Table 5.

Mean plasma 1,25(OH)2D, 25(OH)D, and 1,25(OH)2D/25(OH)D ratio according to calcium intake

Total calcium (mg/d)
Ptrend
<500500-749750-9991,000-1,4991,500-1,999≥2,000
n902432762305828
Plasma 1,25(OH)2D35.534.533.932.932.631.20.002
Plasma 25(OH)D23.022.523.324.525.123.90.002
Plasma 1,25(OH)2D/25(OH)D1.831.681.621.461.421.46<0.0001
  • NOTE: Mean of plasma vitamin D is based on least square means from the regression model adjusting for age, season of blood drawn, and year of assay (1996 or 1998).

    Calcium intake is from 1994 food frequency questionnaire because blood samples were drawn in 1993-1994.