FOLATE

Folate is probably the vitamin whose essential role in pregnancy is most widely known. It is necessary for the production of new DNA, and new DNA is needed for new cells. The growing life within the womb engages in constant cell division, and the mother must expand her blood supply with the production of new red blood cells as well—these activities demand a generous supply of folate.⁵⁰

Adequate folate intake prevents neural tube defects (defects of the brain and spinal cord) and increases birth weight. It may also prevent spontaneous abortion, mental retardation and deformations of the mouth, face, and heart.⁵⁰

The pregnancy RDA for folate is 600 micrograms (mcg) per day. This figure is based on the amount needed to prevent the folate concentration of the mother’s red blood cells from dropping during pregnancy and on urinary markers indicating the amount of folate being used.⁵¹ It assumes that only half of the vitamin is absorbed from food, although this figure is just an average; the rate of folate absorption is dependent on zinc status.

Synthetic “folic acid” is a chemical that is not normally found in foods or the human body. It can be converted into usable forms of folate, but this conversion is limited to about 200 mcg per single dose in healthy volunteers;⁵² it may be even more limited during long-term exposure or in certain people. Synthetic “folic acid” does not cross the placenta; folate crosses the placenta as the naturally occurring 5-methyl-tetrahydrofolate.⁵⁰ Since the synthetic supplements do prevent neural tube defects, pregnant women should use them if they are not going to eat folate-rich diets; whenever possible, however, it is best to meet the folate requirement from foods. Folate-rich foods include liver, legumes, and greens (see Figure 5 and Figure 7).