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 ) .
The association of calcium and vitamin D with risk of colorectal adenomas.
The Polyp Prevention Trial ( PPT ) was a multicenter r and omized clinical trial design ed to determine the effects of a high-fiber , high-fruit and vegetable , low-fat diet on the recurrence of adenomatous polyps in the large bowel . Detailed dietary intake and supplement use data were collected at baseline and at each of 4 annual study visits . Adenoma recurrence was ascertained by complete colonoscopy at baseline and after 1 and 4 y. Recurrence was found in 754 of the 1905 trial participants . We evaluated the association between calcium and vitamin D intake and adenomatous polyp recurrence after adjusting for intervention group , age , gender , nonsteroidal anti-inflammatory drug use , total energy intake , and the interaction of gender and intervention group . Vitamin D models were also adjusted for the location of the clinic site . Dietary variables were adjusted for total energy intake via the residual method . There were no overall significant associations between adenoma recurrence and dietary calcium intake [ odds ratio ( OR ) for the 5th compared with the lowest quintile = 0.91 ; 95 % CI = 0.67 - 1.23 ; P-trend = 0.68 ] , total calcium intake ( OR = 0.86 ; 95 % CI = 0.62 - 1.18 ; P-trend = 0.20 ) , or  dietary vitamin D intake ( OR = 0.93 ; 95 % CI = 0.69 - 1.25 ; P-trend = 0.43 ) averaged over follow-up . Total vitamin D intake was weakly inversely associated with adenoma recurrence ( OR = 0.84 ; 95 % CI = 0.62 - 1.13 ; P-trend = 0.03 ) . Supplemental calcium and vitamin D use during follow-up also were inversely associated with adenoma recurrence ( OR for any compared with no use = 0.82 ; 95 % CI = 0.68 - 0.99 ; and OR = 0.82 ; 95 % CI = 0.68 - 0.99 ; for calcium and vitamin D , respectively ) . Slightly stronger associations were noted for the prevention of multiple recurrences . Our analyses did not suggest a significant effect modification between total calcium and total vitamin D intake ( P = 0.14 ) on risk for adenoma recurrence . This trial cohort provides some evidence that calcium and vitamin D may be inversely associated with adenoma recurrence
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 ) .