Some have been placed on the FDAs bulk drug substances list due to concerns about potency, cardiovascular risk, or potential risk of triggering an immune reaction
Another study 16 examined the use of sublingual vitamin B12 on subjects who ate a raw-food, vegan diet, many of whom had urinary markers of low vitamin B12 levels
Reported effects are generally mild injection-site reactions, fatigue, nausea, lightheadedness
Common symptoms include: Dry, itchy skin Hair thinning or excessive hair shedding Fatigue and weakness Numbness or tingling in hands and feet Difficulty concentrating or brain fog If left unaddressed, a deficiency can lead to more serious issues, such as anemia or neurological complications
Research remains ongoing
This may be the improvement or aggravation that tested agents can exhibit of healing