Please note that this is a bit older (2017). As I personally have a cold quite often I was curious to look into this a bit. Around the same time another metaan

Please note that this is a bit older (2017). As I personally have a cold quite often I was curious to look into this a bit. Around the same time another metaanalysis was published with a similar question [1], but quite different results (i.e. Vitamin D is unlikely to help). Here's [2] an (unfortunately only german) article by an austrian webpage associated with the cochrane collaboration (i.e. that should be considered a relatively trustworthy source) that explains this difference due to the fact that the BMJ metaanalysis included many low quality studies that were excluded in the other metaanalysis. This is an indication that this is might be not a real effect, but an artifact of the low quality evidence this analysis is based on. tl;dr I won't buy Vitamin D supplements. [1] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0162996 https://journals.plos.org/plosone/article?id=10.1371/journal... [2] https://www.medizin-transparent.at/vitamin-d-und-das-immunsystem-was-stimmt/#ref1 https://www.medizin-transparent.at/vitamin-d-und-das-immunsy...