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Dr. Gundry’s The Plant Paradox: A Review of the Evidence

Lectin and Dr. Gundry

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In his book the Plant Paradox (View on Amazon), Dr. Steven Gundry sounds the alarm on the “danger of lectins” as the source for a wide variety of ailments plaguing our modern world, but some aren’t buying it.

Heck, I am writing in defense of Dr. Gundry and I’m not buying it.

That is I don’t believe, as Dr. Gundry does, that we are all helpless victims to the ravages of dietary lectin. Instead, it seems more likely that each of us have foods, some of which may be high in lectin, that we simply don’t deal well with.

As far as lectin is concerned – the scientific reality is that, even with the highest lectin foods, lectins are destroyed by cooking food.

Having said that, there clearly are people who develop sensitivity to a number of plant foods, and if you are one of those people, and assuming you can get enough calories, a lectin free diet of the style Gundry advocates for will almost always (99%) be healthier than a strict carnivore diet.

For our readers interested in which plant foods may be causing problems, the recent podcast episode we did on the future of food sensitivity testing may be of interest.

Anecdotally, I have two friends who have benefitted tremendously from following Dr. Gundry’s protocols.

What are lectins?

Lectins are carbohydrate binding proteins, found in plants, which are thought to act as defense mechanisms against predators. Plants don’t want to be eaten, they want to sprout and grow, and they developed lectins as defense shields, or so the thinking goes.

The theory is not without scientific merit. Many plant lectins do indeed breach the gut wall of the insects that eat them and in so doing demonstrate strong “insecticidal activity.”1 Dr. Gundry believes lectins induce the same inflammatory response in the human gut.

He argues we should do our best to reduce exposure to lectins in our diets as they may be the culprit behind some of the strange and inexplicable autoimmune conditions that seem to be on the rise in the Western world.

Lectins are everywhere

Because lectins are so widespread, and because they are found in what are thought to be the healthiest foods, Dr. Gundry has received a lot of blow back for advancing his theories. For example, tomatoes are full of lectins. Are we really going to have to stop eating tomatoes now?

What will be left to eat?

And that’s one of the main arguments I hear against implementing Gundry’s protocols, they are very restrictive. The Plant Paradox program excludes all grains, nightshades, most dairy (except some goat and sheep dairy) and almost all beans unless they’ve been prepared in a pressure cooker. Think you’ll fall back on chicken? Think again unless you can verify Portlandia style that the birds have been pasture raised.

It’s a good thing that Dr. Gundry has been met with skepticism. There are simply too many nutrition theories out there. One like this, which if true has wide reaching implications for how people eat, should be laughed out of court if there isn’t data to back up the claims.

But that doesn’t seem to be the case with Gundry, he does have some published data and he isn’t saying all people need to be on his protocol, just the sensitive among us.

Altered gut microbiome drives lectin sensitivity

Is it likely that everyone is sensitive to dietary lectins?

No, it’s not likely, but Dr. Gundry isn’t making panacea claims. His essential argument is this: if you’re sick with one of the growing number of autoimmune conditions we face in this country, tired, achy, or just underperforming, lectin is one area you may want to examine.

And here’s the thing: Dr. Gundry isn’t easily dismissed. He’s a Yale graduate, and brilliant heart surgeon who has done some incredible things in his career, including cross species heart transplants (yes, you read that right). Link to his bio here.

His basic case is that many people can no longer digest lectin because the modern world has devastated our intestinal flora.

Add to the list of medications we take the presence of toxic chemicals in everything from cookware to mattresses, and the rise of GMO crops sprayed with known carcinogens like glyphosate, it’s not unreasonable to assume some people might not be equipped with the microbes to properly digest certain lectins. Lectins are controversial, but increased pollution, prescription medications and widespread use of antibiotics seems to be changing the shape of our microbiomes. In his paper, Do Dietary Lectins Cause Disease, allergist David L.J. Freed theorizes that a serious infection could be the triggering event that alters the microbiome in such a way that we become prone to lectin sensitivity and certain autoimmune conditions.

The altered microbiome theory is gaining traction as consensus fact, and the imbalances of the gut that drive Gundry’s claims about lectin. Some have cast him as an outsider, but he’s right in the mainstream of functional medicine. He argues that many people are so used to low levels of inflammation caused by lectin that a state of reduced performance is their “new normal.” But even assuming that a large percentage of the population thrives on lectin, that doesn’t mean we all do.

For example, could a C-section birth, which is thought to be deprive babies of important foundational microbes, combined with a serious infection and a few rounds of broad spectrum antibiotics be just what the doctor ordered for a problem with digesting lectins down the road?

Dr. Gundry has been around for awhile, but I am just now sitting down to do the research, and I must say I was surprised at some of the science that is out there on lectin sensitivity. To be fair, it’s certainly not overwhelming, but there are legitimate reasons to be wary of lectin. Below, I run through some of the major discussion points.

Lectins travel to distant organs in rat models

I was surprised to learn that studies in rats have shown lectins have the ability to get passed the gut wall and deposit themselves in distant organs.2

One of the reasons Gundry recommends avoiding commercial poultry is that the animals are fed grain, a high lectin food. He believes some of his more sensitive patients react to factory farmed chicken because the lectin from the grain feed remains in the bird’s flesh even after it’s slaughtered. Of course, I suspect antibiotics and toxins like arsenic may have something to do with the problem as well, but the lectin angle is fascinating.

There is even some evidence that lectins can travel to the brain. This study is footnote #5 in the Plant Paradox, and it demonstrates (albeit in a worm model) that lectins can travel from the gut to the brain by way of the Vagus nerve where they impact the function of neurons, offering an alternative theory on the cause and development of Parkinson’s disease.

Again, the study cited by Gundry is a worm model, and it’s on the frontier of nutrition science, but nonetheless, there are other papers that show benefits to mental health when removing grains, so it’s something to experiment with and keep in mind when testing out theories behind anxiety for example. This Danish study showed a 40% reduction in Parkinson’s disease in people who had their Vagus nerve removed.

For more, check out Frontiers in Human NeuroScience: Bread and Other Agents of Mental Disease.

To quote the paper:

A grain-free diet, although difficult to maintain (especially for those that need it the most), could improve the mental health of many and be a complete cure for others.

This article from Psychology Today titled “Are Grains Destroying Your Health?” is also worth a read.

Lectins and heart disease

Peanut oil is high in lectin. In a study titled “Lectin may contribute to the atherogenicity of peanut oil,” researchers found that when lectin was reduced in peanut oil by washing, incidence of heart disease dropped significantly in animal models (mice, rabbits and primates).3

Then there is this tiny study which was authored by Gundry in which he shows reversal of endothelial dysfunction for patients who avoided major dietary lectins, stopped eating commercial poultry (also a downstream source of lectin as they are fed grain), ate a Mediterranean diet rich in leafy greens, and supplemented with a regimen of nutrients like pycnogenol and fish oil.  At the beginning of his study, 76% of a group of 200 (120 men and 80 women) had endothelial dysfunction. After 6 months, only 20% still had endothelial dysfunction.

The thing about Gundry’s arguments regarding plants and heart disease is they may focus on the wrong culprit. The evidence for lectin and heart disease isn’t overwhelming, but there is better evidence that those who are heavy absorbers of sterols (the fats in plants) may be at increased risk for heart disease.4 For example, we do know of a rare, but perhaps under diagnosed condition called sitosterolemia that is marked by an inability to clear plant sterol from the blood resulting in accelerated heart disease, sometimes in children.5 Sitosterolemia is associated with mutations in the ABCG8 genes.  However, even when the major sitosterolemia SNPs aren’t present, it is possible that certain people aren’t as effective at clearing sterol as others which could lead to heart disease over time. Perhaps reduced ABCG8 function operates in a similar fashion to reductions in urea cycle function which fall short of a diagnosable illness and instead cause a diminished, but functioning metabolic ability.

Lectins can break down the gut wall

Wheat contains lectins that cause celiac disease and gluten sensitivity in growing numbers of people. I have written previously about labs I had done to rule out celiac disease. While I did not have the classic elevated transglutaminase IgA markers indicative of the disease, I did have elevated tTG 2 IgG antibodies, which tends to suggest a poor reaction to wheat. I did not have a biopsy of my small intestine done, but I have read of cases where an endoscopy was performed on tTG IgG patients and damage to the small intestine was found. It is an accepted medical fact that wheat proteins can cause severe damage in some people.

Wheat proteins do us harm by attacking the gut lining, making the barrier between our intestines and the inside of the body more permeable, which for some, can lead to symptoms ranging from digestive issues to achy joints to problems with mental health.6 Zonulin, a protein which can break apart the “intracellular tight junctions” of the gut wall, is produced when we eat wheat. The theory of leaky gut is that the resulting intestinal permeability lets all sorts of bad guys into our blood stream and the immune system goes wild as a result.7 One of the most successful dietary interventions used to treat Rheumatoid Arthritis is a gluten free Vegan/Vegetarian diet. Of note: some of these RA diet studies have found an “association between disease activity and intestinal flora indicating impact of diet on disease progression.”

Removing wheat is becoming a standard practice for treating Rheumatoid arthritis and we know it’s a must for those that are gluten intolerant.

What about other plant lectins?

Can they breakdown the gut wall in the same way that gluten does?

Yes, for kidney beans. Kidney bean lectins have been shown to facilitate growth of E. Coli in the small intestine.8 The lectin in oats can’t be destroyed by pressure cookers and have an inflammatory effect for many people.9

But then you have evidence of anti-carcinogenic activity by certain soy lectins, a food that is on many people’s avoid list, so it’s not like we have an open and shut case.10

Gundry argues wheat is just the beginning. That many other species of plants contain similar proteins, which may be benign in comparison to wheat, but which can also cause us harm over the long term. Yes, his theories are not proven!

BUT, as long as people continue developing mysterious autoimmune conditions at the pace they are in today’s environment, it’s worth a look.

What about the Blue Zones?

Vegan advocates really don’t want you to follow Gundry’s diet advice because he advocates for eating small amounts of high quality meat and fish, but not too much so  as to keep IGF-1 levels in check.

After all, if the Plant Paradox has validity, the simple message of “everyone would be healthier on a Vegan diet in every instance,” begins to look dubious, and the marketing machines behind these diets can’t have that, so they all started attacking Gundry. One of the most notable was Dr. Greger of Nutrition Facts. In his video titled “The Plant Paradox is Wrong,” Greger rips Gundry as advocating for the discredited blood type diet, with one little problem: the blood type diet has not been totally discredited.

Next, he goes to the Blue Zones (communities where people routinely live to be 100 years old), where he’s on stronger footing. It is true, those who live in Blue Zones consume a lectin heavy diet, with beans as a cornerstone. This has been well documented by researchers like Valter Longo and Dan Buettner in their respective books The Longevity Diet (View on Amazon) and Blue Zones (View on Amazon). However, Longo, whose work I love, recommends “eating at the table of your ancestors”and to avoid foods that your “tribe” hasn’t traditionally eaten. Longo advocates for a largely plant based diet, but also advises readers to identify and steer clear of food sensitivities. To quote Longo:

Whether it’s lactose or kale, quinoa or curcumin, you have to ask whether these were foods common at the table when you, your parents, or your grandparents were growing up. If not, it’s best to avoid them, or consume them only occasionally. The potential problems are intolerances or autoimmunities, such as the reaction to gluten rich foods like bread and past observed in people with celiac disease. Although clear links have not been proved yet, it is possible that consumption of the wrong foods based on ancestry could be associated with many autoimmune diseases, including Crohn’s, colitis and type 1 diabetes.

Hmm, sound familiar? And yet, Longo is a darling of the nutritional world where Gundry has a target on his back. In essence, they are saying the same thing! Gundry doesn’t tell readers to avoid beans, he just suggests cooking in a pressure cooker to destroy lectin count.

As far as the Blue Zones are concerned, I see the fundamental difference as the microbiome. The Blue Zone communities have been living in the same manner, eating the same foods for generations. They are “off the grid” of the industrial food system and therefore have not had the same assault to their intestinal flora that we in modern cities have suffered. In short, they could be in a better position to consume and digest lectin. Regardless, each of these communities have food preparation methods aimed at reducing lectin. You better believe the beans they eat are soaked and slow cooked.

Greger then cites studies demonstrating the positive health benefits of tomato juice, and yet, tomato lectin lives primarily in the seeds, so processed tomato products like juice have had their lectin removed.

Perhaps the most damning argument Greger pulls out against Gundry is the existence of his supplement line, which I can’t defend. It is tacky to write a book warning about lectin and then launch a “Lectin Shield” product.

Closing thoughts – not proven, but plausible

No two people respond to a given food in exactly the same way. I can eat a peanut and feel fine, others will go into anaphylactic shock.

The same is probably true for lectins. On the dark side, Gundry’s book creates even more anxiety around food, which isn’t needed in today’s climate. Many people probably don’t need to avoid lectin.

Having said that, orthorexia begins where the substantive benefits of dietary intervention stops, so it’s not neurotic to exclude foods that have a confirmed deleterious impact on our health and wellbeing. Some people don’t do well with grain, others thrive. In these cases, it’s not helpful to cite nutrition questionnaire studies and say “but 86% of respondents over a 22 year period had 12% fewer incidents of joint pain when eating 35% more fruits and vegetables.”

If your body feels better avoiding oats or beans, don’t eat them.

You have a basis in fact for doing so.

John O'Connor

John O'Connor is the founder of Gene Food, a nutrigenomic startup helping people all over the world personalize nutrition. John is the host of the Gene Food Podcast and a health coach trained at Duke's Integrative Medicine Program. Read his full bio here.

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  1. Patricia D says:

    Mike your information is very interesting and we appreciate you taking the time to share it! Can you also share exactly what you eat each day?

  2. Mike K says:

    Hi everyone, I am a male in my mid age from Finland, more than 5 years ago I started to suffer from something that at first seemed to be only “gluten intolerance”, at first tried to exclude everything which is obviously made from gluten containing grains, however by time it seemed to gotten worse and reminding more of “celiac disease” as I started to react to other foods that did not have any gluten in it, such as some fruits and vegetables, red meat (particularly fatty red meat), dairy, eggs, tried as much organic but never made a difference.

    By these years, as I didn’t become better, I had to go “paranoid” in order to solve and exclude anything my gut couldn’t take (notice that I have no problems with food in the stomach sack what so ever, the reaction to food sets in only after a while when the food starts to seep downwards into the small intestine), I tried as much organic as possible, but still no difference.
    I have later come to suspect that the problems with at least meat, dairy and eggs is that they come from animals fed with “poison” grains, which is very common in Finland, we really don’t have any 100% grass/pasture fed animals, for instance, milk cows producing organic milk are fed with 50% grains.

    So, as I had to leave out a lot of the fiber rich grains I had to get fibers from elsewhere, tried oat but alas I can’t take it either (oat doesn’t have gluten, but still have lectins), at least can’t digest the Finnish brands no matter it says gluten free or organic on the package, tried some Swedish and Danish brand but with the same bad result.
    Last year I found oat from the Baltic countries and it was to my surprise clearly better, but still not perfect.
    Here is how I prepare the oat, I usually rinse the oat several times in cold water whereafter I let it stand in water over the night, min 8 hr., flush out the water next day, rinse one more time and add fresh water and boil it slowly with rock salt, very time consuming but gives the best result! Same process applied to rice which I really can’t otherwise eat. Without this meticulous procedure the oat porridge would hurt me very badly.

    It seems the Western world hemisphere is filled with very refined grain breeds that is much higher in gluten and lectins, few days ago listened on a radio podcast mentioning the gluten has increased 10 times!!!, have yet to look up closer at the studies, but this is very worrisome as it causes leaky gut.
    I only recently stumble upon more detailed information on the GMO craze, and the very severe connection with… LECTINS, I had known for years since having read an article that GMO companies have developed vegetables that increases it’s production of the naturally occurring pesticide-like compounds, which virtually all plants already have in some lesser degree, it was only recently when I stumbled upon this very important subject again that this very “naturally occurring pesticide” in plants were namely the culprit, lectins!
    The GMO companies have produced all sorts of vegetables that produces much higher lectins, and while there are other types of not so healthy GMO’s (such as Bt-corn, which is said to make the GI tract on insects to virtually explode), and the very infamous pesticides such as Glyphosate, but the GMO fortified lectin plants we eat are much overlooked, yet we have more young children than ever before having GI problems and can’t consume dairy and grains etc., we have to ask what is really going on with our food.

    However, over 2 years ago my health deteriorated into a new and scary realm when I suddenly got chronic neuropathic problems, a very broad range of looking like a mix of predominantly MS but also Parkinson and Diabetes, it went so bad I couldn’t walk up the stairs more than 2 floors whereafter I had to pull myself with the help of my hands to get up another few stores.
    I had severe vertigo, tinnitus, double vision, weak legs, very exhausted, shaky hands, very poor fine motor in my fingers as I dropped small things like cutlers from my hands, and the list goes on and on.

    At this stage I first suspected there was something wrong with the dairy products despite consuming organic, but after a long while I made the observation that in particular the more fatty the dairy product, such as cream and cheese, the worse my neuropathic symptoms were, I just had to cut out all dairy although fat free milk was best tolerated.
    Same with fatty red meat, have to cut away ALL fat, but got best results by avoiding red meat and eat only chicken.
    More on the fat story, I noticed I couldn’t consume my Magnesium supplements either, cut them out and started eating walnuts instead in order to get some essential trace elements, then again after a week or two noticed I would get worse of it as the MS symptoms worsened, so had to cut out nuts too as they are very fatty.
    I came to the conclusion I simply couldn’t consume ANY saturated fats in larger quantities, and it wasn’t until another year passed by I stumbled upon yet another very important puzzle piece, the correlation between saturated fats and MS studies by Roy Lawer Swank, a research which lasted for whopping 34 years (some of his papers are on NIH pub-med), the coin finally dropped and confirmed my own suspicions with the fat mystery, the immune system attacks the Myelin sheet which is protecting our nerves, which coincidentally is also made up of fats, and the reason is because of a leaky gut, that is when fats leaks directly into the bloodstream, instead of being broken down in the intestine, the immune system mistakenly attacks other fatty parts of the body, in particular the brain and nerves, and this is why IMHO these brain and nerve diseases are not any diseases but symptoms of a leaky gut, in which the leaky gut condition is sustained by, among few other reasons, the lectins.

    The lectin thing has only gotten to my attention relatively recent and it seems to be a key component behind many intestine and autoimmune diseases, and it’s also my very own observations too, for instance I love nuts but in particular peanuts and cashew nuts are some of the least tolerable, but when one look further into it we find that these “nuts” are Not nuts but legumes full of lectins.
    People who have no digestive disorders and/or autoimmune illnesses wont notice any difference, and Gundry himself says that the low-lectin food is in particular for those who have an autoimmune disorder, and it really helps, so people who do not suffer from any of the terrible gut and autoimmune diseases, please be precautious in your criticism.

    My health today is much better after having reduced gluten, lectins, and focusing on curing the leaky gut, but there is still a long way to go as I have fallen into many pitfalls for the past 5+ years, much due to a very confusing food package labeling regulations which tries to obfuscate as much as possible all the gluten sources etc. it’s an utter horrible situation.
    It’s a known established fact that people suffering from gluten intolerance/celiac and had their gut lining destroyed that it normally takes 1,5 years for the gut to heal, in an interview With Dr Gundry I listened to recently he too mentions it would take 2 years for the gut to heal, whereafter one can slowly start to reintroduce some food.

    Final words, there is something horribly wrong with our food, we have to raise our concerns and make people aware of the situation, at least let us who know have better choices when we visit the grocery store, there’s too little GMO-free and organic alternatives on the shelves and at reasonable prices, at least that’s the sad situation here in Finland, but being part of EU we are abide to follow the regulations from Brussels, and add to that the corrupt big-agri widespread tentacles.
    In essence we have to get away with bad GMO, bad pesticides, but also Hydroponics, yes, imo, when plants grow in a very sterile liquid solution it produces a very bland, taste- and sent less plant void of nutrients, without real soil with all the bacteria in it that makes the micro nutrients available for the plants we can’t get healthy food from hydroponics, although the growers say (probably conditioned and duped by big-agri, behind which we find again same/similar shadow figures in collusion as in behind big-farma, ie. the “world population controllers”, people say it’s all about profits, me thinks “no”, they already have all the money, it looks rather like eugenics. Well, it seems what the conspiracy thinkers have suspected for years something is wrong with our food is coming to light.), so they add a few nutrients to the water and think it produces nutrient rich plants, well, how about Enzymes, without them the plant can Not support the digestive system in breaking down the food we eat, enzymes are a very overlooked topic too, please give us back real soil grown vegetables and fruits full of flavors and nutrients, they are important too for a healthy gut and its bio flora.

    If you read my long winded comment to the end, thank you, it took my an awful amount of time to look up a lot of information and connecting the dots, such as wading through many scientific studies, verify the studies by making changes in my diet which also has taken years to improve and is still in an ongoing changing process, we have today better knowledge about the gut-brain connection epidemic and means to improve our health by the right choice of food, but it also requires we fight for true organic GMO-free food.

  3. Andrew says:

    Correlation does not mean causation. That is the problem with a lot of these studies. E.g., it can be shown that eating ice cream and deaths by drowning is highly correlated, so does that mean eating ice cream causes drownings. Obviously this a fallacious conclusions, but we see this in many of these studies.

  4. Matt says:

    Interesting stuff.

    I have Crohn’s in my colon so I’m a prime candidate for this.

    I avoid dairy, nuts and seeds anyway but I was eating a lot of grains and beans. Anyway, I started seeing symptoms return. Removed them and, literally, 24hrs later I was assymptomatic.

    So, I have been treading very carefully and slowly. From a base diet of meat, fish, fruit and veg I’ve been adding one thing at a time to find out exactly what I react to.

    So far…

    Lentils fine.

    Oats fine.

    But, strangely, rice is really problematic.

    I hear people talk about the lectin families, such as grains or legumes, as if they’re a homogenous thing.

    Could it be much more nuanced?

    That is, intolerance of specific lectins in specific grains, legumes etc?

    Also, I assume that a long period (72hrs or say) fermentation would knock these lectins on the head.

    Kind regards,


  5. Remy says:

    Glad that we still have people with critical thinking ! Yes Dr Gundry’s work isn’t perfect. But it does make plenty of sense for some concerned persons. I would advice this book to the kind of people that D’Adamo calls “reactive génotypes”. There are indeed some folks who ring full immune response toward their environment and food. A lectin free diet allow them to calm down their autoimmune problems and they can, as mentioned in the book, reintroduce some lectin food gradually and carefully. Did it with many people and it works great. The thing is to understand what D’Adamo’s father said long time ago :”one man’s food is another one’s poison”

  6. Alex says:

    “Peanut oil is high in lectin. In a study titled “Lectin may contribute to the atherogenicity of peanut oil,” researchers found that when lectin was reduced in peanut oil by washing, incidence of heart disease dropped significantly in animal models (mice, rabbits and primates).”

    Does this suggest that peanut butter is high in lectins?

    Anyway, many long-lived and healthy populations had beans as a staple. They actually seem protective. Potatoes and tomatoes are also common in human diets. Not all lectins are the same either.

    I’m not sure what to make of Dr. Gundry’s idea. I don’t think there’s empirical support that this matters for most people. Even his small study has so many confounding factors that benefits can’t be attributed to lectin avoidance. Plus, I’m a bit put-off by his profit motive with expensive “Lectin Shield” supplements.

    As far as orthorexia, please don’t give credence to BS diagnoses. Orthorexia pathologizes a passion for optimizing diet just because most people don’t care a great deal. Even the cases of a real problem could have just as easily fallen into a bigger umbrella. There’s no need for a new label.

  7. Amos says:

    Thank you John. I had no health problem and found Dr. Gundry’s theory very logic.
    trying to adopt the Plant Paradox diet, I felt it doesnt do good to me (diarrhea, below right weight…) so I quit.
    this diet, although with reasonable arguments, works good on people with gut / autoimmune problems. Why it is not working on normals, it is unknown, i guess.
    thanks a lot for the summary, made with a deep knowledge.

  8. Natalie says:

    I liked your article and thought it was well done up until the “bullshit” part at the very end. It was unnecessary and discredits you. Now, I will not suggest reading your article to a friend without disclaimer. Professionalism should be respected.

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