Doctor's Note

Also check out these videos:
Some Dietary Supplements May Be More Than a Waste of Money
Risk Associated With Iron Supplements
Dietary Supplement Snake Oil

And check out my other videos on folate. If you’re worried about the gassiness of beans as a source of folate, check out my blog post Beans and Gas: Clearing the Air

For more context, also see my associated blog posts: Breast Cancer & DietSoy milk: shake it up! and Are Multivitamins Just a Waste of Money?

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on folate. If you’re worried about the gassiness of beans as a source of folate, check out my blogpost Clearing the Air. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    • Monica Dewart

      I have a genetic defect known as MTHFR, which makes it impossible for me to utilize folate from food or conventional supplements. I must take methylfolate supplements twice daily for life, as a result. Although I realize this does not entirely return me to “normal” health, I am extremely healthier with the supplement than without. Can you speak to those who have issues with folate utilization?

      • Linda Illingworth,RD

        For those unfamiliar, humans have a gene that
        regulates the activity of an enzyme called MTHF-reductase. This enzyme is
        responsible for methylation or in layman’s terms, activation of several B
        vitamins, in particular folate. This is an important enzyme as the body only
        uses folate in the activated form and methylation is one method the
        body uses to remove toxic intermediaries of metabolism and other substances
        that might otherwise cause harm. Inability
        to activate folate can contribute to symptoms including fatigue, depression and
        elevated homocysteine that can contribute to cardiovascular disease. During pregnancy this enzyme helps provide
        L-methylfolate which is required for proper development of the neural tube or
        nervous system of a developing fetus. It is estimated that up to 30% of the
        population can possess one or more genetic variants of the MTHFR gene. If you have this genetic trait, the activity of MTHF-reductase can be reduced by 30%-70%. Taking a high quality supplement that
        contains folic acid as L-methylfolate and B12 as
        methylcobalamine, can address this deficiency and help reverse symtoms. For the majority of people who don’t possess this trait, getting most of your nutrients from food is always your first choice. You might like to check out these other interesting videos on supplementation: Vitamin Supplements Worth Taking and Should We Take a Multivitamin

        • pgyx

          Thanks for your excellent and detailed response. I wonder if the high prevalence of MTHFR mutations warrants more extensive screening testing for this mutation, at the very least in women who are pregnant or planning to become pregnant. Do you (or other NF viewers/readers) know the cost of this test and whether insurance generally covers the cost?

          • Joseph Gonzales R.D.

            Linda provided some good resources! I’m not an expert on testing methods and unsure what insurance covers the testing. Perfect question for your doctor and healthcare team. Let us know if you find out anything.

          • Amy

            23&Me do the testing and you can get it interpreted with Genetic Genie. $99 USD

          • pgyx


    • Coacervate

      Could someone from the team…Darryl : ) please address Monica et al. regarding this MTHFR issue? I’ve never heard about it.


      • Deborah Harris

        I can’t see that this has been actioned yet????

    • Kathy B

      Dear Dr. Greger,
      I have been taking vitamin supplements for more than 5 years. A multivitamins and a B complex so I think I’ve been taking about 500 mcg of folic acid a day. About 4 months ago I had my yearly blood test done and the result was scary. My folic acid levels (called here in Spain “folic acid erythrocytes”) were up to 1386 ng/mL when the normal parameters are between 112-508ng/mL. My doctor told me to stop taking the supplements and had me do another blood test about a month later. My levels had risen to 1637 ng/mL!! I don’t know what to do and neither does my doctor. She says she’s never encountered these results so of course now I’m worried!!
      What should I do? Am I at a big risk of getting cancer because of these folic acid levels? Is there a way I can cleanse my blood to get rid of the folic acid surplus?
      I stopped taking the supplements but do I need to eat less folate as well, at least until my levels return to normal? I usually have a green smoothie every morning.
      Many thanks for your help!!

    • GreenManager

      My wife is pregnant and she just heard about the risks associated with folic acid in this video by Dr. Fuhrman (

      Can she obtain the required folate by consumption of leafy greens and – if so – how many servings (and of what type) does she need to consume per day?

      Your help is much appreciated!

  • Brandon Becker

    What about folic acid supplements for vegans during pregnancy? Healthy vegan diets are high in folate so it seems possible and certainly preferable to get this nutrient from food rather than supplements.

    • Toxins

      The fact that folic acid is attributed to the diseases mentioned in the video makes taking it as a supplement out of the question in my opinion. Its similar to taking a beta carotene supplement, what they have done is isolated a single carotenoid and super concentrated it in a pill. The prenatal supplements are truly not necessary, especially if one is eating as health a a plant based eater.

      Check our Dr. Greger’s video of the dangers of Iron during pregnancy and the vitamin supplements worth taking.

      • Sasho

        I’m also very interested in this manner.
        Since both question and answer were provided 5 years ago, is there any new information regarding this?
        Is there any significant finding in the last 5 years that is somewhat changing the stand on folic acid and pregnancy?

  • NickyC

    Hi Brandon,
    Correct, a vegan diet high in greens, such as spinach, and legumes, like black beans, will be an excellent source of folate during pregnancy.
    Please note, however, that a vegan diet is often deficient in iodine, which can pose problems during pregnancy. Please check out this video for more information:

    • brok

      Its vitamin b12 you will lack, but require

  • YD

    Should we avoid folic acid in supplements completely? I’m looking into B-complex supplements and almost all of them contain 1 mg of folic acid. Thanks for all the awesome videos!

    • Toxins

      The study measured folic acid at 1 mg or higher. 1 mg is considered the upper tolerable intake of folic acid. They note that .4 mg of folic acid in individuals gets metabolized to folate but higher than that and we get unmetabolized circulating FA which is harmful. If you are eating a well balanced plant based diet the only supplement you would need is vitamin b12. A B-complex is not necessary.

      • YD

        Thank you so much for the reply! Yeah I was also wondering if B-complex was necessary, I heard from some sources that your body really wants all the B vitamins to be taken together. But Dr Greger seems to recommend B 12 supplement only.

        • Toxins

          It is true that almost all whole plant foods contain a mix of the b vitamins, but just because they lack b12 doesn’t mean that the other b vitamins are ineffectively used, nor should we have any reason to believe so.

          • YD

            I guess when I really think about it, it makes sense that since we can get the rest of the B vitamins from a plant-based diet, the only supplement we need is B 12. Thanks again for your reply :)

  • Michael Greger M.D.

    For some context, please check out my associated blog post Multivitamins and Mortality!

  • There are food based vitamins such as MegaFood, which offer folate in the normal food form, from broccoli. 40 percent of population has MTHFR genetic mutations which affect the absorption of folate, to varying degrees. The synthetic folic acid is probably more harmful to these people and on top of that, they may need food based supplements-depending on the health of their gut and which mutation they have. It is insane that folic acid is added to everything.

  • I was on 5mg folic acid daily to offset harmful effects of methotrexate (for Rheumatoid Arthritis) I’m currently off the mtx but has the 5mg a day possibly done my body harm? I know the mtx probably has! :(

  • Is this supplement ok? It contains Folate (5-Methyltetrahydrofolic Acid), not Folic acid:

    • chicovegano

      5 MTHF is the folate that is actually used in the folate cycle to to make B12. If your folate is not able to be converted to 5-MTHF because of an enzyme deficiency (MTHF reductase) then this is the one that will keep your B12 levels up, your homocysteine levels down and keep your methylation happy. Folic Acid (provided by law in all enriched products) is not found in nature but is quite shelf stable in foods, and requires several more steps to turn into 5-MTHF. We are provided so much in our over consumption of enriched foods (think anything with flour that is not 100% whole wheat) that the build up of Folic Acid can be toxic and cause its own problems. And as chicavegana comefrutes commented above, a large segment of the population has the defective MTHF reductase enzyme which greatly puts them at risk.

      • brok

        Dude, you are so wrong. Go back to college

  • eva101

    What is your opinion about L-methylfolate .

  • PM

    Hi Dr. Greger: I was wondering about Perfect Prenatal by New Chapter Organics as is is a whole foods vitamin which includes “folate” not “folic acid”. Also, I am wondering about Seeking Health L-5 MTHF 1000 which claims to provide only folate as “metafolin” for people with the MTHR issue. In general, are vitamins containing “folate” no “folic acid” ok?

    • Tommasina

      I think Dr. Greger would stick to his assertion that getting vitamins from whole foods and not pills, will serve our bodies better. Beans and greens are great, affordable sources of folate. :) Hope that helps.

  • Methyl Kiki

    Dr. Greger, you need a video on MTHFR defects. Some people do process folic acid, but 40% of the population have an MTHFR defect that causes them not to process folic acid into folate. So your recommendation that everyone eat beans and greens is right on target; however, people with MTHFR defects should take a multi and B-complex containing the natural form of folate. In fact, there are studies that link pregnant women who have this defect and take prenatal vitamins containing folic acid are at much high risk for premenopausal breast cancer. That’s 40% of women! (MTHFR polymorphisms, dietary folate intake, and
    breast cancer risk: results from the Shanghai Breast Cancer Study. Shrubsole MJ1, Gao YT, Cai Q, Shu XO, Dai Q, Hébert JR, Jin F, Zheng W.

    Since my entire family has one or two MTHFR defects, I’ve been reading more and more and am astounded by the statistics, some of which you state that are probably related to MTHFR people ingesting folic acid-fortified foods and increasing incidences of various types of cancer, but it’s more than that. It probably has a hand in every western degenerative disease. As you know, methylation is essential for the proper function of most body systems and cellular processes. It is also needed to support glutathione production which neutralizes free radicals, helps the body process toxins and supports proper DNA synthesis and repair and other metabolic processes. It is required for the creation of every cell in your body. Consequently, it is easy to see how this mutation could have a role in many conditions and diseases. And while I agree that if one is a vegetarian or vegan and eats beans and greens and does not take folic acid or eat fortified foods, their folate status will likely be good enough to not have problems with MTHFR; this is unfortunately not the case for the majority. Please do a video on MTHFR. 40% of the population is a lot of people. Get this, 98% of autistic people have this defect. No wonder they may have trouble processing toxins. Great site. Love the information. You do a great service to the many seekers of nutritional and medical knowledge! Many thanks!

  • Matt

    Seems like a more recent summary (and a reading of the study posted) suggests there is not a significant known disease correlation between suggested FA intake and disease:

    • Bruce Cropley

      I’d be interested in an update on this too… :)

  • Consuming MethylFolate in green vegetables trumps all #MTHFR gene polymorphisms.

  • Schweikle

    Yes, I’m very curious to hear the Dr’s opinion on the MTHFR research out there. I asked my doc and she just said it’s “controversial”. I have compound heterozygous mutations and was taking methylfolate in very high quantities daily, but recently stopped because I’m wondering if it’s really making a difference. If I don’t need to be spending $40/month on those pills, that would be great!

    • pgyx

      I recently heard from a physician lecturer that preliminary research suggests *high* doses of methylated B-vitamins (methylcobalamin, methylfolate) may shift the cell reproductive cycle towards cancer formation. He said it’s really just a theory right now, but his current recommendation is to avoid *high* doses of methylated B-vitamins. Those with MTHFR mutations should still take *physiologic* doses of methylated B12 and folate, but avoid high doses.

      I would love to see Dr. Greger do a blog post or video on this issue as I have been unable to find the research the lecturer referenced in making his recommendation and as others have commented, MTHFR mutations are common.

  • julialoha

    Dr. Ben Lynch and Dr. Amy Yasko have a lot of information on line about the MTHFR genetic defects. Lynch says that those of us with MTHFR defects need to take 5-methyltetrahydrofolic folate. He says not to take the wrong kind – folic acid. Synthetic folic acid is not effective and the unmetabolized folic acid hangs around and reduces our T killer cells leading to immune issues. Also, I believe he says it fills up the folate receptors so the real stuff can’t get in. People can get raw genetic data from 23and me to see if they do have MTHFR (and many other) problems and then go to for help deciphering these very complex genetic issues.

  • PLA

    Thanks for your great videos and articles Dr Greger. I mentioned your article on Folic Acid to someone and they said they had read the same studies and the problem with folic acid occurs when little to no vitamin E is ingested. She said that there is no problem with folic acid as long as they take vitamin E as well. Can you look studies again and comment on this. I was considering stopping all folic acid supplementation, but that is not an easy thing to do because nearly all multi-vitamins contain folic acid, not folate.

  • Daniel G

    Hey :),

    nutritional yeast by some brands also contain high doses of folic acid. Which chemical form of folic acid do they contain? Folic acid or the naturally occuring chemical forms of folate? Is nutritional yeast consumption with high doses (or even low doses) of folic acid safe? I have concerns because as far as i know the growing medium of yeast is often fortified with vitamins to achieve such a high content of said vitamins. Therefore my subsequent question is whether the folic acid in yeast is converted into a naturally occuring form.

    Kind regards,

  • Alex

    If one consumed a lot of folic acid in the past and stopped would we expect the folic acid to slowly be assimilated?

  • Alan Burton

    Hello, I have just received my blood test results. As expected urea and creatinine are low because I’m eating only plants. As expected my B12 is low so i will start supplementing this is the reason i went for the test). However, my folic acid is high at 20.5ug/L (the printout states that 3 to 20ug/L is the normal range). Is this a problem or a good thing? Is it merely a healthy side effect of eating a WFPB diet? I couldn’t find the answers to this query on google so if anyone here has some knowledge I’d love to hear it. Thanks, Alan

  • Cris

    Should one worry about folic acid in nutritional yeast? How much is too much. The brand I use says is had 270% amount of folate, but lists folic acid at the very end of the ingredient list. It’s Bob’s Red Mill.