By: Mary Scourboutakos

Neural tube defects are a type of birth defect—affecting the brain, spine or spinal cord—that result from suboptimal folate status.
Folate is a B vitamin that’s naturally found in legumes (like chickpeas, lentils, pinto and kidney beans), seeds, leafy greens (like spinach, collard greens and romaine lettuce) and other vegetables such as asparagus, brussels sprouts and broccoli.

The problem is, people don’t eat enough of these foods. As a result, for many years, pregnant women were at risk for folate deficiency and hence, neural tube defects.

Prenatal supplements were the original solution to this problem as one of their prime ingredients is folic acid, the synthetic form of folate. However, they’re not a fool proof solution because neural tube defects form within four weeks of conception, often before women know they’re pregnant, and thus, before they start taking their supplements.

As a result, in the late 1990s folic acid was mandatorily added to white flour and enriched grain products to ensure that pregnant women would get enough folate, irrespective of whether they take a supplement.

Problem solved? Sort of…

Back in the early 1990s when discussions regarding the addition of folic acid to the food supply were taking place, it was suggested that after fortification was implemented, the dose of folic acid in prenatal supplements should be revised to prevent excessive intakes. The new problem is…the doses were never revised.

Currently, marketed prenatal supplements usually contain 1000 micrograms of folic acid, which is the daily upper limit for folic acid. Meanwhile, it’s recommended that pregnant women should consume about 400 micrograms of folic acid per day for neural tube defect prevention.

With mandatory fortification, three-quarters of a cup of cereal can provide greater than 400 micrograms of folic acid. So if you add a prenatal supplement to a bowl of cereal at breakfast, some bread at lunch, and pasta for dinner, you’re consuming a lot of folic acid!

According to Dr. Deborah O’Connor, a Professor from the University of Toronto who has spent decades studying folate and infant health, this could be a problem. She explained that in animal models, it has been shown that folate can make changes to the genes that are transcribed during development. And while similar data have not been done on humans, she said “if you’re not getting any benefit from those high levels, it would be prudent to cut back given the current status…(because) if there’s no benefit, there’s only a risk.”

From a regulatory point-of-view, she says there’s nothing stopping the industry from changing the amount of folic acid in the supplements. She suggested that the industry’s reluctance to modify the dose in prenatal supplements is probably due to inertia and the fact that “with nutrition you’re always fighting against the more is better philosophy.”

In the meantime, what should women do? In their 2015 clinical practice guidelines, the Society of Obstetrics and Gynecologists recommended a multivitamin containing 400 to 1000 micrograms of folic acid. But currently, there are no prenatal vitamins available with less than 1000. Hence, Dr. O’Connor’s recommendation is “do not use the prenatal, just use a regular multi-vitamin and maybe add a little iron.” Furthermore, she added “care must be taken to ensure vitamin A intakes do not exceed 3,000 mcg retinol activity equivalents (RAE) or 10,000 IU during pregnancy.”

Alas, it’s a classic story, you try to fix one problem, but in doing so, you create another. Hopefully prenatal supplements will be adjusted soon, but in the meantime, prudent folic acid intakes are probably a good idea.