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In addition I see one of the authors's Twitter promoting other discredited research and retracted/removed papers over the past year, such as the now infamous "Dr. Mercola".
https://mobile.twitter.com/bernd_glauner/status/127549493530...
https://www.nytimes.com/2021/07/24/technology/joseph-mercola...
I don't see any reason to think this author is capable of actually conducting a review of this topic, given that they are clearly easily misled by misinformation on the topic (to be charitable).