We conducted a double-blind, placebo-controlled, randomized trial to determine whether 1 year of supplemental calcium intake would augment hip [greater trochanter, GT, femoral neck (FN), total hip (TH)], spine (LS), and femoral mid-shaft (Fmr) BMD in female distance runners. Twenty-three women (age: 23.7 ± 4.7 yrs, height: 165.6 ± 6.3 cm, weight: 55.7 ± 6.1 kg) were randomly assigned to receive either 1000 mg/d of supplemental calcium (N = 13) or placebo tablets (N = 10) for 1 year. BMD was determined by DXA (Hologic 1000-W) and tablet compliance by self-report logs. Compliance averaged 79% and 71% for supplement and placebo groups, respectively. Calcium supplementation did not affect hip or spine BMD, but did prevent loss at the femoral mid-shaft (GT: –0.5% vs. 0.2%, FN: 0.9% vs. 1.1%, TH: –0.3% vs. 0.2%, LS: 0.3% vs. 1.2%, Fmr: 0.1% vs. –1.8%, for calcium vs. placebo, respectively). We conclude that the addition of 800 mg/d of supplemental calcium to the diet of young adult female distance runners with habitual calcium intakes of ~1000 mg/d, prevents cortical but not trabecular bone loss.
At the time the research was conducted, the authors were with the Bone Research Laboratory in the Department of Exercise Science at Oregon State University, Corvallis, OR 97331-4501. K.M. Winters-Stone is now with the School of Nursing at the Oregon Health & Science University, Portland, OR 97239.