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when effective sun exposure for endogenous vitamin D synthesis is minimal. Mean or median responses of serum 25OHD level to total intake in the winter seasons at northern latitudes (> 49.5°N) and in Antarctica (78°S) (summarized in Table 5-4) were analyzed using a mixed effect model by regression following log transformation with study in a random effects model to control for the large study residual variability for: (1) children and adolescents (boys and girls) ages 6 to 14 years in Finland (Ala-Houhala et al., 1988); (2) young and middle-aged adults ages 19 to 59 years from men in Antarctica (Smith et al., 2009), Ireland (Cashman et al., 2008, 2009), and Finland (Viljakainen et al., 2006, 2009), and Denmark (Schou et al., 2003); and (3) older adult women and men > 60 years of age in Ireland (Cashman et al., 2009), the Netherlands (Van Der Klis et al., 1996), Finland (Viljakainen et al., 2006), and Denmark (Larsen et al., 2004). The relationship of serum 25OHD level to total intake of vitamin D is:

• For children and adolescents: achieved serum 25OHD = 8.6 ln(total vitamin D intake), which explains 68.8 percent of the within-subject variability and 98.3 percent of the between-study variability. Predicted CIs were y = 6.0 ln (total vitamin D intake) for lower limit, and y = 11.3 ln (total vitamin D intake) for upper limit.

• For young and middle-aged adults: achieved serum 25OHD = 10.1 ln (total vitamin D intake), which explained 70.3 percent of the within-study variability and 98.4 percent of the between-study variability. Predicted CIs were y = 6.3 ln (total vitamin D intake) for lower limit, and y = 13.8 ln (total vitamin D intake) for upper limit.

• For older adults > 71 years: achieved 25OHD = 10.9 ln (total vitamin D intake), which explains 77.5 percent of the within-study variability and 92.2 percent of the between-study variability. Predicted CIs were y = 7.7 ln (total vitamin D intake) for lower limit and y = 14.2 ln (total vitamin D intake) for upper limit.

• The interaction term between age and the log of total vitamin D intake (p = 0.142), as well as the main effect of age (p = 0.162) were not significant.

NOTE: log(total vitamin D) has been back-transformed to total vitamin D for presentation in this figure.

Specification of Vitamin D Dietary Reference Intakes for Adequacy

The DRIs for adequacy for vitamin D have been introduced previously in Table 5-3. The rationale for each is presented in the discussions below.

Infants 0 to 12 Months of Age

Infants 0 to 6 Months of Age

Infants 6 to 12 Months of Age

 

 

AI 400 IU (10 μg)/day Vitamin D



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