Vitamin D lacks efficacy: A re‐analysis of a systematic review using the REB method

BACKGROUND: The results of randomized controlled trials (RCTs) evaluating the effect of vitamin D on the prevention of acute respiratory tract infections (RTIs) are conflicting. The aim of this study was to assess the level of evidence for the efficacy of vitamin D in preventing acute RTIs by performing a sensitivity analysis of the meta-analysis carried out by Jolliffe and al., using the Rebuild the Evidence Base (REB) method. METHODS: The main inclusion criteria were double-blind, placebo-controlled, open-label RCTs. The exclusion criteria were RCTs in which vitamin D was associated with other nutrients and unpublished RCTs. The primary outcome was the number of people who had at least one RTI, including upper and lower RTIs. A bias analysis was performed of the included RCTs, followed by a hypothetico-deductive analysis to determine whether they were confirmatory or exploratory. Then, we used the REB method to determine the level of evidence for the effectiveness of vitamin D in preventing RTIs. RESULTS: The main meta-analysis included 25 RCTs with a low risk of bias, involving 41 847 people. There was no significant difference between groups in the number of patients who had at least one RTI. According to the REB, there was a lack of evidence when assessing the effectiveness of vitamin D in preventing RTI. CONCLUSION: According to the REB, the analysis of the RCTs, considering the risk of bias, showed that there is a lack of evidence to justify the prescription of vitamin D for the preventing of RTIs.