Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .
Effects of Vitamin D and Calcium on Proliferation and Differentiation In Normal Colon Mucosa: a Randomized Clinical Trial
To investigate the potential efficacy of calcium and vitamin D in reducing risk for colorectal neoplasms and to develop “ treatable ” phenotypic biomarkers of risk for colorectal neoplasms , we conducted a pilot , r and omized , double-blind , placebo-controlled , 2 × 2 factorial clinical trial to test the effects of these agents on cell cycle markers in the normal colorectal mucosa . Ninety-two men and women with at least one pathology-confirmed colorectal adenoma were treated with 2 g/day calcium and /or 800 IU/day vitamin D3 versus placebo over 6 months . Overall expression and distributions of p21waf1/cip1 ( marker of differentiation ) , MIB-1 ( marker of short-term proliferation ) , and hTERT ( marker of long-term proliferation ) in colorectal crypts in the normal-appearing rectal mucosa were detected by automated immunohistochemistry and quantified by image analysis . In the calcium , vitamin D , and calcium plus vitamin D groups relative to the placebo , p21 expression increased by 201 % ( P = 0.03 ) , 242 % ( P = 0.005 ) , and 25 % ( P = 0.47 ) , respectively , along the full lengths of colorectal crypts after 6 months of treatment . There were no statistically significant changes in the expression of either MIB-1 or hTERT in the crypts overall ; however , the proportion of hTERT , but not MIB-1 , expression that extended into the upper 40 % of the crypts was reduced by 15 % ( P = 0.02 ) in the vitamin D plus calcium group relative to the placebo . These results indicate that calcium and vitamin D promote colorectal epithelial cell differentiation and may “ normalize ” the colorectal crypt proliferative zone in sporadic adenoma patients , and support further investigation of calcium and vitamin D as chemopreventive agents against colorectal neoplasms . ( Cancer Epidemiol Biomarkers Prev 2009;18(11):2933–41
Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d .