Folic acid: Can you get too much of a good thing?

Folic acid has certainly been getting a lot of  attention this past week. For pregnant women, meeting their quota of this member of the B vitamin family is critical to the health of their newborn:  research shows  a strong protective link between  women taking folic acid supplements before becoming pregnant  and  a decreased risk  of their having babies with  neural tube defects such as spina bifida. The headlines, though, were about a study finding a possible link between excessively high levels of the vitamin in women and an increased risk for autism in their children.

First things first, the study has been criticized for a number of reasons. It was a small study –  1,391 mothers who gave birth between 1998 and 2013 – considering the amount of attention it received. Researchers found that if a new mother had excessively high levels of folate  in her blood after giving birth, the risk of her child developing autism doubled. The women’s blood folate levels were measured within the first three weeks of delivery but not during the first two trimesters, during the time when the nutrient may impact neurological development.

But if you’re contemplating pregnancy or are already pregnant, keep in mind that those women who had normal levels of the vitamin had a reduced risk of having a child with autism. So don’t panic and definitely don’t pitch your prenatal supplements.

The levels found in those women at risk point to issues that may not currently be known. There could be genetic factors at work or possibly very high levels of supplementation.  The study, though, is a reminder of the concept that when it comes to vitamin supplements, you can get too much of a good thing. And issues surrounding the B vitamin folate, folacin  or folic acid illustrate the concern perfectly.

How our bodies treat nutrients from food sources and vitamin supplements may differ depending on the particular nutrient.  This B vitamin is a perfect example. Folate, the natural form of this vitamin, is found in a range of foods including dark leafy greens, citrus fruits, dried peas and beans and peanuts. Folic acid is the synthetic form and is used in vitamin supplements and fortified foods because it’s more easily absorbed. Together folate and folic acid have become nutrition stars for more than a decade.

Besides having a host of benefits, research pointing to their ability to protect against neural tube birth defects, such as spina bifida, in babies vaulted the vitamin into the limelight. As a result, it’s standard practice for women who are planning pregnancies to take folic acid supplements beforehand. It’s even recommended that simply being in the child-bearing years should warrant folic acid supplementation as many pregnancies are unplanned.

But many women were not getting the message and as a result, both the Canadian and U.S. governments decided on a folic acid fortification plan. It was decided to fortify refined grain products such as bread, cereal, flour, rice and pasta with folic acid.

And the plan has paid off: Since the fortification program was put in place in the mid 1990s, the number of infants born in Canada and the U.S with neural tube defects has dropped dramatically. But as with any public health measures that offer benefit, there can unintended consequences.   Some research is pointing to increased risk of certain cancers, such as colon and prostate cancer,  with high folic acid intakes while folate, the form found in food, is protective.  High intakes of folic acid can also mask a vitamin B12 deficiency, something that’s more common in the 50 plus age group.

While we await more research, it’s key, especially for pregnant women, to evaluate supplement intakes.  Taking a prenatal vitamin and mineral supplement is certainly recommended but adding in a separate folic acid supplement on top of the prenatal supplement is not (unless there is a medical reason). And this doubling up of folic acid supplements is not out of the ordinary. The recommended intake for pregnant women is 600 micrograms per day while the established limit or Tolerable Upper Intake level for folic acid is 1,000 micrograms per day.

Again, more is not better. Many people mistakenly believe that because folic acid is a water-soluble vitamin, you simply get rid of the excess through your urine  with no potential for harm.

But it’s not the case.

In addition, choosing foods naturally high in folate over folic acid fortified options goes hand in hand with healthy eating.  For example, a menu filled dark leafy greens and pulses such as lentils and chick peas is chock full of folate. Selecting whole grains offers folate along with an abundance of key nutrients while refined grains provide folic acid.

But as is so often the case when it comes to nutrition, balance is key.   So is taking nutrition headlines with a grain of salt.

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Categories: Nutrition News, Research Roundup

Author:Rosie Schwartz

Rosie Schwartz is a Toronto-based consulting dietitian and writer.

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