It doesn't get much more basic than the B Vitamins. B1, for instance, is needed to make DNA, the genetic material in all cells. (Quite the resume, that.) B1 is Thiamine and is involved in many body functions, including central nervous system and muscle function. Thiamin is also necessary for the uptake and utilization of oxygen in the blood, the flow of electrolytes in and out of nerve and muscle cells, even digestion and carbohydrate metabolism. B2 is Riboflavin and helps with normal cell growth. Niacin, or Vitamin B3 is often used to maintain healthy cholesterol levels, and the lesser known B6 (Pyridoxine) is required for the synthesis of the neurotransmitters serotonin and norepinephrine. Trust us, you don't want a Pyridoxine deficiency.
More commonly known, Folate, or B9, is often recommended to women of childbearing age to stay mentally sharp (and to prevent neural tube defects in developing babies). And many of us know the cardiovascular benefits of Folic Acid in reducing levels of homocysteine in our blood.