Vitamin D intake and serum vitamin D in ethnically diverse urban schoolchildren

Abstract

Objective Low serum vitamin D, which largely affects ethnic minorities, is associated with obesity and other chronic diseases. Little is known about racial/ethnic differences in intake, particularly in children, or if any differences are associated with differences in serum 25-hydroxyvitamin D (25(OH)D). The objective of the present study was to determine whether racial/ethnic differences in dietary vitamin D intake exist and whether they explain differences in 25(OH)D. Design Vitamin D intakes (Block Kids 2004 FFQ) and 25(OH)D were measured. Race/ethnicity was parent-reported (white (37·9 %), Hispanic (32·4 %), black (8·3 %), Asian (10·3 %), multi-racial/other (11·0 %)). Multivariable analyses were conducted to examine the associations among dietary vitamin D and race/ethnicity, as well as 25(OH)D, independent of BMI Z-score and other covariates. Setting Elementary/middle schools in Somerville, MA, USA, during January-April 2010. Subjects Schoolchildren (n 145) in 4th-8th grade. Results Only 2·1 % met the 2011 RDA (15 μg/d (600 IU/d)). Average dietary intake was 3.5 (sd 2.2) μg/d (140 (sd 89·0) IU/d). No racial/ethnic differences in intake were evident. Most (83·4 %) were 25(OH)D deficient (<20 ng/ml; 16·0 (sd 6·5) ng/ml). In ANOVA post hoc analyses, 25(OH)D levels were lower in Hispanics than whites (14·6 (sd 6·1) ng/ml v. 17·9 (sd 4·6) ng/ml; P < 0·01). Dietary vitamin D was associated with 25(OH)D overall (P < 0·05), but did not explain the racial/ethnic differences in 25(OH)D. Conclusions Most children in this north-east US sample did not meet dietary recommendations for vitamin D and were vitamin D deficient. Dietary vitamin D did not explain the difference in 25(OH)D between Hispanic and white children. Further research is needed to determine if changes in dietary vitamin D by race/ethnicity can impact 25(OH)D levels. © The Authors 2012.