Y
Nashimoto
Mitsue
M
Okuda
Yoko
Y
Miyazaki
Hideo
H
Kasai
Yasunori
Y
Yamamoto
Masaharu
M
D000368:Aged; D000375:Aging; D000818:Animals; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D001842:Bone and Bones / Q000502:physiology*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D008892:Milk; D009752:Nutritional Status; D016226:Phosphorus, Dietary / Q000008:administration & dosage; D017419:Potassium, Dietary / Q000008:administration & dosage; D012424:Rural Population; D012982:Sodium, Dietary / Q000008:administration & dosage; D014807:Vitamin D / Q000008:administration & dosage
D002136:Calcium, Dietary; D004044:Dietary Proteins; D016226:Phosphorus, Dietary; D017419:Potassium, Dietary; D012982:Sodium, Dietary; D014807:Vitamin D