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MTHFR Gene and Hypothyroidism

Is there a connection between MTHFR mutation and hypothyroidism?
MTHFR Gene and Hypothyroidism
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In this article: 

  • What is the MTHFR gene?
  • Variants of the MTHFR gene
  • Health conditions related to the MTHFR gene
  • Relationship to hypothyroidism
  • Testing MTHFR gene
  • How to support methylation pathways

What is the MTHFR gene? 

The MTHFR gene instructs the body to make an enzyme called methylenetetrahydrofolate reductase. (Try saying that ten times fast!) This enzyme helps to process amino acids, which are the building blocks of proteins. MTHFR helps to metabolize one form of the vitamin folate (also called vitamin B9) into another. The methylated folate is necessary for the process that converts homocysteine into methionine - both amino acids. Methionine helps the body to make proteins and other essential compounds.

Variants of the MTHFR genes

There are two common variants in the MTHFR gene, called C677T and A1298C. If the MTHFR gene has either of these two variants, it may lead to a mild or moderate increase in homocysteine in the body. 

The MTHFR gene is hereditary. At conception, you get one copy of the MTHFR gene from each parent. If both parents have variations, your risk of having a double mutation is higher.

Health conditions related to MTHFR gene


Homocystinuria is a disorder in which the body cannot process homocysteine and methionine properly. This condition causes eye problems, abnormal blood clotting, bone issues, and learning problems. Studies show that people with homocystinuria have at least 40 mutations in the MTHFR gene.


Anencephaly is a common type of neural tube defect that occurs during the development of the brain and spinal cord. This condition results in missing large parts of the brain or incompletely formed skull bones. Some studies suggest that variations in the MTHFR gene may associate with a slightly increased risk of neural tube defects.

Spina bifida

Spina bifida is another common type of neural tube defect that causes the bones of the spinal column to not close completely around the developing nerves of the spinal cord. The possible result is permanent nerve damage. Similar to anencephaly, some studies find that variations in the MTHFR gene may also associate with a slightly increased risk of spina bifida. 

It's important to note that most people with MTHFR gene polymorphisms do not have neural tube defects, nor do their children.


Increased homocysteine levels caused by MTHFR gene variations or mutations may be possible risk factors for a variety of common conditions like high blood pressure, blood clots, pregnancy loss, psychiatric disorders, or certain types of cancer. However, studies of MTHFR gene variations in people with these conditions are mostly inconclusive. It's likely that other factors, like family history and lifestyle, play a more significant role in the development of these more common conditions.

Relationship to hypothyroidism

The association between the MTHFR mutation and hypothyroidism is mostly speculative at this point. Some small studies suggest a possible link between MTHFR mutation and hypothyroidism with no definitive results. It is advantageous to note that hypothyroidism may associate with higher homocysteine levels regardless of the presence of an MTHFR mutation.

Testing for MTHFR gene

Testing to identify a mutation in the gene may help you understand how your body processes folate. This knowledge could help decide the right medications and supplements to support a healthy heart and thyroid function. Talk to your doctor if you are concerned about an MTHFR mutation.

How to support methylation pathways

Methylation is the introduction of a methyl group into a molecule or compound, and the removal of a methyl group is called demethylation. The MTHFR gene is a key regulator of methyl group availability, and you can support your methylation pathways with diet & lifestyle choices. 

Support your methylation and homocysteine levels with a nutrient-rich diet. Adequate folate intake can usually "cancel out" the effect of the MTHFR mutation. Folate (B9) is naturally in dark leafy greens, asparagus, avocados, papaya, nuts and seeds, beans, and beets. Spinach, liver, asparagus, and brussels sprouts have the highest folate levels. It is also available as a dietary supplement if you cannot get enough needed nutrients from diet alone. 

Join us in the Thyroid Care Club Facebook Group for more on this topic and many others regarding thyroid health and well-being.


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Katie Wilkinson

Katie Wilkinson, previously serving as the Head of Content and Community at Paloma Health, fervently explores the nexus between healthcare and technology. Living with an autoimmune condition, she's experienced firsthand the limitations of conventional healthcare. This fuels both her personal and professional commitment to enhancing patient accessibility to superior care.

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