Nan Rollings

The effect of calcium supplementation and tanner stage on bone density, content and area in teenage women

One hundred and twelve Caucasian girls, 11.9±0.5 years of age at entry, were randomized into a 24-month, double-masked, placebo-controlled trial to determine the effect of calcium supplementation on bone mineral content, bone area and bone density. Supplementation was 500 mg calcium as calcium citrate malate (CCM) per day. Controls received placebo pills, and compliance of both groups averaged 72%. Bone mineral content, bone mineral area and bone mineral density of the lumbar spine and total body were measured by dual energy X-ray absorptiometry (DXA). Calcium intake from dietary sources averaged 983 mg/day for the entire study group. The supplemented group received, on average, an additional 360 mg calcium/day from CCM. At baseline and after 24 months, the two groups did not differ with respect to anthropometric measurements, urinary reproductive hormone levels or any measurement of pubertal progression. The supplemented group had greater increases of total body bone measures: content 39.9% versus 35.7% (p=0.01), area 24.2% versus 22.5% (p=0.15) and density 12.2% versus 10.1% (p=0.005). Region-of-interest analyses showed that the supplemented group had greater gains compared with the control group for bone mineral density, content and area. In particular, in the lumbar spine and pelvis, the gains made by the supplemented group were 12%–24% greater than the increases made by the control group. Bone acquisition rates in the two study groups were further compared by subdividing the groups into those with below- or above-median values for Tanner score and dietary calcium intake. In subjects with below-median Tanner scores, bone acquisition was not affected by calcium supplementation or dietary calicum level. However, the calcium supplemented subjects with above-median Tanner had higher bone acqusition rates than the placebo group with above-median Tanner scores. Relative to the placebo group, the supplemented group had increased yearly gains of bone content, area and density which represented about 1.5% of adult female values. Such increases, if held to adult skeletal maturity, could provide protection against future risk of osteoporotic fractures.

Dietary caffeine intake is not correlated with adolescent bone gain

OBJECTIVE This study was conducted to determine whether dietary caffeine consumed by American white females between ages 12 to 18 affects total body bone mineral gain during ages 12 to 18 or affects hip bone density measured at age 18. METHODS The Penn State Young Womens Health Study is a longitudinal investigation of bone, endocrine and cardiovascular health in non-Hispanic, white, teenage women. Nutrient and food group intakes were obtained by averaging over 6 years of prospective diet records. The cohort, as of age 18, (n = 81) was separated into three subgroups according to mean daily caffeine intake averaged across ages 12 to 18. Group I (n = 37) consumed less than 25 mg caffeine per day; Group II (n = 33) consumed 25 to 50 mg caffeine per day; and Group III (n = 11) consumed greater than 50 mg caffeine per day. The group mean daily caffeine intakes (SD) were Group I = 14 (6) mg/day; Group II = 35 (7) mg/day; Group III = 77 (27) mg/day. Total body bone gain and hip bone density were determined by dual energy x-ray absorptiometry (DXA). RESULTS There were no significant differences among the three caffeine intake groups for total body bone mineral gain during the ages 12 to 18 or of hip bone density at age 18. The low caffeine intake group consumed more milk (and therefore more calcium) and more fruit per day than did the other two groups. Group III, the highest caffeine intake group, consumed more sugar per day than did the other two groups. The observed differences in nutrient and food intakes among the three groups were not associated with any differences in anthropometric measurements or bone gain among the three groups. CONCLUSION These findings indicate that dietary caffeine intake at levels presently consumed by American white, teenage women is not correlated with adolescent total bone mineral gain or hip bone density at age 18.

The Effect of Enhanced Bone Gain Achieved with Calcium Supplementation During Ages 12 to 16 Does Not Persist in Late Adolescence

Understanding the factors and dynamics that affect the development of peak bone mass is an essential step in the construction of strategies to prevent osteoporosis. The most rapid bone gain in women occurs in early adolescence, when women in the United States consume an average of only 65% of the recommended dietary allowance for calcium of 1200 mg/d (1). The advent of dual energy x-ray absorptiometry (DXA) and the ability to quantify bone changes in children provided the essential key to launching a double-masked, placebo-controlled trial in Hershey, PA, in April 1990 to determine the effect of calcium supplementation on bone gain in teenage women.