Dietary calcium does not interact with vitamin D-3 in terms of determining the response and catabolism of serum 25-hydroxyvitamin D during winter in older adults

作者：Cashman Kevin D^*; Hayes Aoife; O' Donovan Sinead M; Zhang Joy Y; Kinsella Michael; Galvin Karen; Kiely Mairead; Seamans Kelly M

来源：American Journal of Clinical Nutrition, 2014, 99(6): 1414-1423.

DOI：10.3945/ajcn.113.080358

Background: Interactions between calcium and vitamin D may have implications for the regulation of serum 25-hydroxyvitamin D [25(OH)D] and its catabolism and, consequently, the vitamin D dietary requirement. %26lt;br%26gt;Objective: We investigated whether different calcium intakes influenced serum 25(OH)D and indexes of vitamin D activation and catabolism during winter and in the context of both adequate and inadequate vitamin D intakes. %26lt;br%26gt;Design: A 15-wk winter-based, randomized, placebo-controlled, double-blind vitamin D-3 intervention (20,mu,g/d) study was carried out in free-living men and women aged %26gt;= 50 y (n = 125) who were stratified according to calcium intakes [moderate-low (%26lt;700 mg/d) or high (%26gt;1000 mg/d) intake]. The serum 25(OH)D concentration was the primary outcome, and serum calcium, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D [1,25(OH)(2)D], 24,25-dihydroxyvitamin D [24,25(OH)(2)D], the ratio of 24,25(OH)(2)D to 25(OH)D, vitamin D binding protein, and free 25(OH)D were exploratory outcomes. %26lt;br%26gt;Results: A repeated-measures ANOVA showed there was no significant (P = 0.2) time x vitamin D treatment x calcium intake grouping interaction effect on the mean serum 25(OH)D concentration over the 15-wk intervention period. Serum 25(OH)D concentrations increased (P %26lt;= 0.005) and decreased (P %26lt;= 0.002) in vitamin D3 and placebo groups, respectively, and were of similar magnitudes in subjects with calcium intakes %26lt;700 mg/d (and even %26lt;550 mg/d) compared with %26gt;1000 mg/d. The response of serum PTH, 1,25(OH)(2)D, 24,25(OH)(2)D, the ratio of 24,25(OH)(2)D to 25(OH)D, and free 25(OH)D significantly differed in vitamin D3 and placebo groups but not by calcium intake grouping. %26lt;br%26gt;Conclusions: We found no evidence of a vitamin D sparing effect of high calcium intake, which has been referred to by some authors as %26quot;vitamin D economy.%26quot; Thus, recent dietary vitamin D requirement estimates will cover the vitamin D needs of even those individuals who have inadequate calcium intakes. This trial was registered at clinicaltrials.gov as NCT01990872.

• 出版日期2014-6