6 Two ways to measure folate in blood are serum folate and red blood cell folate. Serum folate is a measure of the amount of folate present between absorption and utilization or storage in the body. Red blood cell folate is a more reliable measurement because it measures the folate present over the past three months. Some studies have suggested that folic acid is beneficial because of its effects on the level of homocysteine, a metabolite associated with folic acid. For women with inadequate folic acid, teratogenic levels of homocysteine may build up in the blood and result in NTDs.
Researchers also theorize that folic acid causes spontaneous abortion in fetuses with NTDs.
However, neither of these theories has been supported. Other studies suggest a relationship between folic acid and heart disease. 7 Patients with myocardial infarction, stroke, and deep vein thrombosis have demonstrated elevated homocysteine levels. Folic acid may decrease homocysteine levels in the blood. However, reducing homocysteine levels may not prevent the occurrence of these problems because the level may simply indicate that the person is at risk.