Can Quercetin Help Heal a Leaky Gut?


This is a guest post written by staff nutritionist Kelsey Marksteiner, RD. Click here to read her blog or join her newsletter!

Digestive health is a hot topic these days. Problems in the gut not only play a large part in digestive issues like irritable bowel syndrome or reflux, but the gut has an effect on practically every part of our body.

Imbalances in the gut can create rashes, exacerbate joint pain and even cause depression – it’s no wonder we all want to learn how to keep the gut healthy!

One of the most pressing concerns regarding the gut is something called intestinal permeability, often referred to as “leaky gut”. The barrier of the gut plays an important role in maintaining our health by protecting us from the many things we’re exposed to from the outside world. If you think about it, our digestive tract is technically not “in” our body, it’s outside.

Think about your body as a donut and the digestive tract is the donut hole – technically, not “in” the donut. It’s easy to see now that our gut lining is exposed to everything we swallow – food particles, bacteria, dust, etc – and has to decide what to do with all that material! Think of the gut barrier as the decision-maker: some particles are allowed to pass through, while others are told to move on through.

When functioning normally, the gut barrier keeps us healthy by keeping out potentially hazardous materials and letting nutrients and water in. But when it starts to become more permeable (or “leaky”) than normal, we run into problems.

Of course one of the most important things for preventing excessive intestinal permeability is to eat a Paleo diet that works for you (a la Your Personal Paleo Code; The Paleo Cure in paperback). However, there are definitely other nutritional components that can help, quercetin being one of them!

Mast Cells = Leaky Gut?

Researchers have discovered that mast cells play a part in developing leaky gut. While it’s been known for a long time that severe physical stress (i.e. trauma or surgery) causes intestinal permeability, newer research has shown that chronic stress also has this effect. (1) Interestingly, researchers determined that it is the mast cells in the intestine that are responsible for the increase intestinal permeability in these stressful situations. (2)

You may have heard of mast cells before as the cells responsible for allergy symptoms like congestion, runny nose, etc. This is because when mast cells “degranulate” or become “unstabilized”, they release histamine, the chemical that causes allergy symptoms. But you have mast cells in your gut, too and when they “degranulate” or become “unstabilized” there, they cause leaky gut.

Quercetin for Leaky Gut

Quercetin is one of the most abundant flavonoids present in our food supply, found in high amounts in onions, kale and apples. (3) It is well-known for many things, including its anti-allergy properties, anti-cancer effects, and as an antioxidant. But did you know that it can heal leaky gut, too?

Given that intestinal permeability is caused (at least in part) by unstabilized mast cells in the gut, it makes sense that quercetin would have this effect. This is because quercetin stabilizes mast cells and prevents the release of histamine and other chemicals from these cells. (4) When researchers breed rats to have no mast cells in the gut (thus they are unable to have unstabilized mast cells that release histamine), they no longer develop intestinal permeability. (5)

Quercetin has also been shown to enhance gut barrier function by having a “sealing” effect due to its role in the assembly and expression of tight junction proteins. (6) Tight junctions regulate our intestinal permeability by connecting intestinal cells, thus only allowing the nutrients that we need in and keeping everything else out.

In rats given DSS (a substance that causes colon damage), treatment with quercetin restores barrier integrity and partially heals colitis. (7) Rats given another substance to cause colitis and treated with quercetin preserved normal fluid absorption (which is altered by colitis), counteracted glutathione (our “master antioxidant”) depletion and ameliorated colonic damage at two days. (8)

I’d say that’s some pretty good news for those suffering from leaky gut!

Quercetin in the Diet

Now that we know quercetin is healing substance for a leaky gut, how do we get enough?

Well, the good news is that on a Paleo diet, you should be getting quercetin by eating your fruits and vegetables. Remember that a Paleo diet can, and for most people, should be a diet high in fruits and vegetables, which naturally contain quercetin. But if you’d like to add some extra quercetin to your diet (or you can’t tolerate many fruits and vegetables), a quercetin supplement is also an option.

There is limited data regarding the amount of quercetin in our food, but below are the estimates available. (9) Your best bet is to just eat a wide variety and a lot of plant matter for optimal intake and consider supplementation if needed.

  • Fruits: 2 – 250 mg/kg
  • Vegetables: 0 – 100 mg/kg (onions are especially high at 200 – 600 mg/kg)
  • Tea: 10 – 25 mg/L
  • Fruit juice: 2 – 23 mg/L
  • Red wine: 4 – 16 mg/L

It’s also important to note that other flavonoids such as naringinen seem to have similar healing effects on leaky gut, so including a wide variety of plant matter to increase your intake of many different polyphenols is a great idea. (10) Not to mention that polyphenols improve your gut bacteria, too!

Here’s the take-home message: eat your fruits and veggies for your daily dose of quercetin, or consider a supplement if you can’t tolerate much plant matter or if you’ve got a severely leaky gut. If you’d like to go the supplement route, aim for 800 mg twice a day or 400 mg three times a day for a total of 1,200 – 1600 mg per day. It’s very difficult to get these levels from food, so a supplement is a good choice.

Now I’d like to hear from you. What do you think about quercetin as a gut-healing nutrient? How do you make sure to get enough fruits and vegetables in your diet? Share your thoughts in the comments!


kelseyrd03This is a guest post written by Kelsey Marksteiner, RD. Kelsey is a Registered Dietitian with a Bachelors degree in Nutrition from NYU and a Master’s in Human Nutrition and Functional Medicine. She works in private practice and recommends individualized dietary therapy focusing on biologically appropriate diet principles to aid her clients in losing weight, gaining energy, and pursuing continued health. She is a firm believer that everyone is different, and she tailors her plan for each and every individual. Through her work, she aims to meld the dietary wisdom of traditional cultures with the latest science in integrative and functional medicine to create plans for her clients that work in the modern world. You can learn more about Kelsey on her staff bio page, or by visiting her private practice website. Join her newsletter here!

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Comments Join the Conversation

  1. Paula Kline says

    I so wanted this to work I tried 250 mg Quercetin and it made me very nauseous. Of course it may be because I have gastroparesis also. I tried it a couple of times. Even the PAleo diet is hard for me to do because of the gastroparesis diet I am on. If anyone has any advice I would love to hear from them.

    • says

      Paula, I am not sure if I agree with Kelsey. Not that I have any issue with most of her advice, which for most part is just common sense, especially for people who have been thinking paleo for quite some time already and have come to realize that a more ancestrally oriented diet has tremendous benefits over the long haul. I emphasize long haul, because too few people realize that a life time of wrongs may need quite a bit of time of adjustments to get the desired results. To give a simple example. Going on a three day fast (just water and electrolytes) may cause quite a burden of toxic release (dying bacteria, toxic residue), etc. It may be advisable to begin with two days and slowly build. Switching from glucose burning to fat (ketones) could cause some other headaches. All passing but nevertheless.
      The slow emptying of stomach contents is not of genetic origin as far as I know, though there could be a predisposition which could give rise. Vitamin C is generally considered a motivator of a lot of immune activity. Liposomal VitC is often recommended when higher doses are required .
      T-cells as well microglia benefit. Recent research into especially the latter show how detrimental an overload of polyunsaturated fats is for a proper functioning system.(ROS overload) Microglia have been indicated as our super brain. Only very recently have we been able through different forms of imaging to get a bit of a picture. They are literally everywhere, and they are always on the move, and (!) they communicate wirelessly. So to answer your question, I don’t really think it is quercetin at all. That seems more like fighting the symptoms. It does not get at the underlying cause, or dysfunction. Whether that be diseased mitochondria or over-activated or dysfunctional microglia.
      The first thing I would get out of my diet is the margarines and seed oils, second anything wheat, since most wheat now has glyphosate in it (they desiccate wheat just before harvesting). since glyphosate is a chelator, it binds minerals. That in includes all the crackers and cookies and sauces. Unless organic. I am not a medical doctor, just a researcher into the biochemistry and physics of our metabolism .
      And if you still eat GMO corn, forget all I said.

  2. Kari W. says

    So, with leaky gut you can easily develop sensitivities by consuming certain foods too much (without rotating). Does that mean it’s possible to develop a sensitivity to a Quercetin supplement, since it comes from a food source?

  3. says

    Leaky gut is everywhere, look at all those bloated, pale people all over North America. I think the main reason is corn. It is in everything we consume, the BT variety from Monsanto contains a toxin designed to kill the corn root worm. It causes Leaky Gut in the insect, why could it not do the same to us.

  4. Not_a_mouse says

    Quercetin can induce dispair / depression. mice study.

    Anecdotal evidence: 500-1500mg a day does induce it in me.

    There is more anecdotal evidence on the net.

    I guess the only way to see if quercetin is for you is to try it and being aware of this side effect, and find a dosage where this does not happen… (there was none for me, unless in amounts its in apples)

  5. Janet says

    All I know is from my N of 1. I have terrible seasonal allergies but I become symptom-free when I take quercetin with bromelain. I don’t think I even want to know if there are potential side effects because I feel so much better when I am taking these supplements.

  6. Kevin says

    This is an interesting article.

    Intestinal permeability can be caused by elevated stress hormones and quercetin has a beneficial effect by stabilizing mast cells and reducing histamine release, thus potentially reducing intestinal permeability. Yay!

    On the other hand, quercetin is reportedly a MAO inhibitor and a COMT inhibitor and these are enzymes that breakdown stress hormones, including histamine. Yikes?

    • PC says

      And stress hormones (cortisol) need to be produced to deal with histamine reactions. It’s such a complex relationship!

      Personally I only use quercetin and vitamin C for acute reactions. They’re not perfect but they allow me to function and not be crippled by histamine when neccesary.
      I do much better without them though.

  7. Scout says

    Hi Kelsey,

    my question does not belong directly to this discussion but perhaps you are able to help: A relative of mine suffered from colitis and had a colostomy.. Her lab tests for Vitamin C are terribly, she doesn’t seem to resorb the ascorbic acid anymore. Do you know of any forms or methods how to ingest usable amount of Vitamin C into the blood?

    Actually infusions are the only solution but they are not really practiable and can be given only sporadic whereas the Vitamin C in the serum will be cleaned very fast. So any hint is appreciated. Thank you!

    • PJ (RightNOW) says

      I send Frasier’s suggestion for Liposomal C. The DIY (do it yourself) version may be more emulsified than encapsulated but this still seems to lead to a much greater bowel tolerance, suggestion it’s being digested possibly as a lipid via the lymph peyer’s patches rather than solely in the ordinary way, so even if that is the case, it’s still much better than standard oral intake (and way, way cheaper than buying it).

      Onion soup is said to be a rather absorbable form of vitamin C compared to other foods and supplements. Not sure if it’s true, just passing that along.

  8. Oliver says

    I also wonder about toxicity of Quercetin: for example). “We detected a time-dependent action of quercetin and distinguished an early protective effect from a late toxic one. In addition, we revealed a narrower therapeutic dose-range of quercetin than previously reported in the literature, demonstrating that the toxic effects of quercetin occurred at a concentration only 2-fold higher than the one that produced the greatest protection.”

    So, I suppose 1.200 – 1.800mg is a “safe” dosage then? And for how long should one supplement to prevent a toxic effect due to long-time exposure?

  9. Ann says

    This is all very interesting, would leaky gut cause migraines.I have food sensitivities and react to all alcohol, some fruit and some veg. Apples and sometimes onions are a problem. Headaches and migraines are almost a daily problem. Any suggestions would be appreciated.

  10. Ruth142 says

    Kelsey – thanks for your article.

    Do you think Quercetin could help heal a Coeliac sufferer’s gut? My Dad (age 83) has recently been diagnosed Coeliac after histology evidence of damaged villi. He’s following a 100% strict no gluten diet but not seeing any improvement – his weight is still falling. I’m desperate to help his gut to heal so he can start absorbing food and regain muscle and body fat. He has a great appetite and eats lots of fruit and veg but isn’t absorbing it.
    Your advice would be much appreciated,

    • Clarrish says

      As a fellow Celiac, I must say that gluten free wasn’t enough for me to see improvement. I had to go full on auto-immune paleo to avoid problems with cross contamination and other issues related to leaky gut. Auto-immune paleo means no grains or legumes, PLUS no night shades, eggs, limited nuts, etc. It has not been easy, but when I’m faithful to the diet, the changes are dramatic

      • Cindy says

        Thanks for your post. I too have leaky gut. Awaiting til my daughter to be done with nursing so I can begin the diet. Question for you: since leaky gut causes one not to obtain all the nutrients, would this apply to supplements as well? I wondered if I should wait til my gut is healed to get my money worth from supplements. TIA!

    • Rachael says

      Ruth 142 Try the Auto-Immune Protocol Diet (AIP), or the GAPs Diet for your dad. These diets helped me to heal after my diagnosis of Celiac, and eliminating gluten alone didn’t really help.

    • Peggy says

      There are a lot of things that can affect healing. First, of course, is being absolutely sure the diet is gf. After that, someone who is 83 is not going to be producing normal stomach acid and digestive enzymes. He can try HCl with pepsin with any meal that has protein (ie, not with just veggies and fruit alone), as long as he doesn’t have an ulcer or is taking NSAIDs that leave the stomach prone to ulcers. Digestive enzymes should be fine for him to take, with every meal and snack. Probiotics are essential, just build up slowly. Collagen (bone broth, quality gelatin powder) and glutamine are gut healers. If none of this helps, he may have other food sensitivities irritating the gut, so an autoimmune paleo protocol would be good. Also (but hopefully not), he should talk to his doctor about refractory celiac disease, where even a gf diet doesn’t heal the gut. Good luck to him.

    • Penny says

      I wouldn’t be giving a 3 year old supplements. Lots of fruit and veg would make alot more sense…

      • Marcel says

        Thanks Penny. The problem we have with our daughter is that she is sensitive to a lot of fruit and veg- histamine , oxalates, nightshades, cur cubits and the birch cross reacting foods! So leaky gut is definitely an issue and looking for safe things to help heal her gut.

    • says

      Orthomolecular Nutrition has a great chewable kids quercetin that is called D-Hist, it does have other ingredients combined – I don’t have it in front of me but I believe it might have nettles, bromelain, NAC, and vitamin C. There is an adult version that I use with great benefit. I use the chewable one with my son.

  11. Rita says

    What does one do if they are reactive to sulfur? There is sulfur in quercetin. I need to know of another supplement I can take.

    • Clarrish says

      Really? I too am sensitive to sulfa drugs (they make me vomit), but I hadn’t realized that it was present in quertecin! The more you know and all that

  12. Karin says

    Thank you, Kelsey, for this article. For the past ten years, I have taken two to four 175mg Nettle Quercetin supplements daily as was recommended to me for moderate to (sometimes) severe hay fever symptoms which subsided to a tolerable level over time. I only learned about leaky gut in the past year. A year ago, I changed my eating habits to Paleo-type (80/20) and believe eliminating most inflammatory foods particularly dairy products made the difference. I have recently stopped taking the supplements and have had only two days of sniffles so far this year, an incredible improvement from years past. It seems Quercetin or the combo nettle-quercetin helped before I changed my dietary plan. It’s possible I no longer need supplementation because I get sufficient quercetin through food.

  13. Caleb says

    What if the leaky gut response is somehow beneficial (i.e. an evolutionary strategy to somehow dispense with toxins faster)? Querecetin is just another plant toxin that I’d be suspicious of using long-term.

  14. Kim says

    What causes mast cells in the gut to degranulate? Normally an antigen has to crosslink IgE that is bound to the mast cell in order for it to degranulate and release histamine and other mediators. What would the antigen be in this case?

  15. Natalie says

    I was recently diagnosed with a condition called interstitial cystitis aka painful bladder syndrome (IC/PBS) and quercetin was one of the supplements recommended to treat the lining of the bladder. Symptoms of IC/PBS usually include frequency, urgency, pelvic pain, and flares of pain that feel like a uti. A pain flair can be caused by many things, especially diet and stress. The etiology of this condition is complex, but what eventually happens is that the lining of the bladder becomes inflamed and unable to repair itself and has probably been hit with multiple rounds of antibiotics (confused with utis). Irritating foods and drink can inflame the bladder and allow irritating substances and urine to move into/through the damaged bladder tissue, aggravate mast cells in the bladder, and allow stuff to move into the surrounding blood/tissues, thus resulting in a leaky bladder. Like myself, people with IC also have a tendency to have IBS, allergies, sensitivities, and so on. Many people suspect that IC may have an autoimmune aspect to it. What do you think about “leaky bladder,” autoimmunity, and natural treatments for IC?

  16. Maria says

    Our family suffers from gluten/dairy/egg and banana food allergies (dx by 96 food IgG blood test). Now we notice that eating allergen causes illness. Will Quercetin help heal the gut and eventually resolve our food allergies?

    • Clarrish says

      Resolve meaning cure, as in they are no more? Probably not, IMO. Resolve as in improve? Possibly? Talk to your medical practitioner before trying it out, then hell, come back and let us know?!

  17. Jesse says

    Taking more than 1g of quercetin per day for a long time can be harmful to your kidneys. Probably also want to consider quercetin intake other herbals (Hawthorn has a good amount of it), vitamin C with flavenoid complex bundle-in, and natural diet

    Niacin can be harmful to the liver, but not as much as statins unless you take the time release kind. Statins are evil things. Niacin also increases the odds of suffering from the muscle wasting side effect of statins. Statins also deplete CoQ10. Niacin and fish oil works wonders on your HDL (46 to 65 for me) and triglycerides (185 to 85 for me)

    • Kathryn says

      Would you have reference for the kidney damage with more than 1gram/day. I was recently at a conference and the lecturer stated that the world’s foremost researcher on mast cells was using up to 5 grams/ day so I recommended an increased dose to someone (like maybe 2-3grams/ day.

  18. Britt says


    Wow, this sounds really interesting news. I have reflux and ibs both, and foods containing quercetin make me reflux more and worsen my constipation. So would it be a better option for me to reach out for a supplement instead of an apple or an onion? Is it possible to fix my ibs and reflux symptoms at the same time with quercetin, assuming it heals leaky gut?

  19. Jesse says

    I take 500mg of quercetin twice a day every day, plus 2000mg of niacin (old fashioned flush kind; use the OTC twinlab niacin capsules that druggies use to try to conceal urine dilution, not the expensive prescription niaspan) twice every day (as well of 4g of fish oil and 4g of flaxseed oil twice a day). No allergies for me this year. For bad flushers like me, sucking up the flushing for two weeks or so (when the body no longer flushes unless you miss more than a day or two) guarantees whole body depletion of histamine. THen add the anti-inflamatory effects of the garlic, olive leaf, fish oil, flaxseed oil, and quercetin. No more allergies, and those weren’t the main intention in taking these, avoiding prescription meds for blood pressure was (which wasn’t successful as only Garlic is effective with my BP but that is probably keeping me off of a 3rd med)

    • Jesse says

      Quercetin, fish oil, and garlic are all blood thinners, and it is noticeable with new cuts (and bruises) and shows up in the blood tests.

  20. Carol W. says

    tTG2 Ab and lifelong leaky gut here, Hashi-hypoT, occasional cholinergic urticaria, various skin stuff, gluten-free, etc. … Some 10 yrs ago I experimented with quercetin supps, and the only one that muscle-tested strong on me at that time was Source Naturals liquid quercetin in the dropper bottle fwiw. I suspect potency is an issue with quercetin supplements and may not be well-regulated. … I commonly have a breakfast smoothie that includes the juice of 3 green apples, and eat a red apple for a snack most days. I add raw onions to various dishes. No alcohol. … From my experience of a recent bout of recurring cholinergic urticarial over the last 2 months, I don’t think there’s enough power in these foods and/or the quercetin supp at typical maximum doses on empty stomach to be sufficiently effective, however they’re good on general principles and likely do many other good things. I’ll experiment more with the capers, and with green and black teas, though I dislike the high fluoride content of tea. Being in the high raw subset of paleo, I totally support a diet heavy on the vegetables and fruits. Thanks for a very interesting article, Kelsey.

    • Crippled Me says

      Hey there! I have leaky gut (intestinal inflammation and IgG allergies) since like 3 years. A plethora of other stuff like Hashi´s have showed up in tests but that is non relevant since the last tests show no autoimmunity (I was in strict leaky gut diet this time, no surprise) Since then too, I have chronic eczema and semi chronic cholinergic urticaria. I know the eczema is a no brainer but what about the urticaria? I am pretty sure is related but there is no evidence in google scholar. You are the first leaky gut sufferer that I see states having cholinergic urticaria. BTW after a few months of strict dieting my fucking urticaria disappeared to the point I could exercise.

      What about taking 1500 mg of the Jarrow brand Quercetin per day would that help? I have found that propolis extract has a quick suppresive effect in intestinal inflammation in doses of 6 capsules. Right now I am taking that and Grape Seed Extract, however these last months I have been feasting in whole grain gluten and organic sheep/goat dairy and the effects are very clear today. Keeping up with the diet its been just too much for me, especially regarding the massive weight loss paleo meant for me which made me look even worse.

    • Cat says

      I love! Such a good resource. They found 1 study on intestinal permeability (, and apparently quercetin actually INCREASED permeability (but it was during exercise under high heat conditions, so we can’t infer the effects under resting conditions). Based on that, I think for now it’s best to wait until further human trials or really good anecdata come out. We can’t really conclude anything from the rat studies. I guess I’ll just stick with eating onions. (I’ve never tried capers, and Wikipedia lists them as the best source. How do people usually eat capers? I thought they were used mostly as a condiment.)

      • Penny says

        capers can be used in many ways. My favourite is to make Italian (non Mexican ) salsa verde with them. put flat leaf parsley, capers, olive oil, vinegar or lemon juice and sea salt into a food processor (if you use the salted capers instead of the ones in vinegar than soak them in hot water for a few mins to wash off the extra salt). I leave out the bread :-) puree it to the consistency of pesto. Serve with fish or as a sauce for vegetables. Delicious! easy!

  21. Quinny says

    No wonder I healed my RA on the fruit & vegetable only diet. I wonder if hydrogen peroxide and diatomaceous earth can actually kill the bugs…

  22. DM says

    Leaky gut can be caused by many things: consumption of antibiotics, aspirin, alcohol, processed inorganic foods, stress, flora imbalance, candida overgrowth, unhealthy grain consumption (e.g. wheat), excess sugar, etc. At least in the case of candida, I doubt mast cells play much of a role because it is the candida itself that pokes holes in the gut.

    The greatest source of quercetin is actually capers, then onions. I know that some people dont react well when supplementing quercetin, but you can purchase whole food derived quercetin (e.g. life extension makes a great one). Of course there are many other things that are needed to heal a leaky gut, but quercetin is a great start.

      • says

        I concur Christine. Spice up your daily salad with capers and you’ll be well on your way. However there is another brilliant star on the horizon that Japanese people have known for ages. Newly arrived in Canada, the haskap or honey berry has loganin, outsmarting even quercitin. The research is very new, but pharmaceutical companies are already ordering whatever juice is available to encapsulate it. Concentrated of course. Count on it being the talk for the next decennia

    • elizabeth says

      I do not react well to quercetin; I had finally stabilized my digestion on a personal paleo diet, then started taking Quercetin supplements during allergy season and my digestion was terrible again!

  23. joyce says

    If one wants to supplement with Quercetin, what is the recommended dosage? Empty stomach versus with food, etc.


  24. Wilhelmina says

    I start to understand now my problem could well be leaky gut, highly likely even. With this information I also understand now why I have these histamine issues. Last night I noticed once more I have uticaria factitia. I received histamine pills from the doctor, next to making me sleep better they don’t work at all. Thanks for the post!

    • Clarrish says

      Have you tried Histamine DAO supplements? I started taking toe before each meal and my life has changed as a result — very litter hyperbole here – Changed. My. Life! Xymogen is the brand I was recommended, but any quality gluten-free DAO enzyme supplement may be worth looking in to.

      • Marti says

        Clarrish – What type of symptoms were you experiencing? For how long before you experienced relief? Are you still doing well?

  25. Karen says

    I’m surprised that anyone would suggest that red wine could be healing with regard to mast cell granulation and high histamine. DAO, the enzyme that breaks down histamine, is rendered useless from red wine. So, it would be completely counter productive to ingest red wine when trying to gain more quercetin in the diet, in my opinion. Many people who have mast cell granulation or have high histamine issues also have very low DAO production. So, doing anything to further destroy DAO seems like a bad idea, in my opinion.

    • Karen B says

      I would agree with this. Red wine was the first ‘food’ I had a problem with when I started becoming prone to mast cell degranulation.

    • Ann says

      Some foods that give me the most problems: eggplant, wine (grapes), vinegar (grapes), licorice. I noticed most foods that bother me have seeds. Also tea is to be avoided on the high histamine list as well as many fruits/veggies. Healthy for some is not healthy for all.

      • Clarrish says

        I have to agree. Cutting red wine from my diet was the first time I saw a significant physical difference in my body (my intestinal inflammation is visible in terms of the severity of my psoriasis)

  26. Cathy says

    Good article. Information about the sealing effect is intriguing. I have always considered apples helpful for my digestion. Anytime I am feeling a little ‘off’ in the tummy a few bites of an apple can usually settle things down.

  27. says

    Interesting write up, always looking for new info on healing my gut. I checked PubMed but couldn’t find any human data on quercetin. Are you aware of any?

  28. John Es says

    The Wahls Protocol suggests quercetin as an optional supplement. It is incorporated into the diet for the protocol by suggesting the intake of green tea, onions, and berries. For those with the book, see page 285.

  29. John McDonell says

    Wonderful piece Kelsey. I’m a wondering though what the effect of cooking (especially with water/steam) has on the presence of quercetin?

    I also recently learned that the mechanism for the effects of GMO’s is that they cause intestinal cell walls to shrink, thus causing ‘leaky gut’.

  30. karen says

    Kelsey, thanks for this insightful blog. I’ve had digestive issues which I believe come from a leaky gut. The FODMAP diet has helped me. Both onions and apples are not FODMAP safe foods. Would Quercetin supplements be FODMAP compatible?

    • says

      Karen, FODMAPs are types of carbohydrates found in these foods. Quercetin supplements typically would not contain any carbohydrates, so they should generally be safe for FODMAP-sensitive individuals (as long as there are no other ingredients you are sensitive to in the supplement).

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