Whether or not outcomes such as osteoporosis ( or low bone mass ) and specific types of cancer may be prevented by ' generous ' vitamin D supplementation is unclear and mostly based on indirect epidemiologic data not clearly substantiated by r and omized controlled trials SUMMARY The dose of daily vitamin D supplements needed to prevent rickets is probably much lower than that recommended by most expert committees .
PURPOSE OF REVIEW To underst and the basis for current recommendations for  vitamin D supplementation in childhood and the differences between the recommendations published by major expert committees , using the Medline engine of the US National Library of Medicine and the National Institutes of Health .
Most trials have examined the question of whether a specific daily vitamin D dose is capable or not to prevent rickets ( by study ing surrogate markers of rickets ) .
Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.
BACKGROUND Numerous observational studies have found supplemental calcium and vitamin D to be associated with reduced risk of common cancers . However , interventional studies to test this effect are lacking . OBJECTIVE The purpose of this analysis was to determine the efficacy of calcium alone and calcium plus vitamin D in reducing incident cancer risk  of all types . DESIGN This was a 4-y , population -based , double-blind , r and omized placebo-controlled trial . The primary outcome was fracture incidence , and the principal secondary outcome was cancer incidence . The subjects were 1179 community-dwelling women r and omly selected from the population of healthy postmenopausal women aged > 55 y in a 9-county rural area of Nebraska centered at latitude 41.4 degrees N. Subjects were r and omly assigned to receive 1400 - 1500 mg supplemental calcium/d alone ( Ca-only ) , supplemental calcium plus 1100 IU vitamin D3/d ( Ca + D ) , or placebo . RESULTS When analyzed by intention to treat , cancer incidence was lower in the Ca + D women than in the placebo control subjects ( P < 0.03 ) . With the use of logistic regression , the unadjusted relative risks ( RR ) of incident cancer in the Ca + D and Ca-only groups were 0.402 ( P = 0.01 ) and 0.532 ( P = 0.06 ) , respectively . When analysis was confined to cancers diagnosed after the first 12 mo , RR for the Ca + D group fell to 0.232 ( CI : 0.09 , 0.60 ; P < 0.005 ) but did not change significantly for the Ca-only group . In multiple logistic regression models , both treatment and serum 25-hydroxyvitamin D concentrations were significant , independent predictors of cancer risk . CONCLUSIONS Improving calcium and vitamin D nutritional status substantially reduces  all-cancer risk in postmenopausal women . This trial was registered at clinical trials.gov as NCT00352170
Whether or not outcomes such as osteoporosis ( or low bone mass ) and specific types of cancer may be prevented by ' generous ' vitamin D supplementation is unclear and mostly based on indirect epidemiologic data not clearly substantiated by r and omized controlled trials SUMMARY The dose of daily vitamin D supplements needed to prevent rickets is probably much lower than that recommended by most expert committees .
PURPOSE OF REVIEW To underst and the basis for current recommendations for  vitamin D supplementation in childhood and the differences between the recommendations published by major expert committees , using the Medline engine of the US National Library of Medicine and the National Institutes of Health .
Most trials have examined the question of whether a specific daily vitamin D dose is capable or not to prevent rickets ( by study ing surrogate markers of rickets ) .