So the practical takeaway is not oral is better or SC is better. It is: pick one route, follow the documented per-dose figure for the vial you have, and keep the route constant so that whatever you observe is not confounded by a mid-stream route change
In other words, toxicity from B12 is extremely rare
Vegetarians, vegans, and older adults may be more prone to its deficiency
One small human study found that 7 out of 12 patients with chronic knee pain reported meaningful relief lasting six months or more after a single injection
It has been studied specifically in Achilles tendon, rotator cuff, patellar tendon, and other tendon injury models
Its primary function is to transfer a methyl group to nicotinamide, a form of vitamin B3