most important vitamin supplements
B Vitamins. The eight B vitamins help maintain metabolism, muscle tone, and a sharp mind, says Mary Ellen Camire, Ph.D., a nutrition professor at the University of Maine at Orono. Most important for young women is B9 (folic acid), which keeps red blood cells healthy and guards against cancer and birth defects. Recommended daily folate dosage: 400 micrograms (mcg); 600 mcg if you're pregnant.