I grew up eating baked beans, whole grain bread, oatmeal and barley. I love the glorious smoothness and flavour of a well-blended chickpea hummus -- yum! Turns out humans have been eating pulses, a.k.a. legumes (chickpeas, lentils, dried peas and beans), seeds and grains for quite a long time.
Archaeological evidence puts lentils in Egyptian pyramids and pulses in the Punjab area of Asia around 3300 BC -- clearly our ancestors where onto something. However, if we're to believe any of the internet chatter these days, something about these foods is bad -- cue yet another dietary fad: lectin avoidance for everyone.
What are lectins?
Lectins are a group of proteins found in every living thing such as plants, bacteria and foods (legumes/pulses, seeds and grains especially) -- most are harmless. Even though they're found in all foods, only about 30 per cent of our diet contains lectins in meaningful amounts. In human physiology, lectins seem to play a beneficial role in immune function, cell growth and regulating inflammation.
In plants, the role of lectins is not fully understood, but they appear to be a deterrent to being eaten by microorganisms, insects and animals. By having compounds that can cause indigestion and intestinal damage, animals may think twice before coming back for seconds. When it comes to seeds, it's thought that lectins help plants to be fruitful and multiply -- foraging animals eat the seeds, which pass through their digestive tracts unchanged, allowing them to be dispersed around town via stool.
So, what's the hubbub about lectins?
Like any health fad, most have a seed of truth within them. Just as lectins can cause problems for animals, humans are potentially vulnerable to their toxicity, too. They can cause problems for the digestive tract by binding to intestinal cells, which may lead to cellular dysfunction and increased inflammation. Lectins are also resistant to human digestion and can enter the blood stream unchanged.
Because some lectins, such as phytohaemagglutinin, found mostly in uncooked (raw) or improperly prepared red and white kidney beans, can lead to kidney bean poisoning (abdominal pain, vomiting and diarrhea), lectins have gotten a bad rap.
On a side note, this is why you'll never see sprouted [raw] red kidney beans as a food. Good to know.
Like anything, there's a lot of variation between people and their ability to tolerate foods.
Since plant foods have been part of the human diet for millennia, we've evolved some protection against them -- the immune system produces lectin antibodies, and virtually everybody on the planet has these antibodies in their system.
However, like anything, there's a lot of variation between people and their ability to tolerate foods rich in lectin, such as nightshades (tomato, potato, eggplant, bell peppers, etc), as well as wheat and other grains, or pulses (chickpeas, lentils, dried peas and beans). Ask any nutritional professional who works with digestive issues.
What does the research say?
Under certain conditions, dietary lectins can be problematic. High intakes of lectin-containing foods can irritate the digestive tract, which may aggravate certain intestinal conditions like inflammatory bowel disease (Crohn's and Colitis) or IBS.
Because lectins have been shown to increase the permeability of the intestinal tract (the small intestines become more porous, allowing lectins to enter the blood stream), lectins can stimulate the immune system and trigger it to produce antibodies against the lectins and the tissues that the lectins might be attached to. This is how dietary lectins may be a problem for those with autoimmune diseases such as Celiac disease, rheumatoid arthritis and lupus, for example. Some studies have found a benefit for this subgroup of people when they followed a lectin-reduced or lectin-free diet when their disease is more active.
Of course, we know that the vast majority of people can confidently enjoy lectin-containing pulses, grains and seeds, including those with potential health conditions that might make them more sensitive to them when they're well. This shouldn't be a surprise or sound shocking; this is true for any food. Not all foods can be eaten by all people all of the time, but that doesn't mean lectins should be shunned carte blanche.
Soaking, cooking [boiling and heating] and fermentation degrades most of the lectins in foods.
Do you need to avoid lectin-containing foods?
In a word: no. On their own, lectins are a challenge to the human digestive tract. This is why we smart humans have figured out ways to neutralize lectins so that we can reap the nutritional benefits from the foods they're found in. Several preparation methods can reduce the lectin content of foods up to 90 per cent or more, making them suitable for consumption -- which is good news, as I'm not prepared to give up my hummus. Soaking, cooking [boiling and heating] and fermentation degrades most of the lectins in foods.
Lectins can be a problem when eaten in large amounts from raw foods. Fortunately, we don't eat large amounts and we use a variety of preparation methods when making food. We can all breathe a sigh of relief -- there's no reason to avoid nutritious foods like whole grains, pulses and seeds, however.
And just as it's ridiculous for anti-lectin fans to be telling everyone to avoid them, it's equally overly simplistic to say lectins are nothing to worry about, ever... People with autoimmune and digestive disease may do better on a lectin-reduced diet even if temporarily during flares or increased disease activity. A dietitian can help plan a nutritionally balanced diet in cases like this.
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