Key Takeaways Vitamin B12 is important for making red blood cells and keeping the nervous system healthy
The simple answer: capsules are often chosen for gut-focused support, while injections are often chosen for deeper recovery support
This limitation of standard lab testing approaches stems from how reference ranges are calculated
Example B: 5,000 mcg vial + 5 mL bacteriostatic water: Yields 1,000 mcg per mL
However, deficiency is common, especially in people with low stomach acid, digestive conditions, vegan or vegetarian diets, or age-related absorption decline
Large doses of B12 can trigger acne-like symptoms in a small percentage of people