Nancy F. Butte’s research while affiliated with Baylor College of Medicine and other places

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (<10 kg). Using data for 1,021 babies and infants, we show that the DSR varies non-linearly with body mass between 0 and 10 kg. Using this relationship to predict DSR from weight provides an equation for rCO2 over this size range that agrees well with indirect calorimetry (average difference 0.64%; SD = 12.2%). We propose adoption of these equations in future studies.

Objective Prepregnancy weight may not always be known to women. A model was developed to estimate prepregnancy weight from measured pregnancy weight. Methods The model was developed and validated using participants from two studies (Project Viva, n = 301, model development; and Fit for Delivery [FFD], n = 401, model validation). Data from the third study (Programming Research in Obesity, Growth, Environment and Social Stressors [PROGRESS]), which included women from Mexico City, were used to demonstrate the utility of the newly developed model to objectively quantify prepregnancy weight. Results The model developed from the Project Viva study validated well with low bias (R² = 0.95; y = 1.02x − 0.69; bias = 0.68 kg; 95% CI: −4.86 to 6.21). Predictions in women from FFD demonstrated good agreement (R² = 0.96; y = 0.96x + 4.35; bias = 1.60 kg; 95% CI: −4.40 to 7.54; error range = −11.25 kg to 14.73 kg). High deviations from model predictions were observed in the Programming Research in PROGRESS (R² = 0.81; y = 0.89x + 9.61; bias = 2.83 kg; 95% CI: −7.70 to 12.31; error range = −39.17 kg to 25.73 kg). The model was programmed into software (https://www.pbrc.edu/research-and-faculty/calculators/prepregnancy/). Conclusions The developed model provides an alternative to determine prepregnancy weight in populations receiving routine health care that may not have accurate knowledge of prepregnancy weight. The software can identify misreporting and classification into incorrect gestational weight gain categories.

Background: Nutrition during infancy and toddlerhood may influence health and disease prevention across the life span. Complementary feeding (CF) starts when human milk or infant formula is complemented by other foods and beverages, beginning during infancy and continuing to age 24 mo. Objectives: The aim of this study was to describe systematic reviews conducted for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer the following question: What is the relationship between the timing of the introduction of complementary foods and beverages (CFBs), or types and amounts of CFBs consumed, and the development of food allergy, atopic dermatitis/eczema, asthma, and allergic rhinitis? Methods: The literature was searched using 4 databases (CINAHL, Cochrane, Embase, PubMed) to identify articles published from January 1980 to February 2017 that met predetermined inclusion criteria. For each study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. Results: Thirty-one included articles addressed the timing of CFB introduction, and 47 articles addressed the types and amounts of CFBs consumed. Conclusions: Moderate evidence suggests that there is no relationship between the age at which CF first begins and the risk of developing food allergy, atopic dermatitis/eczema, or childhood asthma. Limited to strong evidence, depending on the specific food, suggests that introducing allergenic foods in the first year of life (after 4 mo) does not increase the risk of food allergy and atopic dermatitis/eczema but may prevent peanut and egg allergy. There is not enough evidence to determine a relationship between diet diversity or dietary patterns and atopic disease. Research is needed to address gaps and limitations in the evidence on CF and atopic disease, including research that uses valid and reliable diagnostic measures and accounts for key confounders and potential reverse causality.

Background: Proper nutrition during early life is critical for growth and development. Objectives: The aim was to describe systematic reviews conducted by the Nutrition Evidence Systematic Review team for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer the following: What is the relation between 1) timing of introduction of complementary foods and beverages (CFBs) or 2) types and/or amounts of CFBs consumed and micronutrient status (iron, zinc, vitamin D, vitamin B-12, folate, and fatty acid status)? Methods: A literature search identified articles from developed countries published from January 1980 to July 2016 that met the inclusion criteria. Data were extracted and risk of bias assessed. Evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. Results: Nine articles addressed the timing of CFB introduction and 31 addressed types or amounts or both of CFBs. Moderate evidence suggests that introducing CFBs at age 4 mo instead of 6 mo offers no advantages or disadvantages in iron status among healthy full-term infants. Evidence is insufficient on the timing of CFB introduction and other micronutrient status outcomes. Strong evidence suggests that CFBs containing iron (e.g., meat, fortified cereal) help maintain adequate iron status or prevent deficiency in the first year among infants at risk of insufficient iron stores or low intake. Benefits for infants with sufficient iron stores (e.g., infant formula consumers) are less clear. Moderate evidence suggests that CFBs containing zinc (e.g., meat, fortified cereal) support zinc status in the first year and CFB fatty acid composition influences fatty acid status. Evidence is insufficient with regard to types and amounts of CFBs and vitamin D, vitamin B-12, and folate status, or the relation between lower-iron-containing CFBs and micronutrient status. Conclusions: Several conclusions on CFBs and micronutrient status were drawn from these systematic reviews, but more research that addresses specific gaps and limitations is needed.

Background: Proper nutrition during infancy and toddlerhood is crucial for supporting healthy growth and development, including bone health. Complementary feeding is the process that starts when human milk or infant formula is complemented by other foods and beverages, beginning during late infancy and continuing to 24 mo of age. Objectives: This article aims to describe systematic reviews (SRs) conducted by the Nutrition Evidence Systematic Review team for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer these questions: what is the relationship between 1) timing of introduction of complementary foods and beverages (CFBs) or 2) types and/or amounts of CFBs consumed and bone health? Methods: The literature was searched with the use of 4 databases (CINAHL, Cochrane, Embase, and PubMed) to identify articles published from January 1980 to July 2016 that addressed these topics and met predetermined criteria for inclusion. For each study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded. Results: Three articles addressed the timing of introduction of CFBs and bone health during childhood (through 18 y of age), and 2 addressed the types and/or amounts of CFBs consumed relative to bone health. Conclusions: Insufficient evidence was available to draw conclusions about the relationships between the timing of CFB introduction and types and/or amounts of CFBs consumed and bone health. Therefore, a grade was not assignable for these SRs. The ability to draw conclusions was limited by an overall lack of research, failure to adjust for several key confounding factors, and heterogeneity in studies with regard to methodology, subject populations, and results. Additional research is needed that addresses these gaps and limitations.

Background: Systematic reviews were conducted as part of the USDA and the US Department of Health and Human Services Pregnancy and Birth to 24 Months Project to examine the relation between complementary feeding and developmental milestones. Objectives: The aim of this study was to describe systematic reviews examining the relationship between timing of introduction of complementary foods and beverages (CFB), and the types and amounts of CFB consumed, and developmental milestones. Methods: The literature was searched using 4 databases (PubMed, Cochrane, Embase, and CINAHL) to identify articles that met predetermined criteria for inclusion. Data extraction and risk of bias assessment were conducted for each included study. The body of evidence for each systematic review was qualitatively synthesized to develop a conclusion statement, and the strength of evidence was graded. Results: Three included articles (1 randomized controlled trial; 2 observational studies) examined timing of introduction of CFB. Eight included articles (3 randomized controlled trials; 5 observational studies) examined types and amounts of CFB. There was insufficient evidence to draw conclusions about the relation between either timing of CFB introduction or types and amounts of CFB, and developmental milestones. Conclusions: The ability to draw conclusions about the relationship between complementary feeding and developmental milestones was restricted by an inadequate amount of evidence with potential for issues with reverse causality and wide variation in design, type/age of outcome assessment, exposure assessment, and reported results. Additional research to address these gaps and limitations would be useful.

Full text available for free here: https://nesr.usda.gov/what-relationship-between-timing-introduction-complementary-foods-and-beverages-and-growth-size-and#full-review Background: The systematic review described in this article was conducted as part of the USDA and Department of Health and Human Services Pregnancy and Birth to 24 Months Project. Objectives: The aim was to describe the relationship between timing of introduction of complementary foods and beverages (CFBs) and growth, size, and body-composition outcomes across the life span. Methods: The literature was searched and selected using predetermined criteria. Data were extracted and risk of bias assessed for each included study. Evidence was qualitatively synthesized, conclusion statements were developed, and the strength of the evidence was graded. Results: Eighty-one articles were included in this systematic review that addressed timing of CFB introduction relative to growth, size, and body-composition outcomes from infancy through adulthood. Moderate evidence suggests that introduction of CFBs between the ages of 4 and 5 mo compared with ∼6 mo is not associated with weight status, body composition, body circumferences, weight, or length among generally healthy, full-term infants. Limited evidence suggests that introduction of CFBs before age 4 mo may be associated with higher odds of overweight/obesity. Insufficient evidence exists regarding introduction at age ≥7 mo. Conclusions: Although several conclusions were drawn in this systematic review, additional research is needed to address gaps and limitations in the evidence on timing of introduction of CFBs and growth, size, and body composition, such as randomized controlled trials that examine multiple outcomes and/or CFB introduction between the ages of 4 and 6 mo, and research that accounts for potential confounders such as feeding practices and baseline growth status and considers issues of reverse causality.

Full text available for free here: https://nesr.usda.gov/what-relationship-between-types-and-amounts-complementary-foods-and-beverages-and-growth-size-and#full-review Background: Systematic reviews (SRs) were conducted by the Nutrition Evidence Systematic Review (NESR) team for the USDA's and the Department of Health and Human Services' Pregnancy and Birth to 24 Months Project. Objectives: The aim was to describe the SRs examining the relationship between types and amounts of complementary foods and beverages (CFBs) and growth, size, and body-composition outcomes. Methods: The NESR team collaborated with subject matter experts to conduct this SR. The literature was searched and screened using predetermined criteria. For each included study, data were extracted and risk of bias was assessed. The evidence was qualitatively synthesized to develop a conclusion statement, and the strength of evidence was graded. Results: This SR includes 49 articles that examined type, amount, or both of CFBs consumed and growth, size, and body-composition outcomes. Moderate evidence suggests that consuming either different amounts of meat, meat instead of iron-fortified cereal, or types of CFBs with different fats or fatty acids does not favorably or unfavorably influence growth, size, or body composition. In relation to overweight/obesity, insufficient evidence is available with regard to the intake of meat or CFBs with different fats or fatty acids. Limited evidence suggests that type and amount of fortified infant cereal does not favorably or unfavorably influence growth, size, body composition, or overweight/obesity. Limited evidence suggests that sugar-sweetened beverage consumption during the complementary feeding period is associated with increased obesity risk in childhood but is not associated with other measures of growth, size, or body composition. Limited evidence showed a positive association between juice intake and infant weight-for-length and child body mass index z scores. Insufficient evidence is available on other CFBs or dietary patterns in relation to outcomes. Conclusions: Although several conclusions were drawn, additional research is needed that includes randomized controlled trials, examines a wider range of CFBs, considers issues of reverse causality, and adjusts for potential confounders to address gaps and limitations in the evidence.

Asprosin is a recently discovered fasting-induced hormone that promotes hepatic glucose production. Here we demonstrate that asprosin in the circulation crosses the blood-brain barrier and directly activates orexigenic AgRP+ neurons via a cAMP-dependent pathway. This signaling results in inhibition of downstream anorexigenic proopiomelanocortin (POMC)-positive neurons in a GABA-dependent manner, which then leads to appetite stimulation and a drive to accumulate adiposity and body weight. In humans, a genetic deficiency in asprosin causes a syndrome characterized by low appetite and extreme leanness; this is phenocopied by mice carrying similar mutations and can be fully rescued by asprosin. Furthermore, we found that obese humans and mice had pathologically elevated concentrations of circulating asprosin, and neutralization of asprosin in the blood with a monoclonal antibody reduced appetite and body weight in obese mice, in addition to improving their glycemic profile. Thus, in addition to performing a glucogenic function, asprosin is a centrally acting orexigenic hormone that is a potential therapeutic target in the treatment of both obesity and diabetes.