Factors associated with calcium absorption efficiency in pre- and perimenopausal women.
BACKGROUND
The amount of calcium ingested by an individual may affect several chronic conditions, including osteoporosis, hypertension, and colon cancer. However, individuals vary in their ability to absorb the calcium they consume.


OBJECTIVE
The purpose of this study was to examine sources of interindividual variation in the efficiency of calcium absorption in women.


METHODS
Fractional calcium absorption was estimated in 142 healthy pre- and perimenopausal women. Dietary habits, lifestyle factors, calciotropic hormones, and vitamin D receptor gene polymorphisms were also assessed.


RESULTS
Calcium absorption values averaged 35% and ranged from 17% to 58%. Fractional calcium absorption was positively associated with body mass index (r = 0.22, P = 0.007), dietary fat intake (r = 0.29, P = 0.001), serum 1,25 dihydroxyvitamin D [1,25(OH)(2)D] concentrations (r = 0.23, P = 0. 006), and parathyroid hormone concentrations (r = 0.21, P = 0.015). Fractional calcium absorption was inversely associated with total calcium intake (r = -0.18, P = 0.030), dietary fiber intake (r = -0. 19, P = 0.028), alcohol consumption (r = -0.14, P = 0.094), physical activity (r = -0.22, P = 0.007), and symptoms of constipation (r = -0.16, P = 0.059). In stepwise regression analysis, dietary fat, dietary fiber, serum 1,25(OH)(2)D, and alcohol consumption emerged as independent predictors of calcium absorption, explaining 21.02% of the observed variation. Women in the lowest tertile of the ratio of dietary fat to fiber had 19% lower fractional calcium absorption values than did women in the highest tertile of ratio of dietary fat to fiber (test of trend, P < 0.001).


CONCLUSIONS
There is a wide range of calcium absorption values in healthy women. The amount of dietary fat consumed relative to dietary fiber appears to have an important role in determining differences in calcium absorption performance among individuals.
Departments of Epidemiology, Education, and Genetics, University of Pittsburgh, USA. wolf@exchange.tc.columbia.edu
R L
RL
Wolf
J A
JA
Cauley
C E
CE
Baker
R E
RE
Ferrell
M
M
Charron
A W
AW
Caggiula
L M
LM
Salamone
R P
RP
Heaney
L H
LH
Kuller
D000042:Absorption; D000428:Alcohol Drinking / Q000378:metabolism; D002136:Calcium, Dietary / Q000493:pharmacokinetics*; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D005260:Female; D005527:Food, Fortified; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control; D011110:Polymorphism, Genetic; D017697:Premenopause; D018167:Receptors, Calcitriol / Q000235:genetics; D012016:Reference Values; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
D002136:Calcium, Dietary; D004041:Dietary Fats; D004043:Dietary Fiber; D018167:Receptors, Calcitriol; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D