do high lectin foods like tomatoes cause inflammation

Lots of people are talking about an anti-nutrient called lectin…and if you read The Plant Paradox, it could have you second guessing your plant-based ways. So let’s talk about it.

One of the most pervasive – and dangerous – stumbling blocks on the road to a healthy, mindful relationship with food is food fear. Particularly when you are feeling unwell and trying to support healing, or if it feels like your body is reacting to specific foods, it can be easy to get caught up in overly restrictive eating plans and worrying about every food choice. When you experience reactions after eating, it’s all too understandable to blame food for making you sick – and fear the consequences of eating ‘the wrong thing’. Which is why I get so frustrated with fear mongers trying to tell you that healthful, simple whole foods are somehow dangerous.

So we really need to talk about lectins and other ‘anti-nutrients’ and their ability to cause inflammation.

Before I go further, it’s important to understand that yes, you can react to foods. To any food. In a multitude of ways. This is not a post dismissing food reactions, not in the least. Many of my clients will temporarily – or permanently – eliminate certain foods to help support their healing. However, in my 11 years of treating people with sometimes severe autoimmunity and digestive disease, only one has definitely felt improvement from reducing high lectin foods. Yep, just one. In fact, an anti-inflammatory diet is filled with high lectin foods and yet, it helps to calm inflammation.

Food, And Your Reactions To It

Whether it is a classical IgE-mediated allergy, a digestion-based intolerance like lactose intolerance or a complex reaction borne out of your current health state and your current dietary pattern (like low FODMAPs in irritable bowel syndrome) – eating certain foods can make you feel worse. However, we need to put this realization in the correct context. Food is rarely the primary cause for your ills…but it can be the primary trigger. For example, peanuts can trigger a life-threatening allergic reaction…but this doesn’t make them an evil food. Eating peanuts won’t cause anaphylactic reactions in 100% of people who eat them. For those who aren’t allergic, peanuts are extremely nutrient dense and beneficial on a plant-based diet.

Which is why I kind of marvel at our collective ability to write off whole categories of foods as harmful due to one potentially tricky component. Grains are a classic example of this. I am the first person to declare that our society’s overconsumption of hyper-processed grain foods plays a huge role in our weight gain, inflammation and disease. And yet, whole and minimally processed grains like wheat berries, quinoa or rye can be incredibly nourishing and energizing foods. This isn’t just my opinion: decades of research point to an association between eating whole grains and lower risk of disease.

However, if you are gluten intolerant, or have serious inflammatory or digestive issues, you may feel better eating fewer (or sticking to specific types of) grains. But it isn’t grains that made us sick in the first place. You see the distinction?

So, in the spirit of understanding, let’s explore a class of molecules known as anti-nutrients, because the internet seems to think they are evil molecular henchman, plotting to take you down. Blogs (and some health professionals) tell us that anti-nutrients rob your body of minerals, cause inflammation and lead to disease. Sounds fairly alarming, doesn’t it? Actually, the very term anti-nutrients seems pretty scary until you realize that by definition (non-nutritive to the body, non-absorbed, can block the absorption of other nutrients) fibre is also an anti-nutrient. And yet, it’s one of our most powerful anti-inflammatory allies.

Aha. Some perspective. So let’s get to this!

Lectins and Inflammation

The book The Plant Paradox (full disclosure: I have not fully read it because the whole concept just gets me too fired up) has popularized the notion that lectins in plant foods make us gain weight and cause inflammation. The author posits that plants don’t want to be eaten…and they poison us with lectins as their primary defense.

So what are lectins?

Lectins are proteins that can recognize and bind sugars. Lectins can also bind to cell membranes. Why do they do this? This binding allows for cell-to-cell signaling, independent of the immune system.

Lectins also pass through the digestive system unchanged, which helps plants spread their seeds through the digestive tract of the animals that eat them. If we absorb them, they are also absorbed unchanged.

Lectins are found naturally in foods like legumes, tomatoes and grains. These are the very same foods with plenty of research to support their health benefits, mind you. However, lectin poisoning is a very real thing…which is why eating raw kidney beans can kill you. Kidney beans contain a lectin called phytohaemagglutinin. When we soak and boil kidney beans, it cuts down the lectin content from as many as 70,000 units to less than 500. Soaking, sprouting, fermenting and cooking all lower lectin count. One more reason to enjoy a good marinara!

Foods with High Lectin Content

I know you wanna know which foods are high lectin…so I’m sharing this list.
Just remember: these foods are not dangerous! They are powerfully nutrient-dense plant foods.

Lectins can be (theoretically) harmful or beneficial

The act of eating itself causes micro damage that is rapidly repaired by the gut. Like, if you eat ANYTHING, a bit of damage is done. That’s normal. Just like if you wake up and breathe air, it will create free radical damage that your body is designed to clean up. So let’s not get our knickers in a knot when you read this next paragraph.

Lectins may slow gut repair or activate immune responses in those who are susceptible. For example, if you have leaky gut due to celiac disease, inflammatory bowel disease or chronic inflammation, lectins could theoretically leak into the blood stream and incite an immune response.

However, going lectin free is never my first (or 10th) course of action. An anti-inflammatory diet, gut-boosting supplements and stress reduction is always my first strategy. In fact, there is evidence that suggests, and practice based learning that is convincing, that eating a high fibre plant-based diet (which is going to include lectins by definition) can help you heal from digestive disease that should theoretically benefit from a low lectin diet. Going lectin free is only something I would consider if the other strategies do not bring about healing. And it’s only happened once in 11 years of practice.

Also, as a category of plant compounds, it’s also important to note that there are lectins with potential health benefits too…such as preventing cancer. We also need to be mindful that the dose makes the poison. We don’t eat raw kidney beans. It’s just not done. The same way that an extremely high dose of water can actually kill you because it can dilute the sodium in your blood to dangerous levels…but adequate hydration is a key part of staying healthy. We don’t call water toxic.

Can lectins cause inflammation?

Because lectins can blunt the gut repair response, it is theoretically possible that they can promote gut barrier dysfunction (AKA leaky gut) in those with preexisting challenges. Gut barrier dysfunction is met with a generalized inflammation response that can show up as, or exacerbate, autoimmunity, skin disorders or arthritis. However, this potential is entirely theoretical as we haven’t seen any human studies make the connection – most of the research is done in the laboratory with purified lectins. Which is not the same as eating whole foods that contain lectins in the same way that taking high doses of supplemental vitamin A can cause birth defects but eating kale salads everyday is a great thing for mom and baby.

The notion that high lectin foods are the cause of our inflammatory concerns is a bit illogical – given that our diet since the 1990s has grown increasingly hyper-processed and it’s low in legumes, whole grains and fruits and vegetables. Hyper-processing will reduce lectins: refined grains like white bread have fewer lectins than whole grains. Tomato sauce and ketchup is often made from peeled tomatoes. Meat is lectin free.

In fact, our vast body of nutritional research suggests a whole food, high plant (AKA lectin containing) diet helps us fight inflammation and combat chronic disease. So, if you want to use the grade school logic employed by hucksters, all of these truths should add up to the fact that lectins are in fact the reason why plant foods are good for you!!! Right???!!! Who’s ready to create the ‘lectin miracle diet’ and make millions off of lectin supplements??

Phytates and Inflammation

Let’s move on, shall we? Let’s talk phytates, another apparently ‘evil’ anti-nutrient.

Phytates are also found in legumes, nuts, seeds and whole grains that can bind and hinder the absorption of iron, zinc and calcium. However, they are also found in foods that tend to be mineral rich. Worth noting. Phytates are not magical molecules that will steal minerals from your body. Their presence just means that the minerals they are coupled with in food may be less bioavailable to you. In countries with high phytate diets, mineral deficiencies may be more common.

Why is phytate present in food? It’s how seeds store phosphorus, another mineral. And phytate, also known as phytic acid or IP-6, is also an anti-oxidant and anti-inflammatory compounds which may have cancer preventative effects. So unless you eat large volumes of raw high phytate foods (like someone on a raw diet), this is one you really don’t need to worry about…in fact, be glad you’ve got phytates in your life! Phytates are actually part of an anti-inflammatory diet, just like fibre.

Side note: If you tend towards a raw vegan diet, this is where the process of ‘activating’ your raw nuts and seeds by soaking or sprouting them pays off. Fewer phytates means more minerals in your body. Do you need to worry about phytates? No way!

Oxalates and Inflammation

Oxalates are organic acids that are naturally produced by the body and also found in nuts, seeds, fruits and vegetables. Some of the most oxalate-rich foods include rhubarb, chard, spinach, beets and peanuts. Oxalate, like phytate, can also bind minerals like calcium and iron to create mineral salts…spinach is a classic high oxalate food which is why it can have tons of calcium but poor bioavailability (unless you steam it!).

Oxalates can also form these mineral salts in your kidneys. This is usually not a problem, unless you have a lot of oxalate in your bloodstream (absorption is variable, and may be tied to microbiome) and a low urine volume (because you aren’t drinking enough water). It is also thought that eating more calcium helps minimize the risk of oxalate stones by preventing it’s absorption. So oxalates aren’t really a concern for the vast majority of us.

There are some sketchy blog posts on the internet about oxalates causing inflammation in the body. At this point, the only credible evidence I’ve seen has nothing to do with dietary oxalates, but an abundance of calcium oxalate crystals in the kidneys AKA kidney stones. You bet kidney stones cause pain and inflammation. Which is why someone with kidney oxalate stones may need to watch their oxalate intake. I say may, because if blood oxalate levels aren’t high, a low oxalate diet isn’t often recommended. And dietary oxalate isn’t the only source of oxalate in the blood. For example, if you take mega doses of vitamin C, the body may transform it into oxalic acid to excrete it from the kidneys.

Don’t fear food…fear the ones selling food fear.

I will say this: our bodies are still fairly mysterious. Perhaps yours is in a bit of a healing crisis and it may not be able to handle the cellular signaling of lectins, or heck, gluten. You may need to work with a dietitian to build a healing diet that doesn’t include these compounds for the time being.

But we are being sold a lie – that real food is dangerous. What’s dangerous is an industrialized food system selling us hyper-processed junk food that is taking over our palettes and replacing real food in our life.

Many of us aren’t feeling well. However, the reason we are so unwell has nothing to do with hidden evils lurking in chickpeas. It has to do with the fact that we generally are super stressed out, inactive and eat hyper-processed nutrient-wasted food. These conditions create an inflammatory state that drives disease – and when that happens, yes, we may need a specialized diet to help us out. Sometimes that means avoiding an otherwise healthy food because it simply isn’t the right one for you.

But, what’s really making us sick is anti-nutrient free foods, such as low lectin white wheat flour, sugar and cheap fat. Not kale, tomatoes and almonds.

Photo Credit: Melissa Quantz