Obese children and adolescents: A risk group for low vitamin B₁₂ concentration

Objective: To assess whether overweight children and adolescents are at an increased risk for vitamin B₁₂ deficiency. Design: Prospective descriptive study. Setting: Two pediatric endocrine centers in Israel. Participants: Three hundred ninety-two children and adolescents were divided into 2 groups as follows: the normal-weight group had body mass indexes, calculated as weight in kilograms divided by height in meters squared, under the 95th percentile (<1.645 standard deviation scores; n=228); the obese group had body mass indexes equal to or above the 95th percentile (≥1.645 standard deviation scores; n=164). Intervention: We measured vitamin B₁₂ concentrations. Low serum B₁₂ was defined as a B₁₂ concentration less than 246 pg/mL, and vitamin B₁₂ deficiency was defined as a concentration below 211 pg/mL. Main Outcome Measure: Vitamin B ₁₂ concentrations corrected for body mass index standard deviation scores, age, and sex. Results: Median concentration of serum B₁₂ in normal-weight children was 530 pg/mL and in obese children, 400 pg/mL (P<.001). Low B₁₂ concentrations were noted in 10.4% of the obese children compared with only 2.2% of the normal weight group (P<.001). Vitamin B₁₂ deficiency was noted in 12 children, 8 (4.9%) of the obese subjects and 4 (1.8%) of the normal weight group (P=.08). After we adjusted for age and sex, obesity was associated with a 4.3-fold risk for low serum B ₁₂, and each unit increase in body mass index standard deviation score resulted in an increased risk of 1.24 (95% confidence interval, 0.99-1.56). Conclusions: Obesity in children and adolescents was associated with an increased risk of low vitamin B₁₂ concentration. We recommend that dietary assessment of obese children should include an estimation of vitamin B₁₂ intake. The possibility of vitamin B₁₂ deficiency in addition to other micronutrient deficiencies should be considered in obese children.