Little known to the public at large. Little understood by the health community. Omnipresent in our conventional food culture. Proven to be at least mildly detrimental for everyone and downright destructive for the more sensitive (and often unsuspecting) among us. We’re talking lectins today: common natural agents on the one hand, cloaked thugs of the anti-nutrient underworld on the other. Our popular health media, if they’ve heard of lectins, certainly never make mention of them. Famous health gurus never deign to speak of them. In short, lectins thrive in the American diet basically unfettered, unscrutinized. Make no mistake, however. They’re a menacing power to be reckoned with. I’ve addressed them on Mark’s Daily Apple in the past (Why Grains Are Unhealthy ) and in my book (The Primal Blueprint ), but I still get a fair number of emails and forum  questions asking for more info. As I always say, let’s break it down….
What Are They?
Before Monsanto, Mother Nature had her own pesticide strategy. (Humans being among the “pests” to be warded off.) In order to avoid being completely decimated by insects, foraging animals and Groks , plant species evolved assorted anti-nutrients that would make said pests regret their gorges with a variety of mostly digestive related ailments. Low grade toxins, in a sense. A workable balance developed between plants that were able to safeguard their species’ survival and the “pest” patrons that were able to benefit from the plants’ nutrition but learned to partake more sensibly from their supply. Given that our primal forefolk foraged widely and ate a surprisingly diverse diet, the system worked.
Lectins are essentially carb-binding proteins universally present in plants (and animals). Just as they protect plant species from Grok-sized predators, lectins also support other immunological functions within plants and animals (against pathogense, parasites, etc.) They also assist in other functions like protein synthesis and delivery in animals. They’re relatively sticky molecules, which makes them effective in binding with their sought after sugars but undesirable for our digestion, in which their binding powers can lead them to attach to the intestinal lining and wreak havoc. (More on this in a minute…)
Given their omnipresence in nature, a certain amount of lectin consumption has always been inevitable. To the benefit of the plants, lectins are also hard to break down. Regular old digestive enzymes only do about half the job . Human ingenuity evolved across traditional cultures to “predigest” lectins through food preparation practices (fermenting , soaking , etc.). In our contemporary dietary culture, however, we too commonly skip these practices yet rely on the highest lectin-containing foods for our primary food sources.
What Foods Contain Them?
The short answer here is basically all plants and animal products  (PDF) to varying degrees. Nonetheless, lectins are concentrated more in some sources than others. Foods with the highest lectin activity include: grains  of all kinds (especially wheat), legumes  (especially soy ), nuts , dairy , and nightshade  plants (e.g. eggplant , tomatoes , potatoes, peppers , etc.). Add to this list the oils  and other derivative products from these food sources. And yet another, lesser known category: GMO  food, since lectins are often spliced into modified varieties  in order to enhance “natural” pest and fungal resistance.
What Do They Do To The Body?
Let’s go back to the intestine again. (Some field trip, eh?) Lectins’ stickiness allows them to bind with the lining, particularly the villi, of the small intestine. The result? Intestinal damage  (with impaired cellular repair potential), cellular death as well as compromised intestinal villi, which means reduced absorption of other nutrients, including minerals and protein. Add to this altered gut flora , which can allow certain harmful bacterial strains like E. coli to run rampant. Furthermore, because the body is now responding full-time to the needs of the injured gut lining, proteins and other resources are redirected from other basic growth and repair processes. Furthermore, lectins have been associated with leptin resistance , a pre-diabetic condition linked to obesity.
Perhaps the most insidious impacts lectins can leave in their wake is this: leaky gut. Leaky gut is a term for the breach in the intestinal lining created by lectins hand in hand with other antinutrients. Once the intestinal breach exists, lectins and other particles (like partially digested food, toxins, etc) can “leak” into the bloodstream.
Once lectins open the door, so to speak, out of the small intestine, they and other fugitive particles are now free to move about the body and bind to any tissue they come across (anything from the thyroid to the pancreas to the kidneys). Of course, the body reacts to these invaders by directing an attack on these particles and the otherwise perfectly healthy tissue they’re attached to. Enter autoimmune mayhem. That’s why lectins are linked with autoimmune disorders like IBS, Crohn’s, colitis, thyroiditis, fibromyalgia, chronic fatigue syndrome, and arthritis. Specific lectins have been associated with particular ailments (like wheat with rheumatoid arthritis), but more research is needed to trace and confirm these connections. What is clear, however, is the potent autoimmune destruction that can result when the intestinal lining experiences this level of damage.
Primal Advice For Limiting Lectins
As mentioned, lectins are literally everywhere. Although it’s impossible to eliminate them altogether, you can significantly reduce your intake.
- Purge the worst offenders. That means grains and soy more than anything, but I’d add other legumes to the list as well. Eliminating the foods that contain the highest lectin activity will slash your overall lectin intake – and impact.
- Cut back on other higher lectin sources. Not everyone wants to nix every dairy or nightshade option. Look at how you can reduce your overall intake of these items while keeping enough to enjoy their flavor and nutrient advantages.
- Gauge your sensitivity. For those of us who are most sensitive to lectins, more dramatic measures might be needed. If you know or believe that you’ve already suffered some serious intestinal damage, you might do well to steer clear of as many high and moderate lectin level foods as possible. That means perhaps forgoing nightshades, dairy, legumes and even nuts and eggs  in addition to all grains and processed foods. Reintroduce desired foods back into your diet by “family” (e.g. dairy, etc.) and be mindful of any physiological effects (however minor) that accompany them.
- Take up old traditions like soaking, sprouting and using bacterial fermentation techniques for any moderate/high lectin foods like beans  you choose to keep in your diet. Fermentation methods are especially effective, virtually eliminating lectins in one study  of lentils. All those kitchen rituals you remember from Grandma? They’re adaptive, essentially pre-digestive techniques practiced by traditional cultures around the globe. Going old school on your favorite nut varieties, for example, cuts those lectin levels dramatically.
- Don’t go wholly raw. Yes, there are legitimate reasons to enjoy raw plants in your diet, but I don’t support the practice as a movement or exclusionary principle for eating . Humans have been cooking for well over a hundred thousand years . Some nutrients are enhanced by heat. Some anti-nutrients (like lectins) are at least partially “disarmed” by it. Cooking methods with a mind toward maximizing overall nutrient value and bioavailability make good Primal sense and can lower your exposure to lectins.
- Diversify! Restrictive diets make us even more susceptible to the downsides of our foods. (Soy formula fed babies  being a dramatic example of this principle.) Make Grok proud and forage more widely for your dinner. Research shows that simply rotating primary foods was enough to limit lectin-related damage in rats  that were given rounds of soy feed. A healthy, mostly low lectin diet will offer enough balance and protective nutrition to blunt the impact of the occasional moderate level lectin sources.
- Avoid GMOs. Hidden lectin is just one more reason to leave GMO  products on the shelf.
- Maintain good overall gut health. Our modern existence sometimes seems like one giant assault against our digestive tracts. Minimize cumulative negative effects and increase positive, protective factors. Eat a healthy diet with Primal doses of probiotics , prebiotics  and good fats . Limit stress and the use of medications like aspirin, NSAIDs  and antibiotics (as well as secondary exposure through antibiotic-administered livestock ). A healthy gut will be better equipped to weather the effects of inevitable but reasonable lectin intake.
Now it’s your turn – for your comments, questions and anecdotes about lectin impact. Let me know your thoughts, and thanks for reading!