Deuterium Dilution Technique Research Articles

Development of a bioelectrical impedance analysis-based prediction equation for body composition of rural children aged 4-8 years in Myanmar.

Background: Reliable and accurate estimates of body composition are essential when studying the various health correlates of disease. Bioelectrical impedance analysis (BIA) is an affordable and feasible body composition assessment technique for clinical and field settings. Total body water (TBW) and hence fat-free mass is estimated by predictive regression algorithms using anthropometric measurements plus the resistance index. Aim: The study aimed to develop a BIA prediction equation for TBW in children in Myanmar using the deuterium dilution technique as the reference method. Methods: The study design was cross-sectional in a school setting with convenience sampling of participants. One hundred and two healthy children (57 boys and 45 girls) with aged 4 and 8 years participated; randomly divided into the prediction group (29 boys and 22 girls) and cross-validation group (28 boys and 23 girls). Whole-body impedance, anthropometric and TBW (by D2O dilution) measurements. The prediction equation was cross-validated using a split-group design and compared to published equations for contemporaneous populations. Results: TBW could be predicted by the following equation. TBW = 0.4597 * Weight (kg) + 0.1564 * Impedance index + 0.6075 (R2 = 0.891, P < 0.0001) with a correlation coefficient of 0.942 and limits of agreement of 0.98 kg TBW on cross-validation. Conclusions: This equation can be used to predict body composition in young (aged 4-8 years) children in Myanmar but because the age range of the participants in the present study was relatively narrow, more research in different age groups is required to establish its broader applicability.

Nutrition and Health in Arab Adolescents (NaHAR): Study protocol for the determination of ethnic-specific body fat and anthropometric cut-offs to identify metabolic syndrome.

The prevalence of adolescent obesity in the Middle-East is considered among the highest in the world. Obesity in adolescents is associated with several cardiometabolic abnormalities, the constellation of which is referred to as the metabolic syndrome (MetS). This multi-country cross-sectional study aims to determine the optimal cut-off values for body fat (BF); body mass index (BMI) z-score; waist circumference (WC) percentile, and mid-upper arm circumference (MUAC) for the prediction of MetS among adolescents from Kingdom of Saudi-Arabia (KSA), Kuwait, Jordan, Lebanon and Syria. A secondary objective is to examine the validity of Bioelectrical Impendence Vector Analysis (BIVA) in estimating BF against the deuterium dilution technique (DDL). In each country, a sample of 210 adolescents will be recruited. Data collection will include demographics, socioeconomic, lifestyle and dietary data using a multi-component questionnaire; anthropometric measurements will be obtained and body composition will be assessed using the DDL and BIVA; blood pressure and biochemical assessment will be performed for the identification of the MetS. Receiver operating characteristic analyses will be undertaken to determine optimal cut-off values of BMI, WC, MUAC and BF in identifying those with MetS. Odds ratios (OR) and their respective 95% confidence interval (CI) for the association of the anthropometric measurements with MetS will be computed based on multiple logistic regression analysis models. The Bland and Altman approach will be adopted to compare BIVA against the reference DDL method for the determination of body composition parameters. This study responds to the need for ethnic-specific anthropometric cut-offs for the identification of excess adiposity and associated cardiometabolic risks in the adolescent population. The adoption of the generated cut-offs may assist policy makers, public health professionals and clinical practitioners in providing ethnic-specific preventive and curative strategies tailored to adolescents in the region.

Body composition assessment in 6-month-old infants: A comparison of two- and three-compartment models using data from the Baby-bod study.

An appreciation of infant body composition is helpful to understand the 'quality' of growth in early life. Air displacement plethysmography (ADP) using PEA POD and the deuterium dilution (DD) technique are commonly used body composition approaches in infants. We evaluated the comparability of body composition assessed using both techniques with two-compartment (2C) and three-compartment (3C) models in 6-month-old infants. Infant fat mass (FM) and percent fat mass (%FM) obtained from a 2C model using PEA POD (2C-PP) and a 2C model using the deuterium dilution technique (2C-DD) were compared to those derived from a 3C model, and to each other, using Bland-Altman analysis and Deming regression. Measurements were available from 68 infants (93% Caucasian, 53% male). The mean biases were not significant between any of the method comparisons. However, significant constant and proportional biases were identified in 2C-DD vs 3C and 2C-PP vs 2C-DD, but not in the 2C-PP vs 3C comparison. Furthermore, we observed significant associations between the mean differences and infants' percent total body water (%TBW). While no significant between-method mean differences were found in body composition estimates, some comparisons revealed significant constant and proportional biases and notable associations between the mean differences and %TBW were observed. Our results emphasise the importance of method choice, ensuring methodological uniformity in long-term studies, and carefully considering and regulating multiple pre-analytical variables, such as the hydration status of the participants.

Children's Attraction to Physical Activity and Its Relation to Physical Activity Level.

Understanding of psychosocial factors of physical activity (PA) in children is crucial in encouraging sustained PA, which in turn is associated with important health outcomes. This study aimed to examine how children's attraction to physical activity (CAPA) is associated with PA. This cross-sectional study was conducted among 219 primary school children (105 boys; 114 girls) aged 7 years old-10 years old in Kuala Lumpur, Malaysia in 2016-2017. Children from three main ethnicities, namely Malay, Chinese and Indian, were recruited. Weight, height and waist circumference were measured; body composition was assessed by deuterium dilution technique. CAPA and level of PA were obtained through self-administered questionnaires and reported as CAPA and PA scores. Median CAPA and PA scores were 3.40 (Q1 = 3.00, Q3 = 3.80) and 2.31 (Q1 = 1.95, Q3 = 2.74), respectively. Significant gender differences were found in CAPA and PA scores, with boys being more attracted to PA (3.16 [Q1 = 2.90, Q3 = 3.44]; P = 0.001) and more physically active compared with girls (2.47 [Q1 = 2.07, Q3 = 3.07]; P = 0.001). CAPA and PA scores correlated positively in both sexes. Boys scored higher than girls in 'liking of games and sports' (ρ = 0.301, P = 0.002) and 'liking of vigorous PA' (ρ = 0.227, P = 0.02) CAPA subscales, which also correlated positively with PA scores. Girls' PA scores correlated with 'peer acceptance in games and sports' (ρ = 0.329, P < 0.001). Boys are more physically active and have higher attraction to PA compared with girls. Differences in PA scores between the sexes were related to gender differences in CAPA scores. Thus, attention should be given to gender differences in CAPA related psychosocial factors when planning interventions to promote PA among children.

Measurement of body composition by deuterium oxide dilution technique and development of a predictive equation for body fat mass among severe neurologically impaired children.

Neurologically impaired (NI) children are at risk of malnutrition, which consequently impacts their health and quality of life. Accurate nutrition assessment is an important step in guiding appropriate nutrition support. Conventional anthropometric measurements among NI children have some limitations. Determining body composition requires more complex equipment, which is not routinely performed. This study was conducted to evaluate the association between anthropometric parameters and body composition assessed using the deuterium dilution technique (DDT) in NI children. A cross-sectional study enrolled severe NI children aged 1-20 years who received home enteral nutrition for at least 3 months. Weight, length, and 4-site skinfold thickness were measured. Body composition was determined using DDT following the International Atomic Energy Agency (IAEA) protocol. A total of 37 NI children (56.76% male, median age 7.2 years) were enrolled. The prevalence of underweight, stunting, and overweight were 22, 38, and 35%, respectively. Body composition analysis showed the mean (SD) of total body water (TBW) and fat mass (FM) were 10.52 (4.51) kg and 9.51 (6.04) kg, respectively. Multivariate GLM analysis showed that the factors associated with FM were age (β = 0.07 [0.05,0.08]; p < 0.001), body mass index (BMI) (β = 0.82 [0.52, 1.12]; p < 0.001), biceps skinfold thickness (BSF) (β = 0.49 [0.23,0.75]; p = 0.001), and subscapular skinfold thickness (SSF) (β = -0.24 [-0.46,0.03]; p = 0.030). A predictive equation for FM was constructed. A high prevalence of malnutrition was found among severe NI children despite enteral nutrition support. Our findings showed that age, BMI, BSF, and SSF were associated with FM. The predictive equation of FM was proposed and needed to be further validated and applied to clinical practice.

Assessment of the performance of the body mass index in diagnosing obesity in community-dwelling older adults in Latin American and Caribbean countries

BackgroundThe body mass index (BMI) ≥30 kg/m2 is the universally accepted cut-off point for defining obesity; however, its accuracy in classifying obesity in older adults is poorly understood. ObjectivesTo assess the performance of the BMI cut-off point ≥30 kg/m2 in classifying obesity in older adults, using the fat mass index (FMI) and fat mass percentage (FM%) as reference criteria; and to establish region- and sex-specific BMI-based cut-off points to classify obesity in older adults. MethodsThe present study is a secondary analysis derived from a cross-sectional project that included a sample of 1463 older adults from ten Latin American and Caribbean countries. Volunteers underwent total body water measurements using the deuterium dilution technique to determine FMI and FM%. Accuracy of the BMI and derived cutoff points was assessed by the area under the receiver operating characteristic curve (AUC). ResultsThe BMI cut-off point ≥30 kg/m2 had low sensitivity for classifying obesity in these older adults compared to the FMI and FM%. The AUC values for the optimal BMI-derived cut-off points showed an acceptable-to-outstanding discriminatory capacity in diagnosing obesity defined by the FMI. There was also a better balance between sensitivity and specificity than with the values obtained by a BMI ≥30 kg/m2 in older subjects in both regions. ConclusionThe BMI cut-off point ≥30 kg/m2 had poor sensitivity for accurately diagnosing obesity in older adults from two regions. The region- and sex-specific BMI-derived cut-off points for defining obesity using the FMI are more accurate in classifying obesity in older men and women subjects from both regions.

Infant body composition at 6 and 24 months: what are the driving factors?

Background/ObjectiveAvailable evidence on infant body composition is limited. This study aimed to investigate factors associated with body composition at 6 and 24 months.Subjects/MethodsMulticenter study with data from a 0 to 6-mo cohort (Australia, India and South Africa) and a 3 to 24-mo cohort (Brazil, Pakistan, South Africa, and Sri Lanka). For the 0–6-mo cohort, body composition was assessed by air-displacement plethysmography (ADP) and for the 3–24-month cohort by the deuterium dilution (DD) technique. Fat mass (FM), fat-free mass (FFM), FM index (FMI), and FFM index (FFMI) were calculated. Independent variables comprised the Gini index of the country, maternal and infant characteristics, and breastfeeding pattern at 3 months. For the 3–24-mo cohort, breastfeeding, and minimum dietary diversity (MDD) at 12 months were also included. Crude and adjusted analyses stratified by sex were conducted by multilevel modelling using mixed models.ResultsAt 6 months, every 1 kg increase in birth weight was associated with an increase of 0.716 kg in FFM and 0.582 kg/m2 in FFMI in girls, whereas in boys, the increase was of 0.277 kg in FFM. At 24 months, compared to those weaned before 12 months, girls still breastfed at 12 months presented a decrease of 0.225 kg in FM, 0.645 kg in FFM and 0.459 kg/m2 in FFMI, and in boys the decreases were of 0.467 kg in FM, 0.603 kg in FFM and 0.628 kg/m2 in FFMI.ConclusionBirth weight and breastfeeding are independent predictors of body composition in early life, irrespective of sex.

Associations between Stunting, Wasting and Body Composition: A Longitudinal Study in 6- to 15-Month-Old Kenyan Children

BackgroundEarly growth and body composition may influence the risk of obesity and health in adulthood. Few studies have examined how undernutrition is associated with body composition in early life. ObjectivesWe assessed stunting and wasting as correlates of body composition in young Kenyan children. MethodsNested in a randomized controlled nutrition trial, this longitudinal study assessed fat and fat-free mass (FM, FFM) using deuterium dilution technique among children at age 6 and 15 months. This trial was registered at http://controlled-trials.com/ (ISRCTN30012997). Cross-sectional and longitudinal associations between z-score categories of length-for-age (LAZ) or weight-for-length (WLZ) and FM, FFM, fat mass index (FMI), fat-free mass index (FFMI), triceps, and subscapular skinfolds were analyzed by linear mixed models. ResultsAmong the 499 children enrolled, breastfeeding declined from 99% to 87%, stunting increased from 13% to 32%, and wasting remained at 2% to 3% between 6 and 15 mo. Compared with LAZ >0, stunted children had a 1.12 kg (95% CI: 0.88, 1.36; P < 0.001) lower FFM at 6 mo and increased to 1.59 kg (95% CI: 1.25, 1.94; P < 0.001) at 15 mo, corresponding to differences of 18% and 17%, respectively. When analyzing FFMI, the deficit in FFM tended to be less than proportional to children’s height at 6 mo (P ≤ 0.060) but not at 15 mo (P > 0.40). Stunting was associated with 0.28 kg (95% CI: 0.09, 0.47; P = 0.004) lower FM at 6 mo. However, this association was not significant at 15 mo, and stunting was not associated with FMI at any time point. A lower WLZ was generally associated with lower FM, FFM, FMI, and FFMI at 6 and 15 mo. Differences in FFM, but not FM, increased with time, whereas FFMI differences did not change, and FMI differences generally decreased with time. ConclusionsOverall, low LAZ and WLZ among young Kenyan children were associated with reduced lean tissue, which may have long-term health consequences.

Comparison of Several Prediction Equations Using Skinfold Thickness for Estimating Percentage Body Fat vs. Body Fat Percentage Determined by BIA in 6-8-Year-Old South African Children: The BC-IT Study.

Body composition measurement is useful for assessing percentage body fat (%BF) and medical diagnosis, monitoring disease progression and response to treatment, and is essential in assessing nutritional status, especially in children. However, finding accurate and precise techniques remains a challenge. The study compares %BF determined by bioelectrical impedance analysis (BIA) and calculated from available prediction equations based on skinfolds in young South African children. A cross-sectional study performed on 202 children (83 boys and 119 girls) aged 6-8 years. Height and weight, triceps and subscapular skinfolds were determined according to standard procedures. %BF was determined with BIA and three relevant available equations. SPSS analyzed the data using paired samples tests, linear regression, and Bland-Altman plots. Significant paired mean differences were found for BIA and Slaughter (t201 = 33.896, p < 0.001), Wickramasinghe (t201 = 4.217, p < 0.001), and Dezenberg (t201 = 19.910, p < 0.001). For all of the equations, the standards for evaluating prediction errors (SEE) were above 5. The Bland-Altman plots show relatively large positive and negative deviations from the mean difference lines and trends of systematic under- and over-estimation of %BF across the %BF spectrum. All three equations demonstrated a smaller %BF than the %BF measured by BIA, but the difference was smallest with the Wickramasinghe equation. In comparison, a poor SEE was found in the three %BF predicted equations and %BF derived from BIA. As such, an age-specific %BF equation incorporating criterion methods of deuterium dilution techniques or 'gold-standard' methods is needed to refute these findings. However, in the absence of developed %BF equations or 'gold-standard' methods, the available prediction equations are still desirable.

Breastfeeding duration is associated with higher adiposity at 6-8 months of age.

Breastfeeding (BF) has been identified as a protective factor against childhood obesity. However, evidence ofthe association between BF duration and adiposity remains inconclusive. Few studies have been conducted among Southeast Asian infants that have measured body composition during infancy using the gold standard stable isotope method. This study aimed to evaluate the association between BF duration and body composition during infancy. Healthy full-term Thai infants aged 6-8 months (n = 60) receiving exclusive or predominant BF for at least 3 months were recruited. Skinfold thickness (SFT) was measured by well-trained investigators. Body composition was assessed by the deuterium dilution technique. Infants with longer BF duration (>6 months; mean 7.5 ± 0.5 months, n = 29) had a higher subscapular SFT z-score than those with shorter BF duration (≤6 months; mean 5.3± 0.9 months, n = 31) by 0.48 (95% confidence interval [CI]: 0.01-0.94). After adjustment for age and sex, BF duration and age at introduction of complementary feeding (CF) were positively associated with fat mass and fat mass index at 6-8 months. One month increase in BF duration and CF age was associated with a 0.37 (95% CI: 0.05, 0.69) kg/m2 and 0.76 (95% CI: 0.18, 1.34) kg/m2 increase in the fat mass index, respectively. After adjusting for infant body mass index (BMI) during the earlier infancy period, the strength of the association was attenuated. This finding may reflect reverse causality where infants with lower BMI received formula or CF earlier. A longitudinal study with follow-up into childhood is warranted to confirm the effects of BF on adiposity in infancy and childhood.

Gains in body mass and body water in pregnancy and relationships to birth weight of offspring in rural and urban Pune, India.

Maternal size, weight gain in pregnancy, fetal gender, environment and gestational age are known determinants of birth weight. It is not clear which component of maternal weight or gained weight during pregnancy influences birth weight. We evaluated the association of maternal total body water measured by the deuterium dilution technique (TBW-D2O) at 17 and 34 weeks of gestation with birth weight. A secondary aim was to examine the utility of bioimpedance spectroscopy (BIS) to determine total body water (TBW-BIS) in pregnancy. At 17 and 34 weeks of pregnancy, ninety-nine women (fifty-one rural and forty-eight urban) from Pune, India had measurements of body weight, TBW-D2O, TBW-BIS and offspring birth weight. At 17 weeks of gestation, average weights for rural and urban women were 45⋅5 ± 4⋅8 (sd) and 50⋅7 ± 7⋅8 kg (P < 0⋅0001), respectively. Maternal weight gains over the subsequent 17 weeks for rural and urban women were 6⋅0 ± 2⋅2 and 7⋅5 ± 2⋅8 kg (P = 0⋅003) and water gains were 4⋅0 ± 2⋅4 and 4⋅8 ± 2⋅8 kg (P = 0⋅092), respectively. In both rural and urban women, birth weight was positively, and independently, associated with gestation and parity. Only for rural women, between 17 and 34 weeks, was an increase in dry mass (weight minus TBW-D2O) or a decrease in TBW-D2O as a percentage of total weight associated with a higher birth weight. At both 17 and 34 weeks, TBW-BIS increasingly underestimated TBW-D2O as the water space increased. Differences in body composition during pregnancy between rural and urban environments and possible impacts of nutrition transition on maternal body composition and fetal growth were demonstrated.

Determination of Fat-Free Mass Density and its Components in Older Hispanic Adults by In Vivo Methods

The densitometry method estimates body composition based on cadaver reference values, mainly the fat-free mass density value of 1.100 g/cm3. However, several changes in fat-free mass components by aging, ethnicity, and excess adiposity could influence their density and affect body composition estimations. The present study aimed to compare the mean fat-free mass component values in older Hispanic adults to cadaver reference values. This cross-sectional study included a sample of 420 subjects aged ≥60 yr from northern Mexico. Fat-free mass was determined by the four-compartment model using air displacement plethysmography, the deuterium dilution technique, and dual-energy X-ray absorptiometry for body density, aqueous and mineral fractions of body weight, respectively. A 1-sample t test was used to compare the fat-free mass density and aqueous, mineral, and residue fractions of fat-free mass from subjects in the study to the assumed cadaver reference values. The mean fat-free mass density value for the total sample of older Hispanic adults (1.096 ± 0.011 g/cm3) was significantly (p < 0.001) lower than the assumed value of 1.100 g/cm3, except in obese older men. The mean aqueous fraction of fat-free mass (74.8 ± 3.3%) was higher than the assumed value of 73.8%, and the mean residue fraction of fat-free mass value was lower (18.3 ± 3.4%) than the reference value of 19.4%. Indeed, only the mean mineral fraction of fat-free mass value (6.8 ± 0.8%) was similar to the reference value. In the total sample, all characteristic mean fat-free mass values in these older Hispanic adults differed from cadaver reference values, except the mineral fraction of fat-free mass value.

New bioelectrical impedance analysis equations for children and adolescents based on the deuterium dilution technique

Body composition in childhood is not only a marker of the prevalence of obesity, but it can also be used to assess associated metabolic complications. Bioelectrical impedance analysis (BIA) shows promise as an easy to use, rapid, and non-invasive tool to evaluate body composition. The objectives of this study were to: (a) develop BIA prediction equations to estimate total body water (TBW) and fat-free mass (FFM) in European children and early adolescents and to validate the analysis with the deuterium dilution as the reference technique and (b) compare our results with previously published paediatric BIA equations. The cohort included 266 healthy children and adolescents between 7 and 14 years of age, 46% girls, in five European countries: Bosnia and Herzegovina, Latvia, Montenegro, North Macedonia, and Portugal. TBW and FFM were the target variables in the developed regression models. For model development, the dataset was randomly split into training and test sets, in 70:30 ratio, respectively. Model tuning was performed with 10-fold cross-validation that confirmed the unbiased estimate of its performance. The final regression models were retrained on the whole dataset. Cross-validated regression models were developed using resistance index, weight, and sex as the optimal predictors. The new prediction equations explained 87% variability in both TBW and FFM. Limits of agreement between BIA and reference values, were within ±17% of the mean, (-3.4, 3.7) and (-4.5, 4.8) kg for TBW and FFM, respectively. BIA FFM and TBW estimates were within one standard deviation for approximately 83% of the children. BIA prediction equations underestimated TBW and FFM by 0.2kg and 0.1kg respectively with no proportional bias and comparable accuracy among different BMI-for-age subgroups. Comparison with predictive equations from published studies revealed varying discrepancy rates with the deuterium dilution measurements, with only two being equivalent to the equations developed in this study. The small difference between deuterium dilution and BIA measurements validated by Bland-Altman analysis, supports the application of BIA for epidemiological studies in European children using the developed equations.

Bioelectrical Impedance Vector Analysis: A Valuable Tool to Monitor Daily Body Hydration Dynamics at Altitude.

Bioelectrical impedance vector analysis (BIVA) is a method used to estimate variation in body hydration. We assessed the potential of BIVA for monitoring daily body hydration fluctuations in nine healthy, normally active males under matching normoxic (NX) and hypobaric hypoxic (HH) experimental conditions. Furthermore, we aimed to investigate whether changes in BIVA may correspond with the development of acute mountain sickness (AMS). Subjects were exposed in a hypobaric chamber to both NX (corresponding to an altitude of 262 m) and HH conditions corresponding to an altitude of 3500 m during two four-day sojourns within which food, water intake and physical activity were controlled. Bioimpedance and body weight measurements were performed three times a day and medical symptoms were assessed every morning using the Lake Louise score (LLS). Total body water (TBW) was also assessed on the last day of both sojourns using the deuterium dilution technique. We detected circadian changes in vector length, indicating circadian body water variations that did not differ between NX and HH conditions (ANOVA effects: time: p = 0.018, eta2 = 0.149; interaction: p = 0.214, eta2 = 0.083; condition: p = 0.920, eta2 = 0.001). Even though none of the subjects developed AMS, four subjects showed clinical symptoms according to the LLS during the first 24 hours of HH conditions. These subjects showed a pronounced (Cohen’s d: 1.09), yet not statistically significant (p = 0.206) decrease in phase angle 6 hours after exposure, which may indicate fluid shift from the intracellular to the extracellular compartment. At the end of each sojourn, vector length correlated with deuterium dilution TBW “gold standard” measurements (linear regression: NX: p = 0.002 and r2 = 0.756, HH: p < 0.001 and r2 = 0.84). BIVA can be considered a valuable method for monitoring body hydration changes at altitude. Whether such changes are related to the development of clinical symptoms associated with AMS, as indicated in the present investigation, must be confirmed in future studies.

Agreement between laboratory methods and the 4-compartment model in assessing fat mass in obese older Hispanic-American adults

Densitometry (Siri's and Brožek's equations), hydrometry (by the deuterium dilution technique), and dual-energy X-ray absorptiometry (DXA) are three methods for estimating body composition. However, because they are all based on certain assumptions, they may not be applicable to aged and obese subjects due to changes in their body composition. Hence, the validity of these "laboratory methods" could be affected in obese older people. The main aim was to assess the agreement between densitometry, hydrometry, and DXA with the 4-compartment (4C) model to estimate fat mass (FM) in obese older Hispanic-American adults. As secondary goals, we explored whether the bias in densitometry and hydrometry results could be improved by modifying the assumptions regarding fat-free mass (FFM) density and hydration factor (HF) values, respectively. In the case of DXA, we explored the factors that contribute to bias. This is a cross-sectional study based on a sample of 171 obese subjects aged ≥60 years from 3 regions of northern Mexico. Body composition was assessed by the 4C model as the reference method and by all three laboratory methods. Agreement of the latter with the 4C model was probed by Bland and Altman analysis, a paired sample t-test, and simple linear regression analyses. In addition, the mean FFM density estimated in this sample, and HF values (published previously) of 0.737 and 0.753 for obese older Hispanic-American men and women, respectively, were considered as ethnic- and gender-specific values. These values were used to modify the densitometric and hydrometric equations in order to improve their bias. Finally, we tested whether the hydration status and indirect markers of adiposity are contributing factors to the bias of DXA using multiple linear regression analysis. Siri's equation overestimated FM by 0.57kg (p<0.01), while Brožek's equation, hydrometry, and DXA underestimated it by 1.24kg, 0.89kg, and 0.79kg (p<0.01), respectively, compared to the 4C model. The bias in the densitometry and hydrometry results was eliminated by substituting the ethnic- and gender-specific values into the equations. Finally, we found that hip circumference contributes to the bias in DXA. The densitometry, hydrometry, and DXA methods are not interchangeable with the 4C model for assessing fat mass in obese, older Hispanic-American adults. The lack of agreement could indicate that the assumptions of each method do not apply to this population.

Relevance of body mass index and bioelectrical impedance analysis vs. deuterium dilution technique to assess excess of fat among young adults

ABSTRACT Our study aimed to assess the nutritional status by using body composition among young Tunisian adults through three measurement methods: body mass index (BMI), bioelectrical impedance analysis (BIA) and deuterium oxide dilution technique (2H2O) and to determine the accuracy of BMI and BIA in order to evaluate the overweight and obesity among young adults in Tunisia. Our study involved 144 young adults. Anthropometric parameters were measured. The fat mass percentage (%FM) was determined by 2H2O and BIA techniques. The analysis of deuterium enrichment was performed using a Fourier transform infrared spectrophotometer (FTIR). According to BMI, 26.4% of subjects were overweight and 5.5% were obese. The mean of %FM estimated by BIA was significantly higher than that determined by 2H2O (29.7 ± 7.7 vs. 26.3 ± 10.6, p < .0001). Consequently, the prevalence of overweight and obesity assessed by BIA was significantly higher than by 2H2O (51.4% vs. 34%, p < .0001). Using BMI, the prevalence of overweight and obesity was similar to that estimated by 2H2O (31.9% vs. 34%, p = 0.544). Compared to 2H2O, BIA overestimates the prevalence of overweight and obesity in young adults. On the other hand, the BMI showed an interesting correlation with the %FM determined by 2H2O.

Relationship between maternal body composition during pregnancy and infant’s birth weight in Nairobi informal settlements, Kenya

BackgroundMaternal nutrition depletion during pregnancy compromises fetal programming, and is a cause of adverse birth outcomes. Maternal body composition measurement using direct body composition assessment methods such as the deuterium...

Grass clover intake and effects of reduced dietary protein for organic sows during summer

Energy spent on thermoregulation and locomotive activity may increase the energy requirements of outdoor relative to indoor housed sows, whilst their protein requirement most likely is comparable on a daily basis but lower per kg of feed. The purpose of this study was to quantify the energy and protein intake from compound feed and grazing and the energy and protein needed for maintenance, maternal retention, milk production, thermoregulation and locomotive activity in organic sows during summer, to understand how nutrition of organic sows could be improved. A total of 41 2nd parity sows (Landrace x Yorkshire; 239 kg at insemination) were reared outdoor under organic conditions for six months. Sows were fed one of two iso-energetic diets, either commercial available gestation and lactation diets (control strategy), or a 12% lower protein supply obtained by diluting the control diets with a low protein supplement. Sows had ad libitum access to a plentiful grass clover sward and were supplied similar amounts of metabolizable energy (ME) from compound feed equivalent to 10% above the energy recommended for indoor sows. Collections of plasma and urine were performed on d 60 and d 100 of gestation and plasma, urine and milk was collected on d 5, 20 and 40 of lactation. On all sample collection days, sows (and piglets; n=671) were weighed individually, sows were back fat scanned and heart rate and locomotive activity was registered with a global positioning system (GPS) tracker. Sow body composition was estimated using a deuterium dilution technique, which allowed retention or mobilisation of protein and fat to be calculated. Grass intake was estimated via plasma pipecolic acid. Daily grass clover intake was on average 420 g DM/d during gestation, 574 g DM/d at peak lactation and 472 g DM/d on d 40 of lactation, corresponding to 2.4, 3.2 and 2.6 kg of fresh grass. There was an increased grass clover intake in the low protein group, as they consumed 14% more grass (37 g DM/d extra) than the sows fed the normal protein compound feed (P=0.007). Estimated milk yield peaked at 16.3 kg/d on d20. This experiment showed no effects of dietary protein level on urinary pH, urea or creatinine and no effects on plasma glucose, urea, lactate, triglycerides, creatinine or NEFA concentrations. It was possible to reduce the protein content of organic compound feed in the summer time as grazing pregnant sows obtained 16-17% of their daily SID lysine requirement from the sward in mid and late gestation. In conclusion, the daily protein- and amino acid requirements were met by feed and grass consumption during pregnancy but not in early and at peak lactation due to insufficient feed intake. The total energy requirement of high yielding second parity outdoor sows during a normal Danish summer was found to be around 32 MJ ME/d during gestation and approximately 130 MJ ME/d at peak lactation.

Effects of crude protein and sodium intake on water turnover in cats fed extruded diets.

The comprehension of strategies to increase urine production may be important, especially in kibble diets to prevent urolithiasis in cats. The effects of increasing amounts of crude protein (CP) and sodium on the water turnover of cats were evaluated using the water balance (WB) method and the deuterium dilution technique. The study followed a randomized block design, with three blocks of eight cats, two cats per food type in each block, and six cats per food. Four extruded diets with different amounts of CP and sodium were evaluated (on DM basis): 28% CP and 0.58% sodium; 39% CP and 0.64% sodium; 52% CP and 0.76% sodium; and 64% CP and 0.87% sodium. Cats were individually housed in cages for 8days to measure WB, urea excretion, and faecal and urine characteristics. Deuterium oxide was used to evaluate water turnover, and during the period cats were housed in a collective cattery. The data were analysed by an F test, and the means were compared by polynomial contrasts. The ɑ level of significance was set at 0.05. The methods were compared by Pearson correlation, and Bland and Altman analysis. The increase in the CP content elevated linearly the renal excretion of urea (p<.001), and, together with the higher sodium intake, elevated the renal solute load, which resulted in a linear increase in urine production and water intake (p<.01). The urine density, metabolic water, and faecal and insensible water losses did not differ (p>.05). The water flux increased linearly when using the deuterium method (p<.001), but the obtained values were 20.85±11.11ml/cat/day higher than those verified using the WB method (p=.001). Higher CP and sodium amounts in dry diets increased the urine production and water consumption of cats, and this can be explored as a possible option to increase urination.

Effectiveness of a Food-Based Intervention to Increase Breast Milk Vitamin A Content at One Month of Infancy

Abstract Objectives Vitamin A requirements in early infancy are met only by breast milk intake. It is critical to ensure adequate breast milk vitamin A levels which also helps develop liver stores. The objective of the study was to evaluate the effect of a maternal food-based intervention on breast milk vitamin A content Methods Pregnant women (n = 50; 24 ± 1 week of gestation) were recruited for the randomized study. A 10 g of a green leafy vegetable powder (mint/coriander/curry) providing about 3200 μg β-carotene/day, for a period of 4 months up to 1 month of lactation were provided for intervention arm. Breast milk (BM) retinol concentration and BM volume were assessed. BM retinol and beta-carotene were assayed by HPLC and BM fat by creamatocrit method. BM retinol: fat ratio was calculated. The dose-to-mother deuterium dilution technique was used to estimate BM volume through enrichment of saliva measured by Fourier Transform Infrared Spectroscopy. Total BM retinol content was calculated from BM volume and the BM retinol (including beta-carotene:1 vitamin A RAE = 12 μg β-carotene). Inadequacy of intake was defined as proportion of infants with intake below a requirement of 400 μg RAE/day. Analysis of co-variance was performed after adjusting for age of mother, change in maternal blood retinol from baseline and BM fat, to compare outcomes between intervention and control arm. Results Maternal age, gestational age, socio-demographic characteristics and baseline vitamin A intake were comparable in both arms. Mean BM volume was similar in the 2 arms (676 ± 102 in intervention vs 630 ± 100 ml/day in control). BM retinol content (0.72 ± 0.12 vs 0.64 ± 0.11 μg/mL; P = 0.029) and BM retinol: fat ratio [0.41 (0.31, 0.47) vs 0.29 (0.21, 0.41), P = 0.011] were significantly higher in the intervention arm. The mean total BM retinol content was significantly higher in the intervention (482.2 ± 100.7 vs 406.5 ± 89.2 μg/day; P = 0.015; Cohen's effect size 0.80). Inadequacy of infant vitamin A intake was 14.3% in the intervention arm as against 39.1% in the control arm (P = 0.065). Conclusions The food-based intervention was effective in increasing vitamin A content in breast milk and thereby vitamin A intake in infants. Funding Sources International Atomic Energy Agency.