Transcript of the No-Bullshit Vegan podcast, episode 66.
B.S.-busting on lectins (a.k.a. "antinutrients");
the pseudoscience of "lectin-free" diets
You’re listening to the No-Bullshit Vegan podcast, episode 66. You’re in for some good old-fashioned bullshit-busting today, all about the idea that lectins (also often called “anti-nutrients”) are bad for our health.
Hey, welcome to the show - I’m Karina, your go-to, no-B.S. vegan fitness and nutrition coach. Thanks so much for joining me today for some serious bullshit-busting about a topic that honestly never should’ve been a “thing” in the first place, but after a few years it’s unfortunately still talked about. First: you’ve heard me say this before but I’ll say it again: reviews of this show on iTunes are much appreciated, and one of the most effective things you can do to support this podcast. So, if you haven’t yet left a star rating and a quick review on iTunes, I’m gonna give you some extra incentive: if you leave a review from now until March 31st, I’ll send you a chapter of my new ebook, Sprouted Gains, for free. It’s the chapter on protein: busting myths in case anyone asks you about it, calculations to figure out your own needs, sample meals, etc. So, leave an honest review on iTunes at nobullshitvegan.com/itunes, take a screenshot of your review before you submit it, and send it to me on Facebook (business page or personal page - just find me). And I’ll send you your free book chapter!
Also a quick shoutout to screen name 50yearsveggienowvegan, who left the following review:
“Always fascinating, so many different aspects of veganism covered, new stuff to think about every time”.
Thank you! 5 decades of being vegetarian is absolutely amazing, and fantastic to hear you’re now vegan.
I’ve been wanting to tackle today’s topic of lectins for a while, but better late than never! The topic sometimes comes up in arguments against veganism, and it also comes up within veganism, when people try to eat a so-called “low lectin” or “lectin-free” diet. Hashtags like #plantparadox (which I’ll explain in a sec) and #lectinfree are still circulating around Instagram, and of course Facebook is rife with misinformation on lectins, including lectin free recipe groups with many thousands of members. And just a few days ago I just saw someone in the Vegan Bodybuilding and Nutrition Facebook group (which I help moderate, and which has over 31,000 members) mention lectins and the fact that we should stay away from foods high in lectins. So, the bullshit is still out there, and I’m taking it upon myself to bust it!
What the heck are lectins?
Lectins are plant proteins that help plants protect themselves (from things like insects, for example). They’re a carbohydrate-binding protein that sticks to cell membranes in the digestive tract. So they basically help cells stick together. This can decrease your body’s ability to absorb certain nutrients, which had lead to the term “anti-nutrient”. They’re also resistant to digestion.
Some lectins, like ricin, are highly toxic. Others are not. People who suggest staying away from all lectins are painting them all with the same brush.
So why the hype around lectins? Why did we suddenly—and recently—start caring about lectins?
Well, in 2017, a certain Dr. Steven Gundry published a book called The Plant Paradox, laying out his theory that lectins are bad for our health and are causing everything from digestive issues to cancer to weight gain. This book essentially started a fad diet, based on misinformation. Not really a new story in the health and diet world, but in many cases—this one included—following such a diet can be detrimental to your health. This is why it’s so important for me to bust bullshit in the veganism/fitness/nutrition/health world—because following many of the bullshit concepts or suggestions can be dangerous.
Where are lectins found? What foods are high in lectins?
Lectins are found in most plant and animal-based foods, but in different amounts.
Foods with the highest amounts of lectins include legumes (which includes peanuts), nightshade vegetables like tomatoes, potatoes, peppers, and eggplant, as well as grains like wheat, quinoa, barley, and rice.
What’s the supposed issue with lectins? Why are they considered “harmful”?
A lot of it comes down to an immune response, and creating inflammation.
Dr. Gundry, in The Plant Paradox, says that lectins can cause digestive issues, higher rates of bacterial and viral infections, and weight gain. He even uses the term “lectin poisoning”. He does acknowledge individual differences in lectin sensitivity, and that some people might digest them with no issues.
Yeah, lectins can cause flatulence (like fiber). And if you ingest enough of them, they can cause digestive issues. Here’s what Precision Nutrition has to say:
“As food passes through the gut, it causes very minor damage to the lining of the GI tract. Normally the cells repair this damage rapidly. Since the purpose of the gut lining is to let the good stuff past and keep the bad stuff contained, it’s important for the cellular repair system to be running at full efficiency.
But lectins can blunt this speedy reconstruction. Our cells can’t regenerate as fast as they need to in order to keep the intestinal lining secure. Thus, our natural gut defenses are compromised after the damage occurs and the gut can become “leaky,” allowing various molecules (including stuff we don’t want) to pass back and forth amid the gut wall. We may also not absorb other important things, such as vitamins and minerals, properly.
When enough lectins are consumed, it can signal our body to evacuate GI contents. This means vomiting, cramping and diarrhea. It’s similar to consuming large amounts of alcohol, which can damage the GI lining and cause GI evacuation.”
I’m gonna touch on this point of “enough lectins” shortly. But first: back to Dr. Gundry.
It’s important to note that Dr. Gundry was a cardiologist. Dr. Michael Greger (of nutritionfacts.org) has a good point in that “MD” is an anti-credential, because it advertises to the world that you’ve got next to no nutritional training.
So Dr. Gundry writes The Plant Paradox all about how horrendous lectins are to our health, and then, of course, he sells a product (for $79.95 USD) called “Lectin Shield” that supposedly reduces the negative effects of lectins.
I’m not going to debunk Gundry’s entire book, because that would take days. But I will tell you that most of the scientific references he uses don’t even relate to the points he’s making, and the book has been thoroughly debunked by others (I’m sharing a bunch of resources at our show notes; nobullshitvegan.com/066).
To give you a taste of his absolute bullshittery, there’s a prominent article on his website, called the “definitive guide to lectins”.
The article contains 8 references, 2 of which are duplicates.
Out of the remaining 6 references, only 3 are actually about lectins. One is a book chapter from 1986 (book chapters are not considered peer-reviewed resources). The second is an article from 1995 on the role of lectins—in plants. There’s a tiny section at the very end that presents hypotheses about lectin effects in higher animals, but there’s no mention of humans, other than “accidental poisoning of humans by raw or insufficiently cooked beans.”
The third is a review article from 14 years ago, concluding that “At high intakes, lectins can seriously threaten the growth and health of consuming animals.”
In the past 14 years, there hasn’t been any definitive research that shows lectins are harmful to humans. The vast majority of the work has been done in labs on animals, feeding them isolated lectins, not real foods. In fact, newer research, including a study from 2017, has found health benefits of lectins, including their antimicrobial, immune system boosting, and anti-cancer properties.
Dr. Gundry’s claim that lectins cause weight gain has been refuted. In fact, studies show that people who eat diets high in lectins, such as lots of legumes, have lower BMIs.
Remember that list of foods that’re high in lectins? Things like beans, lentils, quinoa, rice, wheat? Well, here’s an important point I don’t want you to miss: cooking, sprouting, or fermenting destroys most—if not all—lectins. Who on earth is eating raw beans, raw rice, and raw quinoa?! The high lectin content in raw kidney beans is known to cause major health issues. But nobody eats raw kidney beans. Fermenting beans (like for tempeh) destroys 95% of lectins. Studies have shown that between 10 and 30 minutes of boiling destroys all lectins in beans.
There are no lists of lectin content in foods like there are for things like vitamins and minerals, because it depends a lot on how they’re prepared. There are also differences in lectin content from crop to crop of the same plant. But I’m willing to bet that there are foods on the “safe” list for someone on a lectin-free diet that are higher in lectins than foods that are on the “no-no” list.
Are there people whose digestive tracts react negatively to high loads of lectins? Maybe. Anything’s possible, although it hasn’t been shown in empirical research yet. Even if there are people who have adverse reactions to lectins due to autoimmune issues for example, that doesn’t mean everyone should avoid lectins. That’s kinda like me telling you to avoid eating almonds, hazelnuts, and walnuts, just because I’m deathly allergic to tree nuts.
If you’ve tried a so-called “lectin free diet” and felt much better on it, all the power to you! (Remember that “lectin-free” is not an accurate term, as most—if not all—plant and animal foods contain lectins.) The reason you feel better cutting out things like wheat and legumes, however, is likely not the presence of lectins.
Also, if you lost weight on a lectin-free diet, it wasn’t the lectins. A lectin-free diet eliminates many of the highly processed, highly caloric foods commonly found in the Standard American Diet, and replaces them with whole foods.
Keep in mind that the scientific literature as a whole supports the inclusion of foods like whole grains and legumes in our diets, because of their health benefits.
Here’s what the Harvard School of Public Health has to say, in an article called “Are anti-nutrients harmful?”:
“Though certain foods may contain residual amounts of anti-nutrients after processing and cooking, the health benefits of eating these foods outweigh any potential negative nutritional effects. Eating a variety of nutritious foods daily and avoiding eating large amounts of a single food at one meal can help to offset minor losses in nutrient absorption caused by anti-nutrients.”
Here are a few key lines from a Washington Post piece by Cara Rosenbloom, called “Going ‘lectin-free’ is the latest pseudoscience diet fad”:
“The problem is that online health gurus are painting all lectins with the same brush, and playing up the negative effects without the evidence to back it up. Saying all lectins are poison is akin to saying that you shouldn’t eat button mushrooms because some foraged mushrooms are toxic. It makes no sense.”
“It’s critical to note that the majority of lectin studies have been done with isolated lectins, not actual foods, and have been conducted in test tubes or in animals, not in people. So how can these online health gurus conclusively link lectin-containing foods to certain health issues when clinical trials in humans have not even been conducted yet?”
“Have you ever crunched into a raw kidney bean? I didn’t think so. Hard as rocks, all beans and lentils would be inedible in their raw form. Boiling beans for 30 minutes eradicates most, if not all, of the lectins.”
Here’s a short portion of an article on the Today’s Dietitian website:
“Given the strong scientific data that support the health benefits of pulses, nuts, fruits, and vegetables (ie, foods in which lectin is found), and the scarce scientific evidence available on the harmful effects of lectin, it would be nonsensical for any dietetics professional to recommend a lectin-free diet. Furthermore, because they provide a wide array of important nutrients, removing lectin-filled foods from the diet, especially over a long period of time, can lead to potential deficiencies.”
You get the idea. So now you’re armed with the information you need to bust bullshit around lectins or “anti-nutrients”, and I’m providing a bunch of additional resources at our show notes, which you can access at nobullshitvegan.com/066. You’ll see links to the articles I mentioned in this episode, as well as in-depth debunking of Gundry’s Plant Paradox book.
Please remember to leave a quick review of this show at nobullshitvegan.com/itunes. Take a screenshot of your review before you submit it, send it to me on Facebook, and I’ll send you your free chapter of my Sprouted Gains book.
Thanks for listening!