What is the MTHFR mutation?

Qu'est-ce que la mutation MTHFR?

What is the MTHFR mutation?

In France, women who want to become pregnant are almost all systematically supplemented with folic acid: synthetic vitamin B9, a speciality reimbursed by the social security system, indicated at least three months before conception (if there is a desire to become pregnant), as well as during the first trimester of pregnancy. Indeed, vitamin B9 in its active form (5-methyl-tetrahydrofolate or 5-MTHF) plays an essential role in cell multiplication and participates in the good development of the nervous system of the embryo, in particular the closing of the neural tube.

Folic acid is found in the majority of food supplements and medicines, but it is not an active form of vitamin B9. It is a synthetic form.

In our organism we have an enzyme to make it active: the 5-MTHFR, coded by the MTHF methylation gene. However, it turns out that there is a mutation in this gene in the population, which means that 16% of the female population does not produce an enzyme that functions at 100%. This mutation - which can be heterozygous (only 1 allele of the mutated gene) or homozygous (2 mutated alleles with a loss of activity of 75%, which is very important) - prevents you from correctly transforming this synthetic folic acid into its active methylated form: 5-MTHF (5 methyl-tetrahydrofolate), which has beneficial and indispensable effects on our body.

In Europe, according to some recent estimates (2019), the polymorphism of this enzyme would make 40 to 51% of women heterozygous (CT), 10 to 18% homozygous (TT). In homozygous women, the activity of the enzyme would be strongly reduced (around 75%) and the synthesis of MTHFR would be insufficient, compromising the assimilation of the synthetic form of folic acid. In case of mutation, the synthetic folic acid will accumulate in a non-metabolized form and can have negative impacts on your body, in particular that of altering the functioning of this famous enzyme 5-MTHF.

But what is homocysteine?

Homocysteine is a derivative of the amino acid methionine, which, if present in the blood in excessive quantities, can have negative consequences for your health.

  • the cardiovascular risk (it is 40 times more predictive than cholesterol) because it promotes atherosclerosis (it thickens the blood),

  • Neuropsychiatric risk: its elevation is correlated with the development of Alzheimer's disease Hu Q, Teng W, Li J, Hao F, Wang N. Homocysteine and Alzheimer's Disease: Evidence for a Causal Link from Mendelian Randomization. J Alzheimers Dis. 2016 Mar 22;52(2):747-56. doi: 10.3233/JAD-150977. PMID: 27031476. Xie Y, Feng H, Peng S, Xiao J, Zhang J. Association of plasma homocysteine, vitamin B12 and folate levels with cognitive function in Parkinson's disease: A meta-analysis. Neurosci Lett. 2017 Jan 1;636:190-195. doi: 10.1016/j.neulet.2016.11.007. Epub 2016 Nov 10. PMID: 27840145, or to the risk of developing dementia Wald DS, Kasturiratne A, Simmonds M. Serum homocysteine and dementia: meta-analysis of eight cohort studies including 8669 participants. Alzheimers Dement. 2011 Jul;7(4):412-7. doi: 10.1016/j.jalz.2010.08.234. PMID: 21784352.

  • Its impact on fertility in men and women as well as on the proper development of pregnancy (which is what matters to us here). In men, too high a level is correlated with the quality of spermatozoa: azoospermia, asthenospermia (less mobility and more atypical shape) - or in women (essential for metabolism and hormonal balance), too high a level is linked to certain pregnancy complications (premature babies, complications at delivery, low birth weight, miscarriages). Timmermans S, Jaddoe VW, Hofman A, Steegers-Theunissen RP, Steegers EA. Periconception folic acid supplementation, fetal growth and the risks of low birth weight and preterm birth: the Generation R Study. Br J Nutr. 2009 Sep;102(5):777-85. doi: 10.1017/S0007114509288994. Epub 2009 Mar 30. PMID: 19327193.

Homocysteine can be recycled into either methionine or cysteine to give glutathione, the main antioxidant of the human body! You understand the importance of its recycling. Indeed, a lack of vitamin B6 (essential for the transformation into cysteine), methyl-B9 and methyl-B12 (vitamin B in their active form) is directly correlated to an increase in homocysteine because without them the recycling of homocysteine cannot take place. Vitamins B9, B12 and B6 work together and synergistically, it makes much more sense to take all 3 if supplementing than alone.

We are not all equal in our ability to transform vitamin B9 (folates, folic acid) into methylated vitamin B9 because of this famous genetic mutation.

If you are wondering about your genotype, you can of course do a genetic test or, as a first step, a homocysteine dosage which is a good reflection of your methylation capacity. The optimal level is 7 and not just xtagstartz 10 (a more targeted value than many labs). As with all reactions in the human body, there is a fine balance, too much methylation is not good either.

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