Vitamin B12 is an essential nutrient that is critical to the proper functioning of many of your body's systems. Vitamin B12 converts carbohydrates into glucose, leading to energy production and a decrease in fatigue in the body. The vitamin is known for its many health benefits - in addition to increasing energy, it helps maintain a healthy nervous system, and helps to reduce stress and depression. Vitamin B12 is important to the circulatory system, and can help improve heart and cardiovascular health. Vitamin B12 is important for healthy cell reproduction and renewal and helps to maintain healthy skin, hair and nails.