You might not hear much about lectins these days. Most books on nutrition or intestinal health rarely mention them. This is surprising (and potentially alarming) when you consider that anyone with any sort of digestive issue should be paying close attention to lectins since they're found in so many foods.
What are lectins?
Lectins are specialized proteins found in all plants and plant seeds. Lectins act as a deterrent against creatures consuming plants or seeds by binding to carbohydrate molecules present in cell membranes within the gut. This action disrupts the cell membranes, irritating the gut lining and causing the creature to think twice about ever eating those plants or seeds again.
Of course, humans have been eating plants since the dawn of time (less so with seeds, however). As a result, humans have developed a natural protection against lectins. The lining of the gut is coated with a protective barrier of carbohydrate molecules, or mucus. These molecules act like decoys that neutralize the plant lectins. Even so, high concentrations of lectins can still cause a lot of damage.
Problematic lectins can be found in these primary sources:
- Grains (especially wheat and corn)
- Beans/legumes, especially soybeans, kidney beans, black beans, and peanuts
- Tree nuts, such as almonds, pecans, walnuts, cashews, and pistachios
- Nightshade vegetables, including tomatoes, potatoes, eggplant, and peppers
- Dairy products from cows raised on corn and soybeans
In other words, lectins are found in the foods that Americans eat every day!
Are lectins the same as gluten?
Both lectin proteins and gluten proteins have the potential to damage the gut lining, but they're not the same. Lectin proteins are found in the outer protective covering of the seed, called bran. Whole-grain products are actually high in lectins.
Gluten is a plant storage protein found in the seed's endosperm; it stores amino acids necessary for the seed to sprout. Because plant storage proteins are structured differently from animal proteins, they're hard to digest and can irritate the intestinal tract of animals. While all seeds contain storage proteins, gluten proteins can be the most irritating.
A recipe for digestive dysfunction
Take lectin-loaded food three times daily. Add a significant dose of gluten products, along with plenty of sugar. Top it off with a generous portion of chronic tension that comes from modern living.
Stress worsens the situation because it slows down movement within the intestinal tract. This worsening intensifies the damage from lectins and gluten proteins. Starch and sugar cause the overgrowth of intestinal bacteria, which complicates matters further.
You can wind up with a compromised digestive system and suffer from all sorts of gastrointestinal problems, such as reflux, indigestion, irritable bowel syndrome, gas, bloating, loose stools, or constipation.
A recipe for enjoying normal digestion
Plant lectins aren't nearly as much of a problem as seed lectins since humans are more adapted to eating plants over seeds. For this and many other reasons, keep the following in mind:
At least half of your food should come from vegetables. You should cook most of your food since cooking helps break down lectins (steaming vegetables is a great way to break down lectins yet retain nutrients).
Fish, eggs, and poultry don't contain lectins or other similarly damaging substances, so they're the best source of protein (red meat is a bit harder to digest).
While seeds are nutrient-rich, because of the lectin and other storage proteins, they shouldn't make up any significant portion of your diet.
Grains, beans, and legumes
Lectins can be reduced (but not eliminated) in grains by sprouting and boiling. Baking doesn't significantly reduce the amount of lectins or gluten in wheat products.
Lectins can be reduced in beans by extended soaking, fermenting, or prolonged boiling (raw and/or sprouted kidney beans are poisonous because of their high lectin content). Fermented soybean products, such as tempeh, are lower in lectins than other soy products.
Fortunately, there is an exception to every rule: white rice. The lectins and storage proteins in white rice have a lower potential for harm. The carbohydrates in rice are broken down completely and don't contribute to bacterial overgrowth in the gut.