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DRI Dietary Reference Intakes Calcium Vitamin D
Canadian Vitamin D Intakes and Serum 25OHD Concentrations
As previously mentioned, the available Canadian survey data provided information on vitamin D intake from foods alone; quantified information on vitamin D supplement intake among Canadians, and thus on total intake from foods and supplements, was not available at the time of the study. Figure 7-6 outlines the estimated intakes of vitamin D from foods alone, which overall tend to be slightly higher than those reported for the United States. Median vitamin D intakes ranged from a low of 176 IU/day (women 51 to 70 years) to a high of 264 IU/day (boys 9 to 13 years). Similar to the U.S. population, persons in the 95th percentile of intake of vitamin D from foods would be expected to be considerably below the UL for their life stage.
Comparison between mean intakes of vitamin D and mean serum 25OHD concentrations for Canadians is problematic. For Canada, intake estimates are provided for the survey year 2004 based on the CCHS, whereas the serum 25OHD concentrations available reflect data from the 2007 to 2009 CHMS. The mean serum 25OHD levels for Canadians are shown in Table 7-5, and no effort has been made to compare these with intake estimates. As a general matter, average serum 25OHD concentrations of Canadians are above both the 40 and 50 nmol/L concentration levels. Although average intakes of vitamin D among Canadians from foods alone (i.e., not taking into account supplements) are less than the EAR, measures of serum 25OHD levels are well above the 40 nmol/L level consistent with the EAR. Again, as described earlier, the ability to interpret the prevalence of inadequacy based on serum 25OHD concentrations using the methodology as established in the 2000 IOM report (IOM, 2000) is unclear.
DIFFERENCES BETWEEN THE UNITED STATES AND CANADA: NATIONAL SURVEY DATA FOR CALCIUM AND VITAMIN D
All total intake estimates are subject to uncertainties owing to a variety of factors that affect estimates of food intake, ranging from the depth and nature of the probing carried out to obtain the information on food consumption to the ability of persons to accurately recall and estimate their food intake. Overall, the nature and approach of the national surveys in the United States and Canada are notably similar, which suggest that the small differences seen in intake estimates for calcium and vitamin D may reflect true differences in intake.
With respect to vitamin D intake from foods alone, to the extent a comparison is appropriate given that they reflect different periods—2004 for Canada and 2005 to 2006 for the United States—Canadian intakes of