We all need more energy these days between all the demands life throws at us. Many of us are reaching for sources of energy like caffeine and vitamin supplements. While vitamin B12 is often touted as an energy booster, the truth is a little more complicated. B vitamins are crucial players in our bodies turning fats, proteins, and carbohydrates into energy. B vitamin deficiencies, especially B12 deficiency, will result in fatigue and tiredness.