Sustained Natural Energy. No artificial colors. No artificial flavors. 1000 MCG. 1st Step Pro Wellness. Vitamin B-12, the energy vitamin, is a natural energy source. It is essential for many functions within the body and vital for maintaining optimum health. Data has shown that low levels of B-12 can cause: Anemia, Loss of balance, Numbness or tingling, Weakness, Lack of energy.