To help with research here are a number of useful search engines, please add to comments any you think should be included - I will add them to this list:

Alternative & Natural medicine:

https://www.similarweb.com/top-websites/category/health/alternative-and-natural-medicine/

Top List of Academic Search Engines:

https://paperpile.com/g/academic-search-engines/

Open Access Search Engines:

https://libguides.nyit.edu/c.php?g=61914&p=398484

Internet Archive to search for deleted articles:

https://archive.org/

Ayurvedic Search Engine:

https://sites.google.com/site/searchayurveda/

Research Gate on Traditional Chinese Medicine (TCM):

https://www.researchgate.net/publication/261923437_BioTCM-SE_A_Semantic_Search_Engine_for_the_Information_Retrieval_of_Modern_Biology_and_Traditional_Chinese_Medicine

Orthomolecular Medicine Quality database on supplements and medicines.

http://orthomolecular.org/