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 ) .
Prospective study of vitamin D supplementation and rickets in China.
To determine whether amounts of vitamin D lower than recommended doses are effective in preventing rickets , 256 term infants from two northern and two southern cities in China were studied in a r and omized trial of vitamin D supplementation ( 100 , 200 , or 400 IU/day ) during the first 6 months of life . Cord blood and 6-month blood sample s were collected and radiographs were obtained at 3 to 5 days and at 6 months of age . Cord serum 25-hydroxyvitamin D concentrations were lower in the north than in the south ( 5 vs 14 ng/ml ( 12.5 vs 35.0 nmol/L ) ; p less than 0.01 ) . Wrist ossification centers were less likely to be present at birth in the northern children than in the southern children ( p = 0.009 ) and were more likely to be present in infants born in the fall who had higher cord serum concentrations of 25-hydroxyvitamin D ( p = 0.04 ) . Serum 25-hydroxyvitamin D concentrations were lower in northern children 6 months of age than in southern children ( p = 0.005 ) and were higher with an increasing supplemental dosage of vitamin D ( p less than 0.001 ) , particularly in infants in the north . None of the infants had rickets at 6 months of age . Because of the low serum 25-hydroxyvitamin D concentrations , especially among infants in the north , it may be prudent to supplement the diet with vitamin D at a dose of 400 IU/day
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 ) .