Recent meta-analyses reinforce the finding that 10 - 20 μg per day of vitamin D can reduce all-cause mortality and cancer mortality in middle-aged and older people .
Although vitamin D doses were greater than those assessed in the past , we found no new evidence that supplementation could have an effect on most non-skeletal conditions , including cardiovascular disease , adiposity , glucose metabolism , mood disorders , muscular function , tuberculosis , and colorectal adenomas , or on maternal and perinatal conditions .
The compilation of results from 83 trials showed that vitamin D supplementation had no significant effect on biomarkers of systemic inflammation .
The main new finding highlighted by this systematic review is that vitamin D supplementation might help to prevent common upper respiratory tract infections and asthma exacerbations .
There remains little evidence to suggest that vitamin D supplementation has an effect on most conditions , including chronic inflammation , despite use of increased doses of vitamin D , strengthening the hypothesis that low vitamin D status is a consequence of ill health , rather than its cause .
We further hypothesise that vitamin D supplementation could exert immunomodulatory effects that strengthen resistance to acute infections , which would reduce the risk of death in debilitated individuals .
Effect of Vitamin D3 Supplementation During Pregnancy on Risk of Persistent Wheeze in the Offspring: A Randomized Clinical Trial.
IMPORTANCE Observational studies have suggested that increased dietary vitamin D intake during pregnancy may protect against wheezing in the offspring , but the preventive effect of vitamin D supplementation to pregnant women is unknown . OBJECTIVE To determine whether supplementation of vitamin D3 during the third trimester of pregnancy reduces the risk of persistent wheeze in the offspring . DESIGN , SETTING , AND PARTICIPANTS A double-blind , single-center , r and omized clinical trial conducted within the Copenhagen Prospect i ve Studies on Asthma in Childhood 2010 cohort . Enrollment began March 2009 with a goal of 708 participants , but due to delayed ethical approval , only 623 women were recruited at 24 weeks of pregnancy . Follow-up of the children ( N = 581 ) was completed when the youngest child reached age 3 years in March 2014 . INTERVENTIONS Vitamin D3 ( 2400 IU/d ; n = 315 ) or matching placebo tablets ( n = 308 ) from pregnancy week 24 to 1 week postpartum . All women received 400 IU/d of vitamin D3 as part of usual pregnancy care . MAIN OUTCOMES AND MEASURES Age at onset of persistent wheeze in the first 3 years of life . Secondary outcomes included number of episodes of troublesome lung symptoms , asthma , respiratory tract infections , and neonatal airway immunology . Adverse events were assessed . RESULTS Of the 581 children ,  persistent wheeze  was diagnosed during the first 3 years of life in 47 children ( 16 % ) in the  vitamin D3 group and 57 children ( 20 % ) in the  control group .  Vitamin D3 supplementation was not associated with the risk of persistent wheeze , but the number of episodes of troublesome lung symptoms was reduced , and the airway immune profile was up-regulated ( principal component analysis , P = .04 ) . There was no effect on additional end points . Intrauterine death was observed in 1 fetus ( < 1 % ) in the vitamin D3 group vs 3 fetuses ( 1 % ) in the control group and congenital malformations in 17 neonates ( 5 % ) in the vitamin D3 group vs 23 neonates ( 8 % ) in the control group . [ table : see text ] . CONCLUSIONS AND RELEVANCE The use of 2800 IU/d of vitamin D3 during the third trimester of pregnancy compared with 400 IU/d did not result in a statistically significant reduced risk of persistent wheeze in the offspring through age 3 years . However , interpretation of the study is limited by a wide CI that includes a clinical ly important protective effect . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00856947
Recent meta-analyses reinforce the finding that 10 - 20 μg per day of vitamin D can reduce all-cause mortality and cancer mortality in middle-aged and older people .
Although vitamin D doses were greater than those assessed in the past , we found no new evidence that supplementation could have an effect on most non-skeletal conditions , including cardiovascular disease , adiposity , glucose metabolism , mood disorders , muscular function , tuberculosis , and colorectal adenomas , or on maternal and perinatal conditions .
The compilation of results from 83 trials showed that vitamin D supplementation had no significant effect on biomarkers of systemic inflammation .
The main new finding highlighted by this systematic review is that vitamin D supplementation might help to prevent common upper respiratory tract infections and asthma exacerbations .
There remains little evidence to suggest that vitamin D supplementation has an effect on most conditions , including chronic inflammation , despite use of increased doses of vitamin D , strengthening the hypothesis that low vitamin D status is a consequence of ill health , rather than its cause .
We further hypothesise that vitamin D supplementation could exert immunomodulatory effects that strengthen resistance to acute infections , which would reduce the risk of death in debilitated individuals .