Vitamin B12 is crucial for the body as it supports red blood cell formation, prevents anemia, and is vital for neurological function. It aids in DNA synthesis and plays a role in the metabolism of amino acids and fatty acids. Additionally, it helps maintain myelin sheaths around nerve cells, which is essential for proper nerve signal transmission. Since B12 is primarily found in animal products, supplementation may be necessary for vegetarians and vegans to avoid deficiency-related health issues.