Vitamin B9: The MTHFR Gene and Folate

Are you pregnant or thinking of becoming pregnant? You might want to pay special attention to this nutrient!

Being aware of your specific genes can help you make more informed decisions about the foods and exercises that are right (or wrong!) for your body—all of which can help prevent health problems later down the road.*


Written by: Jamie January 3, 2020

What is Vitamin B9?

The active form of vitamin B9 is known as 5-methyltetrahydrofolate (5-MTHF). Most importantly, B9 helps form healthy red blood cells which affect your energy levels.

It is also an important nutrient if you are pregnant or thinking of becoming pregnant. B9 is an essential nutrient which supports fertility and neural tube development during pregnancy.

Folate Vs. Folic Acid

Folate is the naturally occurring form of vitamin B9.

Folic acid is a synthetic form of vitamin B9 and as a result, the liver must convert it before it can be absorbed in your body. Some people have trouble converting this form due to genetics, more on that later.

How do I get folate?

The following foods are also good sources of folate:

  • Leafy greens
  • Vegetables like asparagus, brussels sprouts, and broccoli
  • Fruits like banana and papaya
  • Avocados
  • Legumes
  • Fortified cereals

What causes low folate?

  • A diet low in fresh fruits and vegetables
  • Excessive alcohol consumption: Alcohol affects folate absorption,
  • Stomach problems: When your small intestine isn’t working well, like with Crohn’s or celiac disease, your body has a hard time absorbing folate.
  • Genetics
  • Medication side effects
  • Your pregnant: A growing baby absorbs folate from the mother.

What are the symptoms of low folate?


  • Fatigue
  • Lack of energy
  • Feeling short of breath
  • Headaches
  • Pale skin
  • Racing heart
  • Weight loss or not feeling hungry
  • Ringing in your ears


  • Neural tube birth defects in the fetus of expecting mothers
  • Megaloblastic anemia: The red blood cells are larger than normal and not fully developed.
  • Low levels of white blood cells and platelets
  • Increased risk of heart disease [1] Although research is inconclusive on this [2]

How do genes play a role?

Certain variants of the MTHFR gene affect the ability to convert folic acid so your body can absorb it.

  • The T variant of the rs1801133 genotype affects folic acid absorption and as a result can lead to folate deficiencies.
    • One copy of the T variant is associated with a 45% reduction in folic acid absorption. Two copies can reduce absorption by 80-90%  as well as cause high homocysteine and low B12 levels [3]
  • The A variant of the rs1801131 genotype affects folate metabolism and can lead to deficiencies.[4]

What can you do about it?

  • Review your genetic predispositions. If you have not done testing, get your genes tested with Secret Sequence!
  • Ask your doctor for a blood test to help monitor your levels.
    • This is especially important if you are pregnant!
  • Eat foods high in folate to get your recommended daily amounts.
    • The recommended daily amount of folate for adults is 400 micrograms (mcg).
    • On the other hand, the recommended amount for adult women who are pregnant or could become pregnant is 400 to 800 mcg a day.
  • Look for the 5-methyl-THF not folic acid vitamins if you must supplement. If you have the MTHFR gene, you will need it, and for people that don’t, it is more readily absorbed anyways.
  • If you have certain risk factors like celiac disease, Crohn’s disease, certain cancers, or certain mutations of the MTHFR gene, it is particularly important to mindful of your folate levels.
  • Be aware of the symptoms of folate deficiency and talk to your doctor if you have any concernsand remember to discuss if you have genes that can affect your levels!

What Comes Next?

New research on the topic is being done all the time. You have the ability to learn more about your DNA, so why wouldn’t you want to learn what changes can make you a healthier you?

One more important reminder: you need to be in control of who you share that information with. Secret Sequence will never sell your data—we never even ask for your name! Safely learn more about yourself and your health: order our Nutrition report today to learn more about your body’s vitamin responses!

*Disclaimer: All information, content, and material of this website is for information purposes only and are not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider.


[1] Li, Y., Huang, T., Zheng, Y., Muka, T., Troup, J., & Hu, F. B. (2016). Folic Acid Supplementation and the Risk of Cardiovascular Diseases: A Meta-Analysis of Randomized Controlled Trials. Journal of the American Heart Association5(8), e003768. doi:10.1161/JAHA.116.003768

[2] Clarke, R., Bennett, D. A., Parish, S., Verhoef, P., Dötsch-Klerk, M., Lathrop, M., … MTHFR Studies Collaborative Group (2012). Homocysteine and coronary heart disease: meta-analysis of MTHFR case-control studies, avoiding publication bias. PLoS medicine, 9(2), e1001177. doi:10.1371/journal.pmed.1001177