Folic Acid Increases Homocysteine


That’s right.

Folic acid increases homocysteine.

This goes contrary to what you’ve read or heard your doctor say.

You read or hear how awesome folic acid is at:

  • lowering homocysteine
  • supporting women experiencing recurring miscarriages
  • reducing neural tube defects

How can I sit here and tell you folic acid increases homocysteine?

Well, because it does.

Folic acid increases homocysteine because:

  • folic acid is not the body’s primary form of folate – l-methylfolate is.
  • folic acid isn’t active at all in the human body until it is transformed by a gene called DHFR
  • the folic acid transforming gene, DHFR, is really, really, r e a l l y slow
  • since this DHFR gene is so slow, folic acid just sits in your blood getting in the way
  • folic acid gets in the way of l-methylfolate so l-methylfolate cannot do its job
  • if l-methylfolate cannot do its job, homocysteine goes up

Don’t take my word for it.

Here are two case studies – just published – demonstrating how two pregnant women had high homocysteine because of folic acid.

Case Study #1

41 year-old female with infertility. A MTHFR genetic test discovers she has a typical MTHFR gene – no variants.

Due to her infertility and starting another egg donation cycle, her doctor prescribes 5 mg of folic acid/day.

She did as recommended.

Luckily, upon routine exams at another clinic, her homocysteine levels were monitored.

  • initial level of 12.2 umol/L on October 26
  • follow up of 17.2 umol/L on February 13

The 5 mg of folic acid was stopped by this clinic’s recommendation on February 17.

They replaced the 5 mg of folic acid with 500 mcg of l-methylfolate.

Just 4 days later, her homocysteine level dropped to 8.2 umol/L


  • Folic acid blocked folate transport and folate receptors
  • The ratio of folic acid:l-methylfolate was very imbalanced towards folic acid. There is a huge amount of folic acid compared to l-methylfolate.
  • L-Methylfolate could not get into the cell and lower homocysteine because folic acid was blocking the folate receptors and folate transporters.
  • Once the folic acid was stopped, the slow DHFR gene could finally turn the folic acid into active l-methylfolate – albeit at a snail’s pace.
  • The ratio of folic acid:l-methylfolate shifts in favor of l-methylfolate. There is less folic acid compared to l-methylfolate.
  • The blocking of transport proteins and folate receptors by folic acid was reduced because less folic acid was available and more l-methylfolate was available.
  • Since more l-methylfolate was available, homocysteine lowered.
  • The l-methylfolate supplement sped the process of lowering homocysteine. It did this by further increasing the ratio of l-methylfolate to folic acid.

Diagram of the Folate Pathway

This StrateGene Genetic Report clearly demonstrates the problem of folic acid.

Note the highlighted yellow ‘folic acid’. These are areas where folic acid is known to interfere with genetic expression.

Regardless of genetic variants or genetic mutations, folic acid is slowing these genes down!

It’s time to stop saying it’s ok to use folic acid because someone doesn’t have MTHFR genetic variants.


  • FOLR1 = folate receptor gene
  • SLC = folate transport gene
  • DHFR = gene which processes folic acid into a more active folate forms
  • MTHFR = gene which makes l-methylfolate – the body’s main form of folate

Folic Acid has to go through ALL of these genes in order to become L-Methylfolate.

Thus, folic acid bogs the entire Folate Pathway down in a big way.

By stopping the use of folic acid – AND – adding l-methylfolate, one can immediately support their Folate Pathway without burdening it to do a bunch of work. In fact, no work is needed as L-Methylfolate bypasses all Folate genes. Now the FOLR1 and SLC genes can use the L-Methylfolate as needed to help reduce homocysteine instead of being blocked by Folic Acid.

Case Study #2

Very similar to case #1

A woman experiencing infertility is taking folic acid. Her homocysteine level is 15.2 umol/L. Upon stopping folic acid and taking 500 mcg of l-methylfolate, her homocysteine level returns to a healthy level within days.

Powerful Takeaways:

  • Folic acid interferes with fertility and homocysteine even in those who do not have MTHFR genetic variants! These are normal MTHFR’s who get messed up from folic acid.
  • Folic acid is actually not helpful. Instead, folic acid interferes with the body’s natural folate
  • Once stopping folic acid, it takes only days to see improvements. Improvements accelerate when supplementing with l-methylfolate.
  • It does not take much l-methylfolate to lower homocysteine – only 500 mcg was used in these two patients. This is contrary to the high dose l-methylfolate recommendations. (sometimes higher amounts are needed but try lower amounts first.)

Action Steps:

  1. Do not use folic acid.
  2. Use l-methylfolate instead – and try first just a little bit – such as 400 mcg
  3. Find a prenatal vitamin with l-methylfolate and no folic acid.

Share your folate story:

  • What have you experienced with folic acid? Comment below.


Source of case studies:

High doses of folic acid induce a pseudo-methyltetrahydrofolate syndrome




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  • DC says:

    Folic Acid Increases Homocysteine – Would like to clarify, does that include taking Folate or only Folic Acid? Thank you!

    • Benjamin Lynch says:

      Folic acid may increase homocysteine. Natural folates like methylfolate and folinic acid support homocysteine metabolism.

  • Megan says:

    I did my own experiments with folic acid to see if it was affecting me. It’s been a year since I started cutting it out of my diet, and am happy to say it’s eliminated, and will stay that way. I’m amazed at how tired and brain foggy it makes me. These symptoms last about 4 hours until it leaves my system. I have also been amazed at the products I find it in. Even licorice candies! Going out for pizza isn’t an option anymore. I can only buy organic flour. I am floored at the things they put it in. Even more interesting is how New Zealand authorities just passed a law this year to put it in their foods. Sad.

  • Juliette says:

    I am really interested in this topic, but from someone who has studied genetics, I am concerned and confused by comments here such as ‘folic acid isn’t active at all in the human body until it is transformed by a gene called DHFR’ and ‘the slow DHFR gene could finally turn the folic acid into active l-methylfolate’. Do you not mean enzyme(s) here, rather than genes? Genes and enzymes are 2 very different things! Statements like this make me question the validity of the article.

    • Benjamin Lynch says:

      Hi Juliette –

      Genes make enzymes. To simplify it for people, I just said ‘genes’.

      You are right that the enzymes do the work.

      It is the genes which have the SNPs – which then cause the enzymes to malfunction.

  • Hi I am very interested in learning more about this topic. Does Dr Lynch have a specific course or material that you could recommend please?

  • Rune Teigland says:

    How can I know that Methylfolate works in me when I am taking it? By taking blood test and looking at the folate level in blood? Or are there other signs?

    • Joy-Dr. Ben Lynch Team Member says:

      You can look at symptoms, folate serum levels, methylation panel, and current conditions markers. In the back of Dr. Lynch’s book, Dirty Genes, he lists great lab tests for folate, B12, and methylation and where to purchase them. Remember that symptoms are a big telling point here!

  • Rune Teigland says:

    I am screened for MTHFR C677T and I am therefore heterozygot. Methylfolate has no barrier to the brain and I should feel it in my brain 5 -10 minutes after taking it. I worked with this for months and finally I managed to have that reaction. My energy level boosted! And my muscles grew very strong. But after some months it faded again. And now I can not get it going. What do I do wrong? I live in Bergen, Norway and it is a long way to doctors that have knowledge about this.

    • Joy-Dr. Ben Lynch Team Member says:

      Please know that we are not authorized to answer your personal medical questions because we are not your treating healthcare professional. Remember that health is holistic. This means that in order to determine the root cause of your issues, you need to look at multiple avenues of health including lab markers, genetics, current conditions/symptoms, lifestyle, diet, and environmental toxins. To do this, your qualified healthcare professional will need to review your full medical history, order lab testing, and determine a protocol tailored for you. Though Dr. Lynch is a naturopathic doctor (ND), he is not your treating physician, and will not have all the information he needs to give you accurate advice – sometimes, a single issue will have underlying causes that can easily be overlooked via a simple, virtual comment or question. It is the responsibility of your qualified healthcare professional to answer your questions and assign a protocol for you. We understand that not all health professionals are trained in this area of biochemistry and nutrition, and it can be frustrating if you feel they don’t answer your questions or help you solve your problems. Because of this we now offer a Physicians Directory where you can find a health professional that is familiar with StrateGene®, nutrigenomics and some of Dr. Lynch’s work. Remember from Dr. Lynch’s book Dirty Genes, health is a four letter word: work. Part of this ‘work’ is finding a health professional that you feel is listening to you and helps you in the ways that you need. We are here to guide you by providing you resources in hopes that you will take the information and put in the work that optimizes your life.

  • Sam says:

    I am Homozygous C677T. Folic acid makes me feel nauseated and fatigued. Thankfully I stopped talking it at about the 3mth mark of my one full term pregnancy by chance. I didn’t know about MTHFR at that point.
    Could the elevit I did take in that first 3mths be the reason for my child being born with severe ties?

    • Joy-Dr. Ben Lynch Team Member says:

      We don’t know exact reasoning as we are not your qualified healthcare professional. However as stated in the article, folic acid can have many side effects. Read Dr. Lynch’s book, Dirty Genes, to find out more. In addition, browse his other articles here to learn more about folic acid dangers.

  • J says:

    How much folate is “too much?” Right now I take 800 mcg a day and I feel good BUT if that’s too much then so be it. I have the MTHFR variant

  • Joanna says:

    Good evening
    Can folic acid be responsible for Obstetric Cholestitis which I developed in my first pregnancy? Im now planning my second pregnancy and I’m absolutely terrified by the prospect of being affected by this terrible condition again. Thank you

    • Joy-Dr. Ben Lynch Team Member says:

      Folic acid that is unused by the body and in high amounts has many negative effects on the body. However there is not direct cause and effect with this condition in research that we have seen. Definitely something to talk to your health professional about to determine the cause and how to prevent for your future pregnancy.

  • Anna Bernasiewicz says:

    This is super helpful! Thank you!
    Can too much folate increase homocysteine too? Or eating a lot of fortified bread/crackers etc?

    • Joy-Dr. Ben Lynch Team Member says:

      I have not seen evidence of that occurring. There is such thing as too low of homocysteine though, and therefore other pathways may need to be supported: Folate is the general term for vitamin B9. Methylfolate, or other natural forms of folate, can help the body to convert homocysteine to methionine, and therefore help support metabolism of homocysteine. But eating fortified breads and crackers contain folic acid, the man-made version of folate, may increase homocysteine such as the article here talks about because it is not molecularly the same as folate. I hope this helps!

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