Signs and symptoms of vitamin B12 deficiency can include fatigue, pale skin, headaches, shortness of breath, fast heartbeat, gastrointestinal issues, mouth inflammation, paresthesias (abnormal sensations), decreased cognitive ability, depression, muscle weakness, imbalance and incoordination, vision problems, and erectile dysfunction
Stomach acid and a digestive enzyme called pepsin break the bond between vitamin B12 and the food protein
Direct absorption, maximum bioavailability
In fact, injections and infusions may be more beneficial for people deficient in B12 due to a digestive issue or because they are older and have less stomach acid
These may be due to defective DNA synthesis inhibiting replication in a site with a high turnover of cells
However, evidence of elevated-B12-induced harm is steadily increasing