Lectins: exposing the manufactured health scare around these plant proteins

Lectins are the new dietary demon responsible for all of our modern health ills – at least if you take YouTube clips and diet books on their word. These lectins are a major driver of inflammation, weight gain and chronic disease it seems. Yet to believe this, you need to ignore the reality that humans have been eating lectin-containing foods like wholegrains and legumes for thousands of years. It is only in modern times that we have been faced with these major health problems. But hey, we need to blame it all on something I guess. And lectins seem like a great way to sell books and supplements. Today I explore what lectins are, the alleged health risks of eating them, and counter that with the health benefits of eating lectin-containing foods.

Lectins are the new dietary bogeyman on the block that has some people positively apoplectic in their concern for them allegedly causing us all manner of health harms. Pushed by popular diet books, one in particular called The Plant Paradox by one Dr Steven Gundry (who is a former heart surgeon), these lectins are supposedly a major cause of obesity, chronic inflammation, autoimmune diseases, cancer and heart disease as well as a shopping list of other problems such as acne, bloating, joint pain, migraines and fatigue. Oh my.

What are lectins?

First off, let’s talk about what lectins are. Lectins are a type of protein found in many plants. We also make them in our bodies. They serve as an important part of our immune defence. For plants, lectins form part of their defence system against predators.

Lectins are found in a wide variety of plant-based foods. These include legumes (such as beans, soybeans, lentils, kidney beans and peanuts), wholegrains, fruits and vegetables such as tomatoes, potatoes and eggplants.

So you can see that traditional foods in diets eaten around the world contain loads of lectins. How on earth has humanity survived this long with all these ‘toxic disease-causing substances in our diet? Yes, I was being sarcastic. Fun fact: the healthiest populations in the world, known as the Blue Zones, eat more lectin-containing foods than anyone else. Go figure.

Lectins in our body

Lectins are able to bind to sugar molecules, which allows them to interact with other proteins and cells. The same properties of lectins that make them a handy way for plants to defend themselves may cause problems for us humans during digestion. Which, I will add straight away, has some truth to it.

The most well-described health problems from lectins are seen as severe reactions in people eating raw kidney beans. Kidney beans contain a type of lectin called phytohaemagglutinin which can cause red blood cells to clump together. This can result in nausea, vomiting, stomach upset and diarrhoea. But did you note that I wrote ‘raw red kidney beans’? Hands up who eats their kidney beans raw? No one. If you cook them, then lectins be gone. Simple.

But from cases involving raw kidney beans, it helps serve the agenda of people who want to scare the pants off you about lectins. You can then build an incredibly selective and biased case of just one food component explaining many of today’s modern health ills. All with the aim of gaining more website traffic to drive book and supplement sales.

Here’s one thing those people won’t be telling you about those red kidney beans: they are a food with one of the highest levels of antioxidants measured. You can see already the issue that you run into by demonising a food or group of foods, in this case legumes, because you want to have people fearful of one component of food. All while ‘conveniently’ ignoring the health benefits of other components of it.

Absorbing nutrients

Now at least in animal and cell studies, there is some research to show that active lectins (that is, lectins that haven’t been neutralised by cooking) can reduce the absorption of some minerals such as calcium, iron, phosphorus and zinc. But this effect is minimal and unlikely to cause nutrient deficiencies in people consuming a varied diet.

If you spent your life worrying about what nutrients in your diet could potentially impair the absorption of other nutrients then you would starve to death. That’s because most nutrients interact to an extent to either improve or retard the absorption of other nutrients. Eat a varied diet and you can hit the snooze alarm on needing to know much more about this.

And to counter the ‘anti-nutrient’ claims made about lectins, many lectin-containing foods are rich in essential nutrients. This makes them an important part of a healthy diet. For instance, legumes are an excellent source of plant-based protein, fibre, and various vitamins and minerals. While wholegrains provide essential nutrients like B-group vitamins, magnesium and selenium.

There is also growing research highlighting the health benefits of lectins. Lectins have been shown to have anti-cancer, anti-microbial, anti-viral and immune-enhancing effects. Add to the list a potential role in lowering blood sugar in diabetes then it shows just how myopic it is for anyone to demonise lectin-containing foods based on just one side of the story.

What this all means is that the health benefits of consuming lectin-containing foods far outweigh any potential harm of lectins in these foods.

Lectins and your gut

It is true though that some people – especially people with IBS – may not tolerate lectin-containing foods so well. Though here it is hard to disentangle the effects of other components of foods high in lectins that are also linked to IBS such as FODMAPs.

But most people tolerate lectin-containing foods very well and because of that, our gut loves us for it. Those same high-lectin foods contain loads of primo prebiotic fibre to feed your gut bacteria.

One quick disclaimer here though is that gluten is a lectin and there is no debate about the need for people with coeliac disease to exclude this from their diet. But there is no need for people with coeliac disease to exclude all the other plant foods that contain lectins.

No, lectins are not ‘inflammatory’

Because lectins can bind to cells for long periods, they could potentially cause an autoimmune response in some people. That has led some people to theorise lectins could play a role in inflammatory conditions like rheumatoid arthritis and type 1 diabetes. Note I used the word ‘theorise’, as there isn’t a lot of human research to support this and blame lectins as the smoking gun.

In fact, a ridiculous amount of human studies have shown that consuming lectin-containing foods, such as legumes and wholegrains, is linked to reduced inflammation and a lower risk of chronic diseases. Theories, like dreams, are free but they’re a great way to sell fad diet books.

Are lectins responsible for weight gain?

But wait, you’ll find plenty of people attesting to the benefit of going on a lectin-free diet, especially for helping with weight loss. The claim here is that lectins contribute to weight gain by promoting fat storage and increasing appetite.

Dig deeper into the food recommendations of a low-lectin diet and you’ll see it’s just smoke and mirrors for a low-calorie, low-carbohydrate diet. No grains, no legumes, very little fruit, and no tomatoes, potatoes, eggplant and bell peppers. That’s a lot of food rules you need to follow so it is hardly surprising that people can lose weight following it. And with weight loss can come improvements in metabolic markers such as inflammation. But it has nothing to do with you having fewer lectins in your diet – you’ve just been conned into following a low-calorie diet that’s all.

And those same high-lectin foods that you are told to cut out, such as wholegrains and legumes, are actually linked to positive weight management and metabolic health. If anything, you want more of these foods in your diet in place of the typical highly processed foods that feature too frequently in the Western diet.

Practical tips

Throughout this post, I have noted that lectins could still be a problem for some people. But these cases are rare. That’s because lectins are most potent in their raw state, and the foods containing them are not usually eaten raw. So here are some tips on reducing lectins in foods.

1. Cooking foods at high temperatures can help reduce lectin content. Boiling, steaming, and pressure cooking are effective methods for reducing lectins in legumes, grains and other lectin-rich foods.
2. Soaking legumes, grains, and seeds overnight before cooking can help reduce lectin levels. Discard the soaking water and rinse thoroughly before cooking.
3. Fermenting foods can break down lectins and make them more digestible. Examples include fermented vegetables like sauerkraut and kimchi, as well as fermented soy products like tempeh and miso.
4. Removing the skin and seeds of fruits and vegetables can help reduce lectin intake. This is particularly relevant for foods like tomatoes, cucumbers, potatoes and peppers.

What it all means

So, let’s wrap all this up. The claims made about the dangers of lectins in food are largely unfounded, exaggerated and not supported by the current body of scientific evidence. Of all the fad diets that are around, the lectin-free diet, heavily championed by one Dr Steven Gundry in his book The Plant Paradox, is one of the worst you could follow. It fills your head with nutritional science nonsense and puts you on a restrictive diet that kills the joy of eating many foods. All the while emptying your plate of some of the most healthy and beneficial foods you could be eating.