Baby-protecting folic acid is getting new attention: Not only does it fight spina bifida, recent research shows it also may prevent premature birth and heart defects.
Now pregnancy specialists are asking if it's time for the government to boost the amount being added to certain foods to help ensure mothers-to-be get enough. But for older adults, there may be a down side to the nutrient: Extra-high levels late in life just might pose a cancer risk.
"Folate is assuming the role of a chameleon, if you will," says Dr. Joel Mason of Tufts University's nutrition research center, who is researching that possible risk.
Folic acid is an artificial version of folate, a B vitamin found in leafy green vegetables, citrus fruit and dried beans. Everyone needs regular folate because it's important for healthy cell growth.
And pregnant women need extra, even before they may know they've conceived. Enough folate in pregnancy's earliest days can prevent devastating birth defects of the spine and brain called neural tube defects, including spina bifida. Those defects have dropped by about a third since the United States mandated fortifying certain breads, cereals and pastas with folic acid in January 1998.
Two major studies in the past month suggest the vitamin may be even more protective.
Texas researchers analyzed nearly 35,000 pregnancies and found that women who reported taking folic acid supplements for at least a year before becoming pregnant cut in half their risk of having a premature baby. Their risk of having very early preemies dropped even more.
Then Canadian researchers analyzed 1.3 million births in Quebec since 1990 to look for heart defects, the most common type of birth defect. They found the rate of serious heart defects has dropped 6 percent a year since Canada began its own food fortification in December 1998.
It's hard to get enough folate for pregnancy through an average diet. So health authorities have long advised that all women of childbearing age take a daily vitamin containing 400 micrograms of folic acid — even if they're not trying to conceive, since half of pregnancies are unplanned. Last month, the U.S. Preventive Services Task Force went a little further, recommending that women take a daily supplement with 400 to 800 micrograms of folic acid daily.
But because only about a third of nonpregnant women take precautionary folic acid supplements, fortifying foods made with enriched flour ensures everyone gets a modest amount.
"The question now is would a little more fortification, or even twice as much fortification, impact that bottom line, as well as those other potential benefits," says Dr. Alan Fleischman, medical director of the March of Dimes.
His group will call together pregnancy and folate specialists this summer to debate that. Complicating that issue is the question about cancer risk when older people — women well beyond childbearing, and men — take lots of folic acid.
Animal studies show too much folic acid, the pill version, can spur some cancers.
Why? While enough folate usually is protective, if people's bodies already harbor some precancerous or cancerous cells, too much may feed their growth, said Tufts' Mason. Older people are more likely to be brewing colon or prostate cancer.
Fortified foods alone wouldn't be enough to harm, but some people can rack up the dose with today's multiple sources.
Until the issue's settled, Mason says, older adults "really ought to think twice about whether you should take a vitamin supplement that contains folic acid."