TikTok Myth of the Week: Why Everyone Is Going Crazy About the MTHFR Gene
Did you know that a significant percentage of the US population has one of the less effective variants of the MTHFR gene? TikTokers love to say this, and it’s true. They will also argue that if you have the MTHFR variant, you need special vitamins and that the wrong vitamins (or even certain medications) will be toxic to you. This is not true , although some influencers have built their entire online personas on such claims.
They’ll tell you that MTHFR (which TikTokers like to call the “mother gene”) is responsible for your (or your child’s) autism, ADHD, depression, anxiety, thyroid problems, or other conditions. They will suggest testing for a gene or vitamin levels in the blood; they will also sell you education that will help you determine which supplements to take. And they will sell you supplements. So many additives.
What exactly is MTHFR?
There are thousands of enzymes in our bodies, each doing one small, specialized job, like a factory worker who tightens one specific bolt on every machine that comes off the assembly line. MTHFR is the name of both one of your enzymes (the little factory worker) and the gene that codes for it. We’ll talk about the gene in a minute, but first let me give you one short biochemistry paragraph that you can skim if you’re not in the mood.
So here it is. MTHFR, or methylenetetrahydrofolate reductase , is an enzyme that converts 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. This is necessary because 5-methyltetrahydrofolate donates a methyl group to homocysteine, forming methionine. Methionine is an amino acid that we need to make protein, making it important for growth, cell division, and life in general.
This pathway involves other enzymes in addition to MTHFR, as well as several chemical compounds known as vitamins. Vitamin B 12 (cyanocobalamin) is also involved in this pathway. The molecule that MTHFR acts on most directly is a form of folate, a relative of folic acid, sometimes called vitamin B9 . Our body needs these vitamins because they are essential for biochemical processes, including this one.
What exactly is the MTHFR gene?
The MTHFR enzyme exists only because our bodies make it, and the instructions for making it are contained in the MTHFR gene in our DNA. (You can think of a gene as a recipe; they often contain instructions for an enzyme or other useful protein.)
You can seethe MTHFR entry in the National Library of Medicine gene database here . In humans, it is found on chromosome 1. (Other animals have their own versions.) It is expressed in many different tissues, including the lungs, thyroid, spleen, and others. We all have an MTHFR gene—two, actually, since we have two copies of each gene—but mine may not be identical to yours.
What are MTHFR variants?
There are different versions of MTHFR, as there are many genes. People sometimes use the term “mutation”, but this is not entirely accurate since the word implies a one-time, recent change. Different versions of MTHFR are more similar to hair color or eye color. You don’t have a brown hair “mutation”, you just have brown hair. Geneticists use the term “variants” to refer to different varieties of a gene.
There are versions of MTHFR that can do their job of methylation quite effectively, and there are versions that are a little less good at their job. The “slightly less good” options are still functional and do not cause serious health problems for most people.
TikTokers will tell you that “44%”, “40% to 70%” or “more than 50% of us” have one of the gene variants that creates a potentially less efficient version of the enzyme, and they wouldn’t be wrong. It’s hard to say how many of us have the MTHFR variant; some variants only form a less efficient enzyme when combined with another variant, or if you have two copies of, say, the T variant of SNP C677T versus two Cs or one of each. Some variants are also more common in some ethnic groups than others. But the bottom line is that MTHFR variants are extremely common.
And the fact that they’re so common should tell you something: If MTHFR variants were as devastating as TikTok suggests, medical understanding of them would be open, rather than something you have to seek specialized knowledge about. Something that affects half the population is, in the technical sense of the term, normal.
What TikTokers say about the meaning of MTHFR
Many MTHFR videos on TikTok follow a similar pattern to cortisol videos : lists of “symptoms” that range from common inconveniences to serious health problems, along with recommendations for supplements and treatment.
MTHFR videos are quite aggressive in pushing you to spend money on testing (either your DNA or vitamin levels) and especially on supplements. Convincing people that they have problems with MTHFR and then selling supplements and/or education to solve these imaginary problems is big business.
What’s wrong with having the MTHFR option, according to these influencers? One pharmacist blames the gene for causing “headaches, inflammation, depression, infertility, gastrointestinal problems, heavy periods and thyroid problems.” (He doesn’t say how to tell if you have thyroid problems.)
A self-proclaimed MTHFR coach says that “ADHD, anxiety, autism, autoimmune problems, chronic fatigue, colon cancer, depression, digestive problems, hormonal problems, migraines, thyroid problems” are “all symptoms of an MTHFR genetic mutation.”
A naturopath blames MTHFR variants for depression, anxiety and “poor detoxification,” saying it causes your neurotransmitters to be “imbalanced.”
There are also many cozy videos from people who say they have struggled with MTHFR themselves. One mother blames MTHFR for her daughter’s speech delays and parasites, explaining that the girl’s little body is “full of toxins” and that the gene predisposes her to “become a drug addict.” Another woman says the gene will “drive you crazy” and that it’s something that “nobody tells you about, nobody tells you.”
Does MTHFR Really Cause Health Problems?
The only reason anyone knows about this gene is because its health effects have been studied. To spoil the intrigue: almost everything stated above has no basis in the scientific literature, or the connections are so weak that scientists are not sure whether they are related to the gene or not.
One of the health conditions associated with this gene is hyperhomocysteinemia, which can occur if you have certain MTHFR variants and don’t get enough folic acid. Elevated homocysteine levels were previously thought to be a risk factor for blood clots, stroke and pregnancy loss. But since the US mandated that grain products be fortified with folic acid, the link between MTHFR and these diseases has disappeared .
Another potential concern with MTHFR is the risk of neural tube problems in infants. Folate (vitamin B9 ) is important in early pregnancy so that the neural tube can develop properly into the brain and spinal cord. In some populations, people with some MTHFR variants are more likely to give birth to a child with a neural tube defect than people with a more efficient form of the gene.
But here’s the important thing: no matter what variant of MTHFR you have, taking extra folic acid will solve the problem. The American College of Medical Genetics and Genomics and the American College of Obstetricians and Gynecologists state that genetic testing for MTHFR is not necessary or beneficial, and that the recommended intake of folic acid (400 micrograms in addition to what you get from food, for a target of 600 micrograms) ) enough for everyone.
Don’t fall for the lie that you need “methylated” vitamins.
One statement I’ve seen repeatedly is that if you have the MTHFR gene (which refers to one of the potentially less effective options), you should buy methylated vitamins such as 5-methyltetrafolate instead of regular folic acid. Many influencers will then say that the unmethylated versions are “toxic” for you.
From here the claims get pretty wild. In one video , the podcaster says she “literally feels like [she’s] going to have a stroke” if she takes unmethylated B vitamins. Another TikToker representing a genetic testing company claims that “Methyl folate prevents neural tube defects.” Folic acid doesn’t prevent anything.”
But it’s exactly the opposite. Folic acid exists in many different forms in food and in the body. Some are more bioavailable than others, and some are more easily broken down by cooking or simply being stored in a supplement bottle. Folic acid is the only supplement that has been shown to prevent neural tube defects in infants . Not methylfolate or any of the dietary folates. This is highlighted in an article in the American Journal of Clinical Nutrition (I put it in bold):
There have been suggestions in both the popular media and the scientific literature that dietary folic acid should be replaced by the more “natural” 5-methyltetrahydrofolate to prevent NTD (neural tube defect). These sentences should be interpreted with caution because
There is currently no evidence that 5-methyltetrahydrofolate can prevent NTDs, whereas folic acid supplementation has been convincingly shown to reduce the risk of NTDs in various populations.
. Importantly, folic acid supplementation in women with the TT MTHFR genotype has been shown to increase folate status above the level considered maximally protective for NTDs (9).
Don’t take, don’t take, substandard vitamins just because TikTok told you to (or because you got this information from a nutrition “coach” you found through TikTok). If you are pregnant or planning to become pregnant, take at least 400 to 600 mcg of folic acid supplements . (People unlikely to become pregnant are still advised to take the equivalent of 400 micrograms, but it doesn’t matter as much whether it’s folic acid or another form of folate.)
By the time you find out you’re pregnant, many of the important steps in neural tube formation have already occurred, so taking folic acid before pregnancy is recommended whenever possible. Since 1998, grain-based foods (including most breads, cereals, etc.) have added extra folic acid, thanks to a US law specifically designed to reduce the rate of neural tube defects . If you have previously had a child with a neural tube defect, talk to your doctor about possibly taking higher doses of folic acid.
Oddly enough, MTHFR TikTokers also warn about the dangers of “over-methylation” if you take methylated vitamins. Your body does not balance between “over” and “under” methylation, and there is no overall “methylation” process that affects everything in your body. As far as I can tell, the idea of under- and over-methylating is a naturopathic/wellness TikTok trope and not something you’ll find in medical research.
MTHFR does not cause “stork bites” or other birthmarks.
Another myth that is repeated on TikTok is that common appearance features of newborns, such as “stork bites”, “sugar bugs” and sacral dimples, are signs that the baby has the MTHFR variant and is prone to certain diseases . These birthmarks are not associated with MTHFR , although even if they were, there would be no cause for concern. Remember that MTHFR testing is not medically useful. Your doctor will not recommend changing anything if you know your child has the MTHFR variant.