Fortifying certain foods with folic acid seemed one of the great public-health successes of the past decade, in reducing the rate of neural-tube defects such as spina bifida in babies. But in light of research suggesting that excess folate levels promote cancer, governments should take a second look to ensure that its approach still makes sense.
Folic acid is the synthetic form of folate, a B vitamin that occurs naturally in dark, leafy greens and grains. Since 1998, both Canada and the United States have required food producers to add folic acid to certain foods, such as white flour and enriched pasta. The rate of neural-tube defects has dropped from 0.86 per 1,000 live births to 0.4, a drop of more than 50 per cent, according to a Canadian study published in 2007 in the New England Journal of Medicine. That means 170 fewer babies a year growing up with such deformities as spina bifida. The U.S. has had similar success.
The birth defects may occur before women know they're pregnant, so women who could become pregnant need to ensure that their diet includes at least 400 micrograms (0.4 mg) a day of folic acid. Hence the requirement that the foods be fortified. It's not quite as hard to avoid as fluoride in tap water, but it's close. It's in Kellogg's Corn Flakes (79 micrograms, of which 60 are synthetic, in a 100-gram serving), frozen waffles (25 micrograms, 19 of them synthetic) and cheese tortellini (74 micrograms, 62 synthetic).
Some research has raised concern about the risks of ingesting too much folate. A new Toronto study published in this month's Cancer Research journal reported high levels of cancer in the offspring of rats given folic-acid supplements before conception, during pregnancy and while breastfeeding. In an American study two years ago, men who took folic acid supplements had an elevated risk of developing prostate cancer. And a Norwegian study, also from two years ago, found patients with heart disease who were treated with folic acid and B12 had a higher cancer rate than those who did not. Health Canada says it views the findings of the published research literature as inconsistent: "It is not possible to conclude that folic acid from fortification has increased the rates of cancer incidence in Canada." It says it continues to follow the latest research.
The research is enough to give pause. It is not time to throw out the bathwater (and definitely not the baby), but governments should refresh the waters of knowledge and policy.