Vitamin D and calcium: the relationship of dietary intakes and blood levels in obese minority adolescents (628.11)

Vitamin D deficiency, defined as 25OH vitamin D < 50nmol/L, and serum calcium level are associated with obesity. However, limited research has investigated the relationship of the active form of serum vitamin D, 1,25OH2 vitamin D (1,25(OH)2 D), in obese minority youth. This study examined the level of 1,25(OH) D, serum calcium and it’s relationship with dietary vitamin D, calcium intake in a convenience sample of 135 obese African American Adolescents (oAAA) (mean age: 14.0±1.4yrs, 66% girls, mean BMI percentile: 98.4±4.9, mean BMI 37.8±7.4kg/m2). Laboratory blood assays were conducted for 1,25(OH)2 D and calcium. The Block Food Frequency Questionnaire (BFFQ) was used to assess dietary intake. Both 1,25(OH)2 D (46.5±19 pg/ml) and serum calcium (9.3±0.9 mg/dl) levels were within the desirable range for adolescents (30‐100pg/ml and 8.5‐10.8mg/dl respectively). However, self‐reported intake of dietary vitamin D (97.9±75.6 vs 600 IU, p<0.01) and calcium (538±297 vs1300 mg/d, p<0.01) were significantly lower than the dietary reference intakes. No relationship emerged between 1,25(OH)2 D, serum calcium and dietary intake. A negative correlation was found between 1,25(OH)2 D and BMI (p<0.05). The findings suggested oAAA have sufficient 1,25(OH)2 D and serum calcium levels, however an inverse relationship exists between 1,25(OH)2 D and BMI. Another source of vitamin D that may impact serum 1,25(OH)2 D levels is exposure to UV light. Further investigation to understand the relationship of vitamin D and weight is warranted.