Abstract
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.