title: Effect of calcium intake on serum levels of 25-hydroxyvitamin D3.
abstract: The effects of high calcium intake on vitamin D metabolism were investigated. To the normal diet of 14 healthy men, 2 g calcium were added daily for 6-7 weeks. The mean serum concentration of 25-hydroxyvitamin D3 increased from 73 +/- 7 to 94 +/- 6 nmol l-1 (P less than 0.05, Student's unpaired t-test; P less than 0.01, paired t-test) in the subjects receiving calcium, whereas there was only a minimal increase, from 67 +/- 5 to 71 +/- 4 nmol l-1 in a control group on a normal diet. At the end of the study the difference between the test group and the controls was highly significant (P less than 0.005). The calcium loading caused a statistically significant depression of the serum levels of 1,25-dihydroxyvitamin D. The results obtained are in agreement with previous studies in rats and indicate that calcium intake is of some importance for the serum level of 25-hydroxyvitamin D3. The findings are discussed in relation to our previous finding that there is a relationship between high 25-hydroxyvitamin D3 levels and hypercalciuria in renal-stone formers.
mesh_terms: D000328:Adult; D000818:Animals; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000652:urine; D002136:Calcium, Dietary / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D051381:Rats
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D002112:Calcifediol; D002118:Calcium