Folic acid is great for pregnant women—in the recommended doses.

What women really think about news, politics, and culture.
April 26 2011 12:37 PM

Folic Acid Follies

Pregnant women should stop popping these pills like candy.

Pregnant woman with pills. Click image to expand.
Take folic acid, but not too much

No woman who's expecting, or expecting to expect, can avoid the advice, from any doctor or health site worth its salt: Take folic acid. The vitamin deserves its exalted status. When women take it before and during pregnancy, it reduces the risk of devastating neural-tube defects in the fetus. It's one of the only things we can do to improve fetal health that is supported by rigorous evidence.

But these days millions of women (and men) are getting high doses of the vitamin—and not because we're piling our plates with natural sources like  spinach and collard greens. Since the late 1990s, the United States has  fortified  many breads, cereals, and pastas with folic acid. And then there are the supplements: both in regular multivitamins and freestanding folic acid pills. For pregnant women, the government recommends a daily dose of 400 micrograms  in addition to any folate, the naturally occurring form of the vitamin. But millions of expectant mothers, as well women who are not yet pregnant,  go hog-wild, taking more than 1,000 micrograms in pill form a day, an amount the government deems the "tolerable upper intake level." Somewhere along the line, it seems, folic acid crossed the line from vitamin to talisman.

But folic acid is a powerful drug, even if its exact workings remain something of a mystery. For the population at large, it might increase or decrease the risk of certain cancers, depending—perhaps—on whether abnormal cells are already present. A recent mouse study also hints that supplements during pregnancy may boost the risk of breast cancer in the pups (though this has yet to be confirmed in humans). Much of the science here is embryonic, and no reason to shun the vitamin. But there are enough question marks that pregnant women would be smart to stop popping it so freely and to stick to the recommended dose.

Advertisement

The discovery that folic acid could reduce the risk of neural-tube defects was a triumph that has helped to protect millions of babies. In a  randomized clinical trial  published in 1991, British epidemiologist Nicholas Wald proved that pregnant women who took folic acid supplements were less likely to have fetuses with malformations like spina bifida, in which the spinal cord doesn't develop properly. Since then, because of the fortification of breads, cereals, pastas, and other grains, as well as the emphasis on supplements during pregnancy, the rate of these birth defects has decreased substantially . In the United States today,  about two-thirds of pregnant women  take supplements with folic acid. Yet Americans have never been able to resist too much of a good thing, and this vitamin is no exception. According to Cathrine Hoyo, an epidemiologist at Duke, one worry has long been that too much folic acid can mask deficiencies in vitamin B12, which are associated with anemia and may be linked to cognitive impairment.

But the big debate these days is over the vitamin's ambiguous relationship to cancer, both in adults and in fetuses. On one hand, a large body of research suggests that getting  adequate amounts  of folate  protects against colon cancer—and possibly prostate cancer, as well. One theory is that the vitamin helps to maintain the integrity of DNA, preventing the kinds of errors that lead to malignancy.

TODAY IN SLATE

Culturebox

The Ebola Story

How our minds build narratives out of disaster.

The Budget Disaster That Completely Sabotaged the WHO’s Response to Ebola

PowerPoint Is the Worst, and Now It’s the Latest Way to Hack Into Your Computer

The Shooting Tragedies That Forged Canada’s Gun Politics

A Highly Unscientific Ranking of Crazy-Old German Beers

Education

Welcome to 13th Grade!

Some high schools are offering a fifth year. That’s a great idea.

Culturebox

The Actual World

“Mount Thoreau” and the naming of things in the wilderness.

Want Kids to Delay Sex? Let Planned Parenthood Teach Them Sex Ed.

Would You Trust Walmart to Provide Your Health Care? (You Should.)

  News & Politics
Politics
Oct. 22 2014 9:42 PM Landslide Landrieu Can the Louisiana Democrat use the powers of incumbency to save herself one more time?
  Business
Continuously Operating
Oct. 22 2014 2:38 PM Crack Open an Old One A highly unscientific evaluation of Germany’s oldest breweries.
  Life
Gentleman Scholar
Oct. 22 2014 5:54 PM May I Offer to Sharpen My Friends’ Knives? Or would that be rude?
  Double X
The XX Factor
Oct. 22 2014 4:27 PM Three Ways Your Text Messages Change After You Get Married
  Slate Plus
Tv Club
Oct. 22 2014 5:27 PM The Slate Walking Dead Podcast A spoiler-filled discussion of Episodes 1 and 2.
  Arts
Culturebox
Oct. 22 2014 11:54 PM The Actual World “Mount Thoreau” and the naming of things in the wilderness.
  Technology
Future Tense
Oct. 22 2014 5:33 PM One More Reason Not to Use PowerPoint: It’s The Gateway for a Serious Windows Vulnerability
  Health & Science
Wild Things
Oct. 22 2014 2:42 PM Orcas, Via Drone, for the First Time Ever
  Sports
Sports Nut
Oct. 20 2014 5:09 PM Keepaway, on Three. Ready—Break! On his record-breaking touchdown pass, Peyton Manning couldn’t even leave the celebration to chance.