Body Composition in Youths Aged 10‒17 Years by Deuterium Oxide Dilution, Air Displacement Plethysmography, and DXA: Validation of the Medical Body Composition Analyzer Bioimpedance Device by a 4-Compartment Model.

BACKGROUND: The medical body composition analyzer (mBCA) incorporates advances in multifrequency technology and has been validated using a 4-compartment (4C) model in adults but not in youths aged <18 y. OBJECTIVES: This study aimed to formulate a 4C model based on 3 reference methods and develop and validate a body composition prediction equation for the mBCA in youths aged 10‒17 y. METHODS: The body density of 60 female and male youths was measured by air displacement plethysmography, total body water by deuterium oxide dilution, and BMC by DXA. Data from the equation group (n = 30) were used to formulate a 4C model. The all-possible-regressions method was used to select variables. The model was validated in a second cohort (n = 30) in a random split design. The accuracy, precision, and potential bias were evaluated by the Bland and Altman procedure. RESULTS: Mean age, weight (W), height (H), waist circumference, and z-score of BMI were 13.6 ± 2.3 y, 54.5 ± 15.5 kg, 156 ± 11.9 cm, 75.5 ± 10.9 cm, and 0.70 ± 1.32 z, respectively. The prediction equation was as follows: FFM in kg (FFMkg) = ([0.2081] ∗ [W] + [0.8814] ∗ [H2cm/RΩ] + [0.2055 ∗ XcΩ])-15.343; R2 = 0.96; standardized root-mean-square error (SRMSE) = 2.18 kg. FFM did not differ between the 4C method (38.9 ± 12.0 kg) and the mBCA (38.4 ± 11.4 kg) (P > 0.05). The relationship between these 2 variables did not deviate from the identity line, was not significantly different from 0, and the slope was not significantly different from 1.0. In the precision prediction model of mBCA, the R2 value was 0.98 and SRMSE was 2.1. No significant bias was found when regressing differences between methods and their means (P = 0.08). CONCLUSIONS: The equation for the mBCA was accurate, precise, had no significant bias, had substantial strength of agreement and could be used in this age group when subjects were preferentially within the constraints of a specified body size.

Pinto Bean Amino Acid Digestibility and Score in a Mexican Dish with Corn Tortilla and Guacamole, Evaluated in Adults Using a Dual-Tracer Isotopic Method.

BACKGROUND: Ultra-processed foodstuffs have been replacing traditional beans with tortillas in the Mexican diet in the last decades. Therefore, scientific support is needed to promote a return to good-quality traditional dishes. OBJECTIVES: This study aims to evaluate the amino acid digestibility and score of pinto beans (Phaseolus vulgaris) consumed with corn tortillas and guacamole in adults using the dual-tracer method. METHODS: The pinto beans were intrinsically labeled using 250 mL of 2H2O (99.8%) per 19 L pot with 3 plants. A paste of cooked beans on toasted corn tortillas and guacamole topping were administered to 3 male and 3 female adults (21-25 years old; BMI, 19-23.5 kg/m2). The protocol was plateau feeding given along with U-[13C]-spirulina protein to evaluate indispensable amino acid (IAA) digestibility using the dual-tracer method. Blood samples were taken in the plateau state. The digestibility of each IAA of the bean protein was calculated by the ratio of its enrichment in the beans to the spirulina in the meal and its appearance in plasma collected in the plateau state, as a percentage corrected by spirulina digestibility. Additionally, the digestible IAA score (DIAAS) was calculated. RESULTS: The 2H enrichment of IAA in the pinto beans was 471 parts per million excess. The isotopic enrichment of 2H and 13C in IAA at 5-8 hours presented plateau states with mean CVs of 12.2% and 13.3%, respectively. The mean digestibility of IAA from pinto beans was 77% ± 1.6%, with the lowest value for threonine. The DIAAS calculated with respect to the pattern requirement for children older than 3 years, adolescents, and adults was 83%, with methionine and cysteine being the limiting amino acids. CONCLUSIONS: A Mexican dish of pinto beans, tortillas, and guacamole is a good source of protein as evaluated in adults and could be promoted as a nutritious snack. The assay is registered with the Ethical Committee of the Centro de Investigación en Alimentación y Desarrollo, A.C. as CE/015/2019.

Metabolic syndrome screening using visceral adipose tissue (VAT) from opportunistic MRI locations in a multi-ethnic population.

OBJECTIVE: To determine if visceral adipose tissue (VAT) area measured through MRI can be used opportunistically to assess the presence of cardiometabolic risk factors and compare its performance to simpler adiposity measures. METHODS: A cross-sectional analysis was carried out on a subset of 1683 participants (856 women) from the Adiposity Phenotype Study (mean age=69.2y; range 59.9-77.4). The association of total VAT area (sum of four cross sections, L1-L2, L2-L3, L3-L4, L4-L5) and each location, as well as BMI and body fat % (per SD) with the metabolic syndrome (MetSx) or its components was evaluated through logistic regression analysis. RESULTS: Total VAT can be accurately predicted using all sites evaluated (R2 range=0.82-0.96). In men, VAT did not show a superior association to MetSx compared to BMI in men. However, in women, VAT was consistently superior to BMI and body fat % in its association to MetSx, independent of ethnicity [odds ratio for BMI, body fat %and total VAT area=2.25 (95% CI: 1.93-2.62); 1.66 (95% CI: 1.36-2.03); 6.20 (95% CI: 4.69-8.21) respectively in all women]. Ethnic-specific odds ratios to MetSx in women ranged from 5.38 to 8.63 for total VAT area and 2.12-4.08 for BMI. CONCLUSION: Total VAT area can be accurately predicted from individual VAT regions in men and women and offers superior association to BMI for MetSx in women but not in men for five ethnicities. Therefore, opportunistic screening for elevated VAT area in women may be warranted across multiple ethnic groups.

A new doubly labelled water anthropometry-based equation for prediction of total daily energy expenditure in older people from low- and middle-income countries.

BACKGROUND: For community-living older people, the ability to estimate total daily energy expenditure (TDEE) with validated predictive equations based on anthropometry is limited. To our knowledge no studies exist for non-Caucasian populations OBJECTIVE: To design and validate an anthropometry-based equation to estimate TDEE using doubly-labelled water (DLW) as the criterion measure, and to assess the performance of three other published equations in community-living older people from rural and urban areas of Brazil, Chile, Guatemala, Senegal, Cuba, and Mexico METHODS: This cross-sectional study measured anthropometry and TDEE using DLW in 69 men and 43 women aged 60-89 years. TDEE was also estimated with an anthropometry-based equation derived from the sub-sample of Mexico (n = 38) and with three other published equations. Predictive accuracy of the equations was tested by an external validation procedure RESULTS: TDEE by DLW in the six country sample was 2411 ± 41 kcal/day (mean ± SE) in men and 1939 ± 51 kcal/day in women. The best new Mexican equation was TDEE, kcal/d = [223.4 + (27.9 × weight, kg) + (239.7 × sex)]; where sex: Man = 1 and Woman = 0; having high precision; R2 = 0.89, lowest RMSE = 149.2, and Cp value of 2.0. This new Mexican equation estimated TDEE accurately in the five country sample and at country level after correction for Guatemalan older men, while the published equations performed poorly CONCLUSIONS: The Mexican equation performed better that other published equations and is recommended to accurately estimate energy requirements for community-living older people in five Latin American and one African country.

An individualized food-based nutrition intervention reduces visceral and total body fat while preserving skeletal muscle mass in breast cancer patients under antineoplastic treatment.

BACKGROUND & AIMS: Breast cancer patients (BCP) during treatment often experience an increase in body weight and fat mass, and a decrease in muscle mass known as sarcopenic obesity, affecting their prognosis and quality of life. We aimed to evaluate the effect of a 6-month individualized food-based nutrition intervention program in nonmetastatic BCP body composition during treatment. METHODS: This is a pre-post study in recently diagnosed women with invasive ductal/lobular breast carcinoma (clinical stage I-III). The individualized nutrition intervention was based on the dynamic macronutrient meal equivalent menu method (MEM). Dietary plans were developed according to WCRF/AICR guidelines, BCP total energy expenditure, 1.2-1.5 g/kgBW/d of protein intake, 5-9 servings/day of fruits and vegetables, and a caloric restriction (500-1000 kcal/d) when applicable (BMI ≥ 25 kg/m2). Follow-up was every 2-weeks and a different diet menu was provided in each session during 6 months. Baseline and final measurements included the assessment of anthropometry, body composition, and physical activity. RESULTS: Twenty-two participants completed the study and at diagnosis 68% were overweighed or obese. After the 6-month nutrition intervention program, BCP lost 3.1 kg (p < 0.01) of body weight, 2.7 kg (p < 0.01) of fat-mass, 400 g (p < 0.01) of abdominal fat, 118 g (p < 0.05) of visceral fat, 1.2 kg/m2 of body mass index and 1.1 kg/m2 of fat mass index (p < 0.01). During the period, no changes were observed in bone mineral density (p = 0.3), fat-free mass (p = 0.1) and appendicular skeletal muscle mass (p = 0.2). Menopausal status in BCP did not modify the effect of the nutrition intervention. CONCLUSIONS: The individualized food-based nutrition intervention program empowered BCP to make informed healthy food choices within their personal preferences, socioeconomic and cultural background. With this type of intervention, nonmetastatic BCP reduced body weight, fat-mass, fat mass index, visceral and abdominal fat, while preserving skeletal muscle mass, during antineoplastic treatment. ClinicalTrials.govNCT03625635.

The "Super-Child" Approach Is Applied To Estimate Retinol Kinetics and Vitamin A Total Body Stores in Mexican Preschoolers.

BACKGROUND: Retinol isotope dilution (RID) and model-based compartmental analysis are recognized techniques for assessing vitamin A (VA) status. Recent studies have shown that RID predictions of VA total body stores (TBS) can be improved by using modeling and that VA kinetics and TBS in children can be effectively studied by applying population modeling ("super-child" approach) to a composite data set. OBJECTIVES: The objectives were to model whole-body retinol kinetics and predict VA TBS in a group of Mexican preschoolers using the super-child approach and to use model predictions of RID coefficients to estimate TBS by RID in individuals. METHODS: Twenty-four healthy Mexican children (aged 3-6 y) received an oral dose (2.96 µmol) of [13C10]retinyl acetate in corn oil. Blood samples were collected from 8 h to 21 d after dosing, with each child sampled at 4 d and at 1 other time. Composite data for plasma labeled retinol compared with time were analyzed using a 6-component model to obtain group retinol kinetic parameters and pool sizes. Model-predicted TBS was compared with mean RID predictions at 4 d; RID estimates at 4 d were compared with those calculated at 7-21 d. RESULTS: Model-predicted TBS was 1097 µmol, equivalent to ∼2.4 y-worth of VA; using model-derived coefficients, group mean RID-predicted TBS was 1096 µmol (IQR: 836-1492 µmol). TBS at 4 d compared with a later time was similar (P = 0.33). The model predicted that retinol spent 1.5 h in plasma during each transit and recycled to plasma 13 times before utilization. CONCLUSIONS: The super-child modeling approach provides information on whole-body VA kinetics and can be used with RID to estimate TBS at any time between 4 and 21 d postdose. The high TBS predicted for these children suggests positive VA balance, likely due to large-dose VA supplements, and warrants further investigation.

Bioelectric Impedance Vector Analysis (BIVA) in Breast Cancer Patients: A Tool for Research and Clinical Practice.

Background and objectives: Body composition assessment can provide information associated with breast cancer patients' (BCP) prognosis, that can lead interventions to improve survival outcomes. The aim of this study was to evaluate the effect of an individualized nutrition intervention program on breast cancer patients using bioelectrical impedance vector analysis (BIVA). Materials and Methods: This is a pretest-posttest study in recently diagnosed nonmetastatic BCP undergoing antineoplastic treatment, free of co-morbidities and dietary supplementation. Body composition was assessed at baseline and 6 months after an individualized nutrition intervention program, by dual-energy X-ray absorptiometry and BIVA. According to BIVA, each participant was located in the bivariate tolerance ellipses for Mexican population (50%, 75%, and 95%). In clinical practice, the 50% and 75% ellipses are considered within normality ranges. Results: Nine nonmetastatic BCP completed the intervention and were included in the analysis. After the intervention, they decreased by 5.8 kg of body weight (IQR, 3-6; p < 0.05), 3.8 kg of fat mass (IQR, 0.1-4.2; p < 0.05), and 1.4 kg of fat-free mass (IQR, -0.1 to 4; p < 0.05) while appendicular skeletal muscle mass remained unchanged (-0.2 kg, IQR, -0.8 to 2.3; p = 0.4). Using BIVA at baseline, five participants were among the 50% and 75% ellipses, mainly located in the area corresponding to edema and low lean tissue, two in the cachexia quadrant and two in the athletic quadrant (≥95% ellipse). After 6 months of intervention, six out of nine participants were in the athletic quadrant and eight of nine BCP were above the 5° phase angle cut-off point. One patient initially presented cachexia (≥95% ellipse); at postintervention her vector changed to the 50% ellipse. Conclusions: An individualized nutrition intervention program designed for nonmetastatic BCP was effective to improve the nutritional status of BCP as assessed by BIVA, therefore BIVA can be a useful tool to monitor changes in nonmetastatic BCP body composition in research and clinical practice.

Effectiveness of the Diabetes Prevention Program for Obesity Treatment in Real World Clinical Practice in a Middle-Income Country in Latin America.

The Diabetes Prevention Program (DPP) is effective for the prevention of type 2 diabetes by weight loss with diet and physical activity. However, there is little evidence as to whether this program could be translated into real-world clinical practice in Latin American countries. The objective of this work was to evaluate the effectiveness of the DPP for the management of overweightness and obesity at 6 and 12 months in clinical practice in Mexico. This was a non-controlled intervention study implemented in five public clinics in northern Mexico. Two hundred and thirty-seven adults aged 45.7 ± 9.9 years with a Body Mass Index (BMI) of 34.4 ± 5.4 kg/m2 received group sessions with an adaptation of the DPP, in addition to nutrition counseling. One hundred and thirty-three (56%) participants concluded the 6 month phase. They showed a significant weight loss, ranging from 2.76 ± 4.76 to 7.92 ± 6.85 kg (p ≤ 0.01) in the clinics. The intention-to-treat analysis showed a more conservative weight loss. Participant retention at the end of 12 months was low (40%). The implementation of the DPP in different public clinics in Mexico was effective in the management of obesity in the short term, but better strategies are required to improve participant retention in the long term.

External validation of the relative fat mass (RFM) index in adults from north-west Mexico using different reference methods.

BACKGROUND: Analysis of body composition is becoming increasingly important for the assessment, understanding and monitoring of multiple health issues. The body mass index (BMI) has been questioned as a tool to estimate whole-body fat percentage (FM%). Recently, a simple equation described as relative fat mass (RFM) was proposed by Woolcott & Bergman. This equation estimates FM% using two anthropometric measurements: height and waist circumference (WC). The authors state that due to its simplicity and better performance than BMI, RFM could be used in daily clinical practice as a tool for the evaluation of body composition. The aim of this study was to externally validate the equation of Woolcott & Bergman to estimate FM% among adults from north-west Mexico compared with Dual-energy X-ray absorptiometry (DXA) as an alternative to BMI and secondly, to make the same comparison using air displacement plethysmography (ADP), Bioelectrical Impedance Analysis (BIA) and a 4-compartment model (4C model). METHODS: Weight, height and WC were measured following standard procedures. The RFM index was calculated for each of the 61 participating subjects (29 females and 32 males, ages 20-37 years). The RFM was then regressed against each of the four body composition methods for estimating FM%. RESULTS: Compared with BMI, RFM was a better predictor of FM% determined by each of the body composition methods. In terms of precision the best equation was RFM regressed against DXA (y = 1.12 + 0.99 x; R2 = 0.84 p<0.001). Accuracy (represented by the closeness to the zero-intercept) was 1.12 (95% CI: -2.44, to 4.68) and thus, not significantly different from zero. For the rest of the methods, precision in the prediction of FM% was improved compared to BMI, with significant increases in the R2 and reduction of the root mean squared error (RMSE). However, the intercepts of each regression did not show accuracy since they were different from zero, for ADP: -9.95 (95%CI: -15.7 to -4.14), for BIA: -12.6 (95%CI: -17.5 to -7.74) and for the 4C model: -13.6 (95%CI: -18.6 to -8.60). Irrespectively, FM% measured by each of the body composition methods was higher for DXA than the other three methods (p<0.001). CONCLUSIONS: This external validation proved that the performance of the RFM equation used in this study to estimate FM% was more consistent than BMI in this Mexican population, showing a stronger correlation with DXA than with the other body composition methods.

Analysis of type 2 diabetes and obesity genetic variants in Mexican Pima Indians: Marked allelic differentiation among Amerindians at HLA.

Prevalence of diabetes and obesity in Mexican Pima Indians is low, while prevalence in US Pima Indians is high. Although lifestyle likely accounts for much of the difference, the role of genetic factors is not well explored. To examine this, we genotyped 359 single nucleotide polymorphisms, including established type 2 diabetes and obesity variants from genome-wide association studies (GWAS) and 96 random markers, in 342 Mexican Pimas. A multimarker risk score of obesity variants was associated with body mass index (BMI; ß = 0.81 kg/m2 per SD, P = 0.0066). The mean value of the score was lower in Mexican Pimas than in US Pimas (P = 4.3 × 10-11 ), and differences in allele frequencies at established loci could account for approximately 7% of the population difference in BMI; however, the difference in risk scores was consistent with evolutionary neutrality given genetic distance. To identify loci potentially under recent natural selection, allele frequencies at 283 variants were compared between US and Mexican Pimas, accounting for genetic distance. The largest differences were seen at HLA markers (e.g., rs9271720, difference = 0.75, P = 8.7 × 10-9 ); genetic distances at HLA were greater than at random markers (P = 1.6 × 10-46 ). Analyses of GWAS data in 937 US Pimas also showed sharing of alleles identical by descent at HLA that exceeds its genomic expectation (P = 7.0 × 10-10 ). These results suggest that, in addition to the widely recognized balancing selection at HLA, recent directional selection may also occur, resulting in marked allelic differentiation between closely related populations.

WHO body mass index for age charts overestimate thinness and overweight compared to international and US charts applied to indigenous and non-indigenous Mexican children

Assessments of whether children are thin (low body mass index for age) or overweight are based on body mass index (BMI for age and sex) charts published by the World Health Organization (WHO), the International Obesity Task Force (IOTF), and the US Centers for Disease Control and Prevention (CDC). We aimed to determine whether these charts indicated different prevalence of thinness and overweight (obesity included) in indigenous and non-indigenous school aged children from different regions and ethnic groups in Mexico. A probability proportional to size, cluster sampling method was employed in four regions of the country. We recruited 1,731 children aged 7.0-9.9 (507 indigenous from six ethnic groups and 1,224 non-indigenous). BMI was calculated according to age, and thinness and overweight classifications were compared according to cutoff values in the WHO, IOTF, and CDC references. The WHO reference generated the highest rates for thinness (12.5%) and overweight (30%) in children across regions and ethnic groups. The CDC reference estimated the lowest rates of thinness in children (5.5%), and the IOTF reference estimated the lowest rates of overweight (24.7%). Estimates of both thinness (8.3%) and overweight (13.4%) rates were lower in indigenous than non-indigenous groups (14.3% and 37.5%, respectively). The WHO BMI for age chart estimated higher rates of thinness and overweight in children compared to the CDC and IOTF charts. Because thinness as indicator of undernutrition status is relatively new, differences in body composition among indigenous and non-indigenous children may justify the need for more appropriate screening criteria to compare the growth status(AU)

La clasificación del estado nutricio de los niños con delgadez o con sobrepeso se realiza empleando el índice de masa corporal (IMC para la edad y el sexo) con las tablas de la OMS, IOTF y CDC. El objetivo de esta investigación fue determinar si estas referencias resultan en diferentes prevalencias de delgadez y sobrepeso (obesidad incluida) en niños escolares indígenas y no indígenas de diferentes regiones de México. Se empleó un muestreo por conglomerados en cuatro regiones del país. Se reclutaron 1,731 niños con edades entre 7,0-9,9 (507 indígenas de cinco grupos étnicos y 1,224 no indigenas) durante 2006 y 2008. El IMC se calculó y se clasificó como delgadez y sobrepeso con los puntos de corte sugeridos por las referencias internacionales. Cuando se compararon las clasificaciones, la referencia de OMS generó la prevalencia más alta de delgadez (12,5%) y sobrepeso (30%) en niños de todas las regiones y grupos étnicos. La referencia de los CDC estimó las prevalencias más bajas de delgadez (5,5%) y la referencia IOTF produjo las proporciones más bajas de sobrepeso (24,7%). Las proporciones de delgadez (8,3%) y sobrepeso (13,4%) fueron más bajas en niños indígenas que en los no indígenas (14.3% y 37.5%, respectivamente). La referencia de la OMS del IMC para la edad produjo las prevalencias más altas de delgadez y sobrepeso en comparación con los estándares de CDC y IOTF. Dado que la delgadez como indicador de desnutrición en niños es de uso reciente, las diferencias encontradas entre indígenas y mestizos pueden justificar el contar con mejores herramientas de tamizaje en estudios de crecimiento(AU)

Effect of the Holiday Season on Weight Gain: A Narrative Review.

Several studies suggest that the holiday season, starting from the last week of November to the first or second week of January, could be critical to gaining weight. This study aims to review the literature to determine the effects of the holidays on body weight. In studies of adults, a significant weight gain was consistently observed during this period (0.4 to 0.9 kg, p < 0.05). The only study in college students found an effect on body fat but not on weight (0.1 kg, p = 0.71). The only study found in children did not show an effect on BMI percentile (-0.4%, p > 0.05) during this period. Among individuals with obesity who attempt to lose weight, an increase in weight was observed (0.3 to 0.9 kg, significant in some but not in all studies), as well as increase in weight in motivated self-monitoring people (0.4 to 0.6%, p < 0.001). Programs focused on self-monitoring during the holidays (phone calls and daily mailing) appeared to prevent weight gain, but information is limited. The holiday season seems to increase body weight in adults, even in participants seeking to lose weight and in motivated self-monitoring people, whereas in children, adolescents, and college students, very few studies were found to make accurate conclusions.

'Dose-to-Mother' Deuterium Oxide Dilution Technique: An Accurate Strategy to Measure Vitamin A Intake in Breastfed Infants.

In Mexico, infants (0-2 years old) show the highest prevalence of vitamin A deficiency (VAD), measured by serum retinol concentrations. Thus, we consider that low vitamin A (VA) intake through breast milk (BM) combined with poor weaning practices are the main factors that contribute to VAD in this group. We combined the assessment of VA status in lactating women using BM retinol and a stable isotope 'dose-to-mother' technique to measure BM production in women from urban and agricultural areas. Infants' mean BM intake was 758 ± 185 mL, and no difference was observed between both areas (p = 0.067). Mean BM retinol concentration was 1.09 µmol/L, which was significantly lower for the agricultural area (p = 0.028). Based on BM retinol concentration, 57% of women were VAD; although this prevalence fell to 16% when based on fat content. Regardless of the VA biomarker used here, infants from the urban and agricultural areas cover only 66% and 49% of their dietary adequate intake from BM, respectively (p = 0.054). Our data indicate that VAD is still a public health concern in Mexico. Adopting both methods to assess VA transfer from the mother to the breastfed child offers an innovative approach towards the nutritional assessment of vulnerable groups.

Antineoplastic treatment effect on bone mineral density in Mexican breast cancer patients.

BACKGROUND: Breast cancer is the most deadly malignancy in Mexican women. Although treatment has improved, it may significantly affect bone mineral status in those who receive it. The aim of this study was to assess the impact of cancer treatment on bone mineral density (BMD) and bone mineral content (BMC), in patients with breast cancer and explore the interaction of menopausal status and clinical stage with cancer treatment on such changes. METHODS: A quasi-experimental design was applied with measurements before and after a chemotherapy treatment in 40 patients with primary diagnosis of invasive breast cancer. BMD and body composition measurements were taken by dual X-ray absorptiometry (DXA) and changes in these variables due to therapy were analyzed using mixed regression for repeated measurements. RESULTS: Significant loss was found in femoral neck and L2-L4 BMD (p < 0.001). Patients diagnosed with osteopenia or osteoporosis received calcium + vitamin D supplementation (600 mg/200 IU day). It showed a protective effect in the decrease of femoral neck BMD and total BMC. BMD loss in both femoral neck and L2-L4 BMD was higher in premenopausal women: 0.023 g/cm2 in femoral neck and 0.063 g/cm2 in L2-L4 (p < 0.001), while in postmenopausal women BMD loss was 0.015 g/cm2 in femoral neck and 0.035 g/cm2 in L2-L4 (p = 0.021 and p = 0.001 respectively). Change in lumbar spine BMD was prominent in premenopausal women with advanced clinical stage (IIB, IIIA, IIIB): 0.066 g/cm2 (p = 0.003). CONCLUSION: The antineoplastic breast cancer treatment with chemotherapy had a negative impact on BMD, in premenopausal women overall, although a differential effect was found according to clinical stage and calcium supplementation status.

Modelo para la estimación de la talla de pie en adultos mexicanos de 20-59 años basado en la longitud rodilla-talón / Model for estimating standing height in Mexican adults for 20-59 years, based on knee length

Actualmente las distancias óseas se utilizan para predecir la talla en adultos que no pueden tener una adecuada bipedestación o no cumplen con la posición adecuada para la obtención de la talla. Existen algoritmos para la estimación de la talla basados en la longitud rodilla-talón, diseñados para poblaciones específicas; sin embargo, existen poblaciones que aún no cuentan con esta herramienta, por lo que se usan ecuaciones ya existentes, que no necesariamente reflejan los factores genético-ambientales para la población de interés. El objetivo de este estudio fue desarrollar y validar modelos predictivos para la talla de pie en adultos mexicanos, con antropómetro de diseño propio y cinta métrica. Se midieron 240 adultos de 20 a 59 años, de ambos sexos, sin problemas aparentes en la columna vertebral. Se midió el peso, la talla de pie y la longitud rodilla-talón. Se desarrolló un modelo predictivo para cada instrumento de medición. La selección de modelos y el desarrollo de las ecuaciones se llevó a cabo mediante los métodos de 'Todas las Regresiones Posibles' y 'Regresión Múltiple'. Se obtuvieron dos algoritmos que no mostraron diferencias significativas entre la talla medida y estimada tras un proceso de validación cruzada. Las R2 para los modelos fueron de 0,93 y 0,92, con un error estándar del estimador (EE) de 2,30 y 2,40 cm, para el antropómetro y la cinta respectivamente. Ambos métodos resultaron aceptables en términos de concordancia, exactitud y precisión. A tallas extremas (altas o bajas), ambos modelos presentaron sesgo, lo cual debe considerarse al aplicar estos algoritmos (AU)

Currently, bone distances are used to predict standing height in adults that might not be able to achieve a correct standing position. Knee length based algorithms for estimating standing height have been proposed and designed for specific populations. However, equations for other populations may not necessarily reflect environmental and genetic factors for the group of interest. The aim of this study was to develop and validate predictive models for standing height in Mexican adults. For this purpose, 240 male and female adults aged 20 to 59 years, with no apparent spine problems were measured. We measured weight, height and knee length, using an anthropometer of our own design and a glass fiber metric measuring tape. A predictive model for each measuring instrument was developed. Model selection and development of equations were carried out by 'all possible regressions and multiple regression' procedures. The predictive models for standing height by the anthropometer and by the measuring tape did not show significant differences between measured and estimated height. The R2 for the two models were 0.93 and 0.92, with a standard error of the estimator (EE) of 2.30 and 2.40 cm, for the anthropometer and the measuring tape, respectively. Both methods were acceptable in terms of concordance, accuracy and precision; however, at very high and low predicted height values, both models showed significant bias, which should be considered when applying these algorithms in different populations (AU)

Environmentally Driven Increases in Type 2 Diabetes and Obesity in Pima Indians and Non-Pimas in Mexico Over a 15-Year Period: The Maycoba Project.

OBJECTIVE: The global epidemics of type 2 diabetes and obesity have been attributed to the interaction between lifestyle changes and genetic predisposition to these diseases. We compared the prevalences of type 2 diabetes and obesity in Mexican Pima Indians, presumed to have a high genetic predisposition to these diseases, to those in their non-Pima neighbors, both of whom over a 15-year period experienced a transition from a traditional to a more modern lifestyle. RESEARCH DESIGN AND METHODS: Prevalence of diabetes, impaired fasting glucose, impaired glucose tolerance, and obesity in Mexican Pimas (n = 359) and non-Pima Mexicans (n = 251) were determined in 2010 using methods identical to those used in 1995. RESULTS: During this 15-year period, age-adjusted diabetes prevalence was unchanged in Pima men (5.8% in 1995 vs. 6.1% in 2010) yet increased in non-Pima men from 0.0 to 8.6% (P < 0.05). Diabetes prevalence tended to increase in both Pima women (9.4 vs. 13.4%) and non-Pima women (4.8 vs. 9.5%). Age-adjusted prevalence of obesity increased significantly in all groups (6.6 vs. 15.7% in Pima men; 8.5 vs. 20.5% in non-Pima men; 18.9. vs 36.3% in Pima women; 29.5 vs. 42.9% in non-Pima women). CONCLUSIONS: Type 2 diabetes prevalence increased between 1995 and 2010 in non-Pima men, and to a lesser degree in women of both groups, but it did not increase in Pima men. Prevalence of obesity increased among Pimas and non-Pimas of both sexes. These changes occurred concomitantly with an environmental transition from a traditional to a more modernized lifestyle.

Impacto del tratamiento antineoplásico en el estado nutricional en pacientes con cáncer de mama / Antineoplastic treatment impact on nutritional status in patients with breast cancer

Introducción: El cáncer de mama es la neoplasia más diagnosticada en mujeres en México y también la de mayor mortalidad. Aunque el tratamiento ha mejorado, puede afectar de forma importante el estado nutricio de quienes lo reciben. Objetivo: Evaluar el impacto del tratamiento antineoplásico sobre el estado nutricio en pacientes con cáncer de mama. Pacientes y métodos: Se aplicó un diseño cuasiexperimental, antes y después de seis meses del inicio del tratamiento quimioterapéutico. Participaron 40 pacientes con diagnóstico primario de cáncer de mama invasivo. Se tomaron medidas antropométricas, de composición corporal mediante absorciometría dual de rayos X (DEXA) así como análisis de la dieta mediante recordatorio de 24 horas y cuestionario de frecuencia de consumo. Además, se cuantificaron los biomarcadores séricos, retinol y Beta-caroteno. El efecto del tratamiento se estimó utilizando regresión linear mixta para mediciones repetidas. Resultados: Se registró una pérdida de tejido magro (p=0.03). Además se encontró interacción del climaterio sobre los parámetros de peso, IMC y grasa corporal; solo en las pacientes preclimatéricas aumentaron estas medidas (p=0.005, 0.006 y 0.001 respectivamente). El retinol sérico disminuyó (p=0.049) pese al incremento en el Beta-caroteno (p=0.030). También se incrementó el consumo de vegetales y hubo una reducción en el consumo de alimentos de origen animal. Conclusión: El tratamiento antineoplásico para cáncer de mama afectó negativamente al peso y grasa corporal, principalmente en las mujeres jóvenes. Pese a las modificaciones dietarias, el consumo promedio de vegetales aún es insuficiente, lo cual se reflejó también en los biomarcadores séricos (AU)

Background: Breast cancer is the most commonly diagnosis malignancy in women in Mexico and also has the highest mortality. Although treatment has improved significantly, it can affect the nutritional status of the recipients. Objective: The aim of this study was to assess the impact of the initial phase of antineoplastic therapy on the nutritional status in patients with breast cancer. Methods: Forty subjects with primary diagnosed of invasive breast cancer were study in a before and after intervention (six months apart) using a quasi-experimental design. Basal and six month after intervention measurements included were anthropometry, body composition by dual X-ray absorptiometry (DEXA), diet by 24-hour recall and food frequency questionnaire, as well as serum Beta-carotene and retinol. The therapy effect was analyzed using repeated measurements mixed linear regression. Results: Lean tissue decreased after the studied period (p=0.032).Addicionally, there was an interaction between weight, BMI and body fat parameters with menopausal status, increasing in these variables due to therapy only premenopausal patients (p=0.005, 0.006 and 0.001, respectively). Serum retinol decreased (p=0.049) despite the improvement in Beta-carotene status (p=0.03). In general there was an increase the consumption of vegetables food products whilst a decrease in animal foods products. Conclusion: The breast cancer antineoplasic treatment had a negative effect on weight and body fat, especially in young women. Although there were some positive dietary changes, vegetables consumption remained insufficient, which was also reflected in serum biomarkers (AU)

Accuracy of body fat percent and adiposity indicators cut off values to detect metabolic risk factors in a sample of Mexican adults.

BACKGROUND: Although body fat percent (BF%) may be used for screening metabolic risk factors, its accuracy compared to BMI and waist circumference is unknown in a Mexican population. We compared the classification accuracy of BF%, BMI and WC for the detection of metabolic risk factors in a sample of Mexican adults; optimized cutoffs as well as sensitivity and specificity at commonly used BF% and BMI international cutoffs were estimated. We also estimated conditional BF% means at BMI international cutoffs. METHODS: We performed a cross-sectional analysis of data on body composition, anthropometry and metabolic risk factors(high glucose, high triglycerides, low HDL cholesterol and hypertension) from 5,100 Mexican men and women. The association between BMI, WC and BF%was evaluated with linear regression models. The BF%, BMI and WC optimal cutoffs for the detection of metabolic risk factors were selected at the point where sensitivity was closest to specificity. Areas under the ROC Curve (AUC) were compared among classifiers using a non-parametric method. RESULTS: After adjustment for WC, a 1% increase in BMI was associated with a BF% rise of 0.05 percentage points (p.p.) in men (P<0.05) and 0.25 p.p. in women (P<0.001). At BMI=25.0 predicted BF% was 27.6±0.16 (mean±SE) in men and 41.2±0.07 in women. Estimated BF% cutoffs for detection of metabolic risk factors were close to 30.0 in men and close to 44.0 in women. In men WC had higher AUC than BF% for the classification of all conditions whereas BMI had higher AUC than BF% for the classification of high triglycerides and hypertension. In womenBMI and WC had higher AUC than BF% for the classification of all metabolic risk factors. CONCLUSIONS: BMI and WC were more accurate than BF% for classifying the studied metabolic disorders. International BF% cutoffs had very low specificity and thus produced a high rate of false positives in both sexes.

Study design of the Maycoba Project: obesity and diabetes in Mexican Pimas.

OBJECTIVE: To focus on the rationale and methods of the Maycoba Project. METHODS: Study population included Mexican Pima Indians (MPI) and Blancos aged ≥20-years, living in the village of Maycoba and surrounding area. Surveys in 1995 and 2010 included a medical history, biochemical and anthropomet- ric measurements. Additionally, socio- economic, physical activity, and dietary interviews were conducted. The 2010 study incorporated investigations on type 2 diabetes (T2D) and obesity-associated genetic alleles and human-envi- ronment changes. RESULTS: The study results are limited to demographic data and description of the eligible and ex- amined sample. CONCLUSIONS: This study may yield important information on T2D and obesity etiology in a traditional population exposed to environmental changes.

Bone mineral density changes in lactating adolescent mothers during the first postpartum year.

OBJECTIVES: This study aimed to compare changes in whole body bone mineral density (wbBMD) during the first postpartum year in adolescent mothers with those of nulliparous adolescents. METHODS: The study included 21 adolescent mothers and 16 nulliparous adolescent non-indigenous Mexican women (State of Sonora) from a low income level. All mothers were assessed at 15 days (0.5 months), 3 months, and 6 months postpartum; 16 were measured at 12 months postpartum. Nulliparous adolescents were assessed in the same periods. Multiple regression models was used to assess adjusted associations of changes in wbBMD (by DPX-MD+ densitometer) with dietary calcium and physical activity assessments (estimated using pre-tested questionnaires), post menarche years, and number of breast feedings. RESULTS: At baseline, no differences were observed between nulliparous and adolescent mothers regarding age, post-menarche years, or BMD values. Changes in wbBMD of -0.56% and 0.77% were observed in mothers and nulliparous adolescents, respectively, after the first 3 months (P = 0.006). Changes in wbBMD in mothers were associated with number of breast feedings and changes in BMI. At 12 months postpartum, the BMD of adolescent mothers was similar to that of nulliparous adolescents. CONCLUSIONS: At 1 year postpartum, adolescent mothers exhibited BMD similar to those of nulliparous adolescents. This result is likely attributable to the breastfeeding practices adopted by mothers during late adolescence.