Physicians prescribe B12 injections primarily for pernicious anemia and other malabsorption disorders like celiac disease or Crohn's
There's been literature about using extracts of other tissues, notably the pineal gland and the thymus, from, you know, late 1800s till this, this 1970s point, that were, they were, you know, starting our story
The same research group further examined the gene expression of AGAT and GAMT in the liver, kidneys, and skeletal muscle with additional four fish species (maraena whitefish, pikeperch, European perch, and Atlantic herring) and demonstrated that the skeletal muscle possessed the highest abundances of mRNAs for both enzymes among all these tissues
PMID: 32229443
It is about 300400 times as sweet as sucrose but has a bitter or metallic aftertaste, especially at high concentrations