Why folic acid isn’t good for you.

Before we delve into the topic of folic acid and folates it’s important to get the language correct. Folate is the term used which includes all types of folate including folic acid. Folic acid does not equal folate, but is a type of folate. Many people, including health professionals, will refer to folic acid as encompassing all types of folate, but this is incorrect.

What is folate and what does folate do?

Folates are a group of micronutrient compounds that are essential for one-carbon metabolism. We can’t make folate, so we must ingest it in foods or supplements to maintain normal functioning. We call folate vitamin B9.

DNAWhat is one carbon metabolism? This is also known as methylation. Methylation is a very important biochemical reaction that is essential for a bunch of important structures in the body including:

  • To make DNA
  • Process chemicals
  • Build neurotransmitters
  • Process hormones
  • Build immune cells
  • Produce energy
  • Produce protective coating of nerves
  • Build and maintain cell membranes

These are very important functions meaning that without adequate folate to power this terrible things can happen like: Neural tube defects, cardiovascular disease, anemia, cancer and cognitive dysfunction etc. So we make sure to get enough to prevent these things as much as possible.

What foods contain folates?

  • Raw, dark leafy greens
  • Sprouts
  • Brewer’s yeast
  • Liver

Naturally occurring folates are unstable which means when you process food containing folate: canning, heating etc the folate content can decrease significantly depending on the type of processing.

Am I getting enough?

With this list of foods we can make a safe and accurate assumption that most North Americans do not get enough folate through diet alone. This along with the prevalence of neural tube defects (NTDs) in newborns are some of the reasons why food folate fortification was started in North America.

In Canada we fortify grains at 150ug of folic acid per 100g grain (4). This has been shown to increase the average folic acid intake to 100-200ug of folic acid /day in women of childbearing age (4). This public health initiative has been shown to reduce the occurrence of NTD’s (4). Good right? Yes great actually – but there are some problems with this program. As we understand more about NTDs we find out that there are significant cases of NTDs that are independent of folate status and are related to low vitamin B12 status (4). Another issue is that fortification uses the synthetic form of folate known as folic acid.

What is folic acid?

Folic acid is a synthetic compound. It requires several steps to be converted to the metabolically active form of folate within your cells. These steps require several enzymes. It is a more stable structure than natural folates and is extremely well absorbed (3). Because of this it is widely used in foods and supplements.

What’s the problem with Folic acid?

  1. Folic acid is not an active form of the vitamin. When you ingest it, your body must reduce it through several reactions before being able to use it for methylation (3). It uses an enzyme called DHFR (dihydrofolate reductase) to help convert it to an active form (5-MTHF). DHFR is a slow enzyme, meaning when you take larger amounts of folic acid much of it doesn’t get converted through this enzyme. In addition to this, some people have genetic polymorphisms (variations) in this enzyme, making it even harder for them to do these reactions.

  3. Dihydrofolate (which is the product of the DHFR enzyme) inhibits the MTHFR group of enzymes (3) which would slow the production of active folate (5-MTHF). Basically if we are using this enzyme a lot (if we are consuming a lot of synthetic folic acid) then we are slowing the enzyme that makes active folate.

  5. High intakes of folic acid can mask the presence of a vitamin B12 deficiency. Typically the dose for masking B12 deficiencies is in the 5000ug / day range of folic acid (4).  Remember that some cases of NTD’s are actually due to low B12 status in the mother.

  7. The extra folic acid that does not get converted sits in your blood as unmetabolized folic acid. Unmetabolized folic has been found in people of all ages including infants, and this is likely due to food fortification with folic acid. We are now learning more about how unmetabolized folic acid can cause problems. Some of the research to date has suggested the following effects from unmetabolized folic acid:
  • Decreases activity of natural killer cells in post menopausal women (2). This could have implications in cancer.
  • Interferes with the functions of natural folates by blocking binding sites, possibly creating a functional deficiency of natural folates (3).
  • Cognitive impairment in the elderly (5)

What can you do?

  1. Get assessed for genetic polymorphisms in folate metabolism. This can give clues as to how vulnerable you might be to folate metabolism issues. Find an ND or other practitioner that is qualified to evaluate this information. I do these types of assessments all the time after running a simple genetic test.

  3. If you are pregnant or planning to become pregnant its important to ensure you are getting adequate folates and B12. Optimally you would take an active folate source such as 5-Methyl THF, however if this is absolutely not available to you then it does make sense to continue to take synthetic folic acid since we know it reduces the occurrence of neural tube defects. If you are taking any folate, make sure to pair it with vitamin B12.

  5. Eat natural folates! Eat whole foods (read: unpackaged) and lots of raw, dark, leafy greens.

  7. If you are taking a supplement ensure it contains an active form of folate such as folinic acid or 5-methyl tetrahydrofolate (5-MTHF). This actually isn’t all that common yet in the supplement industry but will likely change over the next few years.

Questions? Leave us a comment!


Dr. Meaghan McCollum

Meaghan-130x150I am highly qualified in the treatment and prevention of chronic disease, immune dysfunction, sports medicine, allergies, gastrointestinal disorders, hormonal imbalance in both men and women, stress and fatigue. I’ve also received advanced training in prolotherapy, chelation therapy, intravenous vitamin therapy, clinical nutrigenomics and allergy testing.






  1. Scaglione F, Panzavolta G. Folate, folic acid and 5-methyltetrahydrofolate are not the same thing. 2014; 44(5): 480-488
  2. Troen AM et al. Unmetabolized folic acid in plasma is associated with reduced natural killer cell cytotoxicity among postmenopausal women. Journ of Nutr 2005; 189-194.
  3. Smoth D, Kim Y, Refsum H. Is folic acid good for everyone? Am J Clin Nutr 2008;87:517–33
  4. Crider K, Bailey LB, Berry RJ. Folic acid food fortification – Its history, effect, concerns and future directions. Nutrients 2011, 3:370-384.
  5. Morris MS, Jacques PF, Rosenber IH, Selhub J. Circulating unmetabolized folic acid and 5-methyltetrahydrofolate in relation to anemia, macrocytosis and cognitive test performance in American seniors. Am J Clin Nutr 2010;91:1733–

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