A statistical approach to aid examiners in the forensic analysis of handwriting.

We develop a statistical approach to model handwriting that accommodates all styles of writing (cursive, print, connected print). The goal is to compute a posterior probability of writership of a questioned document given a closed set of candidate writers. Such probabilistic statements can support examiner conclusions and enable a quantitative forensic evaluation of handwritten documents. Writing is treated as a sequence of disjoint graphical structures, which are extracted using an automated and open-source process. The graphs are grouped based on the similarity of their shapes through a K-means clustering template. A person's writing pattern can be characterized by the rate at which graphs are emitted to each cluster. The cluster memberships serve as data for a Bayesian hierarchical model with a mixture component. The rate of mixing between two parameters in the hierarchy indicates writing style.

A clustering method for graphical handwriting components and statistical writership analysis.

Handwritten documents can be characterized by their content or by the shape of the written characters. We focus on the problem of comparing a person's handwriting to a document of unknown provenance using the shape of the writing, as is done in forensic applications. To do so, we first propose a method for processing scanned handwritten documents to decompose the writing into small graphical structures, often corresponding to letters. We then introduce a measure of distance between two such structures that is inspired by the graph edit distance, and a measure of center for a collection of the graphs. These measurements are the basis for an outlier tolerant K-means algorithm to cluster the graphs based on structural attributes, thus creating a template for sorting new documents. Finally, we present a Bayesian hierarchical model to capture the propensity of a writer for producing graphs that are assigned to certain clusters. We illustrate the methods using documents from the Computer Vision Lab dataset. We show results of the identification task under the cluster assignments and compare to the same modeling, but with a less flexible grouping method that is not tolerant of incidental strokes or outliers.

Planning Nutritionally Adequate Diets for Groups: Methods Used to Develop Recommendations for a Child and Adult Care Food Program.

Planning nutritionally adequate intakes for large groups of people presents many challenges. Because of between-person variations in both food choices and nutrient requirements, it is necessary to examine nutrient intake distributions and select a Target Median Intake (TMI) that will lead to a low prevalence of inadequate nutrient intakes. The TMI may then be used to guide a feeding or education program. A comprehensive report from the Institute of Medicine evaluated nutrient intakes from the NHANES and recommended new meal patterns for all age groups (other than infants) served by the Child and Adult Day Care Food Program, which provides meals and snacks to children and adults in a variety of care settings. The Estimated Average Requirement, a DRI value, for each nutrient of interest was used to estimate both the prevalence of inadequate intakes as well as the changes in the intake distribution that are needed to reduce unacceptably high levels of inadequacy. For nutrients with an Adequate Intake (AI), the prevalence of inadequacy could not be estimated, but the AI could be used as the TMI. Simultaneously, it was important to ensure that the new intake distributions did not result in intakes that exceeded the Tolerable Upper Intake Level for any nutrient. Data for 2- to 4-y-old children are presented in detail to illustrate this process. Of 18 nutrients examined, analyses showed that intakes of vitamin E, potassium, and fiber should be increased, while intakes of sodium should be decreased. If more recent nutrient standards are used, revised assessments show that calcium intake should also be increased, while potassium intake is adequate. These methods and results should be useful when designing feeding programs for other population groups within the United States, as well as in other countries.

Perspective: Proposed Harmonized Nutrient Reference Values for Populations.

Two core nutrient intake reference values (NRVs) are required for assessing the adequacy and safety of nutrient intakes for population groups: the average requirement (AR) and the tolerable upper level of intake (UL). Applications of such assessments include providing advice to improve intakes, formulating complementary foods, estimating the amounts of nutrients to be added to fortified foods and monitoring changes in intake, and product labeling at the global, national, or regional level. However, there is a lack of unity across country-level organizations in the methodological approach used to derive NRVs, and ARs and ULs are lacking in many compilations, thus limiting the ability to assess nutrient intakes for their population groups. Because physiological requirements vary little across populations globally, and setting reference values requires determining an acceptable level of uncertainty, it is feasible to adapt current recommendations from different sources to harmonize these core reference values. The objective of this review is to demonstrate an approach for harmonizing the NRVs for ARs (here termed "H-ARs") and ULs ("H-ULs") that can be applied on a global scale to assessing intakes across populations. The approach incorporates the framework and terminology recommended by reports from the United Nations University, the National Academies of Sciences, Engineering, and Medicine (NASEM), the Institute of Medicine (IOM), and the European Food Safety Authority (EFSA). After reviewing available alternatives, the proposed harmonized values were selected from standards set by EFSA (for Europe) and the IOM (for the United States and Canada), giving priority to those published most recently. Justifications for the proposed values are presented, along with discussion of their limitations. Ideally, these methods should be further reviewed by an international group of experts. Meanwhile, the H-ARs and H-ULs suggested in this review can be used to assess intakes of populations for many applications in global and regional contexts.

Inadequate nutrient intakes in Filipino schoolchildren and adolescents are common among those from rural areas and poor families.

BACKGROUND: Adequate nutrition during childhood and adolescence is essential to promote growth and development. OBJECTIVE: This study evaluated usual energy and nutrient intakes of Filipino schoolchildren and adolescents. DESIGN: Food and beverage intakes were collected from a nationally representative sample of schoolchildren aged 6-9 and 10-12 years (n = 3,594 and n = 2,971, respectively) and adolescents aged 13-18 years (n = 5,447) using 24-h dietary recalls. The distributions of usual energy and nutrient intakes and the prevalence of inadequate intakes, which is defined as the percent of children with intakes less than estimated average requirements or acceptable macronutrient distribution ranges, were estimated using the Personal Computer Software for Intake Distribution Estimation (PC-SIDE) program. RESULTS: The results showed that the mean energy intakes were 19-35% lower than estimated energy requirement. High prevalence of inadequate intakes was found for most macro- and micronutrients. Prevalence of inadequacies was as follows: protein 12-47%, total fat (as percentage of energy) 38-52%, calcium 92-94%, iron 75-90%, vitamin C 68-96%, folate 61-93%, vitamin A 58-81%, riboflavin 58-91%, thiamin 27-75%, and phosphorus 18-91%. CONCLUSIONS: Generally, prevalence of inadequacy of key nutrients were relatively high among adolescents and schoolchildren, especially those from poor families and rural areas. This study demonstrated that nutrient intakes of Filipino schoolchildren and adolescents were highly inadequate, particularly among the poor and those living in rural areas.

Energy Intake Derived from an Energy Balance Equation, Validated Activity Monitors, and Dual X-Ray Absorptiometry Can Provide Acceptable Caloric Intake Data among Young Adults.

Background: Assessments of energy intake (EI) are frequently affected by measurement error. Recently, a simple equation was developed and validated to estimate EI on the basis of the energy balance equation [EI = changed body energy stores + energy expenditure (EE)]. Objective: The purpose of this study was to compare multiple estimates of EI, including 2 calculated from the energy balance equation by using doubly labeled water (DLW) or activity monitors, in free-living adults. Methods: The body composition of participants (n = 195; mean age: 27.9 y; 46% women) was measured at the beginning and end of a 2-wk assessment period with the use of dual-energy X-ray absorptiometry. Resting metabolic rate (RMR) was calculated through indirect calorimetry. EE was assessed with the use of the DLW technique and an arm-based activity monitor [Sensewear Mini Armband (SWA); BodyMedia, Inc.]. Self-reported EI was calculated by using dietitian-administered 24-h dietary recalls. Two estimates of EI were calculated with the use of a validated equation: quantity of energy stores estimated from the changes in fat mass and fat-free mass occurring over the assessment period plus EE from either DLW or the SWA. To compare estimates of EI, reporting bias (estimated EI/EE from DLW × 100) and Goldberg ratios (estimated EI/RMR) were calculated. Results: Mean ± SD EEs from DLW and SWA were 2731 ± 494 and 2729 ± 559 kcal/d, respectively. Self-reported EI was 2113 ± 638 kcal/d, EI derived from DLW was 2723 ± 469 kcal/d, and EI derived from the SWA was 2720 ± 730 kcal/d. Reporting biases for self-reported EI, DLW-derived EI, and SWA-derived EI are as follows: -21.5% ± 22.2%, -0.7% ± 18.5%, and 0.2% ± 20.8%, respectively. Goldberg cutoffs for self-reported EI, DLW EI, and SWA EI are as follows: 1.39 ± 0.39, 1.77 ± 0.38, and 1.77 ± 0.38 kcal/d, respectively. Conclusions: These results indicate that estimates of EI based on the energy balance equation can provide reasonable estimates of group mean EI in young adults. The findings suggest that, when EE derived from DLW is not feasible, an activity monitor that provides a valid estimate of EE can be substituted for EE from DLW.

Application of Response Surface Methods To Determine Conditions for Optimal Genomic Prediction.

An epistatic genetic architecture can have a significant impact on prediction accuracies of genomic prediction (GP) methods. Machine learning methods predict traits comprised of epistatic genetic architectures more accurately than statistical methods based on additive mixed linear models. The differences between these types of GP methods suggest a diagnostic for revealing genetic architectures underlying traits of interest. In addition to genetic architecture, the performance of GP methods may be influenced by the sample size of the training population, the number of QTL, and the proportion of phenotypic variability due to genotypic variability (heritability). Possible values for these factors and the number of combinations of the factor levels that influence the performance of GP methods can be large. Thus, efficient methods for identifying combinations of factor levels that produce most accurate GPs is needed. Herein, we employ response surface methods (RSMs) to find the experimental conditions that produce the most accurate GPs. We illustrate RSM with an example of simulated doubled haploid populations and identify the combination of factors that maximize the difference between prediction accuracies of best linear unbiased prediction (BLUP) and support vector machine (SVM) GP methods. The greatest impact on the response is due to the genetic architecture of the population, heritability of the trait, and the sample size. When epistasis is responsible for all of the genotypic variance and heritability is equal to one and the sample size of the training population is large, the advantage of using the SVM method vs. the BLUP method is greatest. However, except for values close to the maximum, most of the response surface shows little difference between the methods. We also determined that the conditions resulting in the greatest prediction accuracy for BLUP occurred when genetic architecture consists solely of additive effects, and heritability is equal to one.

Associations between iodine intake, thyroid volume, and goiter rate in school-aged Chinese children from areas with high iodine drinking water concentrations.

BACKGROUND: Excessive iodine intake may have adverse effects on the thyroid, particularly in children, but the safe upper iodine intake concentration in children is unclear. OBJECTIVE: We assessed the adverse effects of high iodine intake from iodine-rich drinking water on thyroid size in children by examining associations between thyroid volume (Tvol), total goiter rate (TGR), and iodine intake. DESIGN: In a multistage cross-sectional survey, we collected two 24-h urine samples on 2 nonconsecutive days and determined 24-h urinary iodine excretion, then calculated habitual daily iodine intake. Ultrasonographic Tvol was measured, and TGR was calculated based on international and Chinese reference ranges for Tvol in children. RESULTS: This study included 2089 children from Shandong province, where the median (IQR) drinking water iodine concentration was 183 µg/L (69-406 µg/L). The median (IQR) 24-h urinary iodine concentrations for the 2 collections were 381 µg/L (203-649 µg/L) and 398 µg/L (202-687 µg/L), respectively. The median (IQR) habitual daily iodine intake of children was 298 µg/d (186-437 µg/d). Tvols were slightly higher in boys than in girls (P = 0.035). The overall TGR was 9.7% and did not differ by sex. The TGR was ∼5% for children aged 7-10 and 11-14 y at iodine intakes of 200-249 and 250-299 µg/d, respectively. With the use of logistic regression and 2-step linear regression, a nonlinear association was observed between Tvol, TGR, and iodine intake, with a threshold intake of 150 µg/d. CONCLUSIONS: Tvol begins to increase in children when iodine intake is ≥150 µg/d, and the TGR exceeds 5% when daily iodine intake is ≥250 µg/d for children aged 7-10 y and ≥300 µg/d for children aged 11-14 y. Our findings suggest that 150-249 and 150-299 µg/d seem to be safe upper iodine intake ranges for children aged 7-10 and 11-14 y, respectively. This trial was registered at clinicaltrials.gov as NCT02915536.

Options for basing Dietary Reference Intakes (DRIs) on chronic disease endpoints: report from a joint US-/Canadian-sponsored working group.

Dietary Reference Intakes (DRIs) are used in Canada and the United States in planning and assessing diets of apparently healthy individuals and population groups. The approaches used to establish DRIs on the basis of classical nutrient deficiencies and/or toxicities have worked well. However, it has proved to be more challenging to base DRI values on chronic disease endpoints; deviations from the traditional framework were often required, and in some cases, DRI values were not established for intakes that affected chronic disease outcomes despite evidence that supported a relation. The increasing proportions of elderly citizens, the growing prevalence of chronic diseases, and the persistently high prevalence of overweight and obesity, which predispose to chronic disease, highlight the importance of understanding the impact of nutrition on chronic disease prevention and control. A multidisciplinary working group sponsored by the Canadian and US government DRI steering committees met from November 2014 to April 2016 to identify options for addressing key scientific challenges encountered in the use of chronic disease endpoints to establish reference values. The working group focused on 3 key questions: 1) What are the important evidentiary challenges for selecting and using chronic disease endpoints in future DRI reviews, 2) what intake-response models can future DRI committees consider when using chronic disease endpoints, and 3) what are the arguments for and against continuing to include chronic disease endpoints in future DRI reviews? This report outlines the range of options identified by the working group for answering these key questions, as well as the strengths and weaknesses of each option.

Usual Intake of Added Sugars and Saturated Fats Is High while Dietary Fiber Is Low in the Mexican Population.

BACKGROUND: The Mexican National Health and Nutrition Survey (ENSANUT) was carried out in 2012. Information from the survey is used to design and evaluate food and nutrition policies in Mexico. OBJECTIVE: The objective of this study was to estimate the usual intake of energy and macronutrients in the Mexican population by using the ENSANUT 2012. METHODS: Twenty-four-hour recall interviews were administered to a nationally representative subsample of 10,096 individuals aged ≥1 y from the ENSANUT 2012. Usual intake distributions and the prevalence of inadequate intakes were estimated by using the Iowa State University method. Student's t tests and tests on the equality of proportions were used to compare usual intakes and prevalence of inadequacy across socioeconomic status, area (rural or urban), and region of residence (North, Center, or South). RESULTS: Energy and macronutrient intakes and indicators of dietary adequacy are presented for children (ages 1-4 y and 5-11 y), adolescents (12-19 y), and adults (≥20 y). At the national level, the estimated mean fiber intake was below the Adequate Intake for all population subgroups, suggesting inadequacies. The estimated proportion with a usual added sugars intake of >10% of total energy intake was >64% in all age groups. The proportion with a usual saturated fat intake of >10% of total energy intake was estimated to be >78% in children, >66% in adolescents, and >50% in adults. Overall, fiber intake was lower and intakes of saturated fat and added sugars were higher in urban compared with rural areas, in the North compared with South regions, and among those with high compared with low socioeconomic status (P < 0.05). CONCLUSIONS: Fiber intake is lower and added sugar and saturated fat intakes are higher than recommended for >50% of the Mexican population aged ≥1 y. These results highlight the importance of improving the diets of the overall population to reduce the risk of noncommunicable chronic diseases.

High Prevalence of Inadequate Calcium and Iron Intakes by Mexican Population Groups as Assessed by 24-Hour Recalls.

BACKGROUND: A National Health and Nutrition Survey (ENSANUT) conducted in Mexico in 1999 identified a high prevalence of inadequate mineral intakes in the population by using 24-h recall questionnaires. However, the 1999 survey did not adjust for within-person variance. The 2012 ENSANUT implemented a more up-to-date 24-h recall methodology to estimate usual intake distributions and prevalence of inadequate intakes. OBJECTIVE: We examined the distribution of usual intakes and prevalences of inadequate intakes of calcium, iron, magnesium, and zinc in the Mexican population in groups defined according to sex, rural or urban area, geographic region of residence, and socioeconomic status (SES). METHODS: We used dietary intake data obtained through the 24-h recall automated multiple-pass method for 10,886 subjects as part of ENSANUT 2012. A second measurement on a nonconsecutive day was obtained for 9% of the sample. Distributions of usual intakes of the 4 minerals were obtained by using the Iowa State University method, and the prevalence of inadequacy was estimated by using the Institute of Medicine's Estimated Average Requirement cutoff. RESULTS: Calcium inadequacy was 25.6% in children aged 1-4 y and 54.5-88.1% in subjects >5 y old. More than 45% of subjects >5 y old had an inadequate intake of iron. Less than 5% of children aged <12 y and 25-35% of subjects aged >12 y had inadequate intakes of magnesium, whereas zinc inadequacy ranged from <10% in children aged <12 y to 21.6% in men aged ≥20 y. Few differences were found between rural and urban areas, regions, and tertiles of SES. CONCLUSIONS: Intakes of calcium, iron, magnesium, and zinc are inadequate in the Mexican population, especially among adolescents and adults. These results suggest a public health concern that must be addressed.

Comparison of 2 methods for estimating the prevalences of inadequate and excessive iodine intakes.

BACKGROUND: Prevalences of iodine inadequacy and excess are usually evaluated by comparing the population distribution of urinary iodine concentration (UIC) in spot samples with established UIC cutoffs. To our knowledge, until now, dietary intake data have not been assessed for this purpose. OBJECTIVE: Our objective was to compare 2 methods for evaluating the prevalence of iodine inadequacy and excess in sex- and life stage-specific subgroups of the US population: one that uses UIC cutoffs, and one that uses iodine intake cutoffs. DESIGN: By using the iodine concentrations of foods measured in the US Food and Drug Administration's Total Diet Study (TDS), dietary intake data from the NHANES 2003-2010, and a file that maps each NHANES food to a TDS food with similar ingredients, we estimated each NHANES participant's iodine intake from each NHANES food as the mean iodine concentration of the corresponding TDS food in samples gathered over the same 2-y period. We calculated prevalences of iodine inadequacy and excess in each sex- and life stage-specific subgroup by both the UIC cutoff method and the iodine intake cutoff method-using the UIC values and dietary intakes reported for NHANES participants who provided both types of data-and compared the prevalences across methods. RESULTS: We found lower prevalences of iodine inadequacy across all sex- and life stage-specific subgroups with the iodine intake cutoff method than with the UIC cutoff method; for pregnant females, the respective prevalences were 5.0% and 37.9%. For children aged ≤8 y, the prevalence of excessive iodine intake was high by either method. CONCLUSIONS: The consideration of dietary iodine intake from all sources may provide a more complete understanding of population prevalences of iodine inadequacy and excess and thus better inform dietary guidance than consideration of UIC alone. Methods of adjusting UIC for within-person variation are needed to improve the accuracy of prevalence assessments based on UIC.

Variation in the iodine concentrations of foods: considerations for dietary assessment.

BACKGROUND: Food-composition tables typically give measured nutrient concentrations in foods as a single summary value, often the mean, without providing information as to the shape of the distribution. OBJECTIVE: Our objective was to explore how the statistical approach chosen to describe the iodine concentrations of foods affects the proportion of the population identified as having either insufficient or excessive iodine intakes. DESIGN: We used food intake data reported by the 2009-2010 NHANES and measured iodine concentrations of Total Diet Study (TDS) foods from 4 US regions sampled in 2004-2011. We created 4 data sets, each by using a different summary statistic (median, mean, and 10th and 90th percentiles), to represent the iodine concentration distribution of each TDS food. We estimated the iodine concentration distribution of each food consumed by NHANES participants as the 4 iodine concentration summary statistics of a similar TDS food and used these, along with NHANES food intake data, to develop 4 estimates of each participant's iodine intake on each survey day. Using the 4 estimates in turn, we calculated 4 usual iodine intakes for each sex- and age-specific subgroup. We then compared these to guideline values and developed 4 estimates of the proportions of each subgroup with deficient and excessive usual iodine intakes. RESULTS: In general, the distribution of iodine intakes was poorly characterized when food iodine concentrations were expressed as mean values. In addition, mean values predicted lower prevalences of iodine deficiency than did median values. For example, in women aged 19-50 y, the estimated prevalence of iodine deficiency was 25% when based on median food iodine concentrations but only 5.8% when based on mean values. CONCLUSION: For nutrients such as iodine with highly variable concentrations in important food sources, we recommend that food-composition tables provide useful variability information, including the mean, SD, and median.

Estimation of the Prevalence of Inadequate and Excessive Iodine Intakes in School-Age Children from the Adjusted Distribution of Urinary Iodine Concentrations from Population Surveys.

BACKGROUND: The urinary iodine concentration (UIC), a biomarker of iodine intake, is used to assess population iodine status by deriving the median UIC, but this does not quantify the percentage of individuals with habitually deficient or excess iodine intakes. Individuals with a UIC <100 µg/L or ≥300 µg/L are often incorrectly classified as having deficient or excess intakes, but this likely overestimates the true prevalence. OBJECTIVE: Our aim was to estimate the prevalence of inadequate and excess iodine intake in children (aged 4-14 y) with the distribution of spot UIC from iodine surveys. METHODS: With the use of data from national iodine studies (Kuwait, Oman, Thailand, and Qatar) and a regional study (China) in children (n = 6117) in which a repeat UIC was obtained in a subsample (n = 1060), we calculated daily iodine intake from spot UICs from the relation between body weight and 24-h urine volume and within-person variation by using the repeat UIC. We also estimated pooled external within-person proportion of total variances by region. We used within-person variance proportions to obtain the prevalence of inadequate or excess usual iodine intake by using the Estimated Average Requirement (EAR)/Tolerable Upper Intake Level (UL) cutoff method. RESULTS: Median UICs in Kuwait, Oman, China, Thailand, and Qatar were 132, 192, 199, 262, and 333 µg/L, respectively. Internal within-person variance proportions ranged from 25.0% to 80.0%, and pooled regional external estimates ranged from 40.4% to 77.5%. The prevalence of inadequate and excess intakes as defined by the adjusted EAR/UL cutoff method was ∼45-99% lower than those defined by a spot UIC <100 µg/L or ≥300 µg/L (P < 0.01). CONCLUSIONS: Applying the EAR/UL cutoff method to iodine intakes from adjusted UIC distributions is a promising approach to estimate the number of individuals with deficient or excess iodine intakes.

Three 24-Hour Recalls in Comparison with One Improve the Estimates of Energy and Nutrient Intakes in an Urban Mexican Population.

BACKGROUND: Population surveys often collect dietary intake data by using one or two 24-h recalls (24HR), mainly to minimize cost and respondent burden. However, in order to increase accuracy in estimating usual intake distributions, a larger number of 24HRs may be advisable. OBJECTIVE: The purpose of this study was to identify whether estimates of the intake and prevalence of nutrient inadequacy based on 3 d are better than those that are based on 1 d of information. METHODS: We conducted a national survey in 31 cities in Mexico using a sample that included 1073 individuals of both sexes, from birth through 79 y of age. Dietary information was collected by using 3 multiple-pass 24HRs (on nonconsecutive days). We estimated intake, adequacy, and prevalence of energy and nutrient inadequacy using information from 1 d and also from 3 d, adjusted for day-to-day variability, using PC-SIDE software. The prevalence of inadequacy was estimated by using the reference values proposed by the US Institute of Medicine. RESULTS: We found high prevalences of inadequacy for fiber (73-99%), iron (31-94%), calcium (2-85%), vitamin A (0.1-61%), and folates (2-80%) among various age and sex groups. Energy intake results showed that the variance in the estimated usual 3-d intake distribution was smaller than the variance of distribution estimated from a single daily intake. We observed bigger differences in prevalence of inadequacy between 1 and 3 d for several nutrients. For example, in preschool children, the prevalence of inadequacy of folate and calcium was 30% and 43%, respectively, with 1-d recalls and 3.7% and 4.6%, respectively, with 3-d recalls. CONCLUSIONS: We conclude that the adjusting-by-variance method using 3 d of 24HR allows for a more accurate estimation of usual intake, dietary adequacy, and prevalence of inadequacy, thereby reducing the measurement error that could compromise the results and conclusions of surveys.

Total Iron Bioavailability from the US Diet Is Lower Than the Current Estimate.

BACKGROUND: Total (heme and nonheme) iron bioavailability from the US diet has been estimated to be 18% based on a single human absorption study. New data, however, suggest that it may be time to revisit this estimate. OBJECTIVE: We estimated total iron bioavailability from the US diet with the use of our recently reported algorithm that estimates nonheme iron absorption and a conservative value for heme iron absorption. METHODS: We used dietary intake and biomarker information from the NHANES 2001-2002, MyPyramid Equivalents Database, and Food and Nutrient Database for Dietary Studies. The survey package in R software was used to estimate means and CIs, taking into account the strata, primary sampling units, and appropriate survey weight. We implemented 2 different approaches to estimate total iron absorption. In the first approach, we included all survey participants but adjusted the geometric mean of nonheme iron absorption to 15 µg ferritin/L serum to mimic values of individuals with no iron stores; in the second approach, absorption was estimated for only nonanemic subjects with no iron stores. A total sample size of 6631 was used based on availability of dietary and iron status biomarker data and C-reactive protein concentration ≤ 6 mg/L. RESULTS: The geometric mean (95% CI) of unadjusted nonheme iron absorption for all subjects was 3.7% (3.6%, 3.8%), higher in female subjects [5.6% (5.4%, 5.7%)] than male subjects [2.6% (2.5%, 2.7%)] (P < 0.0001). Nonheme iron absorption was lower in non-Hispanic whites [3.5% (3.4%, 3.6%)] than Mexican Americans [4.5% (4.2%, 4.8%)] and non-Hispanic blacks [4.4% (4.1%, 4.7%)]. Estimated total iron absorption was 15.5% or 15.1%, depending on which approach was used to carry out the calculations. CONCLUSION: This study provides useful data for evaluating the current value of iron bioavailability from the US diet.

Usual Dietary Energy Density Distribution Is Positively Associated with Excess Body Weight in Mexican Children.

BACKGROUND: Studies suggest a positive association between dietary energy density (DED) and body weight in adults, but evidence in children is inconclusive. OBJECTIVE: The objective of this study was to compare usual DED distributions of nonoverweight vs. overweight or obese (OW/O) Mexican children. METHODS: The study used 24-h recall (24HR) data from 2367 children aged 5-11 y from the 2012 Mexican National Health and Nutrition Survey (ENSANUT 2012). Repeated 24HR measures were obtained in a random sample (∼10%) to estimate usual intake distributions by using the Iowa State University (PC-Side) method. Implausible dietary reports were identified. Multivariate linear regression models were used to evaluate the relation between DED and body mass index status and to compare results with and without PC-Side adjustment and restriction to plausible reporters. RESULTS: A total of 35.1% of the children in the sample were OW/O. The usual DED mean was ∼175 kcal/100 g in both the complete sample and the plausible reporters subsample. Regression models adjusted by PC-Side and for potential confounders showed higher DED in OW/O relative to nonoverweight children for both plausible reporters (9.7 kcal/100 g; n = 1452, P < 0.0001) and the complete sample (7.9 kcal/100 g; n = 2367, P < 0.0001). The DED difference in plausible reporters translates into 88 additional kilocalories in daily energy intake of OW/O children. In the absence of PC-side adjustment, the difference was significant for plausible reporters (P < 0.05) but not for the complete sample (P > 0.10). CONCLUSIONS: A positive association between usual DED and OW/O was found in Mexican children. The association was stronger when only plausible reporters were considered. This suggests that there is a need for strategies to reduce energy density in the diet of Mexican children.

Use of Folate-Based and Other Fortification Scenarios Illustrates Different Shifts for Tails of the Distribution of Serum 25-Hydroxyvitamin D Concentrations.

BACKGROUND: The purpose of food fortification is to affect those at the lower end of the distribution curve for nutrient status while avoiding unintended consequences for those at the high end of the distribution. Vitamin D presents challenges in this regard. OBJECTIVES: We used scenarios to model changes in concentrations of serum 25-hydroxyvitamin D [25(OH)D] based on increases made because of assumptions about fortification. We then examined the outcomes for balance between improving serum 25(OH)D status for those at risk of inadequacy while avoiding high concentrations for those not at risk. METHODS: Data from NHANES 2001-2006 served as baseline serum 25(OH)D concentrations and were used to model shifts in serum 25(OH)D distribution after application of 3 fortification scenarios, including conceptual scenarios and an experiential predictive scenario we developed with the use of statistical modeling of changes in NHANES serum folate concentrations between prefortification and postfortification time periods. RESULTS: All scenarios suggested the possibility of increasing serum 25(OH)D above 125 nmol/L among the proportion of the population at the high end of baseline serum 25(OH)D distribution. The scenario based on serum folate change struck a middle ground between the 2 conceptual scenarios. It predicted a prevalence of 11% <40 nmol/L serum 25(OH)D compared with 17% currently (study baseline), and 8% prevalence of serum 25(OH)D >125 nmol/L compared with <1% currently (study baseline). It also confirmed that fortification affects those at the low end of the status distribution curve differently from those at the high end. CONCLUSIONS: Nutrient inadequacy of the type demonstrated by vitamin D--in which the risk is not universal--requires a thorough exploration of the unintended consequences of the overall shift in the distribution of serum 25(OH)D if efforts are made to use fortification to increase the status of persons at risk of deficiency. Fortification is at best a blunt instrument that must be implemented with caution. Moreover, fortification must be preceded by more research to elucidate the dose-response relation between intake and changes in serum 25(OH)D.

Estimating the population distribution of usual 24-hour sodium excretion from timed urine void specimens using a statistical approach accounting for correlated measurement errors.

BACKGROUND: High US sodium intake and national reduction efforts necessitate developing a feasible and valid monitoring method across the distribution of low-to-high sodium intake. OBJECTIVE: We examined a statistical approach using timed urine voids to estimate the population distribution of usual 24-h sodium excretion. METHODS: A sample of 407 adults, aged 18-39 y (54% female, 48% black), collected each void in a separate container for 24 h; 133 repeated the procedure 4-11 d later. Four timed voids (morning, afternoon, evening, overnight) were selected from each 24-h collection. We developed gender-specific equations to calibrate total sodium excreted in each of the one-void (e.g., morning) and combined two-void (e.g., morning + afternoon) urines to 24-h sodium excretion. The calibrated sodium excretions were used to estimate the population distribution of usual 24-h sodium excretion. Participants were then randomly assigned to modeling (n = 160) or validation (n = 247) groups to examine the bias in estimated population percentiles. RESULTS: Median bias in predicting selected percentiles (5th, 25th, 50th, 75th, 95th) of usual 24-h sodium excretion with one-void urines ranged from -367 to 284 mg (-7.7 to 12.2% of the observed usual excretions) for men and -604 to 486 mg (-14.6 to 23.7%) for women, and with two-void urines from -338 to 263 mg (-6.9 to 10.4%) and -166 to 153 mg (-4.1 to 8.1%), respectively. Four of the 6 two-void urine combinations produced no significant bias in predicting selected percentiles. CONCLUSIONS: Our approach to estimate the population usual 24-h sodium excretion, which uses calibrated timed-void sodium to account for day-to-day variation and covariance between measurement errors, produced percentile estimates with relatively low biases across low-to-high sodium excretions. This may provide a low-burden, low-cost alternative to 24-h collections in monitoring population sodium intake among healthy young adults and merits further investigation in other population subgroups.