A systematic review analyzed data from 16 trials involving 4,083 children under 12 years of age. The researchers looked at how oral vitamin B12 supplementation, alone or with other nutrients, affected health outcomes compared to placebo or no treatment. The evidence ranged from high to very low certainty across different measures.
The study found that vitamin B12 alone significantly reduced the risk of vitamin B12 deficiency compared to placebo. It also increased total vitamin B12 concentrations in the blood. However, adding B12 to other micronutrients did not show a clear benefit over formulations without it for most measures.
For other important outcomes, the results showed little to no difference. Vitamin B12 did not improve height or length, attention, motor skills, or development. It also did not change the risk of anemia. Safety data were limited, with one trial reporting slightly more adverse events when B12 was combined with other nutrients. The review notes that few studies reported on growth, cognition, or development, and some had risks of bias. Readers should understand that while B12 helps fix a deficiency, it does not seem to boost general growth or brain function in these children.