Assessments

Height was measured by Seca 213, to the nearest 0·1 cm twice in each child by a trained team of fieldworkers. Inter- and intra-observer standardisation exercises for anthropometric assessments were conducted before study initiation in the outcome ascertainment team, and these were repeated every 3 months throughout the study duration.

We obtained 3 ml of blood samples from all children at enrolment in a tube containing EDTA (Becton Dickinson). The plasma was centrifuged at approximately 1000 × g at room temperature for 10 min, separated, and transferred into storage vials and stored at −20°C until analysed. Microbiological assays estimated plasma concentration of vitamin B₁₂ and folate^(13,14). Total plasma homocysteine (tHcy), a sensitive and functional marker for both vitamin B₁₂ and folate deficiency, was analysed using commercial kits (Abbott Laboratories, Abbott Park)⁽¹⁵⁾.