The effect of infant vitamin B12 supplementation on neurodevelopment: A follow-up of a randomized placebo-controlled trial in Nepal.

The most critical period for brain development is before a child's 2nd birthday. Standardized tests measuring neurodevelopment are more reliable when administered after this period. Severe vitamin B12 deficiency affects brain development and function. In a randomized, double-blind, placebo-controlled trial in 600 Nepalese infants (6-11 months at enrolment), we found no effect of 2 µg vitamin B12 daily or a placebo for a year on neurodevelopment. The primary objective of the current study was to measure the effect the intervention on the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-IV) full scale intelligence quotient (FSIQ) two years after end of supplementation. We also measured the effect on the Bayley Scales of Infant and Toddler Development 3rd edition (at age 30-35 months, n=555). At the final visit (age 42-47 months, n=533), we used the WPPSI-IV and subtests from the NEPSY-II. We used the FSIQ to estimate subgroup specific effects. The mean (SD) WPPSI-IV FSIQ in the vitamin B12 group was 84.4 (8.4) and 85.0 (8.6) in the placebo group (mean difference -0.5 (95% CI-1.97, 0.94), p =0.48). There were no effect of the vitamin B12 on any of the other neurodevelopmental outcomes, and no beneficial effect in any of the subgroups. In conclusion, providing 2 µg of vitamin B12 for a year in infants at risk of vitamin B12 deficiency does not improve preschool cognitive function.