For confirmed deficiency or pernicious anaemia, NICE Clinical Knowledge Summaries recommend hydroxocobalamin 1mg intramuscularly, with frequency determined by the underlying cause and neurological involvement
Li WR et al (2021) Diallyl sulfide from Garlic suppresses quorum-sensing systems of Pseudomonas aeruginosa and enhances biosynthesis of three B vitamins through its thioether group
And fluoride, though controversial in use, has been shown in research to cause hypothyroidism when ingested or used in large amounts
yields aspartate + NH 4 + ) glutamine (enzyme = glutaminase releases the amide nitrogen
Biochemical and biophysical research communications, 1973, 54(2): 562- 566
More specifically, it causes the active forms to convert to cyanocobalamin, causing a functional deficiency