How Folic Acid prevents NTDs is not well understood. Some studies suggest that it may correct a nutritional deficiency, while others suggest that supplemental Folic Acid helps compensate for errors in how the body processes Folic Acid. For example, a recent study found that as many as one in seven people may carry a genetic mutation (change) that causes them to have a deficiency in Folic Acid, even if they are consuming a diet that contains the recommended amount of Folic Acid. These people have problems breaking down Folic Acid found in food to forms of Folic Acid the body can use, resulting in lower Folic Acid levels in the blood. Studies suggest that women with this gene mutation may be at increased risk of having a baby with a neural tube defect (NTD). However, taking synthetic Folic Acid either by pill or fortified food appears to raise levels of the vitamin in the blood, and thereby reduce the risk of having an affected baby.