***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Vitamin D deficiency and asthma are common at higher latitudes . Although vitamin D has important immunologic effects , its relation with asthma is unknown . OBJECTIVE We hypothesized that a higher maternal intake of vitamin D during pregnancy is associated with a lower risk of  recurrent wheeze in children at 3 y of age . DESIGN The participants were 1194 mother-child pairs in Project Viva-a prospect i ve prebirth cohort study in Massachusetts . We assessed the maternal intake of vitamin D during pregnancy from a vali date d food-frequency question naire . The primary outcome was recurrent wheeze , ie , a positive asthma predictive index ( > or=2 wheezing attacks among children with a personal diagnosis of eczema or a parental history of asthma ) . RESULTS The mean ( + /-SD ) total vitamin D intake during pregnancy was 548 + /- 167 IU/d . By age 3 y , 186 children ( 16 % ) had recurrent wheeze . Compared with mothers in the lowest quartile of daily intake ( median : 356 IU ) , those in the highest quartile ( 724 IU ) had a lower risk of having a child with recurrent wheeze [ odds ratio ( OR ) : 0.39 ; 95 % CI : 0.25 , 0.62 ; P for trend < 0.001 ] . A 100-IU increase in vitamin D intake was associated with lower risk ( OR : 0.81 ; 95 % CI : 0.74 , 0.89 ) , regardless of whether vitamin D was from the diet ( OR : 0.81 ; 95 % CI : 0.69 , 0.96 ) or supplements ( OR : 0.82 ; 95 % CI : 0.73 , 0.92 ) . Adjustment for 12 potential confounders , including maternal intake of other dietary factors , did not change the results . CONCLUSION In the northeastern United States , a higher maternal intake of vitamin D during pregnancy may decrease the risk of recurrent wheeze in early childhood Background Observational studies suggest high prenatal vitamin D intake may be associated with reduced childhood wheezing .  We examined the effect of prenatal vitamin D on childhood wheezing  in an interventional study . Methods We r and omised 180 pregnant women at 27 weeks gestation to either  no vitamin D , 800 IU ergocalciferol daily until delivery or single oral bolus of 200,000 IU cholecalciferol  , in an ethnically stratified , r and omised controlled trial . Supplementation improved but did not optimise vitamin D status . Research ers blind to allocation assessed offspring at 3 years . Primary outcome was any history of wheeze assessed by vali date d question naire . Secondary outcomes included atopy , respiratory infection , impulse oscillometry and exhaled nitric oxide . Primary analyses used logistic and linear regression . Results We evaluated 158 of 180 ( 88 % ) offspring at age 3 years for the primary outcome . Atopy was assessed by skin test for 95 children ( 53 % ) , serum IgE for 86 ( 48 % ) , exhaled nitric oxide for 62 ( 34 % ) and impulse oscillometry of acceptable quality for 51 ( 28 % ) . We found no difference between supplemented and control groups in risk of wheeze  [ no vitamin D : 14/50 ( 28 % ) ; any vitamin D : 26/108 ( 24 % ) ( risk ratio 0.86 ; 95 % confidence interval 0.49 , 1.50 ; P = 0.69 ) ] . There was no significant difference in atopy , eczema risk , lung function or exhaled nitric oxide between supplemented groups and controls . Conclusion Prenatal vitamin D supplementation in late pregnancy that had a modest effect on cord blood vitamin D level , was not associated with decreased wheezing in offspring at age three years . Trial Registration Controlled-Trials.com IS RCT BACKGROUND The effects of vitamin D supplementation in healthy prepubertal children on physiologic outcomes have not been investigated . OBJECTIVE The objective was to evaluate the effects of supplementation with 1000 IU vitamin D(3)/d on calcium absorption . DESIGN In a double-blind , placebo-controlled trial , we r and omly assigned 64 children to 1000 IU vitamin D(3)/d ( n = 32 ) or placebo ( n = 32 ) for 8 wk . Stable isotopes were used to assess calcium absorption . The main outcome measure was calcium absorption before and after supplementation . RESULTS All of the data are shown as means ± SDs . At baseline , vitamin D intake was 221 ± 79 IU/d and calcium intake was 830 ± 197 mg/d . Baseline serum 25-hydroxyvitamin D [ 25(OH)D ] was not significantly correlated with fractional or total calcium absorption . After 8 wk , with baseline values used as a covariate , no differences were seen in fractional or total calcium absorption based on supplementation group ( P = 0.75 and 0.36 , respectively ) . Supplemented children had a significant increase in 25(OH)D concentrations ( from 27.7 ± 7.4 to 36.0 ± 10.3 ng/mL ; P < 0.0001 ) and a decrease in parathyroid hormone ( from 21.4 ± 10.4 to 12.9 ± 7.1 pg/mL ; P < 0.001 ) ; no significant changes in the placebo group were observed . No adverse side effects were noted in either group . CONCLUSIONS Vitamin D(3 ) supplementation at 1000 IU/d increases 25(OH)D and decreases parathyroid hormone in children with average vitamin D intakes below the dietary recommendations of the Institute of Medicine . However , no significant effects of this change on calcium absorption occurred . This trial was registered at clinical trials.gov as NCT 00868738 INTRODUCTION A high peak bone mass may be essential for reducing the risk of osteoporosis later in life and a sufficient vitamin D level during puberty may be necessary for optimal bone accretion and obtaining a high peak bone mass . Dietary intake and synthesis during winter of vitamin D might be limited but the effect of vitamin D supplementation in adolescence on bone mass is not well established . OBJECTIVE To investigate the effect of supplementation with 5 and 10 microg/day vitamin D(3 ) for 12 months in 11- to 12-year-old girls on  bone mass and bone turnover as well as the possible influence of VDR and ER genotype on the effect of the supplementation . METHODS The girls ( n=221 ) were r and omized to receive either 5 microg or 10 microg vitamin D(3 ) supplementation per day or placebo for 12 months . Whole body and lumbar spine bone mass measured by DXA and pubertal status were determined at baseline and after 12 months whereas physical activity and dietary intake of calcium and vitamin D were assessed at baseline . Serum ( S ) 25-hydroxyvitamin D ( 25OHD ) , S-osteocalcin , S-parathyroid hormone , S-calcium , S-inorganic phosphate , urinary ( U ) pyridinoline ( Pyr ) and deoxpyridinoline ( Dpyr ) were measured at baseline and after 6 and 12 months . RESULTS The S-25OHD concentration increased ( p<0.001 ) relative to the baseline values in the groups receiving either 5 microg/day ( mean+/-SD ; 11.0+/-10.3 nmol/l , baseline 41.9+/-17.6 nmol/l ) or 10 microg/day ( 13.3+/-11.8 nmol/l , baseline 44.4+/-16.6 nmol/l ) vitamin D(3 ) for 12 months compared to placebo ( -3.1+/-9.8 nmol/l , baseline 43.4+/-17.1 nmol/l ) . There was no effect of vitamin D-supplementation on biomarkers for bone turnover or on whole body or spine bone mineral augmentation . However , vitamin D supplementation increased whole body bone mineral density ( BMD ) ( p=0.007 ) and bone mineral content ( BMC ) ( p=0.048 ) in the FF VDR genotype but not in the Ff or ff VDR genotypes . CONCLUSION Supplementation with vitamin D ( 5 or 10 microg/day ) over 12 months increased the S-25OHD concentration but there was no effect on indices of bone health in the entire group of girls . However , there was an effect on BMD for a subgroup with the FF VDR genotype indicating an influence of genotype Background The prevalence of allergic diseases is approximately 10 % in infants whose parents and siblings do not have allergic diseases and 20–30 % in those with an allergic first-degree relative .  Vitamin D is involved in the regulation of the immune system and it may play a role in the development , severity and course of asthma and other allergic diseases . Objective The World Allergy Organization ( WAO ) convened a guideline panel to develop evidence -based recommendations addressing the use of vitamin D in primary prevention of allergic diseases . Methods Our WAO guideline panel identified the most relevant clinical questions and performed a systematic review of r and omized controlled trials and non-r and omized studies ( NRS ) , specifically cohort and case-control studies , of vitamin D supplementation for the prevention of allergic diseases . We also review ed the evidence about values and preferences , and re source requirements ( up to January 2015 , with an up date on January 30 , 2016 ) . We followed the Grading of Recommendations Assessment , Development and Evaluation ( GRADE ) approach to develop recommendations . Results Having review ed the currently available evidence , the WAO guideline panel found no support for the hypothesis that vitamin D supplementation reduces the risk of developing allergic diseases in children . The WAO guideline panel suggest not using vitamin D in pregnant women , breastfeeding mothers , or healthy term infants as a means of preventing the development of allergic diseases . This recommendation does not apply to those mothers and infants who have other indications for prophylactic or therapeutic use of vitamin D. The panel ’s recommendations are conditional and supported by very low certainty evidence . Conclusions WAO recommendations about vitamin D supplementation for the prevention of allergic diseases support parents , clinicians and other health care professionals in their decisions whether or not to use vitamin D in preventing allergic diseases in healthy , term infants To determine if human milk provides for adequate growth and bone mineralization during the lst yr of life , 91 term infants were evaluated . Infants were divided into three groups human milk alone , human milk with supplemental vitamin D , and Similac .  Lactating mothers who were receiving supplements of calcium and vitamin D  were also studied to determine the effects of lactation on their bone mineral status . Blood was drawn from infants and mothers for measurements of serum calcium , phosphate , alkaline phosphatase , and 25-hydroxyvitamin D. Bone mineral content was measured by photon absorptiometry . Growth was similar between breast-fed and formula-fed infants . Regardless of type of feeding , male infants grew heavier and longer than corresponding female infants . Serum calcium and phosphate levels were similar among the three infant groups : only 25-hydroxyvitamin D levels at 4 months and serum alkaline phosphatase at 2 wk and 6 months of age were different among the three infant groups . Biochemical and vitamin D values were similar among the lactating mothers . There were no differences in infant bone mineral content among the three groups , but male infants had higher bone mineral content than female infants . There were no effects of the duration of lactation of maternal bone mineral content or vitamin D status BACKGROUND To our knowledge , no rigorously design ed clinical trials have evaluated the relation between vitamin D and physician-diagnosed seasonal influenza . OBJECTIVE We investigated the effect of vitamin D supplements on the incidence of  seasonal influenza A in schoolchildren . DESIGN From December 2008 through March 2009 , we conducted a r and omized , double-blind , placebo-controlled trial comparing vitamin D(3 ) supplements ( 1200 IU/d ) with placebo  in schoolchildren . The primary outcome was the incidence of influenza A , diagnosed with influenza antigen testing with a nasopharyngeal swab specimen . RESULTS Influenza A occurred in 18 of 167 ( 10.8 % ) children in the vitamin D(3 ) group compared with 31 of 167 ( 18.6 % ) children in the  placebo  group [ relative risk ( RR ) , 0.58 ; 95 % CI : 0.34 , 0.99 ; P = 0.04 ] . The reduction in influenza A was more prominent in children who had not been taking other vitamin D supplements ( RR : 0.36 ; 95 % CI : 0.17 , 0.79 ; P = 0.006 ) 
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CONCLUSION Limited information is available addressing primary prevention of allergic diseases after vitamin D supplementation , and its potential impact remains uncertain