Lectins1— sugar-binding plant proteins that attach to cell membranes — may be a hidden source of weight gain and ill health, even in an otherwise healthy diet. In fact, since lectins are present in most plant foods, if you're eating a whole food diet yet find yourself still struggling with weight gain and/or stubborn health problems, lectins may well be a hidden culprit.
Many lectins are proinflammatory, immunotoxic, neurotoxic and cytotoxic. Certain lectins may also increase blood viscosity, interfere with gene expression and disrupt endocrine function.
The problem with recommending an altogether lectin-free diet is that this would eliminate most plant foods,2 which should ideally make up the bulk of your diet. Moreover, in small amounts, some lectins can be quite beneficial,3 so 100 percent avoidance is likely neither possible nor ideal. They key then becomes finding a happy medium where the worst lectins are avoided, and the effect of others are tempered through proper preparation and cooking.
How Lectins Can Wreck Your Health
Before we get into strategies to reduce lectins in your diet, let's review the reasons why. As explained in Dr. Steven Gundry's4 book, "The Plant Paradox: The Hidden Dangers in 'Healthy' Foods That Cause Disease and Weight Gain," some plant lectins can contribute to leaky gut by binding to receptor sites on your intestinal mucosal cells, thereby interfering with the absorption of nutrients across your intestinal wall.
As such, they act as "antinutrients," and can have a detrimental effect on your gut microbiome by shifting the balance of your bacterial flora. Among the worst culprits are wheat germ agglutinin (WGA), found in wheat and other seeds in the grass family.5
Compared to WGA, gluten is a minor problem. According to Gundry, WGA is actually one of the most efficient ways to induce heart disease in experimental animals. Lectins in general are strongly associated with autoimmune disorders, so anyone struggling with a dysfunctional immune system may want to seriously consider experimenting with a low-lectin diet.
One way by which lectins causes harm is through molecular mimicry. By mimicking proteins in your thyroid gland or joint spaces, for example, lectins can cause your body to attack your thyroid and contribute to rheumatoid arthritis. Part of these disease processes is the penetration of the gut wall by lectins and their co-travelers, lipopolysaccharides (LPSs), also known as endotoxins, which tend to elicit very strong immune responses.
Lectin-Rich Foods Best Avoided Entirely
While it may be near-impossible to avoid all lectins, seeing how they're found in most plant foods, your first step would be to eliminate the worst offenders. If you have any kind of health problem in which lectins are a suspected contributor, it would be wise to eliminate the following entirely:6
•Corn-fed meats. This includes most meats sold in grocery stores. To avoid factory farmed, corn-fed meat, make sure the meat you buy is certified grass fed by the American Grassfed Association.
•Casein A1 milk. Casein A2 is the normal protein in milk, present in sheep, goats, water buffalos and some Jersey cows' milk. Unfortunately, most cows today are casein A1 producers. Most store-bought milk will be A1, even if it's organic. The A1 protein is metabolized in your gut to make beta-casomorphin, which can attach to the beta cell of your pancreas and incite an autoimmune attack.
Many who believe they're lactose intolerant are actually just responding to the casein A1 in the milk. If you're going to drink milk, make it raw milk from organic, grass fed casein A2-producing cows. Jersey cows may produce either A1 or A2 casein, so you'll need to confirm the type of milk produced with the farmer. Holsteins are A1 producers and should be avoided.
•Peanuts, cashews and unfermented soybean products. If you want to eat soy, make sure it's traditionally fermented.