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 ) .
Interaction of estrogen therapy with calcium and vitamin D supplementation on colorectal cancer risk: reanalysis of Women's Health Initiative randomized trial.
Although calcium and vitamin-D intake were consistently shown to be inversely associated with  colorectal cancer risk  in several large prospect i ve studies and protective against adenoma and cancer in multiple r and omized trials , the Women 's Health Initiative ( WHI ) of calcium and low-dose vitamin-D supplementation trial found no overall effects on colorectal cancer . However , the previous report did not recognize an important biologic interaction with estrogen therapy . We investigated the treatment interaction of estrogen with calcium and vitamin-D on risk of colorectal cancer via a re analysis of primary data results from the WHI calcium and vitamin-D supplementation trial ( 1,000 mg elemental calcium , 400 IU of vitamin-D3 , or placebo ) , reanalyzing results from women concurrently r and omized to estrogen interventions  and placebo . Results indicate that concurrent estrogen therapy was a strong effect modifier of calcium and vitamin-D supplementation on colorectal cancer risk . While calcium plus vitamin-D supplementation among women concurrently assigned to estrogen therapies suggested increased risk ( Hazard Ratio = 1.50 , 95 % CI : 0.96 - 2.33 ) , among women concurrently assigned to placebos arms of the estrogen trials , calcium plus vitamin-D indicated suggestive benefits ( HR = 0.71 , 95 % CI : 0.46 - 1.09 ) ( p-for-estrogen-interaction = 0.018 ) . Consistent interaction was also found by reported estrogen use ( p interaction = 0.037 ) . Results indicate contrasting effects of calcium and vitamin-D by concurrent estrogen therapy on colorectal cancer risk . Although further clinical and mechanistic studies are warranted , the potential clinical implication s of the apparent interaction of estrogen therapy with calcium and vitamin-D supplementation should be recognized . Important biological mechanisms related to the key membrane receptor megalin and estrogen-dependent protein calbindin are discussed
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 ) .