For more details on homocysteine, see the article: Homocysteine and Vitamin B12 The Steps of the Methionine Cycle Step 1: methionine is converted into SAM by the enzyme methioninadenosyltransferase (MAT) in the presence of magnesium (Mg) and ATP (universal energy donor)
Tonums products are oral and part of a broader, research-focused approach to nutrition and wellness
B12 ampoules are only allowed to be sold by registered pharmacies in Germany, so Amazon is, so to speak , a go-between
Providers familiar with specific syringe sizes may be more efficient and comfortable using them
Active cancer is a relative contraindication: because GHK-Cu promotes cell growth, providers avoid it in uncontrolled malignancy (though ironically it also has anti-cancer gene effects)
However, your diet is not the only factor determining vitamin B12 absorption