Because your body does not readily store excess amounts, toxicity from B12 is very unlikely, even at the higher doses used in injections
At its core, Vitamin B12 helps your body run efficiently
Receptor Selectivity 5-Amino 1MQ demonstrates high selectivity for NNMT, avoiding off-target effects: [3] Does NOT inhibit structurally related SAM-dependent methyltransferases: DNMT1, PRMT3, COMT Does NOT inhibit NAD+ pathway enzymes: NAMPT, SIRT1 This confirms that NAD+ and SAM increases result solely from preventing their degradation by NNMT, not from interfering with their synthesis or utilization enzymes
Good food sources of vitamin B12 include organic meats, beef, poultry, milk, shellfish, fish, eggs, dairy products, wheat germ, soybeans, fortified cereals, orange juice, oranges, and nutritional yeast
Some of these factors are the results of surgeries, genetic factors or chronic conditions which might require higher levels of B12 to ensure that enough is being absorbed by the body
That could be a problem for vegetarians and vegans