Nature?s Field Vitamin B-12 helps you metabolize carbohydrates, fatty acids, and amino acids to produce energy, healthy red blood cells, and nerve functions. Vitamin B-12 is a water-soluble vitamin. It is an important role in cellular energy production. Vitamin B12 also helps to prevent megaloblastic anemia that can make you tired and weak. You will get Vitamin B12 is naturally in a wide variety of animal foods but some people have trouble absorbing vitamin B12 from food.