Objective: To establish the accuracy of an eight-polar tactile-electrode impedance method in the assessment of total body water (TBW). Design: Transversal study. Setting: University department. Subjects: Fifty healthy subjects (25 men and 25 women) with a mean (s.d.) age of 40 (12) y. Methods: TBW measured by deuterium oxide dilution; resistance (R) of arms, trunk and legs measured at frequencies of 5, 50, 250 and 500 kHz with an eight-polar tactile-electrode impedance-meter (InBody 3.0, Biospace, Seoul, Korea). Results: An algorithm for the prediction of TBW from the whole-body resistance index at 500 kHz (height 2/R500 where R is the sum of the segmental resistances of arms, trunk and legs) was developed in a randomly chosen subsample of 35 subjects. This algorithm had an adjusted coefficient of determination (r2adj) of 0.81 (P<0.0001) and a root mean square error (RMSE) of 3.6 l (9%). Cross-validation of the predictive algorithm in the remaining 15 subjects gave an r2adj of 0.87 (P<0.0001) and an RMSE of 3.0 l (8%). The precision of eight-polar BIA, determined by measuring R three times a day for five consecutive days in a fasting subject, was ≤2.8% for all segments and frequencies. Conclusion: Eight-polar BIA is a precise method that offers accurate estimates of TBW in healthy subjects. This promising method should undergo further studies of precision and its accuracy in assessing extracellular water and appendicular body composition should be determined. Sponsorship: Modena and Reggio Emilia University.

Some applications of indirect calorimetry to sports medicine are discussed and exemplified by case reports. In particular, it is suggested that oxigen consumption can be employed to assess the effects of physical activity on fat-free tissues and that the respiratory quotient may offer some insights into the food habits of athletes.

Food composition tables (FCT) were validated against chemical analysis (CA) to assess energy, carbohydrate, lipid, protein and fibre content of the food consumed by Italian Army cadets. The absolute difference between FCT and CA in 2 separate weeks was < or = 0.7% for energy, < or = 4.1% for carbohydrates, < or = 2.9% for lipids, < or = 6.2% for proteins and < or = 31.6% for fibre. It is concluded that FCT can be used to assess energy, carbohydrate, lipid and protein but not fibre intake in this military community.

We studied the effects of cooking on the vitamin and mineral content of vegetables (vegetable soup, cauliflower), meat (beefsteak) and fish (sole) and those of cutting (fruit salad) and squeezing (orange juice) on the vitamin content of fruits. In cooked dishes, vitamin retention ranged between 0 (folic acid, all dishes) and 94% (retinol, sole) and mineral retention between 63 (copper, cauliflower) and 96% (iron, vegetable soup). In orange juice, ascorbic acid appeared to be protected from oxidation for at least 12 h as compared with fruit salad. Our study shows that preparation of foods with techniques available at home may be responsible for losses of vitamins and minerals. Further studies are needed to ascertain the effects of these losses on nutritional status.

Validation studies of bioelectric impedance analysis (BIA) were performed in children with obesity, Duchenne muscle dystrophy and juvenile rheumatoid arthritis. BIA allowed an accurate assessment of total body water in all groups (CV from 4.1 to 5.1%). However, the prediction of extracellular water by BIA was not always satisfactory (CV from 8.5 to 12.5%), being better in the groups of children with the lowest variability in body water distribution.

Acute exposure to high altitude produces characteristic changes in body water distribution from which acclimatized individuals seem to be spared. However, it has been suggested that body water distribution may be different in highlanders (HL) as compared to lowlanders (LL). We studied the distribution of total body water (TBW) between extracellular water (ECW) and intracellular water (ICW) in a group of 20 HL (3200 m above sea level) versus one of 20 LL (900 m above sea level). Subjects were matched for ethnic group (Kirghiz), sex (male), weight (Wt), height and body mass index. TBW:Wt and ECW:TBW were not different in HL as compared to LL (mean +/- SD, 58.5 +/- 5.0% versus 56.0 +/- 4.2% and 40.5 +/- 4.2% versus 40.7 +/- 2.2%; p = n.s. for both). This study does not support the hypothesis that body water distribution is different in HL as compared to LL.

Total body water (TBW) was measured by deuterium oxide (D2O) dilution and predicted from bioelectrical impedance (Z) in nineteen anorexic and twenty-seven control women. The equation of Kushner et al. (1992) based on the impedance index (ZI = height2/Z) gave biases of 0.9 (SD 2.5) and 0.8 (SD 2.5) litres in controls and patients respectively (NS, ANOVA). The ZI-based equation of Deurenberg et al. (1993) gave biases of 1.5 (SD 2.4) litres (NS) and 3.0 (SD 2.1) litres (P < 0.001) in controls and patients respectively. Despite the fact that weight was the most powerful predictor of TBW on the study sample (n 46, r2 0.90, P < 0.0001, SE of the estimate 1.6 litres, CV 5.7%), the formulas of Segal et al. (1991) and Kushner et al. (1992) based on the association of weight and ZI gave an inaccurate prediction of TBW in both control and anorexic subjects, with a bias ranging from -3.2 (SD 2.4) to 2.9 (SD 2.1) litres (P < or = 0.001). Population-specific formulas based on ZI (n 46) gave a more accurate prediction of TBW by bioelectrical impedance analysis on the study subjects, with biases of -0.1 (SD 1.8) and 0.5 (SD 1.7) litres in controls and patients respectively (NS). However, the individual bias was sometimes high. It is concluded that bioelectrical impedance analysis can be used to predict TBW in anorexic women at a population level, but the predictions are less good than those based on body weight alone.

Objectives: To assess the reliability of bioelectric impedance analysis (BIA) for predicting total body water (TBW) and extracellular water (ECW) in obese children. Design: Comparison of five prediction models based on: (i) body weight (Wt), (ii) the impedance (Z) index (ZI=height 2 /Z), (iii) the association of Wt and ZI, (iv) the body surface area (SA) to impedance ratio (SA:Z) and, (v) the body volume (V) to impedance ratio (V:Z). Subjects: Thirty obese and 25 control children of 11.2±1.8 y of age. Measurements: TBW and ECW were assessed by deuterium and bromide dilution; Z was measured at frequencies of 5, 50 and 100 kHz. Results: In controls, Wt explained 11% more variance of TBW than ZI ( r 2 =0.977, SEE=0.9 I, CV=3.8%) and the association of Wt and ZI improved the prediction of TBW only slightly ( r 2 =0.982, SEE=0.8 I, CV=3.5%). The SA:Z and V:Z indexes explained 6 and 33% less variance of TBW respectively as compared to Wt alone. In obese subjects, ZI explained 4% more variance of TBW than Wt ( r 2 =0.914, SEE=1.8 I, CV=6.4%) and the SA:Z ratio was the most accurate predictor of TBW ( r 2 =0.959, SEE=1.2 I, CV=4.4%). However, the increase in the explained variance of TBW associated to the use of the SA:Z ratio was of only 1% as compared to the association of ZI and Wt. The V:Z ratio explained 9% less of variance of TBW as compared to ZI. In both control and obese subjects, the association of Wt and ZI offered the best prediction of ECW ( r 2 =0.807, SEE=1.564 I and r 2 =0.826, SEE=1.035 I, respectively). However, the values of CV were much higher in controls than in obese children (17.5% vs 8.4%) owing to their lower ECW and greater variability in ECW%. ZI was the most accurate predictor of TBW on the pooled sample ( n =55; r 2 =0.910, SEE=1.932 I, CV=7.4%). However, it was a poor predictor of ECW on the same sample owing to its high CV ( n =55; r 2 =0.866, SEE=1.806 I, CV=17.0%). Conclusions: The body surface area to impedance ratio is the most accurate predictor of TBW in obese children but the association of ZI and Wt may be of more interest when BIA is used to estimate both TBW and ECW. The impedance index offers a good prediction of TBW but not of ECW in children with different levels of fatness. Sponsorship: Supported by grant 9304260.CT04 from CNR, Italy.

Food processing has the potential to alter the nutrient quality of foods. This review deals with the effects of home-based cooking and storage practices on the micronutrient content of foods. It describes the effects of cooking, freezing and refrigeration on the vitamin and mineral content of meats, fish, fruit, vegetables and cereals. Based on this review, we suggest that the consumer should be aware of the possibility that losses in nutritional quality of foods may result from an improper use of cooking and storage techniques available at home.

OBJECTIVE:To assess the reliability of bioelectric impedance analysis (BIA) for predicting total body water (TBW) and extracellular water (ECW) in children affected by juvenile rheumatoid arthritis (JRA).SUBJECTS:Thirty-nine children affected by JRA and 23 healthy children of similar age (11.0 +/- 3.6, range 3.0-19.0 y) were recruited for the study.METHODS:TBW and ECW were measured by deuterium oxide and bromide dilution, respectively. Bioelectric impedance (Z) was measured at frequencies of 5, 50 and 100 kHz. The prediction of TBW and ECW from BIA was based on the impedance index (ZI = height2/Z, cm2/omega).RESULTS:TBW standardized per kg of body weight and ECW standardized per litre of TBW were significantly higher in JRA as compared to control patients (59.7 +/- 2.4 vs 57.7 +/- 2.7% and 44.5 +/- 4.6 vs 38.1 +/- 7.9%, with P < 0.005 and P < 0.0001, respectively). Moreover, intracellular water standardized per litre of TBW was significantly lower in JRA than in control subjects (55.5 +/- 4.6 vs 62.5 +/- 8.1, with P < 0.0001). In both controls and patients, the use of ZI at 5kHz offered the more accurate prediction of ECW. However, the use of ZI at 100 kHz did not offer a better prediction of TBW as compared to its value of 50 kHz. Control-generated formulae for predicting water compartments from BIA [TBW = 0.716 x ZI at 100 kHz-1.504, r = 0.934, s.e.e. = 2.2 l;:ECW = 0.430 x ZI5-3.652, r = 0.869(7) s.e.e. = 1.7 l] underestimated TBW and ECW in JRA patients. However, population-specific formulae [TBW (1) = 0.766 x ZI at 100 kHz-0.053, r = 0.939, s.e.e. = 2.8 l; ECW (l) = 0.399 x ZI at 5 kHz-0.283, r = 0.886, s.e.e. = 1.7 l] allowed an accurate prediction of TBW and ECW in JRA patients, taking into account their altered body water distribution.CONCLUSIONS:Altered water distribution impedes the use of formulae developed on healthy children to predict TBW and ECW from BIA and JRA patients. It is hypothesized that chronic inflammation and subclinical malnutrition may be responsible for the altered body water distribution of JRA patients. Traditional body composition models may require adjustments for use in JRA children due to their altered body hydration and water distribution.

Body hydration and extra- to intra-cellular water ratio (ECWICW) have been studied in 12 duchenne muscular dystrophy (DMD) patients and 15 healthy controls. Subjects underwent total body water (TBW) and extracellular water (ECW) assessment by deuterium and bromide dilution, respectively. Multifrequency bioelectric impedance analysis (MFBIA) was performed on all subjects with the aim to establish its accuracy in predicting TBW and ECW in DMD. Body hydration was lower (51.8 ± 2.8 vs 58.5 ± 5.9%, P < 0.01) and the ECW: ICW ratio higher (1.15 ± 0.25 vs 0.70 ± 0.23, P < 0.001) in DMD than in control subjects. Hence, control-generated formulae for predicting TBW and ECW from MFBIA gave inaccurate results in DMD subjects. Population-specific formulae were developed to obtain an accurate prediction of body water compartments in DMD patients.

AbstractWe assessed total body water (TBW) and extracellular water (ECW) in thirty-four non-ascitic cirrhotics and twenty healthy controls by 2H2O and Br dilution. In the same subjects, bioelectric impedance (BI) was recorded at multiple frequencies. Body hydration was similar for controls (mean 55·6 (SD 6·7)), less-severe cirrhotics (Child-Pugh classification A; CPA; n 21, mean 56·2 (SD 6·2)) and moderately-severe cirrhotics (Child-Pugh classification B; CPB; n 13, mean 57·2 (SD 5·4)). However, intracellular water standardized per litre TBW was significantly higher in CPB subjects (mean 27·0 (SD 7·5); P<0·01) compared with CPA (mean 21·3 (SD 10·6)) and control subjects (mean 18·0 (SD 9·8)). Published formulas for predicting TBW and ECW from BI at multiple frequencies were applied to the cirrhotics. These formulas gave accurate predictions of TBW and ECW, although standard errors of estimates were higher for CPB subjects (TBW ≤ 2·5 and ECW ≤ 2·11) than those for CPA (TBW ≤ 2·0 and ECW ≤ 1·81) and control (TBW 1·4 and ECW 0·9 1) subjects

We examined the relationships between bioelectric impedance (BI), body adiposity and body muscularity in a sample of 1540 Italian children aged from 6 to 12 years. BI and the impedance index (height(2)/BI) were found to increase with increasing levels of body adiposity (as determined by arm fat area and by the sum of four skinfolds according to Durnin & Womerseley) and body muscularity (as determined by arm muscle area and circumference), respectively. Based on the comparison with body mass index, relative weight and triceps skinfold, BI was shown to be a better index of body adiposity than height(2)/BI. However, the impedance index was a better index of body muscularity than BI. We conclude that BI and height(2)/BI have the potential to be employed as indexes of adiposity and muscularity, respectively, in childhood. For this reason, we have provided percentile values for BI and height(2)/BI which may be used in italian children from 6 to 12 years of age.

This preliminary communication reports data regarding the distribution between intracellular (ICW) and extracellular (ECW) water compartments in a group of 21 prepubertal young obese children of both sexes in comparison with a group of 18 normal children weight matched for age. Our data indicate that obesity is associated with a highly significant relative expansion of extracellular water (ECW/ICW = 0.61 +/- 0.19 and 0.76 +/- 0.09 in control and obese subjects, respectively; P < 0.0015). This observation, which has been already reported in adult women, suggests that some disturbances of water homeostasis have an early onset and stress the need for an early control of energy imbalance in children. These findings are of great concern also in the field of human body composition, suggesting the opportunity for a critical reevaluation of the assumed constancy of some human body characteristics. Body composition methodologies developed for ''normal'' populations would require adjustment for use in the obese population, since a considerable error would be introduced.

The availability of only a small number of studies on bioelectric impedance analysis (BIA) in non-Caucasian ethnic groups appears to limit reliable utilization of this method in anthropological field studies. In this study, 28 male Turkish-Mongolian subjects native of Kazakhstan (Central Asia) underwent total body water (TBW) and extracellular water (ECW) assessment by deuterium oxide (D2O) and sodium bromide (NaBr) dilution respectively. Bioelectric impedance (BI) was recorded at multiple frequencies. ECW and TBW were calculated from BI at 1 and 100 kHz respectively by applying formulae developed on a sample of Caucasian subjects with a hydration status similar to that of the study population. TBW predicted from BI at 1 and 100 kHz (37.5 +/- 3.31) was highly correlated and not significantly different from that obtained by D2O dilution (39.0 +/- 4.11, r = 0.894, p < 0.0001, SEE = 1.91). Similarly, ECW predicted from BI at 1 kHz (15.1 +/- 1.21) was highly correlated and not significantly different from that obtained by NaBr dilution (15.0 +/- 1.61, r = 0.847, p < 0.0001, SEE = 0.81). It is concluded that selected predictive formulae developed on Caucasian subjects may provide a precise and accurate assessment of ECW and TBW in Turkish-Mongolian populations.