Objective: We aimed to study vitamin B₁₂ deficiency in apparently healthy infants and their mothers and assess its risk factors.

Methodology: Hospital-based, cross-sectional, observational study conducted from July 2016 to December 2017. Consecutive healthy and normally developing infants were enrolled. Red blood cell folate, plasma vitamin B₁₂, homocysteine and methylmalonic acid levels of mothers and infants were assessed.

Results: Seventy-four healthy infants were enrolled; male-to-female ratio was 1.5:1. Anemia in 66.2% (n=49), low plasma B₁₂ in 17.6% (n=13), hyperhomocysteinemia in 48.6% (n=36), plasma methylmalonic acid in 100% (n=74) and ‘confirmed’ B₁₂ deficiency in 38% (n=28) infants was noted. The proportion of hyperhomocysteinemia increased to 75.7% (n=56) infants using a lower cut-off of >10 µmol/L. In mothers, low B₁₂ in 19%, hyperhomocysteinemia in 57% and elevated plasma methylmalonic acid in 100% were noted. Median plasma B₁₂ level was 314 pg/ml (IQR 221-421), median plasma homocysteine 15.4 µmol/L (IQR 11.3-21.7) and median plasma methylmalonic acid was 8.28 (IQR 4.4-13.1). Folate deficiency was noted in 9.4% infants and 12% of mothers. Overall, 63.5% mothers were vegetarian and 64% of the mothers of infants with confirmed vitamin B12 deficiency were pure vegetarians. Odds of developing vitamin B₁₂ deficiency increased by more than 5 times in those whose mothers' serum vitamin B₁₂ levels were low as compared to normal maternal levels (OR 5.42; 95% CI:1.96-16.6; p 0.002).

Conclusion: There is a high prevalence of vitamin B₁₂ deficiency in infants and their mothers. There is urgent need to supplement our population with vitamin B₁₂.