Hi, Desiree. There is evidence that if certain lectin-rich foods aren’t well-cooked they can damage the gut. Poisoning from undercooked kidney beans is documented, and it’s lectins that are blamed. However, legumes have been a part of the human diet, providing fiber, protein, vitamins, and minerals, for at least 8,000 years, and damage to the intestine from well-cooked beans has not been demonstrated.

But to your point, some doctors and researchers have proposed that lectins in many common plant foods may be causing inflammation, leaky gut, and autoimmune diseases. And preliminary research indicates that these concerns are worth investigating.

Lectins are proteins, and we digest most proteins, meaning that our digestive enzymes break them down into harmless amino acids. However, lectins are difficult to digest unless they are cooked. It’s uncooked undigested lectins that can wreak havoc on the intestine. They aren’t unique in this regard; gluten is another problematic protein that resists digestion. Incompletely digested proteins can elicit allergic reactions, and allergies to lectins in wheat, banana, avocado, chestnut, turnip, and corn have been reported. But allergies aren’t the major problem.

Lectins in uncooked foods cause leaky gut by poking holes in the layer of cells—the mucosa—lining the intestine. Lectins also render cells of the intestinal wall unable to digest and absorb nutrients, and they activate white blood cells, promoting inflammation. And preliminary research suggests that lectins might affect the immune system and other tissues outside of the gut. There’s ongoing research on inflammatory effects of peanut lectin, in particular.

Two of the best-studied and most powerful lectins are PHA (phytohemagglutinin), from beans, and WGA (wheat germ agglutinin), from wheat. WGA could be one of the reasons—in addition to gluten—that some people find that wheat doesn’t agree with them. WGA can bind to intestinal cells, and preliminary research suggests that it can increase gut permeability. It can also activate white blood cells and is proinflammatory. WGA is found in the nutrient-rich germ portion of grains, which is removed when grains are refined. There’s more info on wheat in our goop PhD article on celiac disease and gluten intolerance.

Do you need to avoid lectins? They’re everywhere, so you can’t really. And you don’t need to because not all lectins are harmful. They’re found in almost all organisms, including animals, microorganisms, and plants, where they are concentrated in seeds. The foods that contain the highest amounts of the potentially harmful lectins are cereal grains and legumes, with the order of highest to lowest lectin content—according to one analysis—being soybeans, other beans, lentils, peas, fava beans, and chickpeas.

We’ve all eaten beans without suffering from food poisoning. Lectins are inactivated by boiling or pressure-cooking. They aren’t destroyed by microwaving, baking, or roasting. You can’t count on sprouting or fermentation, although these processes may help reduce lectin activity. The recommendation is: Soak beans, then boil or pressure-cook them until well-done. Should we have listened to those cooks and grandmas who boiled veggies until grey-colored and mushy? Should we take heed of Ayurvedic practice, where raw salads are not big on the menu?

Evidence is lacking that lectins in raw plant foods are causing problems for most of us. But we do know that physiology is highly individual, and that food intolerances are poorly understood. It’s possible that eating small amounts of uncooked lectins could contribute to inflammation, immune system disorders, and problems absorbing nutrients. If you feel that a particular raw food bothers you, try cooking it thoroughly and see if that helps. Listen to your gut.