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Pages 1-14

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From page 1...
... and Canadian governments to conduct a review of data pertaining to calcium and vitamin D requirements and to identify Dietary Reference Intakes (DRIs) based on current scientific evidence about the roles of calcium and vitamin D in human health.
From page 2...
... To carry out the request, the IOM established an ad hoc consensus committee of 14 scientists. The committee met eight times, held a public workshop and open sessions to gather information and receive input on the nature of the available data, maintained a website that accepted comments and data from stakeholders, conducted a review of existing data, and developed a report that included the specification of DRI values.
From page 3...
... To ensure comprehensiveness, the committee included relationships that appeared marginal by standard scientific principles as well as those suggested to be of interest by stakeholders. Box S-2 lists these potential indicators in alphabetical order.
From page 4...
... Preeclampsia of pregnancy and other non-skeletal reproductive outcomes Skeletal health (commonly bone health) • Serum 25-hydroxyvitamin D, as intermediate • Parathyroid hormone, as intermediate • Calcium absorption • Calcium balance • Bone mineral content/bone mineral density • Fracture risk • Rickets/osteomalacia *
From page 5...
... These include the difficulty of isolating the effects of a single nutrient under investigation from the confounding effects of other nutrients and non-nutrient factors; the multi-factorial etiology of the chronic diseases the committee considered; the paucity of data from randomized controlled clinical trials, which typically provide the highest level of scientific evidence relevant for DRI development; and the mixed and inconclusive results from observational studies. For indicators associated with excess intakes of calcium and vitamin D, a process similar to that for reference values for adequacy was undertaken and potential indicators of excess intake were identified (see Box S-3)
From page 6...
... The best approach was to estimate vitamin D requirements under conditions of minimal sun exposure. Second, vitamin D when activated functions as a hormone and is regulated by metabolic feedback loops.
From page 7...
... Life Stage Group AI EAR RDA UL Infants 0 to 6 mo 200 mg -- -- 1,000 mg 6 to 12 mo 260 mg -- -- 1,500 mg Children 1–3 y -- 500 mg 700 mg 2,500 mg 4–8 y -- 800 mg 1,000 mg 2,500 mg Males 9–13 y -- 1,100 mg 1,300 mg 3,000 mg 14–18 y -- 1,100 mg 1,300 mg 3,000 mg 19–30 y -- 800 mg 1,000 mg 2,500 mg 31–50 y -- 800 mg 1,000 mg 2,500 mg 51–70 y -- 800 mg 1,000 mg 2,000 mg > 70 y -- 1,000 mg 1,200 mg 2,000 mg Females 9–13 y -- 1,100 mg 1,300 mg 3,000 mg 14–18 y -- 1,100 mg 1,300 mg 3,000 mg 19–30 y -- 800 mg 1,000 mg 2,500 mg 31–50 y -- 800 mg 1,000 mg 2,500 mg 51–70 y -- 1,000 mg 1,200 mg 2,000 mg > 70 y -- 1,000 mg 1,200 mg 2,000 mg Pregnancy 14–18 y -- 1,100 mg 1,300 mg 3,000 mg 19–30 y -- 800 mg 1,000 mg 2,500 mg 31–50 y -- 800 mg 1,000 mg 2,500 mg Lactation 14–18 y -- 1,100 mg 1,300 mg 3,000 mg 19–30 y -- 800 mg 1,000 mg 2,500 mg 31–50 y -- 800 mg 1,000 mg 2,500 mg NOTE: AI = Adequate Intake; EAR = Estimated Average Requirement; RDA = Recommended Dietary Allowance; UL = Tolerable Upper Intake Level.
From page 8...
... Available data were used to link specified serum levels of 25OHD with total intakes of vitamin D under conditions of minimal sun exposure in order to estimate DRIs. For children and adolescents 1 to 18 years of age, EARs and RDAs are specified on the basis of serum 25OHD concentrations of 40 and 50 nmol/L (16 and 20 ng/mL)
From page 9...
... 4,000 IU (100 µg) NOTE: AI = Adequate Intake; EAR = Estimated Average Requirement; IU = International Units; RDA = Recommended Dietary Allowance; UL = Tolerable Upper Intake Level.
From page 10...
... DIETARY INTAKE ASSESSMENT Calcium remains a nutrient of concern given that median calcium intakes from foods in both the United States and Canada are close to the EAR values for most groups. In particular, girls 9 to 18 years of age are falling below desirable intakes when only food sources of calcium are considered, as are women over the age of 50 years.
From page 11...
... Uncertainties On balance, the uncertainties surrounding the DRI values for calcium are less than those for vitamin D because the evidence base is considerably larger for calcium, and the physiology and metabolism of calcium are better understood. The following key issues were identified as introducing uncertainty into DRI values for calcium and vitamin D, as based on bone health outcomes: • The tendency for study protocols to administer a combination of calcium and vitamin D, reducing the opportunity to ascertain ef fects of each nutrient independently; • The lack of data examining the responses and health outcomes BOX S-4 Population Segments and Conditions of Interest Adiposity Persons living at upper latitudes in North America Persons who experience reduced vitamin D synthesis from sun exposure • Dark skin (including immigrant groups and exclusively breast-fed infants)
From page 12...
... This, coupled with the apparent contribution of sun exposure to overall vitamin D nutriture in North American populations, leads to an inability to characterize and integrate sun exposure with dietary intake recommendations as much as may be appropriate, given the concern for skin cancer risk reduction. Thus, for individuals who experience sun exposure, the uncertainty of the DRI is greater than for those who do not; • The lack of clarity concerning the validity of the serum 25OHD measure as a biomarker of effect; • The variability surrounding measures of serum 25OHD concentra tions owing to different methodologies used; • The evidence of the non-linear nature of the relationship between serum 25OHD concentrations and total intake of vitamin D, sug gesting that lower levels of intake have more impact on serum 25OHD concentrations than previously believed and that higher intakes may have less impact; • The limited number of long-term clinical trials related to calcium and vitamin D intake and health outcomes; and • The need to set ULs based on limited data in order to ensure public health protection.
From page 13...
... Moreover, the possibility of risk for subpopulations of concern due to reduced synthesis of vitamin D, such as persons with dark skin or older persons in institutions, is minimized given the assumption of minimal sun exposure as a basis for the DRIs. CONCLUSIONS ABOUT VITAMIN D DEFICIENCY IN THE UNITED STATES AND CANADA Serum levels of 25OHD have been used as a measure of adequacy for vitamin D, as they reflect intake from the diet coupled with the amount contributed by cutaneous synthesis.
From page 14...
... Closing Remarks At this time, the scientific data available indicate a key role for calcium and vitamin D in skeletal health and provide a sound basis for DRIs. The data do not, however, provide compelling evidence that either nutrient is causally related to extra-skeletal health outcomes or that intakes greater than those established in the DRI process have benefits for health.


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