What are the proven advantages of taking prenatal vitamins when you aren't pregnant?

Good for pregnancy: Prenatal vitamins are the most helpful early in the pregnancy since they help prevent neural tube defects. Usually the risk of neural tube defects are highest in the first 4-8 weeks of pregnancy when most people do not even know that they are pregnant. Most ob/gyn recommend woman of child bearing age take prenatal vitamins if they are planning to get pregnant or just in case they get pregnant.