Folate and Synthetic Folic Acid Content in Canadian Fortified Foods Two Decades After Mandatory Fortification.

In 1998, Health Canada mandated folic acid fortification of white flour and enriched grain products to prevent neural tube defects. At the time, neither the Canadian Nutrient File (CNF) nor product labels reflected the actual folate content of foods. We aimed to assess if 20 years post-fortification, the CNF values for total folate and synthetic folic acid accurately reflect amounts determined by direct analysis. Using the 2001 Food Expenditure Survey and ACNielsen Company data, we identified 10 to 15 of the most purchased fortified foods across 7 food categories in Canada. Total folate concentrations were determined by tri-enzyme digestion and microbial assay. Folic acid concentrations were determined using liquid chromatography tandem mass spectrometry. Except for "cooked pastas", mean total folate content of foods (n=89) were significantly higher than CNF values across categories (p<0.05), reflecting 167% ± 54 of CNF values. Similarly, mean folic acid content of foods was higher than CNF values for all categories except "cooked pastas" (p<0.05), with a mean of 188% ± 94 of CNF values; the latter CNF values included uncooked pasta. In sum, 20 years post-fortification, and 10 years since the last direct measurement, CNF and product label values still underestimate actual total folate and the folic acid content of foods. These findings emphasize that dietary estimates established using the CNF may significantly underestimate actual intakes and thus caution should be exercised when interpreting estimates of nutritional adequacy based on these values.

Proportions of trans fatty acids in erythrocytes of Canadian adults before the prohibition of partially hydrogenated oils in foods: results from the Canadian Health Measures Survey 2012-2015.

BACKGROUND: The partially hydrogenated oil (PHO) prohibition came into effect in Canada in September 2018 to reduce the intakes of total trans fatty acids (t-TFAs) and industrially produced TFAs (i-TFAs). OBJECTIVES: We aimed to estimate the red blood cell (RBC) proportions of t-TFA (primary objective) and total 18:1 TFA (secondary objective) of adults in Canada before the PHO prohibition and to identify the population subgroups at risk of higher TFA intakes. METHODS: We pooled data from 4025 adult participants of the cross-sectional Canadian Health Measures Survey cycles 3 and 4 (2012-2015). We estimated mean proportions, relative to total fatty acids (FAs), of RBC t-TFA and 18:1 TFA and their associations with sociodemographic, health, and lifestyle characteristics using multiple linear regression models. RESULTS: The nonadjusted mean RBC proportions of t-TFA and total 18:1 TFA were 0.59% (95% CI: 0.54, 0.63) and 0.27% (95% CI: 0.25, 0.29), respectively. In the adjusted models, the same participant characteristics were associated with t-TFA and 18:1 TFA but differences were generally smaller for 18:1 TFA than for t-TFA. Race, BMI, and alcohol intake were independently associated with RBC t-TFA and 18:1 TFA. Asian and Black participants had lower RBC t-TFA (-0.05% and -0.10% of total FA, respectively) than White participants. Obesity and high risk alcohol drinking were associated with slightly lower (≤0.06%) t-TFA proportions than lower adiposity and alcohol intake concentrations, respectively. CONCLUSIONS: Pre-PHO prohibition in food in Canada, t-TFA proportions were relatively low compared with a proposed threshold of 1% of total RBC FAs, over which cardiovascular disease risk may be higher. Previous voluntary initiatives to reduce i-TFA in the food supply may explain these relatively low RBC t-TFA concentrations. Some population subgroups had higher baseline RBC TFA than other subgroups, but the physiological implications of these small differences, at relatively low baseline RBC TFA proportions, remain to be determined.

Ultra-processed foods and human health: An umbrella review and updated meta-analyses of observational evidence.

BACKGROUND & AIMS: Ultra-processed food (UPF) intake has increased sharply over the last few decades and has been consistently asserted to be implicated in the development of non-communicable diseases. We aimed to evaluate and update the existing observational evidence for associations between ultra-processed food (UPF) consumption and human health. METHODS: We searched Medline and Embase from inception to March 2023 to identify and update meta-analyses of observational studies examining the associations between UPF consumption, as defined by the NOVA classification, and a wide spectrum of health outcomes. For each health outcome, we estimated the summary effect size, 95% confidence interval (CI), between-study heterogeneity, evidence of small-study effects, and evidence of excess-significance bias. These metrics were used to evaluate evidence credibility of the identified associations. RESULTS: This umbrella review identified 39 meta-analyses on the associations between UPF consumption and health outcomes. We updated all meta-analyses by including 122 individual articles on 49 unique health outcomes. The majority of the included studies divided UPF consumption into quartiles, with the lowest quartile being the reference group. We identified 25 health outcomes associated with UPF consumption. For observational studies, 2 health outcomes, including renal function decline (OR: 1.25; 95% CI: 1.18, 1.33) and wheezing in children and adolescents (OR: 1.42; 95% CI: 1.34, 1.49), showed convincing evidence (Class I); and five outcomes were reported with highly suggestive evidence (Class II), including diabetes mellitus, overweight, obesity, depression, and common mental disorders. CONCLUSIONS: High UPF consumption is associated with an increased risk of a variety of chronic diseases and mental health disorders. At present, not a single study reported an association between UPF intake and a beneficial health outcome. These findings suggest that dietary patterns with low consumption of UPFs may render broad public health benefits.

Risk of bias in cross-sectional studies: Protocol for a scoping review of concepts and tools.

Cross-sectional studies are commonly used to study human health and disease, but are especially susceptible to bias. This scoping review aims to identify and describe available tools to assess the risk of bias (RoB) in cross-sectional studies and to compile the key bias concepts relevant to cross-sectional studies into an item bank. Using the JBI scoping review methodology, the strategy to locate relevant RoB concepts and tools is a combination of database searches, prospective review of PROSPERO registry records; and consultation with knowledge users and content experts. English language records will be included if they describe tools, checklists, or instruments which describe or permit assessment of RoB for cross-sectional studies. Systematic reviews will be included if they consider eligible RoB tools or use RoB tools for RoB of cross-sectional studies. All records will be independently screened, selected, and extracted by one researcher and checked by a second. An analytic framework will be used to structure the extraction of data. Results for the scoping review are pending. Results from this scoping review will be used to inform future selection of RoB tools and to consider whether development of a new RoB tool for cross-sectional studies is needed.

The Association between Long-Term DDT or DDE Exposures and an Altered Sperm Epigenome-a Cross-Sectional Study of Greenlandic Inuit and South African VhaVenda Men.

BACKGROUND: The organochlorine dichlorodiphenyltrichloroethane (DDT) is banned worldwide owing to its negative health effects. It is exceptionally used as an insecticide for malaria control. Exposure occurs in regions where DDT is applied, as well as in the Arctic, where its endocrine disrupting metabolite, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) accumulates in marine mammals and fish. DDT and p,p'-DDE exposures are linked to birth defects, infertility, cancer, and neurodevelopmental delays. Of particular concern is the potential of DDT use to impact the health of generations to come via the heritable sperm epigenome. OBJECTIVES: The objective of this study was to assess the sperm epigenome in relation to p,p'-DDE serum levels between geographically diverse populations. METHODS: In the Limpopo Province of South Africa, we recruited 247 VhaVenda South African men and selected 50 paired blood serum and semen samples, and 47 Greenlandic Inuit blood and semen paired samples were selected from a total of 193 samples from the biobank of the INUENDO cohort, an EU Fifth Framework Programme Research and Development project. Sample selection was based on obtaining a range of p,p'-DDE serum levels (mean=870.734±134.030 ng/mL). We assessed the sperm epigenome in relation to serum p,p'-DDE levels using MethylC-Capture-sequencing (MCC-seq) and chromatin immunoprecipitation followed by sequencing (ChIP-seq). We identified genomic regions with altered DNA methylation (DNAme) and differential enrichment of histone H3 lysine 4 trimethylation (H3K4me3) in sperm. RESULTS: Differences in DNAme and H3K4me3 enrichment were identified at transposable elements and regulatory regions involved in fertility, disease, development, and neurofunction. A subset of regions with sperm DNAme and H3K4me3 that differed between exposure groups was predicted to persist in the preimplantation embryo and to be associated with embryonic gene expression. DISCUSSION: These findings suggest that DDT and p,p'-DDE exposure impacts the sperm epigenome in a dose-response-like manner and may negatively impact the health of future generations through epigenetic mechanisms. Confounding factors, such as other environmental exposures, genetic diversity, and selection bias, cannot be ruled out. https://doi.org/10.1289/EHP12013.

Higher incidence of embryonic defects in mouse offspring conceived with assisted reproduction from fathers with sperm epimutations.

Assisted reproductive technologies (ART) account for 1-6% of births in developed countries. While most children conceived are healthy, increases in birth and genomic imprinting defects have been reported; such abnormal outcomes have been attributed to underlying parental infertility and/or the ART used. Here, we assessed whether paternal genetic and lifestyle factors, that are associated with male infertility and affect the sperm epigenome, can influence ART outcomes. We examined how paternal factors, haploinsufficiency for Dnmt3L, an important co-factor for DNA methylation reactions, and/or diet-induced obesity, in combination with ART (superovulation, in vitro fertilization, embryo culture and embryo transfer), could adversely influence embryo development and DNA methylation patterning in mice. While male mice fed high-fat diets (HFD) gained weight and showed perturbed metabolic health, their sperm DNA methylation was minimally affected by the diet. In contrast, Dnmt3L haploinsufficiency induced a marked loss of DNA methylation in sperm; notably, regions affected were associated with neurodevelopmental pathways and enriched in young retrotransposons, sequences that can have functional consequences in the next generation. Following ART, placental imprinted gene methylation and growth parameters were impacted by one or both paternal factors. For embryos conceived by natural conception, abnormality rates were similar for WT and Dnmt3L+/- fathers. In contrast, paternal Dnmt3L+/- genotype, as compared to WT fathers, resulted in a 3-fold increase in the incidence of morphological abnormalities in embryos generated by ART. Together, the results indicate that embryonic morphological and epigenetic defects associated with ART may be exacerbated in offspring conceived by fathers with sperm epimutations.

Mitigating the detrimental developmental impact of early fetal alcohol exposure using a maternal methyl donor-enriched diet.

Fetal alcohol exposure at any stage of pregnancy can lead to fetal alcohol spectrum disorder (FASD), a group of life-long conditions characterized by congenital malformations, as well as cognitive, behavioral, and emotional impairments. The teratogenic effects of alcohol have long been publicized; yet fetal alcohol exposure is one of the most common preventable causes of birth defects. Currently, alcohol abstinence during pregnancy is the best and only way to prevent FASD. However, alcohol consumption remains astoundingly prevalent among pregnant women; therefore, additional measures need to be made available to help protect the developing embryo before irreparable damage is done. Maternal nutritional interventions using methyl donors have been investigated as potential preventative measures to mitigate the adverse effects of fetal alcohol exposure. Here, we show that a single acute preimplantation (E2.5; 8-cell stage) fetal alcohol exposure (2 × 2.5 g/kg ethanol with a 2h interval) in mice leads to long-term FASD-like morphological phenotypes (e.g. growth restriction, brain malformations, skeletal delays) in late-gestation embryos (E18.5) and demonstrate that supplementing the maternal diet with a combination of four methyl donor nutrients, folic acid, choline, betaine, and vitamin B12, prior to conception and throughout gestation effectively reduces the incidence and severity of alcohol-induced morphological defects without altering DNA methylation status of imprinting control regions and regulation of associated imprinted genes. This study clearly supports that preimplantation embryos are vulnerable to the teratogenic effects of alcohol, emphasizes the dangers of maternal alcohol consumption during early gestation, and provides a potential proactive maternal nutritional intervention to minimize FASD progression, reinforcing the importance of adequate preconception and prenatal nutrition.

Higher Than Recommended Folic Acid Intakes is Associated with High Folate Status Throughout Pregnancy in a Prospective French-Canadian Cohort.

BACKGROUND: Folate and vitamin B12 status during pregnancy are important for maternal and neonatal health. Maternal intake and prepregnancy body mass index (ppBMI) can influence biomarker status. OBJECTIVES: This study aimed to, throughout pregnancy; 1) assess folate and B12 status including serum total folate, plasma total vitamin B12, and homocysteine (tHcy); 2) examine how these biomarkers are associated with intakes of folate and B12 and with ppBMI; and 3) determine predictors of serum total folate and plasma total vitamin B12. METHODS: In each trimester (T1, T2, and T3), food and supplement intakes of 79 French-Canadian pregnant individuals were assessed by 3 dietary recalls (R24W) and a supplement use questionnaire. Fasting blood samples were collected. Serum total folate and plasma total vitamin B12 and tHcy were assessed by immunoassay (Siemens ADVIA Centaur XP). RESULTS: Participants were 32.1 ± 3.7 y and had a mean ppBMI of 25.7 ± 5.8 kg/m2. Serum total folate concentrations were high (>45.3 nmol/L, T1: 75.4 ± 55.1, T2: 69.1 ± 44.8, T3: 72.1 ± 52.1, P = 0.48). Mean plasma total vitamin B12 concentrations were >220 pmol/L (T1: 428 ± 175, T2: 321 ± 116, T3: 336 ± 128, P < 0.0001). Mean tHcy concentrations were <11 µmol/L across trimesters. Most participants (79.6%-86.1%) had a total folic acid intake above the Tolerable Upper Intake Level (UL, >1000 µg/d). Supplement use accounted for 71.9%-76.1% and 35.3%-41.8% of total folic acid and vitamin B12 intakes, respectively. The ppBMI was not correlated with serum total folate (P > 0.1) but was weakly correlated with and predicted lower plasma total vitamin B12 in T3 (r = -0.23, P = 0.04; r2 = 0.08, standardized beta [sß] = -0.24, P = 0.01). Higher folic acid intakes from supplements predicted higher serum total folate (T1: r2 = 0.05, sß = 0.15, P = 0.04, T2: r2 = 0.28, sß = 0.56, P = 0.01, T3: r2 = 0.19, sß = 0.44, P < 0.0001). CONCLUSIONS: Most pregnant individuals had elevated serum total folate concentrations, reflecting total folic acid intakes above the UL driven by supplement use. Vitamin B12 concentrations were generally adequate and differed by ppBMI and pregnancy stage.

Phenome-wide association study of genetically predicted B vitamins and homocysteine biomarkers with multiple health and disease outcomes: analysis of the UK Biobank.

BACKGROUND: Although a number of health outcomes such as CVDs, metabolic-related outcomes, neurological disorders, pregnancy outcomes, and cancers have been identified in relation to B vitamins, evidence is of uneven quality and volume, and there is uncertainty about putative causal relationships. OBJECTIVES: To explore the effects of B vitamins and homocysteine on a wide range of health outcomes based on a large biorepository linking biological samples and electronic medical records. METHODS: First, we performed a phenome-wide association study (PheWAS) to investigate the associations of genetically predicted plasma concentrations (genetic component of the circulating concentrations) of folate, vitamin B6, vitamin B12, and their metabolite homocysteine with a wide range of disease outcomes (including both prevalent and incident events) among 385,917 individuals in the UK Biobank. Second, 2-sample Mendelian randomization (MR) analysis was used to replicate any observed associations and detect causality. We considered MR P <0.05 as significant for replication. Third, dose-response, mediation, and bioinformatics analyses were carried out to examine any nonlinear trends and to disentangle the underlying mediating biological mechanisms for the identified associations. RESULTS: In total, 1117 phenotypes were tested in each PheWAS analysis. After multiple corrections, 32 phenotypic associations of B vitamins and homocysteine were identified. Two-sample MR analysis supported that 3 of them were causal, including associations of higher plasma vitamin B6 with lower risk of calculus of kidney (OR: 0.64; 95% CI: 0.42, 0.97; P = 0.033), higher homocysteine concentration with higher risk of hypercholesterolemia (OR: 1.28, 95% CI: 1.04, 1.56; P = 0.018), and chronic kidney disease (OR: 1.32, 95% CI: 1.06, 1.63; P = 0.012). Significant nonlinear dose-response relationships were observed for the associations of folate with anemia, vitamin B12 with vitamin B-complex deficiencies, anemia and cholelithiasis, and homocysteine with cerebrovascular disease. CONCLUSIONS: This study provides strong evidence for the associations of B vitamins and homocysteine with endocrine/metabolic and genitourinary disorders.

Relationships between maternal body mass index and child cognitive outcomes at 3 years of age are buffered by specific early environments in a prospective Canadian birth cohort.

Fetal and child development are shaped by early life exposures, including maternal health states, nutrition and educational and home environments. We aimed to determine if suboptimal pre-pregnancy maternal body mass index (BMI; underweight, overweight, obese) would associate with poorer cognitive outcomes in children, and whether early life nutritional, educational and home environments modify these relationships. Self-reported data were obtained from mother-infant dyads from the pan-Canadian prospective Maternal-Infant Research on Environmental Chemicals cohort. Relationships between potential risk factors (pre-pregnancy maternal BMI, breastfeeding practices and Home Observation Measurement of the Environment [HOME] score) and child cognitive development at age three (Weschler's Preschool and Primary Scale of Intelligence, Third Edition scale and its subcategories) were each evaluated using analysis of variance, multivariable regression models and moderating analyses. Amongst the 528 mother-child dyads, increasing maternal pre-pregnancy BMI was negatively associated with scores for child full-scale IQ (ß [95% CI]; -2.01 [-3.43, -0.59], p = 0.006), verbal composite (-1.93 [-3.33, -0.53], p = 0.007), and information scale (-0.41 [-0.70, -0.14], p = 0.003) scores. Higher maternal education level or HOME score attenuated the negative association between maternal pre-pregnancy BMI and child cognitive outcome by 30%-41% and 7%-22%, respectively, and accounted for approximately 5%-10% greater variation in male children's cognitive scores compared to females. Maternal education and higher quality home environment buffer the negative effect of elevated maternal pre-pregnancy BMI on child cognitive outcomes. Findings suggest that relationships between maternal, social and environmental factors must be considered to reveal pathways that shape risk for, and resiliency against, suboptimal cognitive outcomes in early life.

Exposure to environmental contaminants and folic acid supplementation intergenerationally impact fetal skeleton development through the paternal lineage in a rat model.

Persistent organic pollutants (POPs) are ubiquitous in the environment, which is of concern since they are broadly toxic for wildlife and human health. It is generally accepted that maternal prenatal folic acid supplementation (FA) may beneficially impact offspring development, but it has been recently shown that the father's exposures also influence the health of his offspring. Bone is an endocrine organ essential for whole-body homeostasis and is susceptible to toxicants. Herein, we tested the hypotheses that prenatal paternal exposure to POPs induces developmental bone disorders in fetuses across multiple generations and that FA supplementation attenuates these disorders. We used a four-generation rat model, in which F0 founder females were divided into four treatment groups. F0 females were gavaged with corn oil or an environmentally-relevant POPs mixture and fed either a control diet (2 mg FA/kg), or FA supplemented diet (6 mg FA/kg) before mating and until parturition (four treatments in total). After the birth of the F1 litters, all F0 females and subsequent generations received the FA control diet. Staining with alcian blue and alizarin red S of male and female fetal skeletons was performed at Gestational Day 19.5. Paternal direct and ancestral exposure to POPs delayed bone ossification and decreased the length of long limb bones in fetuses. Maternal FA supplementation did not counteract the POPs-associated delayed fetal ossification and reduced long bone length. In conclusion, prenatal paternal POPs exposure causes developmental bone abnormalities over multiple generations, which were not corrected by maternal FA supplementation.

Associations between folic acid supplement use and folate status biomarkers in the first and third trimesters of pregnancy in the Maternal-Infant Research on Environmental Chemicals (MIREC) Pregnancy Cohort Study.

BACKGROUND: Achieving optimal folate status during early gestation reduces the risk of neural tube defects (NTDs). While inadequate folate intake remains a concern, it is becoming increasingly common for individuals to consume higher than recommended doses of folic acid (FA) with minimal additional benefit. OBJECTIVE: Here, we sought to investigate the determinants, including FA supplement dose and use, of plasma total and individual folate vitamer concentrations in the first and third trimesters of pregnancy. METHODS: Using data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a cohort exposed to mandatory FA fortification, we measured plasma total folate and individual folate vitamer [5-methyltetrahydrofolate (5-methylTHF), unmetabolized FA (UMFA), and non-methyl folates (sum of THF, 5-formylTHF, 5,10-methenyl-THF)] concentrations in the first and third trimesters (n = 1,893). Using linear mixed models, we estimated associations between plasma folate concentrations, total daily supplemental FA intake, plasma vitamin B-12 concentrations, and multiple demographic, maternal, and reproductive factors. RESULTS: Almost 95% of MIREC study participants met or exceeded the recommended daily supplemental FA intake from supplements (≥400 µg/d), with approximately 25% consuming more than the Tolerable Upper Intake Level (>1000 µg/d). Over 99% of MIREC participants had a plasma total folate status indicative of maximal NTD risk reduction (25.5 nmol/L) regardless of FA supplement dose. UMFA was detected in almost all participants, with higher concentrations associated with higher FA doses. Determinants of adequate FA supplement intake and folate status associated with reduced NTD risk included indicators of higher socioeconomic position, higher maternal age, nulliparity, and lower prepregnancy BMI. CONCLUSIONS: In the context of mandatory FA fortification, our data indicate that higher-than-recommended FA doses are unwarranted, with the exception of individuals at higher risk for NTDs. Ideally, prenatal supplements would contain 400 rather than 1000 µg FA, thereby enabling the consumption of optimal and safe FA doses.

Maternal Folate Status and the Relation between Gestational Arsenic Exposure and Child Health Outcomes.

Gestational arsenic exposure adversely impacts child health. Folate-mediated 1-carbon metabolism facilitates urinary excretion of arsenic and may prevent arsenic-related adverse health outcomes. We investigated the potential for maternal folate status to modify associations between gestational arsenic exposure and child health. We used data from 364 mother-child pairs in the MIREC study, a prospective pan-Canadian cohort. During pregnancy, we measured first trimester urinary arsenic concentrations, plasma folate biomarkers, and folic acid supplementation intake. At age 3 years, we evaluated twelve neurodevelopmental and anthropometric features. Using latent profile analysis and multinomial regression, we developed phenotypic profiles of child health, estimated covariate-adjusted associations between arsenic and these phenotypic profiles, and evaluated whether folate status modified these associations. We identified three phenotypic profiles of neurodevelopment and three of anthropometry, ranging from less to more optimal child health. Gestational arsenic was associated with decreased odds of optimal neurodevelopment. Maternal folate status did not modify associations of arsenic with neurodevelopmental phenotypic profiles, but gestational arsenic was associated with increased odds of excess adiposity among those who exceed recommendations for folic acid (>1000 µg/day). However, arsenic exposure was low and folate status was high. Gestational arsenic exposure may adversely impact child neurodevelopment and anthropometry, and maternal folate status may not modify these associations; however, future work should examine these associations in more arsenic-exposed or lower folate-status populations.

Perspective: Human Milk Composition and Related Data for National Health and Nutrition Monitoring and Related Research.

National health and nutrition monitoring is an important federal effort in the United States and Canada, and the basis for many of their nutrition and health policies. Understanding of child exposures through human milk (HM) remains out of reach due to lack of current and representative data on HM's composition and intake volume. This article provides an overview of the current national health and nutrition monitoring activities for HM-fed children, HM composition (HMC) and volume data used for exposure assessment, categories of potential measures in HM, and associated variability factors. In this Perspective, we advocate for a framework for collection and reporting of HMC data for national health and nutrition monitoring and programmatic needs, including a shared vision for a publicly available Human Milk Composition Data Repository (HMCD-R) to include essential metadata associated with HMC. HMCD-R can provide a central, integrated platform for researchers and public health officials for compiling, evaluating, and sharing HMC data. The compiled compositional and metadata in HMCD-R would provide pertinent measures of central tendency and variability and allow use of modeling techniques to approximate compositional profiles for subgroups, providing more accurate exposure assessments for purposes of monitoring and surveillance. HMC and related metadata could facilitate understanding the complexity and variability of HM composition, provide crucial data for assessment of infant and maternal nutritional needs, and inform public health policies, food and nutrition programs, and clinical practice guidelines.

Poor Reporting Quality in Basic Nutrition Research: A Case Study Based on a Scoping Review of Recent Folate Research in Mouse Models (2009-2021).

Transparent reporting of nutrition research promotes rigor, reproducibility, and relevance to human nutrition. We performed a scoping review of recent articles reporting dietary folate interventions in mice as a case study to determine the reporting frequency of generic study design items (i.e., sex, strain, and age) and nutrition-specific items (i.e., base diet composition, intervention doses, duration, and exposure verification) in basic nutrition research. We identified 798 original research articles in the EMBASE, Medline, Food Science and Technology Abstracts (FSTA), Global Health, and International Pharmaceutical Abstracts (IPA) databases published between January 2009 and July 2021 in which a dietary folic acid (FA) intervention was used in mice. We identified 312 original peer-reviewed articles including 191 studies in nonpregnant and 126 in pregnant mice. Most studies reported sex (99%), strain (99%), and age (83%). The majority of studies used C57BL/6 (53%) or BALB/c (11%) mice aged 3-9 wk. Nonpregnancy studies were more likely to use only male mice (57%). Dietary FA interventions varied considerably and overlapped: deficiency (0-3 mg/kg), control (0-16 mg/kg), and supplemented (0-50 mg/kg). Only 63% of studies used an open-formula base diet with a declared FA content and 60% of studies verified FA exposure using folate status biomarkers. The duration of intervention ranged from 1 to 104 wk for nonpregnancy studies. The duration of intervention for pregnancy studies was 1-19 wk, occurring variably before pregnancy and/or during pregnancy and/or lactation. Overall, 17% of studies did not report ≥1 generic study design item(s) and 40% did not report ≥1 nutrition-specific study design item(s). The variability and frequent lack of reporting of important generic and nutrition-specific study design details in nutrition studies limit their generalizability, reproducibility, and interpretation. The use of reporting checklists for animal research would enhance reporting quality of key study design and conduct factors in animal-based nutrition research.

NUQUEST-NUtrition QUality Evaluation Strengthening Tools: development of tools for the evaluation of risk of bias in nutrition studies.

BACKGROUND: Dietary exposure assessments are a critical issue in evaluating human nutrition studies; however, nutrition-specific criteria are not consistently included in existing bias assessment tools. OBJECTIVES: Our objective was to develop a set of risk of bias (RoB) tools that integrated nutrition-specific criteria into validated generic assessment tools to address RoB issues, including those specific to dietary exposure assessment. METHODS: The Nutrition QUality Evaluation Strengthening Tools (NUQUEST) development and validation process included 8 steps. The first steps identified 1) a development strategy; 2) generic assessment tools with demonstrated validity; and 3) nutrition-specific appraisal issues. This was followed by 4) generation of nutrition-specific items and 5) development of guidance to aid users of NUQUEST. The final steps used established ratings of selected studies and feedback from independent raters to 6) assess reliability and validity; 7) assess formatting and usability; and 8) finalize NUQUEST. RESULTS: NUQUEST is based on the Scottish Intercollegiate Guidelines Network checklists for randomized controlled trials, cohort studies, and case-control studies. Using a purposive sample of 45 studies representing the 3 study designs, interrater reliability was high (Cohen's κ: 0.73; 95% CI: 0.52, 0.93) across all tools and at least moderate for individual tools (range: 0.57-1.00). The use of a worksheet improved usability and consistency of overall interrater agreement across all study designs (40% without worksheet, 80%-100% with worksheet). When compared to published ratings, NUQUEST ratings for evaluated studies demonstrated high concurrent validity (93% perfect or near-perfect agreement). Where there was disagreement, the nutrition-specific component was a contributing factor in discerning exposure methodological issues. CONCLUSIONS: NUQUEST integrates nutrition-specific criteria with generic criteria from assessment tools with demonstrated reliability and validity. NUQUEST represents a consistent and transparent approach for evaluating RoB issues related to dietary exposure assessment commonly encountered in human nutrition studies.

A guide for authors and readers of the American Society for Nutrition Journals on the proper use of P values and strategies that promote transparency and improve research reproducibility.

Two questions regarding the scientific literature have become grist for public discussion: 1) what place should P values have in reporting the results of studies? 2) How should the perceived difficulty in replicating the results reported in published studies be addressed? We consider these questions to be 2 sides of the same coin; failing to address them can lead to an incomplete or incorrect message being sent to the reader. If P values (which are derived from the estimate of the effect size and a measure of the precision of the estimate of the effect) are used improperly, for example reporting only significant findings, or reporting P values without account for multiple comparisons, or failing to indicate the number of tests performed, the scientific record can be biased. Moreover, if there is a lack of transparency in the conduct of a study and reporting of study results, it will not be possible to repeat a study in a manner that allows inferences from the original study to be reproduced or to design and conduct a different experiment whose aim is to confirm the original study's findings. The goal of this article is to discuss how P values can be used in a manner that is consistent with the scientific method, and to increase transparency and reproducibility in the conduct and analysis of nutrition research.