18O Dilution Research Articles

Higher Total Energy Expenditure Contributes to Growth Faltering in Breast-Fed Infants Living in Rural Mexico

To investigate the energy requirements of infants living under unfavorable environmental conditions in rural Mexico, we measured the total energy expenditure (TEE) of 40 Otomi infants at approximately 4 or approximately 6 mo of age. Total energy expenditure was estimated by the doubly labeled water method: 100 mg 2H2O/kg and 250 mg 18O/kg were administered orally, after which urine was collected serially for 7 or 10 d. Isotopic enrichment of urine samples was analyzed by gas-isotope-ratio mass spectrometry. Weight and length were measured monthly from birth to 6 mo. Fat free mass was estimated from 18O dilution spaces. Total energy expenditures (mean +/- SD) were 310 +/- 58 and 318 +/- 29 kJ.kg-1 x d-1 at approximately 4 and approximately 6 mo, respectively. Total energy expenditure was higher than that previously observed for breast-fed infants reared under more protected environments (268 +/- 29 kJ.kg-1 x d-1). Weight, length and weight gain were 5.9 +/- 0.8 kg, 60 +/- 2 cm and 2.9 +/- 2.4 g.kg-1 x d-1 at 4.25 mo and 7.1 +/- 0.8 kg, 65 +/- 2 cm and 1.0 +/- 1.2 g.kg-1 x d-1 at 6.27 mo. Growth faltering was evident at 6 mo by clinically significant declines in growth velocities and National Center for Health Statistics Z-scores. Body fat of the Otomi infants averaged 21 +/- 6 and 18 +/- 5 g/100 g at approximately 4 and approximately 6 mo, respectively. Higher rates of TEE narrowed the margin of energy available for growth and thereby contributed to growth faltering in the Otomi infants.

The Relation between Polyphenols and Body Composition in US Hispanics/Latinos: Results from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Study of Latinos Nutrition and Physical Activity Assessment Study (SOLNAS)

BackgroundPolyphenols offer high antioxidant potential that may protect against chronic diseases. Epidemiologic evidence documenting their influence on body composition and obesity risk is limited, particularly among Hispanics/Latinos who are disproportionately prone to obesity. ObjectivesThe aims of this study were to evaluate cross-sectional associations of urinary polyphenols with body mass index (BMI) and body fat percentage (%BF) in a diverse Hispanic/Latino population and to assess the reliability of polyphenol measurements. MethodsParticipants were 442 adults from the Study of Latinos/Nutrition and Physical Activity Assessment Study (SOLNAS) aged 18–74 y. Doubly labeled water was used as an objective recovery biomarker of energy. Polyphenol excretion from 24-h urine samples was assessed. Measures were repeated in a subsample (n = 90) to provide a reliability measure. Anthropometric measures were obtained by trained personnel, and %BF was measured by 18O dilution. Linear regression models were used to evaluate multivariable associations between body composition and polyphenols. Spearman correlation coefficients between BMI and %BF with polyphenols and intraclass correlation coefficients (ICCs) between polyphenol measures were computed. ResultsA weak correlation was observed for resveratrol and %BF (r = −0.11, P = 0.02). In multivariable-adjusted regression models, weak inverse associations were observed for resveratrol and urolithin A with %BF [β ± SE: −0.010 ± 0.004 (P = 0.007) and −0.004 ± 0.002 (P = 0.03), respectively]. For every 50% increase in these urinary polyphenols, there was a 1% and 0.4% decrease in %BF. Urolithin A was inversely associated with BMI (β ± SE: −0.004 ± 0.002; P = 0.02) and with 5% lower odds of obesity in models not adjusted for total energy expenditure (TEE; OR: 0.95; 95% CI: 0.91, 0.99; P = 0.02). For every 50% increase in urolithin A, there was a 0.4-unit decrease in BMI. Associations were attenuated after adjustment for TEE. Reliability study findings were indicative of weak to moderate correlations (ICCs: 0.11–0.65), representing a degree of within-person variation in polyphenol biomarkers. ConclusionsAlthough associations were weak, resveratrol and urolithin A were inversely associated with obesity. Repeated polyphenol urine measures could clarify their long-term impact on body adiposity.

Body composition among Sri Lankan infants by ¹⁸O dilution method and the validity of anthropometric equations to predict body fat against ¹⁸O dilution.

BackgroundBody composition indicators provide a better guidance for growth and nutritional status of the infants. This study was designed to (1) measure the body composition of the Sri Lankan infants using a reference method, the 18O dilution method; (2) calculate the body fat content of the infants using published skinfold prediction equations; and (3) evaluate the applicability of the skinfold equations to predict body fat among Sri Lankan infants against the 18O dilution method.MethodsTwenty five healthy, exclusively breast-fed infants were randomly recruited at well-baby clinics, for this cross-sectional study. Body composition was measured using 18O dilution. Infant body weight, length, skinfold thicknesses and mid upper-arm circumference were measured using standard procedures. The Bland and Atlman pair-wise comparison method was used to evaluate the agreement of body fat generated using the anthropometric prediction equations against the 18O dilution values as the reference.ResultsMean (SD) body weight and length of the infants were 6.5 kg (0.9) and 64.7 cm (2.8) respectively. Mean total body water, fat free mass, fat mass and % fat mass as measured by 18O dilution method were 58.8% (5.0), 4.6 kg (0.8), 1.9 (0.5) and 29.5% (6.1). Total body water and fat free mass were significantly higher in boys when compared to girls. With the exception of three prediction equations (Bandana et al., Goran et al. and Durnin and Wormsley), most of the other commonly used anthropometry-based prediction equations yielded a bias which was not constant but a function of the % fat mass.ConclusionsBody composition of Sri Lankan infants is comparable to the normative data available from the industrialized countries. Most of the commonly used anthropometric prediction equations generated a bias which varies with the size of the body fat. Only three prediction equations (Bandana, Goran, Durnin & Wormsley) yield a constant bias. The Durnin & Wormsely equation showed the smallest bias when compared to the 18O dilution values with the narrowest limits of agreement. Accuracy of some of the prediction equations is a function of gender.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-015-0371-2) contains supplementary material, which is available to authorized users.

Evaluation of air-displacement plethysmography for body composition assessment in preterm infants

Adiposity may contribute to the future risk of disease. The aim of this study was to evaluate the accuracy and reliability of an air-displacement plethysmography (ADP) system to estimate percentage fat mass (%FM) in preterm infants and to evaluate interdevice reliability in infants. A total of 70 preterm and 9 full-term infants were assessed. The accuracy of ADP measurements was assessed by determining reference %FM values using H(2)(18)O dilution measurement. Mean %FM by ADP was 5.67 ± 1.84 and mean %FM by H(2)18O dilution was 5.99 ± 2.56. Regression analysis showed that %FM by ADP was associated with %FM by H(2)(18)O dilution (R2 = 0.63, SE of estimate (SEE) = 1.65, P = 0.006). Bland-Altman analysis showed no bias (r = -0.48, P = 0.16) and 95% limits of agreement were -3.40 to 2.76 %FM. There was no difference in mean interdevice reliability %FM values (8.97 vs. 8.55 %FM) between ADP 1 and 2. Regression analysis indicated a low SEE (1.14% FM) and high R2 (0.91); 95% limits of agreement were -1.87 to 2.71 %FM. The regression line did not differ significantly from the line of identity. ADP is a noninvasive, reliable, and accurate technique to measure preterm infants' body composition in both research and clinical settings.

Physical Activity Level and Adiposity in Community-dwelling People with Spinal Cord Injury

Obesity is a negative sequelae after spinal cord injury (SCI), leading to increased health risk and the eventual onset of cardiovascular disease. Individuals with SCI have been characterised as extremely sedentary, and the daily lifestyle of a wheelchair-bound person is not sufficient to avoid weight/adiposity gain. PURPOSE: This study compared EE, physical activity levels (PA) and adiposity in people with SCI. We also sought to determine whether wheelchair users who self-reported as "regular exercisers" showed differences in EE, PA and amount of body fat when compared to sedentary individuals with SCI. METHODS: Ten individuals with SCI were sub-divided into: (i) a group of wheelchair users engaged in "regular physical activity" for a minimum of 150 min of exercise per week during the last 6 mo (EXE; N=5) and; (ii) a group of people with SCI not undertaking any regular physical activity/exercise (SED; N=5). Total daily energy expenditure (TDEE) was measured by doubly-labeled water (DLW), resting metabolic rate (RMR) was assessed by indirect calorimetry, PA was calculated as TDEE/RMR, and fat mass estimated from total body water, determined by 18O dilution. RESULTS: Although not significant, TDEE and BMR, adjusted for body mass, were lower in SED compared to EXE (SED TDEE = 122±20 kJ·kg-1·d-1 versus EXE TDEE = 128±15 kJ·kg-1·d-1; SED BMR = 78±11 kJ·kg-1·d-1 versus EXE BMR = 93±10 kJ·kg-1·d-1). PA for SED was 1.4±0.2 and for EXE was 1.4±0.1. The percentage of body fat was significantly higher in the sedentary individuals than in physically active people (40.5±2.9% and 28.3±9.4%; P<0.05). CONCLUSION: Although EXE was engaged in at least 150 minutes of exercise weekly, this group showed a non-significantly higher TDEE and BMR, yet similar PAL. In addition, despite the significantly reduced percentage of body fat in the physically active individuals compared to sedentary SCI, both groups are considered 'obese', based on fat mass cut-offs of >22% (men 18+ yr) or > 28% (men 41 to 60 yr). These findings suggest that wheelchair-bound people with SCI need to engage in exercises at higher intensity and/or frequency in order to avoid weight gain increased body adiposity.

Gastrostomy feeding in cerebral palsy: too much of a good thing?

Gastrostomy tube (GT) feeding in children with cerebral palsy (CP) is associated with significant increases in weight gain and, potentially, with overfeeding. This study aimed to measure energy balance and body composition in children with CP who were fed either orally or by GT. Forty children (27 males, 13 females; median age 8y 6mo; range 1y 4mo-18y 11mo) with spastic quadriplegic CP, of whom 22 were gastrostomy-fed and 18 orally-fed, underwent anthropometry, indirect calorimetry, and total energy expenditure determination (doubly-labelled water method). Total body water content (estimated by the 18O dilution method) was used to determine body composition. The Gross Motor Function Classification System (GMFCS) was used to determine the degree of motor impairment. GMFCS levels ranged from I to V; in the gastrostomy group 19 out of 22 were Level V and two out of 22 were Level IV. Within the orally-fed group, 11 out of 18 were Level V and four out of 18 were Level IV. Resting metabolic rate and total energy expenditure of the gastrostomy-fed children were lower but they had a significantly larger triceps skinfold thickness (p=0.01) and fat mass index (p=0.02) than the orally-fed children. Both groups had consistently higher body-fat content and lower fat-free (i.e. muscle and bone) content than the reference population of age- and sex-matched children without disabilities. This study has demonstrated the relatively low energy expenditure and high body-fat content of children with severe CP and highlighted the potential risk of overfeeding with available enteral feeds administered via GT.

Reliability in Estimates of Body Composition of Birds: Oxygen‐18 versus Deuterium Dilution

Body composition in birds was evaluated indirectly by 18O and 2H dilution. Body composition was determined by whole-body chemical analysis of eight adult roosters (Gallus gallus). In vivo measurements of total body water (TBW) were carried out using doubly labeled water (2H2 18O). Estimated dilution spaces using both the plateau and intercept approaches were compared with the results obtained by carcass lyophilization. Both 18O and 2H slightly overestimated TBW compared with the results obtained by lyophilization, by 2.2%+/-1.9% and 5.7%+/-0.2%, respectively; both differences were statistically significant (P<0.01). The difference between these isotope estimations was significant (P<0.001). However, isotope dilution spaces and TBW were highly correlated. There was a strong inverse relationship between total body fat and TBW percentages (r2=0.98, P<0.0001). The relation between TBW and body protein was significant. Water content in lean body mass (72.8%) obtained in our study was very close to that reported in mammals, demonstrating no fundamental difference in tissue water content between birds and mammals. Estimated body fat and protein values from isotopic dilution did not significantly differ from values obtained by direct chemical analysis (P>0.05), except for body fat in the Pace and Rathbun approach (Table 3). Although estimation of TBW and body composition by isotope dilution is time consuming and expensive, deuterium offers a reliable and low-cost alternative compared with 18O. The advantage of in vivo estimation of TBW with isotopic dilution in combination with the regression approach is that it permits repeated measurements of body composition on the same birds under laboratory and free-living conditions.

Skinfold thickness versus isotope dilution for body fat assessment during simulated microgravity: results from three bed-rest campaigns in men and women with and without countermeasures

Because body composition is altered during head-down bed rest (HDBR), body mass can not be used as an index of energy balance. Consequently diet allowances should not be based on body mass evolution but on fat mass changes. Though criticized, skinfold thickness (ST) is the costless, easiest and fastest method to use for such an objective. The aim of this study was to compare the percentage of body fat (%BF) estimated by ST with the isotope dilution of H2 18O. We compiled data from three HDBR campaigns, one on women (n=8) in November 1998 and two on the same men (n=8) in December 1997 (without countermeasure) and January 1998 (with thigh-cuffs countermeasure), according to a crossover design. Body composition was assessed before and after 6 days of HDBR. %BF was derived from the biceps, triceps, sub-scapular and sup-iliac ST according to Durnin and Wormersly (1974). Fat-free mass was measured on the same day by H2 18O dilution and fat mass was calculated by the difference with body mass and expressed as a percentage. Based on precision tests, the minimum measurable change by ST was 1.1%BF for single measurement point. Both intercepts (F (4,30)=0.89, P=0.45) and slopes (F (4,30)=0.74; P=0.57) of the ST versus dilution relationships were not affected by the periods (December vs January), experimental conditions (control vs HDBR vs HDBR + thigh cuffs) or sex allowing the derivation of a common relationship %BF(st)=0.94 x %BF(dil) (F (1,47)=97.9, P<0.0001; non-significant intercept excluded) with a bias between methods of -1.7+/-2.0 %BF (95% CI: -5.8, 2.4 %BF). ST can be used to measure %BF during HDBR provided great care is placed on training and changes are higher than 1.1 %BF. If the method can be applied for in-flight energy balance monitoring given the high observed energy deficit, a tight monitoring of the individual nutritional status as needed during simulation appears, however, dubious based on this solely method.

Longitudinal changes in energy expenditure in girls from late childhood through midadolescence1–3

Longitudinal data on energy expenditure in children and adolescents are scarce. The purpose of this study was to examine changes in energy expenditure and physical activity in girls from late childhood through midadolescence. We measured total energy expenditure (TEE) by doubly labeled water, resting metabolic rate (RMR) by indirect calorimetry, body composition by 18O dilution, and time spent in activity by an activity diary in 28 initially nonobese girls at approximately 10, approximately 12, and approximately 15 y of age. Changes with age in TEE, RMR, and activity energy expenditure (AEE), both in absolute terms and in adjusted analyses, and in physical activity level (PAL) and time spent sleeping, being sedentary, and in moderate and vigorous activity were evaluated by mixed-model repeated-measures analyses. Absolute TEE and AEE increased significantly from age 10 to age 15 y (P < 0.0001 for both). Absolute RMR at ages 12 and 15 y did not differ significantly, despite significant increases in fat-free mass and fat mass between the visits. PAL was significantly higher (P < 0.0001) at age 15 y than at age 10 or 12 y, whereas time spent being sedentary increased significantly from age 10 to age 15 y (P < 0.001), and AEE adjusted for fat-free mass appeared to decrease over the same interval. Conclusions drawn regarding changes with age in physical activity depend on the measure of physical activity assessed.

Assessing risk factors for obesity between childhood and adolescence: II. Energy metabolism and physical activity.

To assess the effect of energy expenditure, including resting metabolic rate (RMR), total energy expenditure (TEE), and activity energy expenditure (AEE), as well as substrate oxidation (respiratory quotient [RQ]), on the development of obesity in a large cohort of Native American children with a high propensity for obesity. During the summer months of 1992 to 1995 and again 5 years later, 138 (65 boys and 73 girls) 5-year-old Pima Indian children were studied. At baseline and follow-up, height and weight were measured; body composition was assessed with the use of 18O dilution; RMR and RQ were assessed with the use of indirect calorimetry; TEE was measured with the use of the doubly-labeled water method; and AEE was calculated (TEE - [RMR + 0.1 x TEE]). In addition, an activity questionnaire was used to assess participation in sporting activities as well as television viewing during the previous year. Linear regression models were used to assess the effects of the baseline variables on the development of obesity. Pima Indian children were markedly overweight at both 5 and 10 years of age. Cross-sectionally, percentage of body fat and body weight at 5 and 10 years of age were negatively correlated with sports participation and positively correlated with television viewing. Most important, there was a marked change in the correlation between body size and activity between 5 and 10 years of age: at age 5 years, weight was positively correlated with AEE and PAL, but at age 10 years, the correlation with AEE was lost and that with PAL was negative. However, prospectively, none of the variables measured at baseline was a predictor of percentage of body fat at age 10 years after adjustment for percentage of body fat at age 5 years. At age 5 years, obesity is associated with decreased participation in sports and increased television viewing but not with a decreased PAL. At age 10 years, obesity is associated with decreased participation in sports, increased television viewing, and a decreased PAL, suggesting that a decrease in PAL in free-living conditions seems to follow, not precede, the development of obesity.

Leptin responses to physical inactivity induced by simulated weightlessness.

Physical inactivity induced by head-down bed rest (HDBR) affects body composition (BC). Leptin is involved in BC regulation by acting on fuel homeostasis. We investigated whether leptin and counterregulatory hormone levels are affected by a 7-day HDBR. Fasting blood was sampled daily (0700) in males (n = 8) and on alternating days in females (n = 8) for measurements of leptin, insulin, norepinephrine (NE), epinephrine (Epi), growth hormone (GH), cortisol, nonesterified fatty acid (NEFA), and glucose. BC was measured by H(2)(18)O dilution. Energy intake (men 10.5 +/- 0.2 MJ/day, women 7.9 +/- 0.3 MJ/day) and BC were unchanged by HDBR. Increased levels of leptin (men 40%, P = 0.003; women 20%, P = 0. 050), insulin (men 34%, P = 0.018; women 25%, P = 0.022), and the insulin-to-glucose ratio (men 30%, P = 0.049; women 25%, P = 0.031) were noted. GH, NE, Epi, and cortisol levels were unaltered. NEFA dropped in both sexes, but glucose decreased only in women. In conclusion, HDBR increased leptin levels independently of stress response, changes in fat mass, energy intake, or gender. These changes were correlated to the insulin-resistance development in men. Further analyses are required, but the results have to be considered for longer HDBR periods with 1) the well-described drop in energy intake and 2) the BC changes.

Comparison of High‐Calorie, Low‐Nutrient‐Dense Food Consumption among Obese and Non‐Obese Adolescents

The purpose of this study was to determine whether obese adolescents eat more high-calorie low-nutrient-dense foods than non-obese adolescents. Using a cross-sectional design, 22 non-obese and 21 obese adolescents kept 14-day food records. Records provided estimates of total daily energy intake and caloric intake from five categories of high-calorie, low-nutrient-dense (HC) foods: candy, chips, soda, baked goods, and ice cream. Body composition was determined by 18O dilution and daily energy expenditure by doubly labeled water. Percentage of energy intake reported (%report) was calculated as the ratio of reported energy intake to measured energy expenditure (x 100%). Both groups underreported energy intake, but the percentage reported was significantly greater in the non-obese group (78.2+/-20.5% non-obese vs. 55.5+/-21.8% obese, p<0.001). Consumption of calories from chips and soda was similar among non-obese and obese adolescents. However, total energy intake from all HC foods was higher in the non-obese group than among the obese (617+/-356 kcal/day vs. 362+/-223 kcal/day; p<0.01) and represented 27.2+/-10.5% and 19.9+/-9.6% of reported energy intake in the non-obese and obese groups, respectively. After adjustment for under-reporting, the percentage of calories provided by each of the HC foods was similar in the obese and non-obese groups except for ice cream, which remained significantly greater in the non-obese group (p<0.05). Our findings suggest that both non-obese and obese adolescents consume a substantial portion of reported calories from HC foods and that obese adolescents do not consume more calories from these foods than non-obese adolescents. These data offer no evidence to support the widespread notion that obese adolescents eat more "junk food" than non-obese adolescents. Health professionals who treat obese adolescents must be aware that the excess calories in their diets may come from a variety of food sources and not solely from high-calorie snack foods.

Maternal diabetes status does not influence energy expenditure or physical activity in 5-year-old Pima Indian children.

Children of women who have diabetes during pregnancy are more likely to become obese by early adulthood than those of women with normal glucose tolerance during pregnancy. Obesity can result from either excess food intake, low levels of energy expenditure or both. In our study, we tested whether maternal diabetes status influences total energy expenditure (TEE by doubly labelled water), resting metabolic rate (RMR by ventilated hood) and physical activity level (PAL = TEE/RMR and assessed by activity questionnaire). Measurements were taken in 88 5-year-old Pima Indian children, 24 children of women with diabetes (2-h plasma glucose > or = 11.1 mmol/l) diagnosed before or during pregnancy and 64 children of women with normal glucose tolerance (2-h plasma glucose < 7.8 mmol/l during pregnancy and no prior history of abnormal glucose tolerance). Although birth weight was higher in children of diabetic than of nondiabetic women (mean +/- SD; 3.8 +/- 0.6 vs 3.5 +/- 0.4 kg, p < 0.03), there were no differences in weight (26.4 +/- 6.9 vs 24.2 +/- 5.6 kg) or per cent body fat (18O dilution; 33 +/- 8 vs 31 +/- 8%) between the groups at 5 years of age. There was no difference in TEE (6508 +/- 1109 vs 6175 +/- 942 kJ/d) or in RMR (4674 +/- 786 vs 4483 +/- 603 kJ/d) expressed as absolute values or after adjustment for weight and sex (TEE) or fat-free mass, fat mass, and sex (RMR). Physical activity level was also similar between the groups (1.40 +/- 0.12 vs 1.38 +/- 0.12). These results suggest that maternal diabetes status does not influence energy expenditure in the children by 5 years of age. Thus the greater obesity seen at older ages in the children of women with diabetes could be due to excess energy intake. Alternatively, if energy expenditure does have a role in the aetiology of obesity in these children, perhaps it does so only in older children.

Factors affecting the 2H to 18O dilution space ratio in infants.

In the doubly labeled water (DLW) method, for measurement of energy expenditure in humans, calculation of carbon dioxide production rate is influenced by the ratio (R) of the dilution spaces of the tracer isotopes 2H and 18O. Recent publications have recommended use of a fixed value for R, using a mean population value (meanR) rather than individually derived experimental values. However, most of the data considered previously were derived from adults. Infants are characterized by rapid rates of energy deposition and high body water content, either of which could influence isotope kinetics. We have considered whether use of a fixed R value is suitable for DLW studies of infants, and whether the adult (meanR) value is appropriate. Data from 281 DLW measurements in healthy infants aged 6 wk to 12 mo were analyzed. Mean R of all measurements was 1.036 (SD 0.019), very similar to (meanR) values recommended for adults. We found analytical precision could account for almost all between-subject variation at a single time point. However, we also found relationships between R and age and weight gain, indicating that physiology does influence the space ratio. The effect of weight gain on R was negligible, but changes of (meanR) with age, reflecting changes in percentage body water during infancy, were of sufficient magnitude to affect calculation of energy expenditure significantly. Our analysis suggests that use of a fixed ratio at a single time point in infancy is acceptable, but that the appropriate value of (meanR) changes over the first year of life.

Body composition and energy expenditure of patients with chronic cardiac failure.

Patients with acute cardiac failure have excess body water, and it is commonly assumed that this is also so in patients with stable chronic cardiac failure (CCF). To investigate this, we measured total body water (TBW) using stable isotope dilution and single-frequency bioelectrical impedance (BIA), and also extracellular volume (ECV) using bromide dilution in 12 patients with CCF and eight matched control subjects. TBW [kg(-1) bodyweight] was similar in the two groups [median 18O dilution 53.2% (range 46.5-57.1%) in patients vs. 54.8% (47.9-62.7) in control subjects; BIA 56.6% (42.7-73.1) vs. 58.0% (52.0-68.6)]. ECV was also similar in the two groups [0.25 Lkg(-1) (0.20-0.29) vs. 0.25 (0.19-0.35)]. There was a strong correlation between stable isotope and BIA measurements of TBW for all subjects (r = 0.76), but BIA overestimated TBW by a mean difference of 2.4 kg (limits of agreement of -4.1 kg to +8.9 kg). Body fat content was similar in the two groups, whether measured by skinfold anthropometry, whole-body densitometry or by 18O dilution. Resting energy expenditure (REE), calculated from indirect calorimetry, and total energy expenditure (TEE), calculated from the ratio of 2H to 18O elimination rate after drinking doubly labelled water, were also similar in the two groups. It is concluded that the patients with stable CCF in this study had normal ECV and TBW, and so excess body water did not account for their persistent symptoms.

Sensitive measures of nutritional status in children in hospital and in the field

Protein-energy malnutrition and obesity are the most common nutritional disorders that complicate the clinical course of children with neoplastic diseases. Sensitive measures of nutritional status should be used to detect these problems in children with cancer. Height and weight measurements are the mainstay of the nutritional assessment of the child. These measurements can be converted to growth velocities or to height-for-age and weight-for-height Z-scores or percent of expected values to provide a measure of the degree of under- or over-nutrition in the child. Skinfold thickness and circumference measurements of the arms, legs and/or trunk may be useful to characterize the changes in peripheral fat depots and muscle mass, respectively. However, the assessments of body composition using these measurements are subject to methodological error because selected skinfold sites are excluded. Whole-body potassium, measured by 40K counting, and total body water, measured by deuterium or 18O dilution, serve as "gold standards" to determine the lean body mass and body fat status of the child, but these techniques may not be practical in all settings. The assessment of the nutritional status of the child serves as a guide to early nutritional intervention. Indicators for early nutritional intervention include: (1) height-for-age and weight-for-height or -age Z-scores more than 2 SD below the mean for age, (2) height-for-age measurements less than 95% of expected, (3) weight-for-height measurements less than 90% or greater than 120% of expected and (4) height velocities less than 5 cm/year after 2 years of age. Early nutritional intervention is essential to restore normal body composition, reverse linear growth arrest, promote tolerance to chemotherapeutic and radiation regimens and improve the quality of life in children with cancer.

Body composition in adults with cerebral palsy by dual-energy X-ray absorptiometry, bioelectrical impedance analysis, and skinfold anthropometry compared with the 18O isotope-dilution technique

The aim of this study was to determine in adults with cerebral palsy the accuracy and practicality of standard methods used to estimate body composition. The sample consisted of 20 adults (13 men and 7 women) aged 20-55 y with various degrees of cerebral palsy. Percentage body fat was estimated from skinfold thickness, bioelectrical impedance analysis (BIA), and dual-energy X-ray absorptiometry (DXA), and compared with the reference measure of percentage body fat from total body water by 18O dilution. Values derived from use of BIA and skinfold thickness, estimated by using the Jackson-Pollock equation, were significantly different from those derived with use of 18O dilution (P < 0.001 and P < 0.001, respectively). There was no significant difference between percentage body fat measured with DXA and that measured with 18O. There was favorable agreement between DXA and 18O (mean difference: 0.06 +/- 9.6%), but not between skinfold thickness (mean difference: 6.33 +/- 12.3%) or BIA (mean difference: -6.55 +/- 13.6%) and 18O. Although DXA was the best measure for predicting percentage body fat in the sample, its high cost prohibits its use as a practical method. The best-fitting regression equation specific for this sample by using anthropometric measures to predict percentage body fat was as follows: 8.76 - (7.34 x sex) + (0.32 x weight) + (0.38 x biceps skinfold) (R2 = 0.84, P < 0.001, SEE = 4.85). This equation needs to be cross-validated in an independent sample of adults with cerebral palsy.

Prediction of percentage body fat from anthropometric measurements: comparison of New Zealand European and Polynesian young women

The prediction of total body fat from simple anthropometric measurements was examined in 42 white (New Zealand European and 40 Polynesian women aged 18-27 y. Percentage body fat (%BF) was determined from measurements of total body water (TBW) by 18O dilution. Mean (+/- SD) body mass index (BMI; in kg/m2) averaged 29.2 +/- 7.9 (range: 16.5-48.0) for the New Zealand European group and 31.2 +/- 7.9 (range: 19.8-51.8) for the Polynesian group, %BF calculated from TBW was similar in the two groups (40.5 +/- 9.9% for the New Zealand European compared with 39.1 +/- 7.5% for the Polynesian group). BMI was significantly correlated with height in the Polynesian group but not in the New Zealand European group. The relation between BMI and %BF was curvilinear for both groups. At a fixed %BF, BMI was higher in the Polynesian group than in the New Zealand European group. A BMI of 30 for the New Zealand European group corresponded to a BMI of 34 for the Polynesian group at an equivalent %BF (42%). Prediction equations for %BF developed from skinfold thicknesses or girth measurements were ethnicity dependent. We conclude that the BMI criterion for obesity in whites requires revision for use in Polynesians.

Free-living energy expenditure and behaviour in late infancy

OBJECTIVESThe energy requirements of infants are determined by body size, growth rate, and physical activity. Little is known of the determinants of energy expended on activity. The relation between free-living...

Human milk protein does not limit growth of breast-fed infants.

The efficiency with which breast- and formula-fed infants utilize dietary nutrients is likely to provide insight into their relative requirements for the growth process. We measured longitudinal changes in growth, body composition, and dietary intakes in breast- and formula-fed infants and estimated the gross efficiency with which dietary nitrogen and energy were used for lean body mass and body fat deposition. Lean body mass and body fat were determined in 10 breast-fed and 10 formula-fed infants at 6-week intervals during the first 24 weeks of life by the 18O dilution technique. Dietary nitrogen and energy intakes were determined from the amount of milk and food consumed and the nutrient content of the feedings. The gross efficiency of nutrient utilization was calculated for each infant from the cumulative dietary intake and the change in body composition with time. Length and weight gains and lean body mass and body fat accretion during the first 24 weeks of life were similar between breast- and formula-fed infants despite significantly higher nitrogen and energy intakes of the formula-fed group. The gross efficiency of dietary nitrogen utilization for lean body mass deposition was almost two-fold lower in formula- than in breast-fed infants, whereas the efficiency of dietary energy utilization for lean body mass and body fat deposition was similar between groups. Despite apparent differences in the efficiency of nitrogen utilization, there was no association between lean body mass deposition and dietary protein intake, implying that human milk protein does not limit growth quantitatively in breast-fed infants. These differences in nutrient utilization illustrate the biologic adaptability of human infants who are equipped with mechanisms that promote normal growth despite the variability of their nutrient intake.