Vitamin B12 plays a crucial role in energy metabolism by aiding in the conversion of nutrients into usable energy. It is essential for the production of red blood cells and supports DNA synthesis, which is vital for cell division. The vitamin also helps maintain nerve health and can influence overall energy levels. Additionally, B12 contributes to the metabolism of fatty acids and essential amino acids, thus facilitating energy generation during physical activity. A deficiency can lead to fatigue and diminished physical performance.