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 .
Human Interventions to Characterize Novel Relationships Between the Renin–Angiotensin–Aldosterone System and Parathyroid Hormone
Observational studies in primary hyperaldosteronism suggest a positive relationship between aldosterone and parathyroid hormone ( PTH ) ; however , interventions to better characterize the physiological relationship between the renin – angiotensin – aldosterone system ( RAAS ) and PTH are needed . We evaluated the effect of individual RAAS components on PTH using 4 interventions in humans without primary hyperaldosteronism .  PTH was measured before and after study ( 1 ) low-dose angiotensin II ( Ang II ) infusion ( 1 ng/kg per minute ) and captopril administration ( 25 mg × 1 ) ; study ( 2 ) high-dose Ang II infusion ( 3 ng/kg per minute ) ; study ( 3 ) blinded crossover r and omization to aldosterone infusion ( 0.7 µg/kg per hour ) and vehicle ; and study ( 4 ) blinded r and omization to spironolactone ( 50 mg/daily ) or placebo for 6 weeks . Infusion of Ang II at 1 ng/kg per minute acutely increased aldosterone ( + 148 % ) and PTH ( + 10.3 % ) , whereas Ang II at 3 ng/kg per minute induced larger incremental changes in aldosterone ( + 241 % ) and PTH ( + 36 % ; P<0.01 ) . Captopril  acutely decreased aldosterone ( −12 % ) and PTH ( −9.7 % ; P<0.01 ) . In contrast , aldosterone infusion robustly raised serum aldosterone ( + 892 % ) without modifying PTH . However , spironolactone therapy during 6 weeks modestly lowered PTH when compared with placebo ( P<0.05 ) . In vitro studies revealed the presence of Ang II type I and mineralocorticoid receptor mRNA and protein expression in normal and adenomatous human parathyroid tissues . We observed novel pleiotropic relationships between RAAS components and the regulation of PTH in individuals without primary hyperaldosteronism : the acute modulation of PTH by the RAAS seems to be mediated by Ang II , whereas the long-term influence of the RAAS on PTH may involve aldosterone . Future studies to evaluate the impact of RAAS inhibitors in treating PTH-mediated disorders are warranted
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 .