is confounded by the effects of calcium especially since calcium alone appears to have at least a modest effect on BMD. The report from the WHI (Jackson et al., 2006), a very large cohort study, has limited applicability to the question of the effect of vitamin D on bone health among women because of relatively high levels of calcium intake (baseline mean calcium intake of approximately 1,150 mg/day at randomization plus 1,000 mg/day supplement) and the confounding due to hormone replacement therapy. Given these data plus the inability to extrapolate the variability seen in the requirements surrounding persons 70 or more years of age to this life stage group, the RDA for women 51 through 70 years of age is set at 600 IU of vitamin D per day, the same level as that for younger adults. With respect to men 51 through 70 years of age, there is also no basis to deviate from the RDA set for younger adults. The available evidence for men is extremely limited, and there are not data to suggest that bone health is enhanced by vitamin D intake among men in this life stage group. An RDA of 600 IU/day is established for these men.
The DRIs for these two life stage groups assume minimal sun exposure.
Pregnancy The EAR for non-pregnant women and adolescents is appropriate for pregnant women and adolescents based on: (1) AHRQ-Ottawa’s finding of insufficient evidence on the association of serum 25OHD level with maternal BMD during pregnancy and (2) the 1 available RCT (Delvin et al., 1986) and 14 observational studies reviewed in Chapter 4 regarding vitamin D deficiency and genetic absence of the vitamin D receptor (VDR) or 1α-hydroxyalase, which all demonstrate no effect of maternal 25OHD level on fetal calcium homeostasis or skeletal outcomes. Of the limited number (i.e., four) of observational studies that suggest an influence of maternal serum 25OHD levels on the offspring’s skeletal outcomes later in life (so-called developmental programming), one study reports associa-