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

To assess whether overweight children and adolescents are at an increased risk for vitamin B(12) deficiency.

Prospective descriptive study.

Two pediatric endocrine centers in Israel.

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).

We measured vitamin B(12) concentrations. Low serum B(12) was defined as a B(12) concentration less than 246 pg/mL, and vitamin B(12) deficiency was defined as a concentration below 211 pg/mL.

Vitamin B(12) concentrations corrected for body mass index standard deviation scores, age, and sex.

Median concentration of serum B(12) in normal- weight children was 530 pg/mL and in obese children, 400 pg/mL (P<.001). Low B(12) concentrations were noted in 10.4% of the obese children compared with only 2.2% of the normal weight group (P<.001). Vitamin B(12) 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).

Obesity in children and adolescents was associated with an increased risk of low vitamin B(12) concentration. We recommend that dietary assessment of obese children should include an estimation of vitamin B(12) intake. The possibility of vitamin B(12) deficiency in addition to other micronutrient deficiencies should be considered in obese children.