As the building blocks of a healthy body, B vitamins directly impact your energy levels, brain function, and cell metabolism. Vitamin B complex may help prevent infections and help support or promote: cell health. Vitamin b, Vitamin B12, along with B6 are best for energy. Almost every cell in the body uses B12. Besides helping form red blood cells, B12 converts fat and protein to energy. A B12 deficiency causes tiredness and anemia.B vitamins play a vital role in maintaining good health and well-being.