Several sources, including news@nature and the Washington Post, reported today that relative to the early 1990s, the average blood level of folate in women is declining. Folate deficiency is associated with neural tube defects during fetal development. So women of child-bearing age are encouraged to take folate supplements even if they are not pregnant or actively trying to get pregnant. Incidence of neural tube defects has declined by approximately 25%, presumably because we are all taking folate.

So why are folate levels declining? It’s not clear, but officials from the U. S. Centers for Disease Control and Prevention have several ideas. Obese individuals metabolize folate differently than thin people and may need to consume more folate than their thin counterparts. Because obesity is on the rise, that may explain the decline in average folate levels. Alternatively, diet trends may be to blame. In the U. S., the Food and Drug Administration requires that enriched flour used in cereals and breads be fortified with folic acid. But in 2003, the Atkins diet craze encouraged us all to trade in our Cheerios for steaks. Now diet gurus are encouraging people to eat whole grains, which unlike their processed counterparts, are not supplemented with folic acid.

So, women should consume far more folate. That is, unless you remember this bizarre news item from last spring, reporting that each generation of obese pregnant mice fed folate and other methyl donors had increasingly heavier offspring.