TABLE 1

Characteristics of Study Sample and Distribution of Serum 25(OH)D (N = 2955)

Sample Size (% of Total Sample)aMean Serum 25(OH)D, ng/mL, (SE)Pb
Overall2955 (100)32.1 (0.69)
Gender<.001
    Female1577 (49.3)29.8 (0.63)
    Male1378 (50.7)34.2 (0.91)
Race/ethnicity<.001
    Non-Hispanic white760 (66.3)36.1 (0.86)
    Non-Hispanic black1040 (15.2)21.0 (0.55)
    Mexican American1005 (8.3)27.2 (0.48)
    Other150 (10.2)26.4 (1.03)
Age.06
    12 y394 (12.4)34.0 (1.08)
    13 y386 (12.4)30.2 (0.10)
    14 y383 (14.3)32.5 (1.15)
    15 y353 (11.3)31.9 (1.11)
    16 y392 (12.9)33.0 (1.42)
    17 y377 (13.1)31.7 (1.28)
    18 y341 (11.6)30.6 (1.11)
    19 y329 (11.9)32.3 (1.15)
Weight<.001
    Normal2069 (74.0)33.0 (0.72)
    At risk for overweight454 (14.8)31.2 (1.30)
    Overweight395 (10.4)27.5 (0.70)
    Missing37 (0.97)
Region<.001
    Northeast327 (18.7)33.5 (1.47)
    Midwest543 (23.3)35.5 (1.60)
    South1347 (36.0)29.3 (0.92)
    West738 (22.1)31.7 (1.67)
Metropolitan area.05
    Urban1391 (48.0)30.6 (0.99)
    Rural1564 (52.0)33.4 (0.97)
Income index<.001
    Low1682 (40.6)28.9 (0.65)
    Medium690 (31.2)34.1 (0.92)
    High297 (22.3)35.3 (1.79)
    Missing286 (7.9)
Education<.001
    ≤8th grade678 (11.6)29.1 (0.92)
    9th–11th grade557 (14.1)28.7 (1.02)
    High school graduate941 (33.9)32.0 (0.89)
    College768 (40.3)34.1 (0.92)
    Missing1 (0.09)
  • a Weighted proportion.

  • b Missing data were excluded for P-value computation in relevant univariate analysis.