A B12 supplement is a dietary supplement that contains vitamin B12. Vitamin B12 is an essential nutrient that the body cannot produce on its own. It is found in animal products such as meat, fish, and dairy products. People who do not eat animal products or who have difficulty absorbing vitamin B12 from food may need to take a B12 supplement.
Vitamin B12 is important for many bodily functions, including the production of red blood cells, the functioning of the nervous system, and the metabolism of food. A deficiency of vitamin B12 can lead to a variety of health problems, including anemia, fatigue, and nerve damage. Taking a B12 supplement can help to prevent or treat these problems.