Devastating Birth Defects Decreasing With Food Fortification
An increase in folic acid fortification, however, could trigger an unhealthy consequence: pernicious anemia. This form of anemia, or iron-poor blood, damages the brain and nerves and is caused by a deficiency in vitamin B-12. Increased folic acid levels can interfere with detecting this deficiency.
On the flip side, however, folic acid decreases blood levels of homocysteine. High levels of homocysteine are a risk factor for heart disease. It's conceivable that increased folic acid may lower risk of heart disease, but the evidence is not yet in.
In the meantime, Leavitt says, "if you're sexually active and there's any possibility of pregnancy, you need to be supplementing folic acid because just about half of all pregnancies in this country are unplanned. ... women can't safely wait until they make a definite decision to conceive to start."