Dr. Gundry Is Wrong About Lectins

And Dr. Mercola Is Wrong About Oxalates

Dear GreenSmoothieGirl: What’s your take on Dr. Gundry’s philosophy? He thinks potatoes, tomatoes, bell peppers, lentils and beans make people sick.

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I’m going to take this subject on, about why Dr. Gundry is wrong about the “anti-nutrient” called lectins. It’s a case of not understanding the true cause and effect.

Here’s the abstract of why you should completely disregard Gundry’s body of work: every natural food contains lectins; cooking destroys active lectins that could hurt you; there are countless types of lectins, most harmless and many helpful; and everyone from T. Colin Campbell PhD to David Katz MD to Michael Greger MD have thoroughly debunked Gundry’s theories.

But while we’re here, talking about “anti-nutrients,” let’s also take Dr. Joe Mercola on, since he’s been pitching the Carnivore Diet (and eating it) the last couple of years. He literally told me to my face a few years ago, when his plate was a giant rib-eye, and my plate was a giant salad, “That shit’s going to kill you.”

First of all, an important disclaimer: I realize that some people are reactive to foods high in lectins, such as legumes (beans, lentils, split peas), tomatoes, and peppers.

Dr. Gundry’s theories not even being supported by his references at the end of the book has been thoroughly covered by other reviewers. And nutrition books don’t face peer review, so publishers generally face little backlash from printing inaccurate information.

For the most part, I’ll leave that aside, but just mention that when you claim something is healthy or unhealthy, and I look up the reference that supposedly proves it, that reference should actually support your claim.

But let’s talk about why you might be reactive to beans and lentils and tomatoes, other than that you must avoid all foods with “anti-nutrients” in them. 

Dr. Gundry may have cause-and-effect mixed up. Reactivity to lectins happens when your gut is in dysbiosis. Entire books have been written on all the different names for gut imbalances and diseases, so the Cliff’s Notes is: most Americans (and I do mean the vast majority) have too few good bacteria, and too many bad bacteria, plus their gut is “leaky,” meaning that undigested food particles escape the gut into the bloodstream, through a damaged one-cell-thick barrier.

This doesn’t just leave you wide open to repeated infections; it also means you don’t digest food well, and in addition to being at risk for auto-immune diseases and cancer long-term. In the short term, you’re likely to have reactions to foods that have actually served mankind well for 2,000 years.

Beans, lentils, tomatoes, peppers and many other foods that contain lectins, are staples in the five Blue Zones. So Dr. Gundry claims that lectin-rich foods cause all our diseases, but the evidence shows exactly the opposite.

That is, the five cultures of people currently living on the planet, representing many millions of people, who live to be over 100 years old, at 30 times the rate of Americans, eat lots of foods high in lectins. And they have extraordinarily low rates of diseases.

Why should we look at the Blue Zones? Not everyone wants to live to be 100+, but everyone wants to avoid cancer, heart disease, and auto-immune diseases–and the Blue Zones do.

And every single one of those cultures eat a diet far richer in lectins than Americans eat. For instance, the Mediterranean Diet is very high in legumes, and vegetables including tomatoes and peppers. The published papers and books on the Mediterranean Diet number in the thousands, because of the indisputable evidence.

That is, those eating the native diet (not the standard American exported diet that younger generations have adopted) have a tiny fraction of diseases across all major categories, than we Americans do. Americans actually eat very few beans and lentils, most of us–and most Americans don’t eat any vegetables in the course of a day, unless you count potatoes and ketchup.

But what Americans do, that damages our gut microbiome, causing food reactivity, is two things, which I’ll say in the most simple, admittedly reductionistic way possible:

One, we take an extraordinary amount of gut- and liver-damaging pharmaceutical products, especially antibiotics. The average American, including children, takes an antibiotic about once a year. They wipe out a broad range of probiotic organisms meant to keep the “bad guys” (or pathogenic bacteria and other microorganisms) in check.

Two, we eat a processed-food diet, and a diet higher in animal products than almost any other country (Brazil and Australia may eat even more meat than we do, and only the Scandinavian countries rival us, in dairy products). Inflammation is the result of eating dairy products, sugar, flour, and junk food. Inflammation causes an erosion in the strong and diverse microbiome that a healthy person has, wherein they can eat tomato-based lentil soup to their heart’s content.

I don’t know if Dr. Gundry actually believes that lectins are the problem, or if he just became enamored over time, with sales of his fad-diet books in the millions, plus all the spinoff products, selling “lectin-blocker” supplements.

My guess is that his heart was in the right place, and he had a liver/gut problem and felt better eliminating beans and many vegetables.

But the most important point is that gut dysbiosis can be healed, and many people do so. Since we have a 30’ to 35’ long digestive tract, compressed into a very small space, we require a high-fiber diet to keep our GI tract clean and our liver, gallbladder, and cardiovascular system functioning optimally.

Vegetables and legumes are two of the highest-fiber categories of foods, and when we eliminate those, we tend to eat other foods very low in fiber, and the tradeoff for eating a low-fiber diet is constipation, risk for colorectal cancers, polyps, diverticulitis, gas and bloating, and liver disease.

When we eliminate all the lectin-rich foods, we also eliminate all the food classes high in fiber. That is, most vegetables; legumes; nuts and seeds; and whole grains–the only class of high-fiber foods left are greens and fruit.

(And actually there are lectins in both of those food classes, as well, in lesser amounts! So, you’d be eliminating all the well-researched healthiest foods on Earth, if you bought into Gundry’s fear tactics about lectins!)

One must then wonder if the real reactivity may be to fiber. And if that’s so, the “cleansers” of the colon and the blood are eliminated, which puts you at much higher risk for virtually every class of disease, but especially cardiovascular disease and cancer.

If we eliminate 5 of the 7 high-fiber classes of foods, which are the least-expensive classes of foods as well, we now have a very expensive diet that is also getting harder to find, in 2022, and we’re likely to see our healthcare costs increase with the low-fiber diet (plus his supplements of course!) that Dr. Gundry markets very cleverly.

Even if, in the short term, food sensitivities for some small subset of the population is eliminated.

The problem with most of these fad diets, is that they focus on “moving the needle” in the short term, with a biomarker or two, and ignore the long-term effects, such as high risk for diseases of all types, if you overeat fat, or if you eliminate 5 of 7 categories of plant-based whole foods–or even all 7 classes of plant-based whole foods. (Because they have that bogeyman, lectins, in them.)

I would even argue that it’s not eliminating lectins that moves the needle for people’s health, in Dr. Gundry’s testimonials. It’s that Gundry’s fad diet – like all diets the past 30 years – ban processed food.

So, people go on his diet, they stop eating junk food, and then they give credit to removing lectins, for any health gains. Again, it’s a cause of misplaced cause-and-effect.

There’s also the issue that many theorize that “anti-nutrients,” despite their onerous-sounding name, actually play important, positive roles in the human body. Given that (a) high-lectin foods are staples for all of the healthiest people on Earth; and given that (b) most of the high-lectin foods are cooked before you eat them (especially legumes and grains), thereby neutralizing them, the whole raging lectin debate is mostly just a “tempest in a teapot.”

Heal your gut and you’ll likely find your reactivity to lectin-rich foods disappear.

Part of healing the gut is eating a high-fiber diet. A great accompaniment, though, is eating homemade fermented foods, such as kefir, sauerkraut or kimchi.

Taking an (actually living) probiotic supplement and an enzyme supplement can help, too. I’ve done extensive tests of 20 brands of probiotics, on two occasions, sent to me by my readers. Both times, I found that 80% of the brands I tested have no living probiotics in them, and 10% have a very minor amount of living “good bacteria” in them. And so, it’s only about 10% that have a broad range of living probiotics in them, to support a healthy gut or to rebuild a healthy gut.

The good news is, if you’re reactive to foods like potatoes and tomatoes, this can and should be temporary, and a return to gut balance can be the fix, rather than eliminating most of the most nutrient-dense foods on Earth, in favor of low-fiber, very expensive meat and dairy because they’re the only foods left.

“Lectin-blockers” are not the answer, and have no legitimate science behind them. All you need to do to neutralize lectins in beans is to cook them–which you would do anyway; no one eats raw beans.

Now, a quick note on Dr. Joe Mercola’s claim that oxalates are bad for you, which is false or a similar case of misplaced cause-and-effect, as well. You’ve read long enough already, but I covered this topic in detail on the GreenSmootheGirl blog long ago.

The Cliff’s Notes version is: most people are not reactive to oxalates; again, if they are, usually improving your overall nutrition profile and sealing the gut are the answers; and finally, foods high in oxalates are also the most nutrient-dense foods on Earth, so eliminating oxalates means also eliminating important nutrition.

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