Doctor's Note

This is the second of a three-part video series on interacting with our intestinal tenants. In Fawning Over Flora, I first discussed another short-chain fatty acid our good gut bacteria can make from fiber, called propionate. I conclude the series with Tipping Firmicutes to Bacteroidetes. For a sampling of other videos on keeping our colon happy, see Kiwifruit for Irritable Bowel SyndromeFlax and Fecal FloraIs Dragon Fruit Good For You?; and Bristol Stool Scale.

For further context, check out my associated blog posts: Boosting Gut Flora Without ProbioticsTreating Parkinson’s Disease With Diet; and Avoid Carnitine and Lethicin Supplements.

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  • Michael Greger M.D.

    This is the second of a three-part video series on interacting with our intestinal tenants. Yesterday’s video-of-the-day Fawning Over Flora discussed another short chain fatty acid our good gut bacteria can make from fiber called propionate. For a sampling of other videos on keeping our colon happy, see Kiwifruit For Irritable Bowel Syndrome, Flax and Fecal Flora, Is Dragon Fruit Good For You?, and Bristol Stool Care.

    If you haven’t yet, you can subscribe to my videos for free by clicking here.

    • HemoDynamic, M.D.

      Short vid, but-I-rate it (get it–butyrate ;D ) . . . sweet? 

      Well I never thought of my fecal bacteria as sweet.  But the sweetness is derived from knowing I am doing the right thing by teaching a plant based diet to all my patients who will listen.

      This is also added information to my arsenal about why I prescribe Probiotics to my patients who are on antibiotics.

      Keep the good info comin’ Dr. G. while I defend my arsenal of nuts.

    • ys

      Please do a video on candida

  • JeanMarie

    Is it beneficial to still take a probiotic supplement even if you are eating vegan?

    • HemoDynamic, M.D.

      If you are on antibiotics then Yes!  And for about 3 days after you stop the antibiotics you should take the probiotic.

      Otherwise, if you are eating plants and not taking antibiotics then no supplementation needed.

      It has been my practice experience that this practice of probiotic supplementation tends to reduce the antibiotic associated diarrhea and abdominal discomfort.

      • T.T. can you say to take AB’s during patient’s treatment, when this renders them less effective! They should be taken for couple of weeks ‘after’ only

        • jazzfeed

          I don’t believe PBs render ABs less effective. But ABs kill PBs, which are essential. The suggestion then is to take a PB during a course of ABs but AS FAR AWAY IN TIME AS POSSIBLE from the AB. So if you’re taking an AB at noon and midnight, take a PB at 6pm and 6am.

  • Veganrunner

    Good morning,

    So I have been experimenting with buckwheat grouts. I thought, ” what do I do with these?” so first I cooked them as the package suggested. 20 min. They turned out mushy. So then I thought? 20 min is nothing I bet I can just soak overnight. Sure enough, after rincIng the okra like slim they were great. I ate them mixed into my oatmeal with pastacio nuts, pumpkin seeds, and rice milk.

    And buckwheat is nutrient dense!

    • Thea

       Veganrunner:  Thanks for the cool idea.  I’m always looking for ways to expand my food repertoire (in a good way).

    • Michael Greger M.D.

      I agree buckwheat is wonderful, but there is a compound in buckwheat grass called fagopyrin which can cause photosensitivity. How you’re prepping them now is totally fine, but if you end up sprouting them, I’d recommend doing it in the dark (so they don’t green), rinsing frequently (fagopyrin is a fluorescent red pigment you can see being washed away in the pinkish rinsewater), keeping the sprouting to under 8 days, and not making them a substantial part of your diet. But your deslimed breakfast sounds yummy!

      • Veganrunner

        Thanks for the heads up. Got it-don’t sprout.

        • Vera Springate

          In the US buckwheat groats are sold in 2 ways: with and without hull.  Stores like Whole Foods sell with without hull, and they are light green in color.  The other kind, with hull, can be bought at Eastern European, Persian, etc. stores.  There are good instructions on how to cook it on the package (but I can’t recall if they’re in Russian…).  In Russia where I’m from buckwheat is eaten only with hull.  Bring to boil – with little salt – 1 cup of buckwheat and 2 cups of water.  Turn heat to low and cook uncovered for another 20 min or so until water disappears plus a little longer.  The grain at the bottom of the pan should be sort of dry (not mushy). It might even stick to the pan, and that’s OK, as long as it doesn’t burn.  Turn the heat off, cover and let it sit until it’s cooled down.  Grains should be separate from each other when it’s ready to eat.  It’s fine to be heated in the microwave for 30 sec or so.  I also heat it up in the skillet with small amount of olive oil for a minute or so.  It gets crispy this way.

          • Vera

            Correction to above –

            Stores like Whole Foods sell them without hull…

          • Thea

             Vera:  That’s such cool information.  Thanks for taking the time to share it with everyone.  I have had buckwheat some, but I had not known of cultural variations or that I could get it two different ways.  Neat.

    • Charzie

      Some cultures toast them first, then it becomes “kasha”. The part about the fluorescent red pigment is fascinating, I wanna find my old blacklight from my hippie days! LOL!

  • Some other things “good” bacteria like :

    xylitol (sugar alcohol also used in nasal sprays; super toxic to dogs though)

    • Paddycakes

      Ugh! Do a Google search on Xylitol–it’s poison.

      A search of patents online explains one process for making xylitol, tell
      me if this sounds healthy? You begin with some source material
      containing xylan. One commonly used source is corn imported from China.

      1. First the xylan needs to be broken down in a process called acid
      hydrolyzing. The results of this process leave us with xylose and acetic
      acid. The process of hydrogenation is carried out at higher pressures
      and temperatures ranging from 158 degrees Fahrenheit and higher.
      Hydrogenation needs a catalyst, so a substance called Raney nickel can
      be used which is a powdered nickel-aluminium alloy.

      2. The acetic acid needs to be removed as the material safety data sheet describes it as, “Very hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Hazardous in case of skin contact (corrosive, permeator), of eye contact (corrosive).”

      3. Then the hydrolyzing acid and organic residues must be removed, this is done by heating the mixture and evaporating it.

      4. The resulting syrup, now free of acetic acid, hydrolyzing acid, nick-aluminum and other residues.

      5. The syrup is crystallized by stirring ethanol into it.

      6. The crystalline xylitol is now separated in a centrifuge from the ethanol and from the sorbitol remaining in solution.

      7. Viola, you have xylitol.

      Health Claims

      It is obvious to me, as it might be to you, that xylitol, in addition to
      killing bacteria, will probably kill just about anything. This clearly
      explains why it is only recommended to be used in small doses. Yet if
      you go to a health food store, you will see larger sized bags of xylitol on the shelf, promoting its many health uses. Duh.

      Health Concerns

      In lab tests, xylitol will kill a rat 50% of the time in a dosage of 16.5
      grams of xylitol for every 1000 grams of rat. Medium rats weigh 100-120 grams, or say .25 pounds. That means, to kill a 100 gram rat, you need only to get the rat to consume, 1.65 grams of xylitol.

  • Freepam

    Ok, I’ve just finished your whole store of videos. What an amazing amount of information. It’s already changed my life ;-) Thank you so much!
    I’m sick right now from reacting to goat milk and gluten so I’m cleaning up my diet completely and dropping meat and fish at the same time.
    I’ve been vegan and fruitarian before but, although I loved the fruitarian best and felt good on it for a year, I realized it wasn’t working for the diabetes type 1 I have. So I went on the GAPS diet to heal my gut. 
    What I don’t understand is that the GAPS and the Dr Wahl diet and even Paleo, all have so many adherents that swear by it. I would think after watching all these videos that all 3 diets would make everyone sick. How can so many people turn around very sick, autistic children with a meat-based diet?
    It’s very confusing.

    • Guest

       Diets like Paleo also have you eat a lot of Veggies and Fruits and Zero processed foods.  So you remove a lot chemicals and still get the phyto-nutrients.  So at the end of the day their diet is much cleaner than the average American diet which would score a 12.  Paleo also does not eat conventionally raised meats… only grass fed no hormone or wild meat.  So while they eat meat (too much in my opinion) they have eliminated all the processed stuff and chemicals that are really getting us sicker.

      • DanielFaster

        Isn’t meat just really hyper processed animal feed? Murder and suicide at the same time.

  • lillylangtree

    Thank you, great info Dr. Greger.  I eat a plant based diet.  I drink 1 to 2 raw drinks every day since April and I feel great.  Growing up, my mother juiced a lot of carrots and parsley drinks for us, so i have been use to them.  Tonight I made a drink for my family made from garden fresh zuchini, cilantro (great for inflammation), mango, blueberries, banana, pineapple, coconut oil, 3 tablespoons chlorella, spirulina, wheat grass and alfalfa mix, molasses (for iron), 3 tbls chia seeds, 3 tbls lecithin and powdered mag.  Both my husband and mother also have a cooked dinner but this is my dinner and it really is filling.  I have had so  much energy since drinking this drinks.  I forgot, I also add raw digestive enzymes.  Do I need them?  Thanks for all of your great information!  I just love seeing a Doctor that believes health is the best defense from dis-ease!!

  • bee


    Do u recommend probiotics for people with dysbiosis?  I had a stool analysis done and I have Klebsiella pneumoniae 3+ and low beneficial bacteria.  This is actually significantly better than my stool test a year ago, which showed much more serious dysbiosis, but I went off my probiotics and enzymes and switched to a fruit-based diet, which healed a lot of the dysbiosis. However, almost a year later, the Klebsiella is still there.  Any suggestions?  Would raw/salt-free sauerkraut help restore beneficial gut flora balance or are probiotics necessary?  If so, any brand u recommend and length of use?

    Lastly, the stool test showed some pancreatic/gallbladder insufficiencies (so, low enzyme production).  Would digestive enzymes benefit me, or is there a more natural way to fix this?

    I am currently following the 80-10-10 diet, but it is difficult to get enough cals/pro…I want to switch to Dr Fuhrman’s Nutritarian Diet…what are your thoughts on this?  My body is having a hard time making the switch to legumes/starches/fats.


  • LynnCS

    bee.. I haven’t been diagnosed with what you have, but suffer from a myriad of intestinal disorders. Maybe it doesn’t apply, but just wanted to say that I find digestive problems with the high fruit…might just be the bananas for me. Still testing, but I also changed a little to add some of the cooked starches a la McDougall/Bernard etc. I get a lot of gas and diarrhea with those. I do best all raw. I prefer the all produce diet with less fruit than 80-10-10, but can’t really do all one or the other. The best I have been was the 1st year I followed Dan McDonald’s ideas about raw green smoothies, some juicing, and lots of green salads. I use a lot of supergreens as salad greens, not just lettuce, although love me some romaine. Dara Dubinet has some great ideas for all raw and talks a lot about 80-10-10 too. I did lose a lot of weight, which was good for me. I am going to get off the cooked starches again and try again with the mostly raw green smoothies etc. I like them too because I can include some of my favorite herbal ingredients for stress, etc. Also, I feel I need the fiber and juices don’t give me that. Also chewing is a really important part of digestion. Just my 2cents. Lynn

  • Ronald Chavin

    The beneficial chemicals manufactured by lactobacilli and bifidobacteria which cause weight loss and prevent cancer include propionate, acetate, butyrate, conjugated linoleic acid (CLA), and conjugated linolenic acid (CLNA). These beneficial bacteria convert linoleic acid (LA), which tends to cause weight gain and, at least in animals, cancer, into the beneficial conjugated linoleic acid (CLA), which does just the opposite:

    Long-chain omega-3 fatty acids also cause weight loss and prevent cancer:

    Unlike the “bad” omega-6 fatty acid, linoleic acid, conjugated linoleic acid works well at helping us to live longer by preventing cancer, heart disease, and a dozen other killer diseases. CLA softgels, which are made from Non-GMO (high linoleic) safflower oil, work well at building bone strength, muscle strength, and causing weight loss. Make sure that the CLA softgel you buy is at least 80% CLA and not more than 20% unwanted fatty acids that cause weight gain and cancer:

    • Lara

      I am confused…lactobacilli and bifidobacteria are fermicutes. I thought we needed more bacteriodetes?
      It seems most of the probiotics I thought were ‘good’ are fermicutes.

  • Sask

    I have a question about candida and the relationship between candida, sugar, specifically fructose, and fat. Is it better to reduce the about of fat consumption to eleminate candida overgrowth or is it better to eliminate all sugar including fructose to eleminate candida overgrowth? I have hear a lot about fat being the culprit and not the good healthy fruit sugars when it comes to candida overgrowth. I look forward to hearing from you and your thought on the matter.

  • AC

    Xylitol supplies butyrate and propionate to the digestive tract, yet it is (if memory serves) listed as “harmful” in one of your artificial sweetener videos. Am I missing something? I thought you considered both of these substances extremely beneficial.

    • Thea

      AC: Dr. Greger listed xylitol as harmful because the product is not absorbed properly and causes diarrhea. In other words, while I do not speak for Dr. Greger, I believe he has decided that the bad outweighs the good.

      When determining the healthfulness of any food, the goal when possible would be to look at the whole food and weight the pros and cons. So, while a food may have some benefits when looked at one way (say, has butyrate), if the pros don’t outweigh the cons (say, diarrhea) , then the food would be listed as harmful. Of course, we don’t always know all the pros and cons and also, pros vs cons can be a matter of personal opinion. The devil is in the details. Dr. Greger gives his opinion. We can decide what we do with it.

      Another thought: sometimes it is helpful to keep in mind that Dr. Greger’s videos are often focusing on a single issue – say antioxidants or whatever – and the statements in that video need to be understood within that focus. In other words, not all videos are (or can) take every health factor into account.

      That said, since the amount of xylitol that I personally eat doesn’t seem to cause digestive upset, I’m not concerned about it since I understand what Dr. Greger’s issue with xylitol is.

      Hope that helps.

    • Toxins

      I do not remember Dr. Greger discussing the benefits of these 2 compounds, but perhaps the risks outweigh the benefits. Xylitol has a dehydrating effect in that is leaches water out of the intestines which can lead to diarrhea.

  • AC

    The lethal dose of xylitol is around 22g/kg, which means I have to eat around 500 teaspoons. That’s ten cups of straight xylitol. Xylitol kills some bacteria because they absorb it as they would glucose for energy, but they cannot metabolize xylitol for energy, so they use energy trying to expel it, only to absorb more xylitol and have to use energy to expel it again. At some point they run out of energy and die. Xylitol also metabolizes into propionate and butyrate in the digestive tract, and as far as I know these are extremely beneficial for human health.

    • Charzie

      I haven’t found much research on it, and it isn’t a sweetener, but an amazing fiber… konjac or glucommanan, a starch made of a specific yam-like root, essentially flavorless on it’s own, and easy to use, it seems to have great promise. It’s used to make the non caloric shirataki or “miracle noodles” and is a great fun ingredient to play around with! It will thicken sauces, dressings, and gravies, make vegan gel like desserts ala jello, all kinds of applications! It comes as a powder that you dissolve in liquid, and it swells, not needing cooking like cornstarch, etc. Heating it does make it swell faster and dissolve quicker, but it isn’t needed. No calories, fiber filled, and so far very healthy, incredibly versatile, what more can you ask for?

  • geny

    I have a question on the best probiotics on the market, I live in Quebec City we have many type of probiotics and I heard from one of my friend, that the best is from plants, not from human or milk extract. He tell me about the probiotics: BB from USA…
    Can you help me?

    The other question concern some acne that have begin few months ago in my back, mostly the upper back. Do you have any idea of what it could be? Is it food allergies (i’m vegan) or my liver??

    Thanks a lot and have a beautiful day :)

  • Derrek

    Probiotics are expensive but I have really bad farts. I may have dysbiosis and high levels of bad bacteria. What can I do to increase the good bacteria as I’m vegan and eat very little processed food. Would fermenting veggies help? Thanks!

  • Derrek

    Any ways to naturally treat candida? I have a yeast smell and danruff. I am looking for a natural way to treat it.

  • Alison

    On a related topic: I cannot find anything addressing Candida or Yeast Overgrowth in you subject index. A recent stool culture puts my yeast levels at +4, and my doctor has me on Amphoteracin B, an anti-fungal, as well as probiotics and The Candida Diet. The diet is difficult for a vegan to follow as it becomes extremely limited. How can I know I really have a problem, and how can I tell if this protocol is working?

  • Darryl

    Just wanted to share a good article profiling Jeff Leach, “affectionately known as ‘Dr. Sh*t'”.

    How Good Gut Bacteria Could Transform Your Health By Gretel Schueller, Eating Well

  • Joel Santos

    Hi dr greger what do you think of yakult? It’s not vegan but it claims to be a very good probiotic. Thanks!!!

  • Natasha

    Hi, I am trying to find information or resources for whole food, plant based eaters that have been diagnosed with SIBO/intestinal permeability (likely is a form of damage done from prior animal products consumed and SAD diet habits before going plant-based?). None of the functional or traditional practitioners I have seen thus far support plant-based diet and keep telling me the only way I can heal is to eat animal products and saturated fats. I have experienced the benefits of a plant-based diet firsthand and will never go back to my former poor dietary habits as I believe firmly that it was my poor diet that caused the inflammation throughout my body in the first place. Any resources or references would be greatly appreciated, as I just don’t know where to look and am at my wits end. Thank you for your time.

    • Joseph Gonzales R.D.

      HI Natasha. I am not sure what is best? Here is some information I researched about SIBO.

      Small intestinal bacteria overgrowth (SIBO) may be linked to a lactase deficiency. Celiac disease can make SIBO worse. Some research suggestsmalabsorbed fat may increase SIBO in subjects with tropical sprue (TS), which “is a common cause of malabsorption syndrome among adults in tropical countries including India. TS is diagnosed by specific criteria, which include biochemical tests showing malabsorption of two unrelated substances, abnormal duodenal histology, absence of other causes of malabsorption and persistent response to antibiotics and folate. Pathogenesis of this disease is unknown. Bacterial infection has been proposed to cause this syndrome in view of small bowel bacterial colonization in most patients and overgrowth in a proportion, which responds to antibiotics4. In fact, frequent occurrence of small bowel bacterial colonization, overgrowth and predictable response to treatment with antibiotics might suggest that the name TS or tropical malabsorption is a misnomer. It should rather be considered as a condition associated with small intestinal bacterial overgrowth (SIBO) and colonization in the tropics in absence of an anatomical cause.” I included that explanation because of the possible link between TS and SIBO.

      This study shows how gut bacteria can be manipulated to help gut-related diseases. The study is free. It may be the best one I’ve seen on the topic. Hopefully others can weigh-in. More videos on the related topics: Boosting Good Bacteria in the Colon Without Probiotics and The Leaky Gut Theory of Why Animal Products Cause Inflammation. So to me eating animal protein doesn’t make much sense. What is the theory or research behind that? I am not saying there is none but I am curious. Maybe try it out, see how you feel? No harm in that. I always encourage folks to work with their healthcare team even if they disagree on a few points. If you find the practitioners are not helpful after your trial, consider seeing a dietitian who specialized in plant-based diets. Good luck!

  • Amber

    Do you know of any research into the vegan diet and fighting candida? Any help would be appreciated, as I keep reading about paleo/low carb diets being the only way to beat it and I presume that you would prescribe a fairly high carb diet?

    I’ve been following your videos for a while and love all of the fascinating topics that you cover, but feel utterly lost when it comes to beating candida.

    Please help shed some light on this topic – it would help so many women,

  • Susan Lerner

    What about Kombucha and Water Kefir for probiotics?

  • Cathy Katin-Grazzini

    I’d love a video that covers the benefits or risks of various fermented foods. It’s helpful to know kimchi & kombucha are harmful, but what about the vast universe of other fermented foods like sourdough breads, fermented pancakes like dosa/idli, fermented veggies like sauerkraut, soy-based miso/natto/tempeh/soy sauces/Braggs aminos, cultured soy yogurt or fermented plant-based “cheeses” etc. Prebiotic foods are terrific if the biodiversity of our microbiome is still intact. Then our bacteria can still bloom. But if we were born in the post-War America, the biodiversity of our gut bacteria probably has already declined. Are there beneficial probiotic foods we should incorporate into our diets?