1. Body composition was assessed in 28 healthy subjects (body mass index 20-28 kg/m2) by dual-energy X-ray absorptiometry, deuterium dilution, densitometry, 40K counting and four prediction methods (skinfold thickness, bioelectrical impedance, near-i.r. interactance and body mass index). Three- and four-component models of body composition were constructed from combinations of the reference methods. The results of all methods were compared. Precision was evaluated by analysis of propagation of errors. The density and hydration fraction of the fat-free mass were determined. 2. From the precision of the basic measurements, the propagation of errors for the estimation of fat (+/- SD) by the four-component model was found to be +/- 0.54 kg, by the three-component model, +/- 0.49 kg, by deuterium dilution, +/- 0.62 kg, and by densitometry, +/- 0.78 kg. Precision for the measurement of the density and hydration fraction of fat-free mass was +/- 0.0020 kg/l and +/- 0.0066, respectively. 3. The agreement between reference methods was generally better than between reference and alternative methods. Dual-energy X-ray absorptiometry predicted three- and four-component model body composition slightly less well than densitometry or deuterium dilution (both of which greatly influence these multi-component models). 4. The hydration fraction of fat-free mass was calculated to be 0.7382 +/- 0.0213 (range 0.6941-0.7837) and the density of fat-free mass was 1.1015 +/- 0.0073 kg/l (range 1.0795-1.1110 kg/l), with no significant difference between men and women for either. 5. The results suggest that the three- and four-component models are not compromised by errors arising from individual techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

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Higher fruit and vegetable intakes may have positive effects on bone mineral status in both younger and older age groups, especially at the spine and femoral neck. The specific mechanisms remain to be ascertained, but vitamin C, other fruit-specific antioxidants, and lifestyle may play a role.

Calcium supplementation of pregnant Gambian women had no significant benefit for breast-milk calcium concentrations or infant birth weight, growth, or bone mineral status in the first year of life.

Factors influencing the change in bone mineral after 3 mo of lactation were investigated in 47 breast-feeding mothers, 11 formula-feeding mothers, and 22 nonpregnant, nonlactating control subjects. At 6-8 wk postpartum, the breast-feeding group had a mean (+/-SD) calcium intake of 34.8+/-13.2 mmol/d and breast-milk volume, calcium concentration, and calcium output of 0.865+/-0.230 L/d, 7.41+/-1.25 mmol/L, and 6.41+/-2.00 mmol/d, respectively. There was no relation between calcium intake and any breast-milk variable. Dual-energy X-ray absorptiometry of the whole body, spine, hip, and forearm was performed at 0.5 and 3 mo. There were significant decreases in bone mineral content at the spine (3.96%; 95% CI: 4.86%, 3.06%), femoral neck (2.39%; 95% CI: 3.61%, 1.17%), total hip (1.51%; 95% CI: 2.45%, 0.60%), and whole body (0.86%; 95% CI: 1.29%, 0.43%) in breast-feeding mothers but not in formula-feeding mothers or nonpregnant, nonlactating women. These changes were not related to calcium intake, breast-milk calcium concentration, vitamin D-receptor genotype, postpartum weight change, or use of the progesterone-only contraceptive pill. After adjustment for bone area, breast-milk volume and height were identified as significant predictors at the spine, such that greater decreases were associated with taller mothers (P = 0.007) and those with greater breast-milk volume (P = 0.001). This finding suggests that the marked bone mineral changes observed in breast-feeding mothers represented a physiologic response to lactation that was independent of dietary calcium supply.