The fact that most MAs on results from RCTs did not show a beneficial effect does not disprove the hypothesis suggested by observational findings on adverse health outcomes of low 25OHD levels
Background A large number of observational studies have reported harmful effects of low 25-hydroxyvitamin D ( 25OHD ) levels on non-skeletal outcomes .
We performed a systematic quantitative review on characteristics of r and omized clinical trials ( RCTs ) included in meta-analyses ( MAs ) on non-skeletal effects of vitamin D supplementation .
Vitamin D and calcium intake in relation to type 2 diabetes in women.
OBJECTIVE The purpose of this study was to prospect ively examine the association between vitamin D and calcium intake and risk of type 2 diabetes .  RESEARCH DESIGN AND METHODS In the Nurses ' Health Study , we followed 83,779 women who had no history of diabetes , cardiovascular disease , or cancer at baseline for the development of type 2 diabetes .  Vitamin D and calcium intake from diet and supplements was assessed every 2 - 4 years . During 20 years of follow-up , we documented 4,843 incident cases of type 2 diabetes . RESULTS After adjusting for multiple potential confounders , there was no association between total vitamin D intake and type 2 diabetes . However , the relative risk ( RR ) of type 2 diabetes was 0.87 ( 95 % CI 0.75 - 1.00 ; P for trend = 0.04 ) comparing the highest with the lowest category of vitamin D intake from supplements . The multivariate RRs of type 2 diabetes were 0.79 ( 0.70 - 0.90 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from all sources and 0.82 ( 0.72 - 0.92 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from supplements . A combined daily intake of > 1,200 mg calcium and > 800 IU vitamin D was associated with a 33 % lower risk of type 2 diabetes with RR of 0.67 ( 0.49 - 0.90 ) compared with an intake of < 600 mg and 400 IU calcium and vitamin D , respectively . CONCLUSIONS The results of this large prospect i ve study suggest a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes
The fact that most MAs on results from RCTs did not show a beneficial effect does not disprove the hypothesis suggested by observational findings on adverse health outcomes of low 25OHD levels
Background A large number of observational studies have reported harmful effects of low 25-hydroxyvitamin D ( 25OHD ) levels on non-skeletal outcomes .
We performed a systematic quantitative review on characteristics of r and omized clinical trials ( RCTs ) included in meta-analyses ( MAs ) on non-skeletal effects of vitamin D supplementation .