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Ask Anni | What Do I Need to Know About MTHFR?

A nutrition expert answers - what type of folate is best? And how do I supplement safely?

Welcome to the Ask Anni series. Every Thursday on the blog, I’ll be answering your most asked questions and giving you evidence-based answers. This week on Ask Anni, many of you are wondering, “What do I need to know about MTHFR?

It might look like an abbreviation for a colorful choice of words, but I assure you it isn’t. MTHFR stands for methylenetetrahydrofolate reductase, and many use this abbreviation in reference to a gene mutation that has gotten a lot of attention in recent years. How do you know if it affects you?

Read on to find out about MTHFR, gene mutations, and more from a nutrition educator and expert.

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Metabolism & MTHFR

MTHFR is an enzyme. Its job is to break down folate into an active form that the body can use.

It’s important to understand the metabolism of folate on a basic level before diving into the details of gene mutations and other folate facts. I have a whole article on folate, in addition to a free guide included with this article.

These two images illustrate the basic pathway of folate metabolism. The image on the left shows the pathway of folic acid in someone without an MTHFR mutation. The image on the left show how metabolism is blocked in a person with an MTHFR mutation.

Images courtesy of Rootine

Can folic acid be harmful?

Depending on the level left unmetabolized, and the level can reach especially high level in those with MTHFR gene mutations, the answer is yes. Folic acid can be harmful.

Folic acid can compete with naturally occuring or fortified sources of folate during digestion. Unmetabolized folic acid essentially just sits in the bloodstream and can cause some serious problems.

Association with Cancer Risk

High levels of folic acid left unmetabolized may not be directly linked to cancer, but have been associated with cancer risk.

May Mask a B12 Deficiency

In all ages, but especially the elderly where B12 becomes a major concern, high levels of folic acid not broken down and floating around in the blood can cause problems.

In this situation, blood tests will often tell you folate levels are fine when in reality, you just have a ton of unmetabolized folic acid sitting static in the blood and folic acid competing for metabolism during digestion and very little nourishment actually occurring.

Older adults are at particular risk for impaired vitamin B12. The signs and symptoms of Vitamin B12 and Folate deficiencies can look similar, from anemia down to the changes of the blood cells on the cellular level.

Vitamin B12 deficiency can lead to increased dementia risk and degenerative nerve diseases. It’s important to understand that folate can hide these deficiencies.

How to Take Your Vitamins

Supplementing the Right Way for YOU

Regardless of whether or not you have a MTHFR gene mutation, I suggest in almost every case to try and get folate from whole foods first.

However, in some cases, supplementation is necessary. For example, pregnant women may need to ensure intake of this vital nutrient to avoid neural defects in their children.

Folic acid is the most commonly available form of supplementation. It is sold in almost every drug store and online. As we discussed above, this synthetic form of the vitamin can cause multiple problems, which is precisely why I never recommend it.

However, folic acid is sometimes added to store-bought foods and multivitamins for fortification purposes. My advice? Always look at the label.

  • If you have a MTHFR mutation, avoid these products the best that you can, most of the time.

  • If you don’t have the MTHFR mutation, it’s up to you. Personally I prefer the taste of homemade bread and whole foods, so I would encourage you to seek out another product if you can.

  • For some products, it may be simply unavoidable. I have the MTHFR gene mutation myself and so I’m diligently always searching for alternatives to items with folic acid. I love the Smarty Pants multivitamins because they are made with the most bioavailable form of folate. Products like nutritional yeast have been harder to find not fortified with folic acid. I guess what I’m trying to say is this: do your best to avoid folic acid when you can, but don’t let a little nutritional yeast stop you from ingesting a nutrient-rich recipe.

What do you recommend when taking supplements during the conception & pregnancy process?

If you are not trying to get pregnant, I recommend a reliable birth control. Whether or not you have a MTHFR mutation, a reliable birth control is an important part of your health as a woman.

As mentioned in my article on folate, it is possible for a woman to not even know she is pregnant until it is too late for her to do anything about folate intake to protect her baby from defects. A good birth control helps put a woman in charge of her reproductive plan.

If you are trying to get pregnant or plan to become pregnant within the next 6 months, discuss your folate needs and fertility with your healthcare providers. If you aren’t meeting with a dietitian currently, now might be the best time to start.

Folate is crucial during the first few weeks of pregnancy, following conception. Women also have increased needs for folate during pregnancy and while breastfeeding.

The Bottom Line

Generally, my best advice for anyone is to supplement with a third-party tested, active folate form of L-methylfolate (5-MTHF).

Getting exposed to a little folic acid isn’t the end of the world, but significant use can pose significant problems. This is especially true for those with a gene mutation of MTHFR, and risks can increase with age or life stage (i.e. pregnancy). As a nutritional professional, I would advise you to:

1. Attend routine screenings and appointments. These regular meetings with your healthcare providers can help them to see deficiency from signs showing on the outside as well as sneakier symptoms on the inside.

2. Find out your folate status and whether or not you have a MTHFR mutation. Now- hold on a sec. Don’t go googling “gene testing for MTHFR” right away. Many companies promise accurate and expensive tests when there is an easier way to see where you are at.

Schedule an appointment with your healthcare provider and ask to have your homocysteine levels checked. The short story is that folate metabolism helps keep homocysteine levels in check. A homocysteine imbalance is a simple, minimally invasive, inexpensive solution to finding out your folate status.

There is a downside to this method. The results of the test tell you your homocysteine levels and your healthcare provider will likely recommend a course of action based upon that. The test itself won’t tell you whether or not you have a MTHFR gene mutation.

The test is telling us about your folate status. If you have an MTHFR mutation that isn’t causing serious problems, it may not show abnormal homocysteine levels. If your mutation is causing serious side effects, it will likely be reflected.

Either way, homocysteine levels are an accurate measure of how folate metabolism is occurring in your body and can tell you regardless of mutation what your body needs to take a step in a healthier direction.

3. Know how to read a nutrition label and determine what meets your folate needs.

Recommended Brands

These brands are my most commonly recommended supplements when it comes to folate. Be sure to understand the Upper Limits (UL) when looking for an excellent folate supplement.

These brands are not part of some sponsored post -- I truly just think they are a great option for affordable healthcare. Check out the following brands:

Folate Supplements


  • Smartypants -- Women’s Organic with Probiotics available at Amazon

  • Doctor’s Best -- Amazon

  • Pure Encapsulations -- Amazon


FREE Patient Resources

Do you like getting things for free? So do we!

Click here your FREE 6-page download😍👇🏼✨

Free 6 page pt guide to folate by Anni W
Download • 1.27MB


Professional Resources

Frustrated trying to remember folate facts? It's hard to keep track of all the vitamins!

With this easy to navigate guide, never forget the facts again! With purchase, a high-quality PDF file will be available for download. Turn it into posters, handouts, and even more. It's simply the best way to avoid stress and know your folate facts before meeting with a patient!



Arnarson A. Folic Acid vs. Folate -- What’s the Difference. Healthline. 2019.

Genomic Medicine. A Genetic Test You Don’t Need. Cleveland Clinic. 2020.

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