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DRI Dietary Reference Intakes Calcium Vitamin D
basis for the suggested benefit before drawing conclusions. Despite the many claims of benefit surrounding vitamin D in particular, the evidence did not support a basis for a causal relationship between vitamin D and many of the numerous health outcomes purported to be affected by vitamin D intake. Although the current interest in vitamin D as a nutrient with broad and expanded benefits is understandable, it is not supported by the available evidence. The established function of vitamin D remains that of ensuring bone health, for which causal evidence across the life stages exists and has grown since the 1997 DRIs were established (IOM, 1997). The conclusion that there is not sufficient evidence to establish a relationship between vitamin D and health outcomes other than bone health does not mean that future research will not reveal a compelling relationship between vitamin D and another health outcome. The question is open as to whether other relationships may be revealed in the future.
Of great concern recently have been the reports of widespread vitamin D deficiency in the North American population. Based on this committee’s work and as discussed below, the concern is not well founded. In fact, the cut-point values used to define deficiency, or as some have suggested, “insufficiency,” have not been established systematically using data from studies of good quality. Nor have values to be used for such determinations been agreed upon by consensus within the scientific community. When higher cut-point values are used compared with those used in the past, they necessarily result in a larger proportion of the population falling below the cut-point value and thereby defined as deficient. This, in turn, leads to higher estimations of the prevalence of deficiency among the population and possibly to unnecessary intervention incorporating high-dose supplementation in the health care of individuals. National survey data suggest that the serum 25-hydroxyvitamin D (25OHD) levels in the North American population generally exceed the levels identified in this report as sufficient for bone health, underscoring the inability to conclude that there are significant levels of deficiency in the population.
Specifically in terms of the new DRIs and challenges for calcium and vitamin D nutriture, several points can be highlighted, within the context of the limitations of estimates of dietary intake, which tend to be underestimates of actual consumption. First, for calcium, adolescent girls continue to be a group at risk for low intakes from food sources. Older women use calcium supplements in greater proportion, and some may be at risk for excess intake as a result of the use of high-dose supplements. If supplements are needed to ensure adequate calcium intake, it would appear that lower dose supplements should be considered. Many older women have baseline calcium intakes that are close to or just below requirements, and therefore the practice of calcium supplementation at high levels may be unnecessary. This is a special concern for calcium supplement use given