When adverse effects occurred, they were typically mild and transient, with the most common being mild to moderate headaches (similar frequency to placebo groups), minor injection site reactions (redness, slight swelling), and gastrointestinal effects at higher oral doses (nausea, diarrhea)
B12 is a necessary component of the Krebs Cycle, the series of chemical reactions that generate ATP
If you have certain digestive disorders, including pernicious anemia, or have had gastric bypass surgery, oral B12 will simply not work because you can't absorb it correctly
Long-Term Protocols: The most clinically relevant studies evaluated subcutaneous doses of 0.25 mg (250 mcg), 0.5 mg (500 mcg), and 1 mg (1,000 mcg) administered daily for 24 weeks