DEAR DOCTOR K: I'm a healthy woman in my 40s. Should I take extra folic acid to boost my immune system?
DEAR READER: Folic acid is, essentially, a vitamin. We all need vitamins. Indeed, the word "vitamin" was coined to refer to a substance that was essential to human life. The natural form of folic acid, folate, occurs in some foods, including vegetables, fruits, and dried beans and peas.