What Is MTHFR and Why Does It Matter?
- Kimberly Lemler
- Jul 8
- 4 min read
You may have heard someone mention MTHFR and wondered what it means. MTHFR stands for methylenetetrahydrofolate reductase, a gene that helps your body convert folate (vitamin B9) into its active form, called methylfolate. This active folate is essential for a process called methylation, which is like a master switch for many important functions in the body.
I was recently tested and it was determined that I have one copy of each variant. This answers SO MANY questions I have had for many years!! At the end of this article I will list what I am taking to turn this ship around and how I got tested...
When methylation works well, your body can detox, make hormones, regulate mood, support brain health, and generate energy. But when there’s a problem with the MTHFR gene, those systems can slow down, sometimes drastically.
It’s estimated that 40 to 60% of people have a variation in this gene, and many don’t even know it.
Understanding the MTHFR Gene Variants: 677 and 1298
There are two main gene variants related to MTHFR:
C677T
A1298C
You inherit one copy from each parent. If you have:
One variant (heterozygous), your enzyme activity may drop slightly.
Two of the same variant (homozygous), your MTHFR activity can drop by 60 to 70%, especially with the 677 mutation.
One of each (compound heterozygous), this can also slow function, though often not as severely as homozygous 677.
Common Symptoms of MTHFR Variants
Many people live with an MTHFR mutation without knowing it. But if your body isn’t processing folate well, you might notice:
Chronic fatigue
Brain fog
Mood swings or anxiety
Trouble concentrating
Headaches
Hormone imbalances
Fertility struggles
High homocysteine levels
Sensitivity to medications or chemicals
How MTHFR Affects the Body and Why It Matters
Your MTHFR gene plays a central role in methylation, a process your body uses for hundreds of essential tasks. When that process slows down, it causes ripple effects throughout the body.
1. Detox and liver function slow down Your body can struggle to clear out toxins, medications, heavy metals, and excess hormones like estrogen. This can lead to estrogen dominance, which may cause weight gain, PMS, headaches, heavy periods, and increased risk for fibroids or hormone-related cancers.
2. Cortisol stays high Because methylation is involved in how your body breaks down stress hormones, poor MTHFR function can lead to chronically elevated cortisol. This puts you in a constant fight-or-flight state, which drains energy, increases belly fat, disrupts sleep, and wears down your adrenal system over time.
3. Neurotransmitters get out of balance Your brain needs methylated B vitamins to make serotonin, dopamine, and other brain chemicals. When methylation is sluggish, you may feel anxious, moody, irritable, or mentally drained.
4. Homocysteine rises MTHFR helps keep homocysteine, a byproduct of protein metabolism, within healthy limits. If it builds up, it can damage blood vessels and increase the risk of heart problems, stroke, and blood clots.
The MTHFR and Mitochondria Connection: Why You're So Tired
This is where it all comes together.
Your mitochondria are the tiny engines inside your cells that make energy in the form of ATP (adenosine triphosphate). They rely on nutrients including methylfolate, B12, B2, magnesium, and others to do their job.
When MTHFR isn’t functioning well:
You don’t produce enough methylfolate. That slows methylation which disrupts how nutrients are activated...which directly affects how well your mitochondria make energy
The result? You’re constantly running on low battery. This is why extreme fatigue is one of the most common complaints in people with MTHFR mutations. No matter how much you rest, your body may not be producing the energy it needs at the cellular level.
In other words, you’re not just tired. You’re underpowered.
How to Support Your Body If You Have MTHFR Variants
The goal isn’t to fix the gene. You can’t change it. But you can give your body the support it needs to function better.
Use methylated B vitamins Look for methylfolate (B9), methylcobalamin (B12), and P-5-P (B6). These are active forms your body can use immediately without extra conversion.
Avoid synthetic folic acid It’s found in fortified foods and cheap multivitamins. People with MTHFR variants may not convert it properly, and it can actually block methylfolate from doing its job.
Eat nutrient-dense, real foods Leafy greens, cruciferous vegetables like broccoli and Brussels sprouts, clean protein, and healthy fats all support detox, hormone balance, and energy production.
Support detox pathways daily Drink plenty of water, sweat regularly, eat fiber, and reduce alcohol and environmental toxins to take pressure off your liver.
Manage stress Chronic stress burns through nutrients, especially B vitamins. Make space for deep breathing, rest, light movement, and quiet time.
Limit exposure to chemicals Choose clean personal care and cleaning products. Avoid plastic containers and pesticide-heavy foods when possible.
If you’ve been feeling off for a while...tired all the time, overwhelmed, foggy, anxious, or hormonally out of balance, and nothing seems to help, it’s worth exploring MTHFR. It’s not the only piece of the puzzle, but for many people, it’s a big one, like it is for me.
Understanding your genetics can help you stop guessing and start supporting your body with exactly what it needs to feel better and function better, starting at the cellular level. What I take: Methylated B12 by Mary Ruth Organics Methyl B Complex by Ortho Molecular How I got tested: MTHR Test
~Kimberly Medical Disclaimer:
The information provided in this blog is for educational and informational purposes only and is not intended as medical advice. It is not a substitute for professional medical diagnosis, treatment, or guidance. Always consult with your physician or a qualified healthcare provider before making changes to your health regimen, especially if you have a medical condition, take prescription medications, or are pregnant or nursing.


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