Estrogen and Calcium Supplement Use Among Japanese-American Women: Effects Upon Bone Loss when Used Singly and in Combination

We examined the effects of estrogen and calcium supplementation upon bone loss among a cohort of Japanese-American women. The women averaged 64 years of age (age range 45-81) and 14 years postmenopause at their initial examination in 1981. They returned at 1-3-year intervals for subsequent examinations, most recently in 1992-1994. At each examination, bone mass was measured at the calcaneus and distal and proximal radius. The women had low average dietary calcium intakes (median intake 384 mg/day). Women taking calcium supplements reported a median supplement intake of 355 mg/day; over 75% of the women taking estrogen took the equivalent of 0.6 mg/day or more of conjugated estrogens. Women taking estrogen had uniformly slower bone loss at all three sites. Compared to women not taking estrogen, whose bone loss averaged about 1% per year, women taking estrogen had 0.75-0.85% per year decreased bone loss at the three bone sites. By contrast, women who stopped estrogen had greater than average loss rates (0.35-0.65% per year greater). Calcium supplementation also reduced bone loss, but to a lesser extent than estrogen: bone loss decreased 0.25% per year at the radius sites, but was not slowed at the calcaneus. The calcaneus is more trabecular than the radius sites, which may explain the lack of response. We also examined combined estrogen and calcium supplement use.(ABSTRACT TRUNCATED AT 250 WORDS)