Vitamin B12 has many different roles in our body, such as supporting the healthy function of our nerve cells, brain function and DNA synthesis. It also prevents anemia, supports bone health, prevents health disease, improves mood and energy levels, not mentioning being essential for healthy hair, skin and nails.
The human body unfortunately can't produce this essential vitamin which is found naturally in certain animal-derived foods, for this reason deficiency is very common, especially in people who are vegetarian or vegan. For other people who regularly consume animal-derived foods, the deficiency can occur because some individuals are unable to fully absorb vitamin B12 from the food they eat.
Getting enough vitamin B12 through your diet is extremely important. However, if you can't obtain enough for dietary reasons or have a condition that affects absorption, injections are a simple way to increase your vitamin B12 intake.