Food fads come and go. Certain foods or compounds are demonized, and rightfully so at times, but sometimes not so rightfully. Right now, lectins have become a focus for some to avoid. But are lectins really bad? Or is it just another marketing or low carb/high protein fad?

First of all, what are lectins? Lectins are a family of proteins found mostly in grains and legumes, and are becoming a new buzzword in the wellness world [1]. Some are actually equating lectins to gluten, and promoting a lectin-free diet.

What many people don’t understand is that there is a good and bad side of pretty much any food, and lectins are not an exception. Scientists have researched this isolated compound for a long time and have established that there are both positive and negative aspects to it. But that’s completely normal among such compounds.

While some lectin compounds have toxic properties, some are completely nonthreatening [2].  Let’s review the lectin controversy and whether you should be worried, what you should do, and how to find balance.

What are Lectins And Where Do They Come From?

Lectins are a family of naturally occurring proteins that bind to carbohydrates that can be found in both animal and plant foods, but occur in larger amounts in the latter. Proteins are essential to the human body and play various physiological roles. For instance, proteins help molecules and cells pair up to perform various immune system functions.

All foods contain lectins to some degree. However, only about 30 percent of the foods we consume contain significant amounts of lectins. Seafood, dairy products, and plants in the nightshade family contain a considerable level of lectin. The protein is, however, most abundant in grains and legumes — including peanuts, soybeans, and beans. The presence of lectins in plants is not clear and some experts attribute it to survival.

Beans In The Hands Of The Hands Of The Workers

As a survival mechanism, the abundance of lectin in plants serves to discourage animals from feeding on them in large amounts. Humans are animals and the high concentration of lectins in some of these plants can discourage consumption. Cases of problems with the digestive tract have been reported after consumption of foods with high concentration of lectins.

Should You Be Worried?

Some have claimed that lectin-rich foods can contribute to issues such as inflammation, irritable bowel syndrome, and obesity. These issues seem to be largely overblown without the facts to really back it up, as we will examine in detail below. Here are a few lectin facts to help ease your mind:

There are many types of lectins; scientists are yet to figure all of them out. Each type of the lectin plays a different role in your body, and this is where most of the confusion stems from. One of the key roles of lectins are to help molecules and cells in the body stick together and accomplish various roles in the human body.

On top of that, lectins have been said to possess anti-cancer potential. They play a critical role in the improvement of our immune systems and are microbial in nature [3].

The problem with lectins in the human body arises from their role in helping molecules and cells stick together. The stickiness blocks the absorption of various nutrients into the bloodstream. When that happens, the lectins are said to be ‘anti-nutrients.’ Yet, as we will discuss below, many now believe that it is for those that already have compromised gut health that lectins may pose a potential issue.

Claims About The Dangers Of Lectins

Several articles have been published on various platforms discussing how lectins can be damaging to your health and how they should be avoided. Most of this information is based on a recent book released by a doctor claiming that lectins cause serious health conditions by inciting a chemical warfare within your body.

But nowadays, lectins are found in nearly every food we consume, including whole grains, seeds, legumes, nightshade vegetables like tomatoes, peppers, potatoes, and eggplant, out-of-season fruits, eggs, and dairy. So, the real question is: Um, what are we supposed to eat?

Whole Grain Wheat Kernels Closeup

Lectins cannot all be bundled into one category, since they exist in several forms and each food carries a different level of concentration [4]. In animal studies, researchers have shown that lectins can be resistant to digestion and will remain partially undigested in the gut [5].

Other studies have indicated that some types of lectins can bind to the cells within the digestive tract and cause cell membrane disruptions. But these studies have however been carried out in vitro – with animals and not humans. This is significant because in such lab studies, a high amount of lectins or the studied compounds may be added to a petri dish and inflammation will be shown. This is not necessarily how the lectins would be consumed or how they would react in our bodies, however. Generally, the role of dietary lectins on human health remains largely unstudied.

Here are some of the purported claims against lectins:

1 – They Trigger Weight Gain

This claim has been disproven in research with lectin-containing foods! Systematic reviews from multiple studies have indicated that increased intake of fruits and vegetables does not adversely impact on body weight [6]. (Seems like this would be a duh! statement. :)  But I wanted to link a study here anyways against this claim).

In a separate study focusing on whole grain consumption for over 12 years, increased whole grain intake was found to be associated with a reduced body mass index (BMI) as well as waist circumference in children and adults. Both populations were found to be significantly less obese as compared to those who did take whole grains [7].

Furthermore, a systematic review of the effects of dietary pulses (including legumes like lentils and chickpeas) on the body weight found that individuals who included such foods in their diets actually experienced weight loss [8].

2 – They Cause Inflammation

This claim is questionable. There is limited research findings on the effects of nightshade vegetables on inflammation (and some with auto-immune conditions may choose to avoid nightshades). However, it’s known that fruit and vegetable intake can decrease inflammatory markers [9].

Round and long fresh organic raw purple and green brinjal or eggplant or aubergine. Healthy and delicious purple eggplants on wood table.

It can also possibly reduce the risk of suffering certain chronic diseases or conditions associated with inflammation [10]. Lectins found in wheat have been shown to induce an inflammatory response in animals, but studies on the effect of such lectins in humans is still lacking [11].

3 – They Are Toxic

The word ‘toxic’ is an overstatement. Although kidney beans when take raw has been shown to induce gastrointestinal issues like nausea, diarrhea, and vomiting, the practicality of eating rock hard, raw kidney beans in any substantial quantity is very unlikely [12].

Cooking beans destroys lectins and make them totally safe to consume. It’s recommended by the Food and Drug Administration (FDA) that you should boil your beans for a minimum of 30 minutes before consumption. Slow cookers shouldn’t be used for that duration since the temperatures won’t get high enough.

Possible Effects Of Lectins On Your Body

One of the most common negative effects of consuming lectins is flatulence. The consumption of uncooked or under cooked grains and legumes can lead to problems such as vomiting, diarrhea, and nausea. Lectin poisoning is hypothesized by some to be a major cause of bacterial food poisoning, but that is yet to be proven.

Lectin can also lead to some possible short-term issues in the digestive tract, but may not have a detrimental long-term impact. When you ingest food, it causes minor damages to the digestive tract as it passes from one level of digestion to the next. But that’s normal, and the body has its own way of mending these minor damages as they happen to prevent complications and keep the gut lining as efficient as possible. The cells need to keep regenerating as fast as they can so as not to compromise the digestion process.

After ingesting foods with high levels of lectin, the process seems to be blunted, thus exposing the intestinal lining. The ‘stickiness’ of lectin may hamper the speedy regeneration of cells to reconstruct the damaged lining. This allows the passage of components, some of which aren’t usually absorbed into the bloodstream and into the body. The absorption of minerals, vitamins, and other important nutrients is also impacted (anti-nutrients).

Picture of raw purple potato.

When you consume lectin-rich foods in large amounts, your digestive tract may react by trying to evacuate the content of your stomach — and that may lead to diarrhea, cramping, and vomiting.

Other Health Issues

Other indirect effects of lectin attacks on the intestinal lining include general inflammation, joint pain, and skin rashes. This is due to the broader effects of a leaky gut. The body’s immune system agents are directed to the stomach to fight the unwanted guests getting past the gut lining.

In some people, the gut lining is more sensitive to lectins in food, for different reasons. This is a KEY point- for those that already have compromised gut health, lectins may pose a bigger potential issue. For instance, people suffering from the irritable bowel syndrome or Chrohn’s disease may be more sensitive to lectins.

Exotic fruits. Summer photo concept. Mango. Papaya. A pineapple. Avocado. Kiwi. Pitahaya. Kumhvat. Copyspase. Fresh fruits. Exotic fruits on a gray background. Blueberry. Strawberry. Physalis. Tamarind. Lemon.

I believe that the controversy surrounding hyper-focusing on lectins is unwarranted. Most ALL foods have the potential to be ‘bad,’ but we have to weigh the potential “bad” with the benefits. The argument that supports the singling out of lectins is not convincing.

How can lectins be neutralized or reduced?

Proper cooking and preparing can radically reduce exposure to lectins and toxic amounts- which include steps we would do naturally!

1 – Cooking

Proper cooking reduces legume activity in the food thus eliminating the chances associated complications. In fact, boiling your grains and legumes properly eliminates all the toxicity from the lectin in them [13].

A study on the toxicity in soybeans showed that boiling for five to ten minutes gets rid of the lectin activity. Therefore, avoiding the consumption of grains and legumes due to fear of lectin makes no sense at all. Usually, people don’t eat raw beans, do they?

2 – Soaking

Cooking isn’t the only method of reducing lectin activity in your food. Soaking is probably the most old school method of preparing grains and beans. If you ever wondered why your grandma had long soaking, rinsing, and boiling sessions when preparing her legumes and grains, wonder no more.

These processes make digestion easier as they also help reduce lectins. Soak your beans overnight and change the water frequently. You can add baking soda (sodium bicarbonate) to the mixture to further neutralize lectins.

3 – Fermenting

Fermenting food products allows the digestion and conversion of the harmful substances in the food by the beneficial bacteria. Fermentation neutralizes the lectins in the grain and legumes [14]. Even some of the healthiest people in the world eat fermented food products such as miso, natto, tempeh, etc. People living in areas where grain eating is common use fermentation as a method of treating the grains before consumption.

It’s important to note that some people will still have lectin problems even after eating foods treated using some of these methods. Sometimes, it’s not possible to remove all the lectin in the grains or legumes, and if you are sensitive or have compromised gut health, you may still have an issue.

Chickpeas soaked in water in a bowl on wooden background

For a person with generally good or moderate health and gut health, lectins aren’t probably going to be a problem. For instance, soaking your beans all night will not eradicate lectins entirely; you still have to boil them properly [15]. Don’t use a slow cooker if the temperature is not high enough to destroy the lectins.

You may hear or read claims that a lectin-free diet will cure diseases, but such statements  don’t have scientific basis derived from actual clinical trials. At this moment, no one can say that lectins from cooked food can impact the health of a person without a pre-existing issue of lectin sensitivity.

A lectin-free diet means avoiding fruits, peppers, whole grains, potatoes and other veggies, seeds etc (as well as eggs and dairy). It’s pretty much the entire grocery list. That kind of diet eliminates a whole lot of key nutrients and is unsustainable. The campaign against lectin-rich foods seems to be another iteration of a low-carb, high animal protein diet.

Who Should Worry About Lectin Rich Foods?

Any healthy person who has never had any issues with lectin before doesn’t have a real reason to be worried [16]. For instance, if you love eating beans and your body doesn’t seem to have a problem with it, keep enjoying properly cooked beans.

Otherwise, there is no need to create a problem where none exists. The proponents of a lectin-free diet cite several prevalent health problems in America and blame them on lectin rich foods, including obesity. Obesity is a result of sugar enhanced, low fiber, low nutrient highly processed foods. Telling people to avoid whole grains, legumes, fruits, and vegetables (lectin rich foods) to avoid becoming obese is misleading.

Close-up view of fresh tomatoes. Young juicy tomatoes. A lot of tomatoes. Heap of tomatoes. Summer agriculture farm market tray full of organic tomatoes. Fresh tomatoes. Above colorful fresh tomatoes.

As stated earlier in the article, consuming too much lectin from improper cooking, or the highly unlikely case of eating a large amount or raw kidney beans, can be a problem though. High lectin concentration can lead to massive digestive issues, and in some instances, it can be downright poisonous [17].

Again, the good news is that lectin concentration can be neutralized by proper preparation before cooking.

Bottom Line

Our grandmothers seem to be the only people who remember how to prepare these foods, and probably the last of the generation that will never know what the lectin intolerance even means. Most foods are not perfect; there is always a negative side if we look. The big focus on lectins is taking us out of looking at the whole picture.

Whole grains and other lectin-rich foods are not perfect, but they do have a lot of benefits, and most of the problems associated with lectin can be avoided through simple processes such as boiling and soaking. We should all be careful not to over consume lectins — that goes for all foods — but completely avoiding lectin-rich foods is an exaggeration [18] and something that I do not recommend.

Focus on whole foods, excellent gut health and a balanced overall lifestyle for true health and wellness!

In love and health,

Kimberly

References:

[1] Going ‘lectin-free’ is the latest pseudoscience diet fad
[2] Do dietary lectins cause disease?
[3] Lectins as bioactive plant proteins: a potential in cancer treatment.
[4] Lectins: production and practical applications
[5] Dietary lectins can stimulate pancreatic growth in the rat
[6] Systematic review and meta-analysis of the effect of increased vegetable and fruit consumption on body weight and energy intake
[7] Whole grain consumption trends and associations with body weight measures in the United States: results from the cross sectional National Health and Nutrition Examination Survey 2001–2012
[8] Effects of dietary pulse consumption on body weight: a systematic review and meta-analysis of randomized controlled trials
[9] Fruit and vegetable consumption and its relation to markers of inflammation and oxidative stress in adolescents
[10] Critical review: vegetables and fruit in the prevention of chronic diseases
[11] The Dietary Intake of Wheat and other Cereal Grains and Their Role in Inflammation
[12] Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins
[13] EFFECT OF SOME PROCESSING METHODS ON HEMAGGLUTININ ACTIVITY OF LECTIN EXTRACTS FROM SELECTED GRAINS (CEREALS AND LEGUMES)
[14] Reduction in antinutritional and toxic components in plant foods by fermentation
[15] Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins
[16] Going ‘lectin-free’ is the latest pseudoscience diet fad
[17] Do You Really Need To Worry About Lectins? A Skeptic Asks All Of Your Burning Questions
[18] The Next Gluten

At the Japanese grocer! I love seeing what’s going on, food-wise in markets, when I’m on the road. Sending you love! xo

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