Study design and eligibility criteria.
illness or disease
RECRUITMENT
This study was nested within a larger randomized controlled trial of oral iron supplementation that included 480 non-pregnant Cambodian WRA from the rural Kampong Thom province. The primary trial aimed to assess the non-inferiority of 18 mg iron as ferrous bisglycinate compared with 60 mg iron as ferrous sulfate on mean ferritin concentrations and other biomarkers following 12 weeks daily supplementation.Study inclusion criteria involved healthy, non-pregnant women 18 to 45 years old who consented to participate in the study by providing blood and stool samples and resided in the study location for the entire study period. The women lived in villages within the following health center catchment areas: Prey Kuy, Tboung Krapeu, and Srayov. Participants were excluded if they had any known illness or disease, were pregnant, or were taking antibiotics, non-steroidal anti-inflammatory drugs, dietary supplements, or vitamin and mineral supplements in the previous 12 weeks. Women were recruited by convenience sampling (rolling recruitment began in December 2019), and if eligible, they were enrolled once they provided written consent. Women were randomized at the health center level with a 1:1:1 allocation ratio to either ferrous sulfate, ferrous bisglycinate, or placebo (