What are lectins, and what is a lectin-free diet? Why are some people choosing to avoid lectins, and what does the science say about the influence of lectins on health?
Lectins have become a big topic of conversation lately, with many influencers proposing a multitude of benefits to following a lectin-free diet. Proponents suggest that going lectin-free can do everything from curing digestive issues and autoimmune disorders to weight loss. I don’t take testimonials as evidence, however, so today we’re going to unpack what the science actually says.
What are lectins?
Lectins are a protein that binds to carbohydrates. Essentially, they act kind of like velcro between carbohydrates, binding them loosely together while still allowing them to separate if needed. Found in all plants, it has been widely suggested they act as a protective mechanism. This theory is just that, however, as we still aren’t completely sure what purpose lectins have in plants.
Which foods contain lectins?
Pretty much all of them. Plants, animals, and microorganisms alike contain lectins in varying amounts. They’re found in the highest amounts in plant foods like beans, lentils, and whole grains.
What is the lectin-free diet?
If at this point, you’re confused about how a person could completely avoid lectins, you’re right to be confused. It’s literally impossible to completely avoid them since every single plant and animal product contains them. Some foods are higher than others, however, which is where the guidelines for following a lectin-free diet come from. The lectin-free diet advocates avoiding foods highest in lectins like legumes, whole grains, and nightshade vegetables (tomatoes, potatoes, eggplant, etc).
Why are people going lectin-free?
Proponents of lectin-free diets suggest that lectins are dangerous for the body. Some are acid-resistant, meaning that they can pass through our stomach without being broken down. They’re also binders, which some claim makes them “antinutrients” and prohibits certain nutrients from being absorbed by the body. As we’ll discuss later, however, the actual amounts consumed by the average person is not that significant. Some suggest that this is dangerous and leads to inflammation, malabsorption of nutrients, weight gain, autoimmune disorders, cancer, you name it.
What does the science actually say?
The science when is comes to lectins is pretty sparse. Most research is in rat or other animal models, or was performed outside of the human body. (If you want to know more about what to look for when reading nutrition studies, click here.) Essentially, there’s ZERO good research to support any of the claims made by those who suggest we should all go lectin-free. There’s even some ongoing research looking into potential beneficial effects of lectins in certain foods on inhibiting tumor growth. At this point, however, there’s nothing solid to suggest we should avoid them, or that we should be using them to try and treat disease.
Where is the fear around lectins coming from then?
Lectins pass through our stomach without being broken down and are largely indigestible. Large amounts of active lectins have also been found to be toxic in humans in large quantities and cause significant gastrointestinal distress. Sounds scary, right?
There’s one important piece that often doesn’t get mentioned though when proponents of going lectin-free try to promote their diets, books, and supplements: it’s incredibly unlikely that a person would be able to ingest potentially toxic levels. Lectins break down when they’re processed or cooked, and the foods they’re highest in are foods that are almost always cooked. I mean, when’s the last time you ate a bunch of raw, uncooked beans and wheat?! Science suggests that just 10-15 minutes of boiling destroys the majority of lectins in foods. The reality is that the dose makes the poison, and the likelihood of a person consuming enough lectins to be dangerous is very very low.
So, as a dietitian, what are your thoughts on lectins and people going lectin-free?
Honestly, it makes me pretty mad that medical professionals (*cough* Dr. Gundry *cough*) are exploiting people’s fears for profit. Once again, we don’t have any good evidence to suggest lectins are dangerous in the way they’re typically consumed.
As far as going lectin-free, I have a LOT of concerns. Lectins are found in the highest amounts in foods that contain so many nutritional benefits. Avoiding them invariably means avoiding some pretty terrific sources of fiber, vitamins, minerals, and antioxidants. Anybody who wants to go lectin-free should ABSOLUTELY consult a Registered Dietitian Nutritionist to make sure that they aren’t missing out on any key nutrients as a result of this restrictive diet.
We have TONS of excellent research suggesting that whole-grains, fruits, vegetables, and pulses (legumes) are beneficial for human health. Pretty much all of those things also contain high amounts of lectins. Any potential negative side effects of lectin consumption (which we don’t have proof of) is likely far outweighed by the other, evidence-based, benefits of these foods.
I also just take major issue with the blatant bias proponents of lectin-free diets have. Oh, you’re also selling “lectin blocker” supplements that are over $50 a bottle?! How convenient for you.