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RDA for persons more than 70 years of age would be higher due to this variability. In addition, there is insufficient evidence to provide assurances that 600 IU/day vitamin D is as effective as 800 IU/day. By comparing the projected RDA based on the simulation analysis (600 IU/day) with the available evidence indicating benefit at 800 IU of vitamin D per day, taking into account the uncertainties would result in an estimation of an RDA of approximately one-third higher than the simulation analysis suggests. Overall, this is a small increase that is not known to increase the possibility of adverse events while providing a certain level of caution for this particularly vulnerable and potentially frail segment of the population. This approach is predicated on caution in the face of uncertainties, and it is anticipated that newer data in the future will help to clarify the uncertainties surrounding the level of intake of vitamin D that could be expected to cover 97.5 percent of persons over the age of 70 years.

The EAR of 400 IU/day and RDA of 800 IU/day for this life stage group, consistent with the DRIs for other life stage groups, assume minimal sun exposure.

Adults 51 Through 70 Years of Age

A question in establishing an EAR and RDA for this life stage group is the relevance of vitamin D in affecting bone loss due to the onset of menopause. Men in this life stage group have not yet reached the levels of bone loss and fracture rates associated with aging as manifested in persons more than 70 years of age and, unlike their female counterparts, they are not experiencing significant bone loss due to menopause. However, a portion—in fact perhaps the majority—of women in this life stage group are likely to be experiencing some degree of bone loss due to menopause.

As discussed above for adults more than 70 years of age, the available data do not suggest that median requirements increase with aging, resulting in support for an EAR of 400 IU/day, the same as for younger adults. Likewise, the EAR for both women and men in the 51 through 70 year life stage group is set at 400 IU of vitamin D per day.

With respect to women 51 through 70 years of age, fracture risk is lower than it is later in life; and as such, it is not entirely congruent with the situation for adults more than 70 years of age. Further, findings for this age group are at best mixed, but are generally not supportive of an effect of vitamin D alone on bone health. Although the AHRQ analyses of studies using vitamin D alone found the results to be inconsistent for a relationship with reduction in fracture risk, more recent studies have trended toward no significant effects (Bunout et al., 2006; Burleigh et al., 2007; Lyons et al., 2007; Avenell et al., 2009b). For those studies showing benefit for BMD with a vitamin D and calcium combination, interpretation

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