Vitamin B12 plays a key role in many bodily functions ... For example, a healthy person taking a 500 mcg oral B12 supplement will only absorb about 10 mcg. Although uncommon, it is possible ...

B12 supplements can come in a variety of forms — spray, liquid, capsule — which can make it difficult to know what to buy. That’s why we asked registered dietitians which ones they’d actually ...

On the other hand, 250–500 mcg daily is good for maintenance. Higher doses may be needed for severe vitamin B12 deficiency. 3. Sublingual (under the tongue) or injections are better for those ...

If you don't get enough vitamin B12, you might experience adverse side effects like numbness, tingling, and canker sores. B12 shots contain about 100 micrograms of B12, which is roughly 40 times ...