Myth #1: All Lectin-Containing Foods are Bad for You.
We’re smack in the middle of summer and you know what that means — the farmer’s markets are overflowing with fresh, colorful fruits and vegetables. The month of August reminds us of all the incredible nourishment the earth can provide. It really is a beautiful site to see!
Unfortunately, many of those famously vibrant and delicious summer vegetables contain lectins, which have gotten a bad rap over the last few years.
What are lectins — and are they all bad?
Lectins are a family of proteins that are known for seeking out sugars in the body and attaching to the surface of cells. They are found in most plants but they don’t actually have any nutritional value for humans. Instead, they exist to help protect plants from not only viruses, bacteria, and fungi but also herbivorous invertebrates (worms) and vertebrates (insects) that threaten to kill them as they grow. 10
Some common lectin-containing foods include beans, peanuts, lentils, tomatoes, potatoes, eggplant, fruits, and grains such as wheat.1
As innocuous as they might sound, lectins have become a huge source of controversy in some circles. “For as long as people have speculated dietary lectins are harmful, others have conjectured that they may be protective,” says Michael Greger, M.D. 2
And anyone who has read Dr. Gundry’s book, The Plant Paradox, may believe that lectins are the worst thing on the planet for you. In my book, Happy Gut, I included a section on the emerging research showing the negative health consequences of consuming lectins, which are often blamed for causing gut health issues and weight loss resistance. Quickly, the word “lectin” became a bad one. As a result, many of us reluctantly removed them from our plates.
As time went on, I had a gut feeling this wasn’t the whole story on lectins. After all, in places like Sardinia, Italy, where people live well into their 100s, lectins are a major part of the standard diet. How could they be bad for you, if they have such a rich history in worldwide cultures that enjoy longevity?
Now, a few years later, I have a new perspective on lectins that I want to share with all of you. You’ll be happy to know that with my approach to lectins, total lectin avoidance isn’t the only solution to your gut health and weight maintenance woes.
Is there a more balanced perspective on lectins?
As more lectin facts and figures presented themselves, I realized a few things. First, the blanket statement that “all lectins are bad” is a myth. This is true for many reasons, but first and foremost, it’s because believing that all lectins are “bad” assumes that all lectins are the same, which, of course, they aren’t.
The truth is that lectins are found in most plant foods, but only about one-third of those foods contain a significant amount. 3 And as you can see in the table below, even foods that are known for being lectin-containing may not be as bad as you think. Here’s my list of high, moderate, and low-lectin foods.
Lectin-Offending Foods (Worst to Best)
As you can see, some lectin-containing foods create more of a problem than others, depending on the amount of lectin in the specific food and even the way the food is prepared before you eat it. In general, cooking foods decreases the lectin content and makes them easier on your body.
It’s also important to know that all of the foods above contain different types of lectins. In fact, there are so many different types of these proteins that they’re organized into several different classes, all with distinct names. For example, leguminosae is the type of lectin found in soybeans and p>gramineaep is the lectin found in wheat germ.
And while all lectins are part of the same family of proteins, they can have very different side effects in the body. For example, the lectin in red kidney beans, called phytohaemagglutinin, can cause red blood cells to clump together 14 and create red kidney bean poisoning. Eating just four raw kidney beans could create severe nausea, vomiting, diarrhea, and severe abdominal pain. 15 On the contrary, eating some of the other foods on the list above may cause only mild symptoms — or no symptoms at all.
As you can see, not all lectin-containing foods have the same amount of lectins, and not all lectins are created equal. We do ourselves a major disservice when we lump them all together.
It’s possible that the lectin solution doesn’t have to involve eliminating lectins altogether, which to me just doesn’t seem like a sustainable or enjoyable, long-term solution; instead, determine whether there’s a lectin threshold that as long as we stay below, we won’t experience significant issues. But there’s more to consider…
Do lectins have health benefits?
Most of the research on lectins has been done on animals, which means we shouldn’t assume the results will also be true for humans. This is true both for studies that show that lectins may be damaging to human health but also for those that show a positive health benefit for humans, which some actually do.
For animals, lectins help regulate immune function and cell growth 5. In humans, lectins can help cells interact with each other and can also help slow down the rate at which cancer cells multiply. 6 They may even be potential treatments for illnesses created by bacteria, fungi, and viruses, due to their anti-bacteria, anti-fungal, and anti-viral properties. 7
As antioxidants, lectins can protect cells from damage caused by free radicals. They also slow down how your body breaks down and absorbs carbohydrates, steadying blood sugar levels and preventing high insulin. 8
Lectins themselves don’t contain nutrients, but lectin-containing foods provide nutrients including B vitamins, minerals, and healthy fats. Large population studies show that some lectin-containing foods can potentially lower rates of heart disease and type 2 diabetes while helping you lose weight. 9
Clearly, when evaluating lectins, the whole story is much more complex than what lectin-loathers may be willing to admit. We have to weigh the potential risks with the potential benefits.
What are the real risks associated with lectins?
Speaking of risks, the hype over lectins is not totally ungrounded, because lectins do have a dark side. Consuming lectins can cause symptoms that range from mild bloating and gas to nausea, vomiting, stomach upset, and diarrhea. I think we can all agree that these are side effects we’d all like to avoid. The thing is they mostly happen when high-lectin foods are consumed raw.
Lectins are actually considered anti-nutrients because they block the absorption of other important nutrients. 11 For example, animal and cell studies show that active lectins can interfere with how your body absorbs minerals, especially calcium, iron, phosphorus, and zinc.12
Lectins can impact the gut microbiota, but they also impact inflammation and immune function. 27 Some lectins can be resistant enough to digestion to enter the circulation and create widespread havoc. 28 Lectins have an affinity to all types of tissues in the body, including the ability to bind to cells in the thyroid, liver, pancreas, kidneys, prostate, breasts, eyes, and brain.
Among their other problems, lectins can:
- Disrupt metabolism
- Promote enlargement or damage to key internal organs and tissues
- Adversely impact hormones
- Compromise your immune health 29
- Contribute to diseases like Parkinson’s disease 30
The list goes on and on, but one important lectin side-effect to pay close attention to is their effect on the immune system and more specifically, in relation to autoimmunity, which is when your immune system starts attacking your body’s own tissues.
Is there a lectin-autoimmune connection?
Lectins are very sticky molecules; once you absorb them, they can bind to many tissues, including the thyroid, pancreas, and even collagen in our joints, as stated before. There, they attract white blood cells to these tissues, potentially leading to an autoimmune response. 31
The research has not yet been conclusive as to lectins’ role in promoting autoimmune disease. However, research from the 1990’s noted that wheat gliadin, a “lectin-like” substance, binds to the inner lining of the digestive tract and by doing so, may contribute to celiac disease — an autoimmune intolerance of gluten.
Lectins can also mess with fat-regulating hormones, like insulin. Lectins block insulin receptors so they cannot receive signals, which leads to insulin resistance. This causes your body to require more insulin to balance the same amount of sugar in the blood and leads to fat deposits around the middle, weight gain, obesity, and eventually Type 2 diabetes.
Lectins & Appetite Control
Lectins can also create leptin resistance. Leptin is a very important hormone that regulates feelings of fullness. Under normal circumstances, the more leptin in circulation, the less hungry you should be.
However, the brains of people who are obese do not respond to the leptin signal. Their levels are high, but these levels are not sensed by their brain to signal that they are full and they should stop eating.
Leptin resistance makes you still feel hungry even when you’ve already had all the food you need.
Lectins can also contribute to inflammatory diseases, including inflammatory bowel disease, diabetes, rheumatoid arthritis, and celiac disease. Lectin-containing foods may actually be at the root of chronic pain syndromes that many people suffer from. One study found that plant lectins can act as a “danger signal” that activates inflammation and potentially promotes these inflammatory diseases. 32
Clearly critics have a strong argument that lectins play a role in issues, like obesity, chronic inflammation, and autoimmune diseases. But like I mentioned before, we have very little human research on the ideal amount of lectins humans should eat and the long-term impact of lectins. 33
Now that we know that not all lectins are created equal, and that they have both positive and negative health consequences, let’s explore why everyone doesn’t react the same to lectins.
Why does everyone react so differently to lectins?
Clearly, lectins may have some drawbacks, but that still doesn’t help you on your quest towards figuring out what you should eat and not eat. Do we all need to cut lectins out of our diet, even if we don’t have symptoms? Why do some people eat lectins without an issue, while others can’t tolerate them at all?
After years of diving into the research on lectins, I think we’ve been giving lectins an unfair amount of blame for the symptoms we experience after eating them. Lectins may just be a red herring — the easy scapegoat — for the true missed problem that is lurking inside you.
So what’s the indolent problem hiding behind lectins? An UNHAPPY GUT. The gut may actually be the missing link as to why lectins are more troublesome for some and not others. Because the health of your gut plays a BIG ROLE in how damaging lectins can be. In other words, all of the leptin problems can occur even more so when you have an unhealthy gut. We’ll dive deeper into this in Myth #2 — Everyone has a lectin issue: The Lectin Paradox.
Should YOU be eating lectins?
You probably already have a hunch as to whether lectins are an issue for you. If you’re still not sure, you can take the following steps to test your lectin tolerance or reduce your lectin intake. None of these require you to eliminate lectins from your diet completely or for good so you can still enjoy some of the delicious, lectin-containing foods during August.
How to Test Your Lectin Tolerance
1. Stick to Low-Lectin Foods:
Eat lectin-containing foods but only the ones that are in the low or medium columns in the table above.
2. Use Traditional Food Preparation Techniques:
Eat lectin-containing foods but make sure you’re using traditional food preparation techniques like fermenting, sprouting, rinsing, and soaking to decrease the lectin-content of high-lectin foods. (I’ll write more about this in my upcoming blog posts.)
3. Follow a Lectin Elimination Diet:
If you eliminate lectins and your symptoms disappear, and then return when you add lectins back in, that’s a really clear sign you’ve got a lectin issue, but there may be more to the story. [Hint, hint: Lectins aren’t the ONLY problem. We’ll get to that in the next blog.] I will say that most people who do the Happy Gut 28-Day Cleanse — which is a lectin-limited diet — feel less bloated, have more energy, and even drop unwanted pounds in just 28 days.
At the end of the day, the lectin issue is much more complicated than a simple “all lectins are bad” statement. Because lectin tolerance depends on so many factors, there is a time and place to eliminate lectins completely. However, to permanently cut out lectin-containing foods — many of which are delicious and full of beneficial nutrients — doesn’t always have to be the only solution.
In next week’s blog, I’ll do a deep dive into the complicated relationship between lectin intolerance and gut health issues. In the meantime, as someone with a “happy gut,” I’m happy to say I’m going to continue enjoying organic yellow heirloom tomatoes from the farmer’s market in season as well as properly-prepared Cuban black beans, because they are simply — DELICIOUS! [And I might be biased, because I’m Cuban. :-)] Enjoy!