Dear Goop, I’ve heard that many plant-based foods contain lectins which are said to damage the intestines and cause problems throughout the body. I am a vegetarian and wonder how that can be – do lectins in food really harm me? -Wish
Hello Desiree. There is some evidence that certain foods rich in lectin that are not well cooked can damage the intestines. Poisoning from undercooked kidney beans has been documented, and lectins are blamed for this. However, legumes have been a part of the human diet for at least 8,000 years and provide fiber, protein, vitamins, and minerals, and damage to the intestines from well-cooked beans has not been proven.
But on your point, some doctors and researchers have suggested that lectins in many common plant foods can cause inflammation, leaky gut, and autoimmune diseases. And preliminary research shows these concerns are worth investigating.
Lectins are proteins, and we digest most proteins, which means our digestive enzymes break them down into harmless amino acids. However, lectins are difficult to digest if not cooked. It’s uncooked, undigested lectins that can wreak havoc on the intestines. You are not unique in this regard; Gluten is another problematic protein that resists digestion. Incompletely digested proteins can cause allergic reactions, and allergies to lectins in wheat, banana, avocado, chestnut, beet, and corn have been reported. But allergies are not the main problem.
Lectins in uncooked foods cause leaky gut by poking holes in the layer of cells – the mucous membrane – that lines the gut. Lectins also make cells in the intestinal wall unable to digest and absorb nutrients, and they activate white blood cells, which increases inflammation. Preliminary research suggests that lectins could affect the immune system and other tissues outside of the gut. In particular, the inflammatory effects of peanut lectin are constantly being researched.
Two of the best-studied and strongest lectins are PHA (phytohemagglutinin) from beans and WGA (wheat germ agglutinin) from wheat. WGA, along with gluten, could be one of the reasons some people find that wheat doesn’t match them. WGA can bind to intestinal cells, and preliminary research suggests it can increase intestinal permeability. It can also activate white blood cells and is pro-inflammatory. WGA is found in the nutrient-rich germ fraction of grain that is removed during grain processing. For more information on wheat, see our Goop PhD article on Celiac Disease and Gluten Intolerance.
Do you need to avoid lectins? They are everywhere so you really can’t. And you don’t have to, because not all lectins are harmful. They are 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 from highest to lowest lectin content – according to one analysis – being soybeans, other beans, lentils, peas, fava beans, and chickpeas.
We all ate beans without suffering from food poisoning. Lectins are inactivated by boiling or pressure cooking. They are not destroyed by microwaves, baking or roasting. You cannot rely on sprouting or fermentation, although these processes can help reduce lectin activity. The recommendation is: soak the beans, then boil or pressure cook until they are through. Should we have listened to the cooks and grandmas who made vegetables gray and mushy? Should we pay attention to Ayurvedic practice, where raw salads are not big on the menu?
There is no evidence that lectins in raw plant-based foods cause problems for most of us. But we know that physiology is very individual and that food intolerances are poorly understood. It is possible that consuming small amounts of uncooked lectins can contribute to inflammation, immune system disorders, and problems absorbing nutrients. If you feel that a certain raw food is bothering you, try cooking it thoroughly and see if that helps. Listen to your gut.
The extent to which lectins affect our health may not be well understood. But one thing is clear: too much alcohol puts a strain on the intestines. I love having alternatives for cocktail hour, and my premixed mocktail is a Kin Spritz. It’s refined, tangy and refreshing.