Doctor's Note

More on the benefits of exercise in:

Don’t have time? Yes you do! See: Standing Up for Your Health.

What else can we do to preserve our immune function? See:

Nutritional yeast that’s fortified can also be a convenient source of vitamin B12 (Safest Source of B12).

For more context, check out my associated blog post: Why Athletes Should Eat More Nutritional Yeast.

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  • David

    Excellent discovery!! Thank You!!!!
    A little “dab” (sprinkle) will do you :-)

    • HemoDynamic, M.D.

      You’re supposed to eat it, not put it in your hair! :-)
      (Ah, the memories of the Brylcream ads–For men who use their heads about their hair.)

  • elsie blanche

    Cool. Is there an alternative you are aware of that you think would achieve the same benefits of this nutritional yeast/brewers yeast, in this regard? Say, Broccoli, beans, fruit, etc.?

    • Brandon Klinedinst

      I believe the form of beta-glucan discussed in this video (1-3, 1-6) is also the kind found predominantly in mushroom species too. The kind found in grains (especially oats) is also known to be biologically active, but not as much. It contains a different beta-glucan format (1-3, 1-4).

      • elsie blanche

        Thank you.

      • DanielFaster


        • Brandon Klinedinst

          The kind of beta-glucans found in grains like barley is not the same kind of beta-glucan discussed in the video. However, both are known to have immune boosting advantages.

  • Thanks again Dr. Greger for ferreting out some fit facts we can use!

  • Rich

    Nice finding. I’ve found using multi B-vitamin supplements (higher dosage versions w/B12) helpful in maintaining respiratory immune robustness in athletes. Have you experienced this?

  • Eva

    Have you seen Dr Baylock’s studies of Nutritional Yeast being an excitoxin? Can you research this and see if it is true? Thanks so much!

    • elsie blanche

      I also am curious of this. There are people out there that swear this stuff is toxic. I’ve always wondered why they are so passionate and serious about pointing out how bad nutritional yeast is for humans…is there something to this?

      • Ashwin Patel

        Is Brewers Yeast/Bakers Yeast safe for people suffering from Inflammatory Bowel disease? Is pure Beta Glucan safer?
        Antibodies to Saccharomyces cerevisiae in patients with Crohn’s disease and their possible pathogenic importance.

        • elsie blanche

          Interesting. I hope Dr. G will explore this further.

    • Andrea Kladar

      I’m also interested in this research as well. I’m curious what kind of research was done by Dr. Blaylock on this. Was it an actual trial or just a hypothesis?

  • Plantstrongdoc M.D.

    Data suggests that long term excessive exercise may cause myocardial fibrosis and risk of malignant ventricular dysrhythmias and may increase coronary artery calcification. Mortality is lower in people doing moderate excercise than in sedentary people, but probably also lower than in people doing excessive exercise . The U curve again.

    • Aaron Kester

      Dr O’Keefe is basically the Gary Taubes in trying to prove that running is bad for your health. He has an agenda and cherry picks data to support a more hunter gatherer level of physical activity. Of course a few people in the running community found a lot to critique with what he had to say:

      • Plantstrongdoc M.D.

        In the article I refer to, I dont think that the author tries to prove that running is bad for your health, I think the point is that extreme levels of excercise is not (heart) health promoting. I dont no anything else about the author, but why would anybody have an interest in claiming that running or exercise is bad for your health?

        • Aaron Kester

          I should clarify, no he isn’t trying to say running or physical activity is bad for humans, but like I said, O’Keefe wants us to believe we need to be only as physically active as hunter gatherer populations were and that anything more than that is inherently bad for you. You will find his name listed here along with Lauren Cordain and other prominent Paleo promoters on research regarding a Paleo lifestyle That right there should raise some red flags. I know the articles I posted are only journal articles and opninon pieces, but they do outline some of the issues with his research and data analysis. Here is another response I forgot to post as well

          • Plantstrongdoc M.D.

            OK, I get your point. My agenda is not to defend this point of view, but O`Keefe is not the only scientist raising concern about excessive exercise and heart health, and we probably all know of professional athletes dropping dead at a young age, and that is in my opinion a reason to concern, so I think it is a legitimate guestion to raise. Of course running, biking, crosstraining, spinning is health promoting, but maybe there is a safe upper limit.

          • Aaron Kester

            Ya, I’m definitely not trying to go to the other side and say there is no safe upper limit, but I would have to say we honestly just don’t know what it is at this point from what I’ve looked at. The problem with O’Keefe is that he is trying to get the data to say something it doesn’t at this point in time. But there are reports that go both directions on this issue and hopefully we know more in the near future with the amount of interest their currently is in marathons, ultra running, triathlons, etc.

          • Aaron Kester

            There is quite an interesting study that will be published soon looking at French Tour De France cyclists and rates of mortality, heart disease, cancer, etc. It would be one of the best studies to date at least showing that for people that have engaged in very strenuous levels of repetitive exercise, we aren’t seeing this U shaped curve in terms of the benefits of high intensity physical activity. Of course this is just 1 population study, but we really have yet to see a real trend showing mortality in even the people that exercise well over an hour a day in a responsible manner.


          • DanielFaster

            Thanks, Aaron, as a late middle age amateur bike racer this is very encouraging info to reassure my doctor. However, not sure TDF racers are good role models: in 1960 it was won by a chain smoker and as recently as the 80’s racers had to ask not to be bunked with smokers; before that amphetamines were found in the jersey pockets of cyclists who died on the road from heart attacks; Chris Horner who just won the Vuelta Espana is known to eat McDonald’s and Burger King death patties between GMO pillows after stage wins. On the other hand it may be a good sample since their habits do seem to reflect society in general. So far David Zabriskie is the only vegan TDF racer I know of in 2011,, out of a field of 189/yr (much less than 1%), so as a group they are still behind the curve. A lot of the old-school trainers/coaches like Joe Friel still swear by animal protein and refined carbs, hard to change that momentum.

          • Aaron Kester

            Ya I have little knowledge of the health habits of French Tour De France riders, hopefully the study will highlight this issue, but if they do tend to live unhealthy lifestyles with the only exception being they exercised for hours a day,that could help increase the relationship between exercise and decreased mortality, cancer, heart disease, etc.

          • DanielFaster

            Most of the riders in the TDF, as well as the other 3-week stage races in Italy and Spain, are not French, but they seem to more or less reflect cultural norms. It will indeed be interesting to see if the study considers confounding factors to narrow the focus on the effects to intense endurance activities.

          • JOJO

            That study may not be terribly relevant to the average strenuous exerciser given the widespread doping in competitive bike racing.

      • Andrea Kladar

        I’ve watched presentations by Dr. Keefe. I was an ironman triathlete before becoming aware of his views and continue to be an ironman triathlete after seeing his research.
        That is – a vegan triathlete of course :-).

  • Wendy

    Nutritional yeast does not contain B-12!. I was always told that Nutritional Yeast was s non-meat product but it had B-12. I just bought some and the box said “Nutritional Yeast with B-12”. The box next to it just said “Nutritional Yeast”. I read the ingredients on the one with B-12 and it is a ADDED INGREDIENT not naturally in it.
    On the happy side we use nutritional yeast on more things than pop-corn. It is usually added into many of our sauces and salad dressings. Be creative with it.

    • Toxins

      Perhaps the b12 was an added ingredient for the brand you bought, but nutritional yeast has naturally occurring b12 as well.

      • Aaron Kester

        I’ve consistently been told from multiple sources there is no naturally occurring vitamin B12 in nutritional yeast and that it has to be added. Yeast itself does not naturally create vitamin B12, only bacteria do. That link you provided is almost definitely fortified nutritional yeast

        • Toxins

          Yeast is a microorganism, not a plant. The link I provided is to the USDA nutrition database, they typically state whether an item is fortified or not. In this instance, they did not, which tells me that it is naturally occurring.

          • Aaron Kester

            Yeast are classified as fungi. They are unicellular eukaryotes which means that they are single celled organisms that consist of membrane-bound nuclei and other organelles. Bacteria on the other hand are prokaryotes which implies that they do not contain a membrane-bound nucleus or other organelles.

            Your link shows that the nutritional yeast used for their analysis was KAL brand nutritional yeast flakes. Here is a link to that states vitamin B12 was fortified as were other B vitamins:

            Theoretically some species of bacteria that can produce B12 could potentially grow along with S. cerevisiae (the species of yeast used in nutritional yeast) in the wild, commercially produced nutritional yeast is grown in controlled conditions that would normally not allow those bacteria to grow. Therefore, nutritional yeast should not be relied upon as a source of B12 unless it is fortified, which it is in almost all cases.

          • Toxins

            Thank you for sharing this information. I did not realize that KAL was a brand name. I am aware of the distinction between fungi and bacteria, but I did indeed think yeast was a bacteria without investigating or thinking much of the matter. After further investigating, I do indeed see that yeast is a fungi.

          • Aaron Kester

            My pleasure. I didn’t mean to call you out, but I just didn’t want there to be any confusion from anyone when it comes to B12 as we know that can create major problems for most people if they aren’t finding a reliable source. But luckily almost all brands of nutritional yeast I have seen are in fact fortified, so it shouldn’t be an issue what brand you used.

        • elsie blanche

          The literature I’ve read claims that B12, if it occurs in nutritional yeast naturally (as in, the nut. yeast did not have B12 added to it), is a B12 analogue, thus, not a true form of B12, and of no B12-related benefit. Thoughts?

          • Aaron Kester

            I have no knowledge of whether the natural B12 on nutritional yeast would be active or inactive, but I think it would be largely irrelevant because I’ve never seen manufacturers that allow bacteria to grow alongside their yeast strains.

          • JOJO

            I use Bragg’s nutritional yeast which is fortified with the B vitamins including folic acid and B12, but more for the cheesy flavor. Anyone with pernicious anemia or eating 100% plant based diet has to fortify with B12. I have pernicious anemia and I eat a whole foods, plant based, minimally processed diet, inject B12 monthly, have normal B12 blood levels, and am as healthy as a horse.

        • HereHere

          I recall reading a dietitian stating that nutritional yeast, except Red Star, is not a reliable source of B12. That was either from the Vegetarian Resource Group or Jack Norris, RD. Each of these sources vary on their recommendation of B12 for vegan diets, with the VRG recommending 2000 micrograms/week (or perhaps it was 1000 mcg twice per week, which is similar).

          • Aaron Kester

            Here is Jack’s postion:

            Eating fortified foods is fine and is mostly how I get vitamin B12 (I take a 1,000 µg pill once in awhile). But brewer’s and nutritional yeast do not have vitamin B12 unless they are fortified with it. You also have to take care not to let them sit out in the light as that can damage B12.

          • Toxins

            I have heard this as well from Jeff Novick. Its best to supplement anyway, otherwise we’d have to consume nutritional yeast 3 times a day.

  • 6rtury

    I’ve been using nutritional yeast for about 10 yrs. One side effect I’ve not read about is the neon-tint hue it gives to urine as short as 30-min after ingestion. The effect is short-lived, but is constant. Has anyone else noticed this? Is it naturally occuring or is there an added dye in this product. None is mentioned anywhere.

  • 6rtury

    I need to corredt my post of 7 minutew ago. I meant to say it imparts a nluorescent yellow tint to the first urine after ingestion.

  • 6rtury

    Gads — I am groggy. Corrections of below: …correct…minutes…and fluorescent. Note final corrections. Sorry

    • Aaron Kester

      That tint is a result of the excess B vitamins being excreted through your urine. Perfectly normal and happens to pretty much everyone.

  • Laurie Masters

    Dr. Greger – I’m very interested in your thoughts on this article:
    Nutritional Yeast—Super Supplement or Neurotoxin?

  • Kman

    This finding is VERY exciting for me! What about vegemite? Could someone please offer their opinion if Vegemite would have the same benefits?

  • lovestobevegan

    The Unusual Suspects Salad

    -6 fronds organic* kale, de-stemmed (if large stems) and torn into pieces
    -3 leaves purple cabbage, chopped
    -1 green or red pepper, diced
    -1 small summer squash or zucchini, diced
    -1 small cucumber, diced
    -3 slices onion, chopped
    -1 cup cooked lentils
    -1 tbsp sunflower seeds
    -2 tbsp fresh cilantro, chopped
    -1 slice lemon
    -black pepper
    -sea salt
    -1-2 tbsp nutritional yeast

    Combine all ingredients except lemon, pepper, salt, and yeast. Toss ingredients and squeeze lemon slice over top and mix in lemon pulp. Season to taste with sea salt and black pepper and top with nutritional yeast.

    *Kale may contain pesticide residues of special concern so choose organic.

    ~Complements of lovestobevegan

  • seachangeau

    there is a debittered brewer’s yeast. ‘nutritional yeast’ is sadly adulterated with synthetic b vitamins (person who asked if it was toxic answer is yes.)

  • L

    I may be entering the ER today since my doc cant see me anytime soon for possible candida. I dont think a supplement like these would be safe. I cant eat or drink anything without a terrible hangover-headache and I get so dizzy I feel drunk.
    Dr Greger, please do a video on fungal-infections.
    I cant have a banana without a debilitating headache and severe paranoia.
    Its like being on drugs,even my thoughts are not me.

  • MG63

    “We have tested IGF-1 about every 3
    months since 2003. We test it along with the IGF binding proteins 1, 2
    and 3, insulin, T3 and the VAP test.

    We wanted to see how total
    protein fared against the above battery of tests as well as individual
    protein concentrates including whey, brewers yeast, soy protein
    isolate, nonfat yogurt, kefir. and a mixture of individual amino acids.
    The results were frightening — each one of these substances sent IGF-1
    significantly higher — independent of total calorie intake.

    goal was to customize our CR diet to produce IGF-1 in the lower third
    of the reference range and to get IGFBP1, which is an indicator of
    SIRT1 activity, glucagon activity, etc., at the high end of the
    reference range.

    This is consistent with the downregulation of
    energy availability and of anabolic activity that is shown in
    long-lived CR animals.

    I have found, however, that protein
    absorbability makes a greater difference in IGF-I (and the binding
    proteins) than total protein, if the protein is from vegetables and
    grains, beans (this does not mean concentrates), and fruits.””

    As seen above, nutritional yeast has been associated with an increase in IGF-1 activity.

    From the linked discussion:

    “Elevated IGF-1 levels in adults can increase the growth rate of cancer.
    Even isolated plant proteins (like soy) can raise IGF-1 levels. We
    want lower IGF-1 levels especially as we get older.

    The above studies showed that higher “total” protein levels raised
    IGF-1, and so keeping “total” protein levels low, was important.” – Jeff Novick, RD

    The Cron-o-meter assesses Red Star Nutritional Yeast as 56.7% protein as a percentage of calories.

    I wonder how the runners would have fared with plant-based nutrition post-race, like a baked potato or an apple, as opposed to supplemental yeast.

    • Jay M

      > whey, brewers yeast, soy protein isolate, nonfat yogurt, kefir and a mixture of individual amino acids.
      > each one of these substances sent IGF-1 significantly higher

      IMO, good reason to stay away from yeast supplements.

  • Hi Dr. G. I am a very physically active vegan- bodybuilding, spin classes etc. and was very interested in this video about nutritional yeast. The problem is that every time I eat something which contains nutritional yeast, I get this awful blood filled blister in my mouth. It is painful until it bursts. Then it turns white and takes about a week to heal. The last one I got was right on my tongue! I usually one get one blister and it forms while I am eating the food. Is this something I should be concerned about? I don’t get any other symptoms. Is there anything I can do to prevent these blisters from happening? Thank you!

  • Shane

    You briefly mention in this video, regarding nutritional yeast, that you “use it mostly to sprinkle on popcorn”. I have been doing this all year, and I love the taste. But now I want to boost the health promoting effects of popcorn even further, by eliminating the use of oils, and adding dulse/seaweed flakes (for iodine) as a salt replacement – but I cannot find any videos in which you specifically talk about popcorn (or how you prepare it yourself). If I switch to a hot-air popper, how could I get nutritional yeast and other sprinkled goodies to actually “stick” to the popped kernels? Does anybody else have ideas to share?

  • Amy Caruthers

    It appears that there is controversy regarding nutritional yeast due some research that it raises IGf1 levels because of the synthetic folic acid, and had been linked to colorectal and other cancers. This is very concerning to us plant-based folks who use it liberally in place of cheese! It’s rumored that neither Dr. Goldhammer at True North or Jeff Novick approves of it Apparently Dr Fuhrman has research why ONLY to consume the non- fortified version, since it’s the synthetic folic acid that is suspiciously involved in raising IGf1. I’m finding it difficult to ferret out the facts as regards what to buy, if at all! Can you shed some light on this topic for us? Thanks so much!

    • Jay M

      IGF is more likely a function of branched amino acids (ie leucine, isoleucine, valine) than folic acid.

      • Amy Caruthers

        So are you saying that regular nutritional yeast that can be found in bulk in, for example, Whole Foods is safe to eat? It is probably the fortified version

        • Jay M

          Based on below abstracts, my conclusion is that the increase in IGF-1 associated with nutritional yeast is more likely a function of it’s branched amino acids ( than that of folic acid. Yeast is a concentrated, protein-rich food (91% of cals). 2 heaping tables spoon provides approx 9 g of protein. It is safe to eat. It can be used to reduce reliance on animal products. I prefer not to as I think I get enough protein from fruits and veggies and because of a leaky gut issue.

          Abstract ( suggest folic acid could decrease the risk of colon, breast and prostate cancers mainly in wine drinkers, whereas it increases the growth of preneoplasic cells of the latter cancers.
          24465421) suggests folic acid supplementation may promote the progression of established mammary tumors in rats.
          16728583 suggests folic reduces risk of colon cancer by decreasing IGF-IR.
          16111879 suggests folic deficiency retards rat embryo skull bone development via IGF-IR.
          25207954 suggests maternal vitamins and folics supplementation reduces childhood leukemia.
          23682073 suggests folic prevents the initial occurrence of sporadic colorectal adenoma in Chinese older than 50 years of age.
          24090688 suggests folic supplements before and possibly during pregnancy may protect against childhood brain tumors.
          There are many other abstracts related to using folic acid conjugates to kill cancer cells.

        • Jay M

          I personally wouldn’t take nutritional yeast as I don’t need to push IGF-1 levels.
          If I had to take it, I would consume the non-fortified one. I’m a minimalist :)

  • Amy Caruthers

    Jay, I appreciate your responses regarding nutritional yeast. I understand you don’t use it, but if you were to use it for flavor( not protein supplementation) which kind would you use or recommend – the synthetic fortified folic acid kind or the unfortified folate? It seems that there are mixed reviews! Thanks so much.

  • noe

    very interesting! i heard that the sweet nutritional yeast don’t have this good proprieties like the natural and bitter one, it is that true?
    because in the process to take out the bitter flavor you lost some vitamins

  • C B

    How much nutritional yeast is too much?? If one consumes more than the recommended dose daily, are there negative effects as a consequence?

  • Hi Dr. Greger! What about some videos and links that claims that the nutritional yeast are a cousin of MSG?

  • John Axsom

    I’ve never heard of nutritional yeast. I am going to have to go out and buy some. I guess you can find it at the health food store. Is there anything I should be looking for as far as brands go? I also had questions about the benefit of popcorn, but since I see from the video that Dr. Greger eats popcorn, I feel better about consuming popcorn.

    • Thea

      John Axsom: Nutritional yeast has become so popular, you can even find it in some mainstream grocery stores, such as Fred Meyer. (At least the Fred Meyers in my state carries it, and they have the best price in my town.) Just look in the bulk section. You are right that health food stores should also carry it. And if you are at a loss, then getting it on-line should be pretty easy.
      Note that nutritional yeast comes in shapes such as powder and flaked. The flaked is usually more expensive and there are people who prefer flaked. I prefer powdered myself and I think that works better in recipes.
      There are also various brands and prices. I have found that the various brands do taste slightly differently, so it might be worth trying a few brands. Also note that some brands have the B12 (added) and some do not.
      FYI: If you look at all the desserts and snacks people eat, popcorn is a pretty great choice depending on what gets put on it. But if I remember correctly, popcorn is a pretty high calorie dense food. So, people who want to lose weight should stay away from it or consume only rarely. Also note that while Dr. Greger counts popcorn as a whole grain in his Daily Dozen, there is a world of difference nutritionally between a popped or puffed grain and a grain in it’s whole natural state that has just been boiled. In other words, there is a world of nutritional difference between popcorn and say barley or brown rice or wheat berries. That’s something to keep in mind if you plan to have popcorn a lot. For more info about grains, Brenda Davis RD (who was once a guest blogger on NutritionFacts and mentioned favorably by Dr. Greger) has a great little video on the topic: Whole Grain Heirarchy:
      Does this help?

      • John Axsom

        Thanks for the information. Yes, this helps a lot. Last night, after reading the original article and seeing Dr. Gregr eating popcorn in the video, I went and had 4 bowls of popcorn and it really tasted good. But, now that you have told me that pop corn is a high density caloric food. I will just eat one bowl of popcorn only once in a while as a treat and not as a staple, because I am still trying to lose some belly fat.

  • emp

    I wasn’t aware until I looked into it, though nice to know my regular consumption of barley has been including β-glucans. I’m now considering the use of brewer’s yeast. Instead of mere disease prevention, it may be time to encourage as you say optimal health. The taste of brewer’s may be an indication of other substances, much like detailed in this study, Vegetable Bitterness is Related to Calcium Content. Sadly, there’s quite a few others not listed since North Americans are not used to them. Perhaps promoting their use will make them someday easier to find.

  • Karen

    Hi, I just discovered this video as I have a son who is an elit alpine skier and has had lots of problems with intense training and respiratory illness (mycoplasma, TWAR) so he will definitely be trying this!! I have another question: Do you know of any research that has been done on extra protein requirements for vegan athletes. This is a big concern for his coaches and I am just saying he doesn´t need more protein per say, just more calories as protein will increase with increased caloric intake. Any helpful articles or topics regarding this issue would be so greatly appreciated!!