LECTINS
Previously published 25/10/2018.
What are lectins?
Plant Lectins are a line of defence against microorganisms, pests, and insects. They also allow seeds to remain intact as they pass through animals’ digestive systems for later dispersal. Lectins are resistant to human digestion and can enter the blood unchanged.
Lectins are proteins that can bind to cell membranes by attaching to a sugar anchor. They offer a way for molecules to stick together without involving the immune system, which can influence cell-to-cell interaction.
Lectins are abundant in raw legumes and grains and are most commonly found in the part of the seed that becomes the leaves when the plant sprouts, but also on the seed coat (bran). They’re also found in dairy products and certain vegetables like tomatoes. While lectin content in food is fairly constant, the genetic altering of plants has created some fluctuations. Plus, we eat a lot more grains than we are supposed to. Our Western diet is based on grain and grain products, which are often highly processed in many ways.
Lectins are thought to play a role in immune function, cell growth, cell death, and body fat regulation.
Because we cannot digest lectins, we often produce antibodies to them.
Almost everyone has antibodies to some dietary lectins in their body.
This means responses vary between individuals and can create intolerances or give the same symptoms as gluten or lactose intolerance.
There are some lectins that no one should consume.
Red Kidney Beans, for example, should never be sprouted. They contain phytohaemagglutinin, a lectin that can cause poisoning.
The poisoning is usually caused by ingesting raw, soaked kidney beans. Just a few beans can trigger symptoms — raw kidney beans contain 20,000–70,000 molecules (lectins), while fully-cooked beans usually contain much less, about 200–400.
“In humans, lectins resist digestion and may affect the lining of the intestines and nutrient absorption.”
While many types of lectins cause negative reactions in the body, there are also health-promoting lectins that can decrease the incidence of certain diseases. The body uses lectins to achieve many basic functions, including cell-to-cell adherence, inflammatory modulation and programmed cell death.
“Some lectins are antioxidants, which protect cells from damage caused by free radicals.”
As previously explained, lectins can cause damage to the gut wall by attaching to a sugar anchor on the cell membrane. Although it causes minor damage to the lining of the GI tract, it is normally repaired very quickly. Since the purpose of the gut lining is to let the good stuff through and keep the bad stuff contained in the lumen of the gut, it’s important for the cellular repair system to be running at full efficiency.
Sometimes, lectins can impact gut wall repair, and overwhelmed cells cannot regenerate as fast as needed to keep the intestinal lining secure — compromising the gut’s integrity, a leading cause of “leaky gut”. Larger molecules can, therefore, enter the bloodstream and cause havoc — a much broader immune system response as the body’s defences attack the invaders. Symptoms can include acne and skin rashes, joint pain, and many symptoms associated with systemic inflammation.
When someone suffers from Crohn’s disease or irritable bowel syndrome, the gut lining seems more sensitive to food lectins. This might be due to the high turnover of cells and the greater presence of immature cells.
Unrefined grains are more nutritious than refined versions because they contain more nutrients. However, they also provide more lectins (and other anti-nutrients. e.g. phytic acid, also known as phytate).
While this was likely never a problem when we grew and harvested grains in our fields, we now consume far too many whole grain products. Before the invention of modern agriculture, grains were a minor and seasonal crop. Now, we go to the supermarket and can leave with a cart full of pasta, bread, rice, quinoa, amaranth, oats, barley, and more.
Top 5 lectin-rich foods
1. Beans:
Beans, especially red kidney beans, contain high concentrations of lectins. Raw or undercooked, they can unleash a storm of digestive distress.
Soak dried beans overnight (at least 8 hours)
Rinse thoroughly
Boil in four times their volume of water. Using a pressure cooker also helps further.
Remember, canned beans are already cooked and safe to eat.
2. Peanuts
These popular legumes contain peanut agglutinin (PNA). PNA can trigger allergic reactions and mess with your blood vessels and platelets. To reduce lectin content:
Boil or roast peanuts
This destroys 98-100% of their lectins
3. Cashews
Cashews pack a double punch with anacardic acid and cardol, potentially causing skin irritation and allergic reactions. They also contain phytic acid. To enjoy cashews safely:
Soak for at least 6-8 hours (ideally overnight)
Roast or boil before eating
4. Whole Grains
Whole grains, especially wheat, are packed with lectin. They also contain phytic acid. To maximize nutritional benefits:
Soak, sprout, or cook (boil or pressure-cook) whole grains before consumption
5. Nightshade Vegetables
Aubergines, tomatoes, peppers, and white potatoes belong to the nightshade family, known for their high lectin content. Unsurprisingly, these vegetables may exacerbate symptoms in people with gastrointestinal conditions. To minimise potential risks:
Avoid eating nightshades raw
Peel potatoes before cooking
The Lectin Lowdown
Despite the concerns, lectin-containing foods offer numerous health benefits that outweigh potential risks for most people. If you don’t know food intolerances or sensitivities, there’s no need to avoid lectins. Instead:
Diversify your diet with a variety of plant foods
Avoid consuming large amounts of a single food
Properly prepare lectin-rich foods to reduce their lectin content
If you experience persistent digestive issues, consult a registered dietitian to evaluate your diet and identify any underlying conditions.
How to reduce your exposure to lectins and phytic acid?
Soaking, fermenting, sprouting, and cooking will decrease lectins and free up essential nutrients.
Soaking beans and legumes overnight, changing the water a few times, and adding sodium bicarbonate to water may help neutralise lectins further, so draining and rinsing again before cooking.
Fermentation allows beneficial bacteria to digest and convert many of the harmful substances (sourdough bread or beer, which are still considered fermented grains).
Cooking with seaweed can help reduce the lectin and phytate content, especially when cooking beans and legumes, as seaweed can attract and trap them and be eliminated via the bowel.
“Boiling, steaming or soaking lectin-containing foods like whole grains minimizes their lectin content, making them unlikely to cause harm.”
Some experts hypothesise that it is no coincidence that the top eight allergens also contain some of the highest amounts of lectins (e.g., dairy, egg, wheat, soy, peanuts, tree nuts, fish and shellfish).
The Last Word
Lectin-containing foods like beans, whole grains and nuts are also associated with lower rates of Type 2 diabetes and cardiovascular disease. Many lectin-containing foods like tomatoes and potatoes are rich sources of B vitamins, protein, dietary fibre, minerals and healthy fats.
When prepared properly, the health benefits of these foods surpass their potential harm,
“There’s no conclusive evidence that avoiding lectins benefits everyone.”
If you don’t have any food intolerances or sensitivities, there’s no need to avoid lectins. Instead:
Diversify your diet with a variety of plant foods
Avoid consuming large amounts of a single food
Properly prepare lectin-rich foods to reduce their lectin content.
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