4 Reasons Why Tomatoes Cause Bloating

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On September 24, 2025

Why Tomatoes Can Cause Bloating

Salad, ketchup, pasta sauce — so many of the things you might eat contain tomatoes. So, why exactly does this popular ingredient cause bloating? Here are the most common reasons.

1. Tomatoes Contain Fructose

Fructose is a type of sugar naturally found in fruits and vegetables. Tomatoes are often considered vegetables in the kitchen, but they’re technically fruits, which explains their sweet taste. The fructose in tomatoes may be linked to bloating for multiple reasons.

For instance, people with irritable bowel syndrome (IBS) may be more susceptible to bloating after eating foods that contain fructose. When your body can’t absorb fructose properly, it can ferment in the colon. This can lead to uncomfortable gastrointestinal symptoms like bloating, gas, and diarrhea.

However, people without IBS may also have fructose intolerance. This happens when the body has a hard time absorbing or breaking down fructose in foods like tomato products. But because the symptoms of fructose intolerance can look similar to IBS, it can be difficult to diagnose.

2. Tomatoes Are Rich in Fiber

It’s important to eat enough fruits and vegetables, in part due to their high fiber content. Fiber is an essential nutrient that we all need. However, too much of a good thing can have negative effects. Moving from a low-fiber diet to a high-fiber one too quickly can upset your stomach.

One cup of chopped tomatoes contains about 3.2 grams of fiber.

Because tomatoes are a good source of fiber, they may increase your risk of an upset stomach. “Tomato skins, which is where most of the fiber is, can contribute to bloating,” explains Christa Brown, RDN, a registered dietitian who specializes in type 2 diabetes management.

With their moderate amount of fiber and high water content, tomatoes are made up of about 95 percent water. Due to their fiber and water content, eating tomatoes can facilitate regular bowel movements. However, if you’re eating large quantities of tomatoes and have an otherwise low-fiber diet, bloating can also occur.

It’s important to note that bloating caused by water doesn’t usually last too long. But if you’re feeling bloated because you rapidly increased your fiber intake, your body may be producing too much intestinal gas, which can contribute to bloating. Your best bet is to slowly increase your fiber intake and drink plenty of water to reduce unwanted bloating.

3. Tomatoes Are Acidic

Despite their high water content, tomatoes are relatively acidic. And it’s important to note that acidic foods in general can cause acid reflux, which may lead to pain and bloating. If you have a sensitive stomach, eating tomatoes could irritate the lining of your stomach and raise the risk of bloating.

“Tomatoes are considered an acidic food, targeting a pH level of under 4.6,” Brown says. “This causes a rush of stomach acids to help digest the tomato, which results in bloating.”

Experiencing significant bloating after eating tomatoes, though, might be a sign of an intolerance — a chemical response that may only occur after eating a certain amount of the trigger food. Like dairy products, chocolate, and citrus fruits, tomatoes are a common cause of food intolerances. Food intolerances, in turn, can cause bloating and distention (or a swollen stomach).

Because tomatoes and tomato-based products have high acidity levels, they can cause indigestion (pain in the upper abdomen that can occur after eating). And one of the hallmark symptoms of indigestion is bloating.

4. Tomato Skin and Seeds Contain Lectins

Lectins refer to a family of proteins that bind to carbohydrates, and these proteins often get a bad reputation for causing gastrointestinal symptoms like nausea and bloating. Most plants contain lectin, and these proteins are often found in a variety of foods, like legumes, grains, fruits, and vegetables.

However, tomatoes are one of the foods that contain a higher amount of lectins. These lectins are typically found in the tomato skin and seeds.

Most experts agree that the nutritional advantages of high-lectin foods outweigh the potential consequences of lectins. Still, bloating is a mild side effect of eating foods that have a high lectin content.