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Lectins in Tomatoes: How to Enjoy Tomatoes on a Lectin-Free Diet

July 21, 2023 (Last Updated: December 28, 2023)

This article is a comprehensive guide on why and how to reduce lectins in tomatoes, and how to pick the best juicy, sweet, and flavorful tomatoes.

Tomatoes are widely used in various dishes worldwide due to their versatility and appealing taste. Their vibrant hues and delicious sweet and tangy profiles can enhance the flavor of numerous meals, such as pizzas, pasta sauces, salsas, stews, curries, and salads.

However, there is a potential drawback to their consumption. Despite offering certain health benefits, tomatoes naturally contain high levels of lectins, which are anti-nutrients that may lead to undesirable effects. But don’t worry, tomato lovers, you can still eat tomatoes if you prepare them correctly!

Do tomatoes have lectins?

Yes, tomatoes contain lectins, proteins found in most plants’ seeds, grains, skins, rinds, and leaves, but are particularly high in the nightshade family, to which tomatoes belong.

Lectins bind to carbohydrates (sugars) and to sialic acid, which is why they are sometimes called ‘sticky proteins.’ They can interrupt messaging between cells and cause toxic or inflammatory reactions.

You can’t conceive your diet without tomatoes? I hear you!

Several years ago, if you asked me which food I would eat for the rest of my life without getting bored, I would have said tomatoes and cheese. I used to hear people who did not like tomatoes and thought they were weirdos (sorry if you are one of them!).

I would have tomatoes in various forms, for almost every meal. One fresh tomato for breakfast, some cherry tomatoes in my lunch salad, and a tomato-based sauce for dinner.

Growing up on a farm, with vine-ripened tomatoes during summer, I was aware the out-of-season tomatoes I bought from the supermarket were not the real tomatoes I knew. I would still eat them, even though they were rubbery and tasteless.

Back in my childhood, I heard people saying that if you take out the seeds from certain veggies (or even fruits!), they become easier to digest.

It was about 10 years ago when I was having my lunch salad in the office kitchen and complaining to a colleague about my heartburn getting more intense. She looked at my plate and suggested that it might be the tomatoes causing it. She even mentioned that removing the seeds could make a difference.

Well, guess what? I didn’t do anything, and my heartburn worsened to the point where I couldn’t sleep without popping an antacid. That’s when I stumbled upon the concept of lectins, and something clicked, finally. I was ready to give up anything to get rid of that nasty acid reflux.

While removing tomatoes from my diet, at least temporarily, was not the complete answer, it was part of a bigger story about some pesky anti-nutrients called lectins and digestive problems.

Fresh tomatoes
Tomato plants on vines

What are lectins, and why are tomatoes high in lectins?

Lectins are a protein found in various foods, especially in legumes, beans, whole grains, and some fruits and vegetables, including tomatoes, zucchini, cucumbers, potatoes, peppers, and eggplants.

These proteins serve a protective function for plants against predators. Their primary role is to bind to carbohydrates, which allows them to communicate between cells and perform various biological functions.

And while more information is needed, research suggests that dietary lectins can cause digestive problems, coeliac disease, autoimmunity, rheumatoid arthritis, and peptic ulcers.

While humans should naturally be able to withstand a certain amount of lectin attack, our lifestyles, environmental toxins, and heavily processed diets have weakened our guts’ ability to defend against the harmful effects of lectins.

Despite some health benefits, tomatoes are high in lectins, found in abundance in the skin and seeds. These lectins act as a defense mechanism for the tomato plant, discouraging insects and other animals from eating them by causing digestive discomfort.

While this is highly effective for the plant, the same mechanism can also affect humans, potentially leading to digestive problems and autoimmune diseases in certain individuals, particularly those with a sensitivity to lectins and leaky gut.

That’s why some people, like myself, may choose to follow a low-lectin or lectin-free diet and take steps to reduce the lectin content in high-lectin foods.

Removing the skin from the tomatoes. The lectins in tomatoes are in the skin and seeds.
Removing the seeds from the tomatoes. The lectins in tomatoes are in the skin and seeds.

How to remove lectins in tomatoes?

Here is the good news: you don’t have to give up tomatoes for good if you love them.

However, an initial total elimination of harmful lectins is necessary for repairing and restoring the lining of your gut. Depending on how sensitive you are to lectins, that can be for a few days, weeks, or even months.

Here are a few ways to reduce the amount of harmful lectins in tomatoes, while still enjoying their taste and health benefits.

1. Remove the skin and seeds of the tomatoes

Firstly, most of the lectins in tomatoes are in the skin and seeds, so a simple way to lower their lectin content is to peel and deseed them. This might take some extra time in the kitchen, but the health benefits are well worth the effort.

You can easily peel tomatoes by blanching them – make a small ‘x’ incision on the bottom, immerse them in boiling water for about a minute, then transfer them into cold water. The skin will slip right off. After that, cut the tomatoes open and scoop out the seeds.

When I use them for salads, cold platters, or sandwiches, I prefer not to blanch them and remove the skin using a vegetable peeler. For some varieties of tomatoes, the skin will come off easily, just by using a pairing knife.

If you are a kitchen geek like myself, you might want to check out this tomato knife, perfect for slicing delicate tomatoes or berries as well as thick-skinned fruits like citrus or avocados. I got one years ago because I loved tomatoes so much.

Tomatoes in various colors cut in half on a plate
Removing skin and seeds where the lectins

Tomato salad on a plate

2. Pressure-cook the tomatoes

Secondly, cooking is another effective way to reduce the lectin content in foods, and pressure cooking is the most potent method. The high heat and pressure can effectively neutralize most of the lectins.

So, when you’re preparing a dish that calls for tomatoes, consider using a pressure cooker. This method is particularly useful when making soups, sauces, or stews with tomatoes.

You can get away with using whole tomatoes when pressure-cooking them. However, I prefer to remove the seeds anyway.

3. Use a tomato passata to make tomato-based sauces

When making a low-lectin homemade pizza, pasta sauce, or ketchup, use a store-bought tomato passata, preferably organic, imported from Italy, with clean ingredients (just tomatoes or added salt).

Tomato passata, a smooth, uncooked tomato puree that has been strained of seeds and skins, is a staple in many kitchens, particularly in Italian cuisine. Because it’s free from the skin and seeds – where most lectins in tomatoes are found – passata inherently has a lower lectin content than whole tomatoes.

4. Use a good quality tomato paste

Tomato paste, a thick concentrate made by cooking tomatoes for several hours to reduce water content, straining out the seeds and skins, and cooking the liquid again to achieve a rich, concentrated flavor, is a common ingredient in many dishes.

Find a good quality paste with no other questionable ingredients, and add it to your sauces and stews that require tomato paste.

Bruschetta made lectin-free by removing skin and seeds in the tomatoes

Ways to enjoy tomatoes on a lectin-free diet

There are so many ways you can still enjoy tomatoes if you embrace a low-lectin or lectin-free diet. These are my favorites, but the sky is the limit!

  • Make a pizza sauce using tomato passata
  • Make ketchup using tomato passata
  • Add peeled and deseeded tomatoes to salads and platters
  • If you eat dairy products, try a Caprese salad with buffalo mozzarella or burrata, basil, extra virgin olive oil, flake salt, and peeled and deseeded heirloom tomatoes.
  • Make a tomato salsa with peeled and deseeded tomatoes
  • Make bruschettas using peeled and deseeded tomatoes
  • Add peeled and deseeded tomatoes to stews and sauces
  • Add tomatoes, tomato paste, or tomato passata to pressure-cooked sauces, stews, and soups
Sliced lectin-free pizza

How to pick the best tomatoes

Not all tomatoes are created equal. The only tomatoes worth eating are:

  • Organic, ripened on the vine, locally sourced from the farmer’s market, or your garden. That means that the best time to eat fresh tomatoes is during their season, which usually is, in the Northern Hemisphere, July, August, and September.
  • Organic tomato products made in Italy or from trusted local sources, using peeled and deseeded, vine-ripened tomatoes, with no questionable ingredients.

The perfectly round, red, shiny tomatoes found in supermarkets are usually rubbery and tasteless. They often undergo a process known as forced or artificial ripening. This method enables growers to harvest tomatoes while still green and firm, making them easier to transport without damage. Once they reach their destination, these green tomatoes are exposed to ethylene gas, a natural plant hormone that fruits release during ripening.

This treatment triggers the ripening process in the tomatoes, causing them to turn red. This process focuses on changing the tomato’s color and does not give the fruit the time it needs to develop its full range of flavor and nutrients.

Tomatoes in various colors

Conclusion on lectins in tomatoes

Nothing like beautiful, juicy, and sweet tomatoes ripened on the vine. They will not look perfect and might come in various colors (from yellow to orange, to pink, to all shades of red).

And if you worry about lectins in tomatoes, you can enjoy these fresh, delicious fruits during the season if you remove the peels and seeds, or pressure cook them.

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