Tomatoes are packed with nutrition. They're also a member of the nightshade family of plants, which have been rumored to cause inflammation. Here, we'll separate myth from fact.
tomatoes on designed background
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Tomatoes have come under scrutiny over the past few years in terms of their health value. While there's no doubt that tomatoes are nutritious, as they provide a good source of vitamin C and potassium, plus fiber, beta carotene and lycopene, tomatoes are also a member of the nightshade family of plants. Because they are a nightshade, you may have heard that tomatoes cause or aggravate inflammation. But is there any truth to that?

Yes, You Should Eat More Fruits and Vegetables

Produce is one food category whose health value and necessity in the diet are rarely questioned. This is for good reason, since research consistently suggests that the nutrients and compounds in fruits and vegetables reduce inflammation and, therefore, improve certain health conditions that may be driven by inflammation, such as blood pressure, cholesterol and insulin resistance.

Eating an adequate variety of colorful fruits and vegetables (think five servings a day) is associated with a 13% lower risk of early death compared to eating just two total servings per day, according to a 2021 meta-analysis published in Circulation. Getting plenty of fruits and veggies was also specifically linked to a decreased likelihood of dying from heart disease, cancer and respiratory disease.

What Are Nightshades?

For some time, tomatoes have been getting a bad reputation. More people have questioned whether eating tomatoes and tomato products may increase inflammation. That's because tomatoes are a type of plant known as a nightshade. These plants are part of the Solanaceae family, which includes tomatoes, white potatoes, eggplant, bell peppers, chile peppers, tomatillos and spices made from nightshade plants, such as paprika and cayenne pepper. There are lots of myths and misconceptions about eating nightshades because they contain a family of compounds called alkaloids that have been rumored to be toxic and inflammatory. Here, we separate truth from fiction.

Myth vs. Truth: Nightshades Contain Toxic Chemicals

True, but stick with us. Alkaloids are toxic compounds naturally found in these plants that are designed to protect them from insects, disease and herbivores. Solanine is the primary alkaloid in tomatoes, and it's also found in white potatoes and eggplant. Solanine can cause digestive upset and nausea when eaten in very large amounts, but this is extremely hard to do. When that solanine poisoning does occur, it's usually from eating young, green potatoes, not tomatoes.

Myth vs. Truth: Nightshade Vegetables Cause Inflammation

This is mostly a myth. The consensus among researchers is that nightshade vegetables do not cause inflammation. However, it's possible to have a sensitivity or intolerance to any food, including nightshades, notes the Cleveland Clinic. Food sensitivities are often a reflection of the overall level of inflammation in the body. Once overall inflammation declines, many find the culprit food isn't a problem anymore.

Myth vs. Truth: Nightshades Cause GI Problems and Joint Issues

There's some truth to this since consuming excessive amounts of solanine from nightshades like green potatoes can cause digestive issues. But as mentioned above, eating this much is hard to do. While some people with inflammatory conditions like rheumatoid arthritis report that their joint issues get worse after consuming nightshades, science does not support that they aggravate symptoms, and there is currently no recommendation that people with these conditions avoid these vegetables, notes the Arthritis Foundation. Because autoimmune diseases are inflammation-driven, many people with arthritis find that their immune systems are hypersensitive to foods that may have never bothered them prior to diagnosis.

Food intolerances like this vary greatly by individual, the body's current state of inflammation and trigger food. It doesn't necessarily mean you should cut out nightshades altogether. You may find that your symptoms are triggered by just one nightshade but not others. An elimination protocol over several weeks can help you determine this, and you may even find that the culprit isn't a nightshade but something else in your diet. Talk to your health care provider to learn if this could be helpful for you.

The Bottom Line

For most people, there's little reason to avoid tomatoes. Rather, it's quite the opposite. Tomatoes can be part of your overall produce intake because of their healthful nutrients and compounds, such as lycopene, beta carotene and vitamin C, all of which act as antioxidants and exert anti-inflammatory effects in the body.

If you have an autoimmune or other inflammatory-related condition, pay attention to see if you notice any change in symptoms in the 48 hours after eating a nightshade vegetable. Also, consider working with your health care provider and dietitian to follow an elimination protocol to pinpoint foods that are problematic and trigger your symptoms. Otherwise, if you find tomatoes delicious and feel good eating them, whip up Spaghetti & Spinach with Sun-Dried Tomato Cream Sauce, a Caprese Sandwich or Eggs in Tomato Sauce with Chickpeas & Spinach.