The effect of calcium carbonate supplementation on bone growth and mineral accretion was studied in 143 boys aged 16-18 yr, randomized to 1000 mg Ca/d or a matching placebo for 13 months. Anthropometry and dual-energy x-ray absorptiometry of the whole body, lumbar spine, hip, and forearm were performed before, during, and after the intervention. The intervention resulted in greater bone mineral content (BMC) of the whole body (+1.3%, P = 0.02), lumbar spine (+2.5%, P = 0.004), and hip (total +2.3%, P = 0.01; neck +2.4%, P = 0.02; intertrochanter +2.7%, P = 0.01). This was associated with greater height (+0.4%, P = 0.0004, equivalent to 7 mm), lean mass (+1.3%, P = 0.02), and lumbar spine bone area (+1.5%, P = 0.003). The increases in BMC diminished after size adjustment, suggesting that the intervention effect was mediated through an effect on growth. The BMC response at the intertrochanter was greater in subjects with high physical activity (+4.4%, P = 0.05). There were no other significant interactions with physical activity, plasma testosterone, calcium intake, or tablet compliance. We conclude that calcium carbonate supplementation of adolescent boys increased skeletal growth, resulting in greater stature and bone mineral acquisition. Follow-up studies will determine whether this reflects a change in the tempo of growth or an effect on skeletal size that persists into adulthood.

Correction to: European Journal of Clinical Nutrition (2004) 58, 1462–1471. doi:10.1038/sj.ejcn.1602006 Following the online publication of the above paper, the authors have identified an error in Table 4 and would like to apologise for any confusion this might have caused. The correct table is reproduced below.

BACKGROUND Osteoporosis may be prevented or delayed by maximizing peak bone mass through diet modification and physical activity during adolescence. OBJECTIVE We studied whether increases in calcium intake and physical activity effectively increase the bone mineral status of adolescent girls aged 16-18 y. DESIGN We conducted a 15.5-mo study of calcium supplementation (1000 mg Ca/d as carbonate) in 144 adolescent girls aged 17.3 +/- 0.3 y ( +/- SD). The subjects were randomly allocated to an exercise (three 45-min exercise-to-music classes/wk during term time) or nonexercise group. Dual-energy X-ray absorptiometry of the whole body, spine, forearm, and hip was performed before and after intervention. RESULTS The mean (+/- SD) percentage of subjects compliant with supplement taking was 70 +/- 27% and with exercise class attendance was 36 +/- 25%. Baseline calcium intake was 938 +/- 411 mg/d. Calcium supplementation significantly increased size-adjusted bone mineral content. The effect was stronger in subjects with good compliance (percentage difference +/- SE): whole body, 0.8 +/- 0.3% (P < or = 0.01); lumbar spine, 1.9 +/- 0.5% (P < or = 0.001); ultradistal radius, 1.3 +/- 0.6% (P < or = 0.05); total hip, 2.7 +/- 0.6% (P < or = 0.001); femoral neck, 2.2 +/- 0.7% (P < or = 0.001); trochanter, 4.8 +/- 0.9% (P < or = 0.001). Attendance at > 50% of the exercise sessions was significant at the total hip (1.4 +/- 0.7%; P < or = 0.05) and trochanter (2.6 +/- 1.2%; P < or = 0.05). CONCLUSIONS Calcium supplementation and exercise enhanced bone mineral status in adolescent girls. Whether this is a lasting benefit, leading to the optimization of peak bone mass and a reduction in fracture risk, needs to be determined.

Our previous studies raised two hypotheses: first that suboptimal early nutrition and second that human milk have enhancing effects on long-term bone mineralization. To test these hypotheses experimentally, we measured whole body and regional bone mineral content (BMC) and bone mineral density (BMD), using dual-energy X-ray absorptiometry and single-photon absorptiometry, and bone turnover at 8-12 years in 244 preterm children (128 boys) who participated in a prospective randomized study of diet during the neonatal period. Dietary randomizations studied were: banked human milk (BBM, n = 87) versus preterm formula (PTF, n = 96) as the sole diet or as a supplement to mother's expressed breast milk (EBM); PTF (n = 25) versus term formula (TF, n = 36) as sole diet. Ninety-five term children of the same age were also studied. First, preterm children were shorter and lighter than term children (height SD scores -0.49 (1.1) vs. +0.22 (0.9), weight SD scores -0.41 (1.2) vs. +0.38 (1.0)) and had significantly lower whole-body BMC than their peers; decrements were also evident at some regional sites. These differences disappeared after adjusting for bone area, body size, and pubertal status. Second, children previously randomized to BBM versus PTF or TF versus PTF showed no significant differences in anthropometry, BMC, BMD, or osteocalcin (OC). Third, there was no independent effect of the proportion of EBM on BMC, BMD, or OC and no interaction between randomized diet and the amount of EBM received. Fourth, plasma OC was significantly higher in preterm children than in term children (12.4 vs. 11.0 ng/ml, p < 0.005) and in preterm children who had received a low-nutrient (BBM/TF) as opposed to a high-nutrient diet (PTF) during the neonatal period (12.9 vs. 11.9 ng/ml, p = 0.03). In conclusion, preterm children are shorter, lighter, and have lower bone mass than their peers at age 8-12 years. The lower BMC is, however, appropriate for the bone and body size achieved. Despite large differences in early mineral intake, early diet does not affect bone mass in preterm children, and fresh human milk has no specific effect. However, poor nutrition during the neonatal period may result in higher bone formation rates during childhood.

1479 The relationship between time spent participating in leisure-time activity and several physiological measurements of fitness on bone mineral status were investigated in a group of 131 female sixth-form students, 17.3±0.3 years of age. Total time spent per week playing sport or exercising (PA) was calculated from a physical activity questionnaire (adapted from the Allied Dunbar Fitness Survey UK, 1992). Fitness measurements included; estimated VO2 max. score from a progressive shuttle run test, diastolic blood pressure (DBP) using an automated device and non-dominant grip strength (GS) from isometric dynamometry. Whole-body and regional measurements of bone mineral content (BMC) and bone area (BA) were made by Hologic QDR 1000/W. Regression models with variables transformed into natural logarithms were constructed to examine the effect of physical activity and fitness on BMC adjusted for BA, weight, and height. (Table)TableThese results indicate a positive correlation between total leisure-time activity and size adjusted BMC at the spine and hip. A stronger positive relationship was found between the measures of fitness on bone at all skeletal sites investigated in this group of female adolescents. This illustrates the potential benefit of participation in regular physical activity and an enhanced fitness level on bone mineral status that was independent of bone and body size, which could lead to the optimisation of peak bone mass and a reduction of osteoporotic risk in later life. Supported by MRC and an award from the Mead Johnson Research Fund

1476 To test the hypothesis that increasing Ca intake and taking part in regular exercise are important for the optimisation of peak bone mass, 131 female sixth-form students, 17.3±0.3 y, took part in a 15-month intervention study. The girls were randomly assigned, double-blind, to Ca (1000mg/d, Calcichew-500, Shire Pharmaceuticals) or placebo. Stratified by supplement type, they were randomly allocated to an exercise (n=75) or control group(n=56). The exercise group was invited to participate in 45 min exercise classes, 3 times a week. Supplement compliance was 70±27%. Attendance at exercise classes was 36±25% with 27% girls participating in >50%. Whole-body and regional bone mineral content (BMC) was measured before and after intervention (Hologic QDR 1000/W). TableTableValues are mean percent difference (SE) between intervention and control groups in BMC at outcome, corrected for bone area, body weight, height and baseline BMC. Ca supplementation increased size-adjusted BMC, especially at the hip. The effect was greater in girls with higher compliance. Attendance at>50% classes had a modest effect which was significant only at the hip. There was no difference in response to supplementation between the exercise groups. A follow-up study will determine whether these findings represent a permanent effect on peak bone mass.