Lectins, Love Them or Leave them?

We’re all familiar with that schoolyard rhyme: “beans, beans, they’re good for your heart….” As adults we roll our eyes, but have you ever wondered where the rest of that rhyme came from, or why foods like legumes are so tough to digest?

Turns out that most of our foods contain certain compounds that, by nature, are difficult on our digestive systems – because they’re not really meant for our digestive systems at all! Now, that doesn’t mean we can’t tolerate them but more and more research is helping us learn the reasons why some foods can be tough on our systems, and what the implications are of consuming them. In the case of beans and legumes, amongst other foods, the main culprit we’re learning more about is lectins.

Lectins are a kind of protein that’s found in a variety of plant- and animal-based foods. In fact, almost all plant and animal substances contain them in small amounts!

We know proteins are the building blocks of muscles and are critical to our health so the question for most of us is: if lectins are just proteins, how could they be bad for us?

Simply put, lectins bind cells together, and in particular, they bind to sugars. Their ability to lessen the body’s ability to properly absorb nutrients puts lectins in a special category known as ‘antinutrients’. Because we can’t digest lectins, they tend to pass through our systems unnoticed which, for most people, means antinutrients like lectins don’t pose much of a problem at all! In fact, in small amounts, lectins can have numerous health benefits. They’ve been shown to have an important role in immune function, cell growth, and might even be helpful in cancer therapy.

However, lectins can wreak havoc for people who consume a diet with lots of high lectin foods and for those who suffer from GI disorders or immune deficiencies. In more severe instances where GI disorders and immunity dysfunction are at play, lectins can have quite a serious effect on the gut lining and tight junctions that keep the intestines functioning well. To read more about tight junctions (TJs), check out my article about Leaky Gut Syndrome here.

If they’re not meant to be digested, what purpose do lectins serve?

Lectins have a distinct and important purpose in nature – it’s just that the purpose is for the organism’s survival, and not for human consumption. The most important function lectins have in the plant world is to act as a natural insecticide, protecting plants, grains, and legumes from natural predators. And they’re great at it too. When predatory insects come in contact with them, the lectins completely disrupt insect metabolism, preventing invasions and attacks on the plants. Part of a plant’s defense mechanisms, lectins are a natural way to strengthen crops against common pests.

To update that schoolyard rhyme: the more lectins you consume the more discomfort, nausea, vomiting, diarrhea, flatulence, and importantly, malabsorption of nutrients you might experience.

If these sound like familiar symptoms, that could be because the 30% of foods that have high levels of lectins are ones we commonly eat such as dairy, nightshades (like tomatoes and peppers), whole grains, seeds, GMO foods, and yes – beans and legumes.

Some experts have suggested that removing all lectins from your diet can help the gut to recover from antinutrient-caused distress and that this could be critical to treating GI and immunity disorders. Still, many others have pointed to the various preparation techniques that people have used around the globe to help weaken and eliminate lectin proteins, making these staple foods much easier to enjoy!

We caution against removing whole categories of foods unless truly necessary, especially because foods high in lectins also have other essential benefits such as fibre and minerals, that our bodies need. Instead, we want to provide you with a variety of methods you can use to prepare high lectins foods that are centuries old, and globally trusted to make these foods easier to digest.

These are our favourite four ways of preparing legumes, grains, and seeds so you can keep them in your diet without worrying about the negative effects of lectin protein. Prepare them mindfully, and with the help of a few tried and true techniques to get the most out of them:

1. Soak

Beans (canned or dried) in particular benefit from soaking, as do many harder grains and pseudograins like oats, rye, barley, wheat, and quinoa. Soaking and rinsing legumes and grains help to shake free starches, acids, and proteins, making minerals more bioavailable as well as make them easier to digest. Put yours in a larger bowl and cover with water by about 2 inches. Allow them to soak for a few hours up to overnight. Drain fully and rinse again until the water runs clear. As an extra tip: we like to add a 1” piece of kombu or dulse seaweed to the water when soaking beans – it further helps to break down lectins and make beans easier to digest!

2. Sprout

For most beans and seeds sprouting deactivates lectins completely. Why? Because you’re no longer eating them in their contained form. Rather, since they’ve begun the initial stages of germination, they’ve evolved from that seed state. The nutrients are even more available when you sprout, and it’s a lot of fun for the family when you have a hand in ‘growing’ your own food.

This works for almost all legumes except for alfalfa in which, interestingly, lectins increase when sprouted!

3. Boil or Pressure Cook

It seems obvious that if you were going to eat legumes or grains you would boil or pressure cook them first – but these techniques actually have many benefits and ridding beans of lectins is one of them. Studies show that boiling soybeans, red beans, and many others at 212°F/ 100°C for a minimum of 10 minutes reduces lectins to negligible amounts.

4. Ferment

Fermenting foods is the act of allowing good bacteria to grow in the food. The new good bacteria break down and convert would-be harmful proteins including lectins. This is an ancient and common approach across many cultures to consuming foods that are otherwise difficult to digest. In fact, fermented foods are great for you for many reasons because good bacteria is also known as probiotics – one of the most important factors in overall gut health. Just think of tofu, tempeh, miso, kefir, and natto as great examples of fermented foods that would contain high levels of lectins prior to fermentation and you can see why this technique is so far-reaching!

To your best health,

Dr. Amy Tung, ND, MSCP

Naturopathic Doctor | Menopause Society Certified Practitioner

References:

Rhodes, Jonathan M. Genetically modified foods and the Pusztai affair. BMJ. 1999 May 8; 318(7193): 1284.

Miyake K, Tanaka T, McNeil PL, 2007 Lectin-Based Food Poisoning: A New Mechanism of Protein Toxicity. PLoS ONE 2(8): e687. doi:10.1371/journal.pone.0000687

DeMarco, Vincent G., et al. Glutamine and Barrier Function in Cultured Caco-2 Epithelial Cell Monolayers. J. Nutr. July 1, 2003 vol. 133 no. 7 2176-2179.