Vitamin B12 levels in children and adolescents on plant-based diets: a systematic review and meta-analysis

Context The popularity of plant-based diets, characterized by a partial or complete exclusion of animal products, has increased significantly over the last 10 years. The exclusion of animal products removes the most common sources of vitamin B-12, which can lead to vitamin B-12 deficiency and result in irreversible damage, such as growth stunting. Objective This aim of this systematic review and meta-analysis was to qualitatively evaluate all studies on this subject and to quantify the potential difference in vitamin B-12 levels in healthy children and adolescents aged 5 to 18 years. Data Sources PubMed and Embase databases were searched for relevant studies investigating vitamin B-12 levels in healthy children and adolescents aged 5 to 18 years on plant-based diets. Data Extraction Studies were assessed qualitatively with the AXIS tool and quantitatively with Stata 16.0 software. Data Analysis Overall, children and adolescents on plant-based diets had a significantly lower vitamin B-12 level than omnivorous children and adolescents (-97 pmol/L; 95%CI, -187 to -7; I-2 = 98.5%), a difference that remained statistically significant after adjusting for methodological confounders. After subgroup analyses, this effect was not statistically significant for children and adolescents on vegetarian diets but remained significant in children and adolescents on vegan or macrobiotic diets. Moreover, total vitamin B-12 intake nullified the mean difference in vitamin B-12 levels. Conclusion Despite high heterogeneity across studies, these results indicate that children and adolescents on plant-based diets, especially those on vegan and macrobiotic diets, may be at risk of developing vitamin B-12 deficiency.