4 Reasons Why Tomatoes Can Cause Bloating, and What to Do About It

About 10 percent of people experience bloating regularly and up to 25 percent of people complain of occasional bloating, according to the Cleveland Clinic. And certain foods may be to blame.

Bloating is typically caused by gas trapped in the intestines, and tomatoes could be a culprit. Here's why this happens, and how to avoid bloating from tomatoes.

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.

People with irritable bowel syndrome (IBS) may be more susceptible to bloating after eating foods that contain fructose. When fructose isn't absorbed properly, it can ferment in the colon. This can lead to uncomfortable gastrointestinal symptoms like bloating, gas and diarrhea, according to September 2016 research in ‌Medical Hypotheses‌.

Some people — even those without IBS — may have fructose intolerance. This happens when the body has a hard time absorbing or breaking down fructose in foods like tomato products, per the Cleveland Clinic. The symptoms overlap with IBS, so it can be difficult to diagnose.

It's important to eat enough fruits and vegetables in part due to their high fiber content. Fiber is an essential nutrient that many people are lacking but too much of a good thing can have negative effects. Going from a low-fiber diet to a high-fiber one can upset your stomach.

"Tomato skins, which is where most of the fiber is, can contribute to bloating," explains registered dietitian Christa Brown, RDN.

One cup of chopped tomatoes contains 2.2 grams of fiber, according to the USDA. People assigned female at birth (AFAB) should aim for 25 grams of fiber per day and people assigned male at birth (AMAB) should aim for grams per day, per the Academy of Nutrition and Dietetics. A serving of tomatoes has around 5.7 to 8.8 percent of your daily fiber needs.

With their moderate amount of fiber and high water content — the fruit is almost 95 percent water by weight — tomatoes promote regular bowel movements. These generally positive attributes can trigger bloating, particularly if you eat large quantities of tomatoes or your diet is low in fiber.

Bloating caused by water is typically short-lived while bloating brought on by a sudden increase in fiber is often accompanied by intestinal gas.

Despite their high water content, tomatoes are relatively acidic. If you have a sensitive stomach, eating tomatoes could irritate the lining of your stomach, triggering inflammation and minor 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 intolerance — a chemical response that may only occur after eating a certain amount of the problematic food. Like dairy products, chocolate and citrus fruits, tomatoes are a common cause of food intolerance. Food intolerance, in turn, can cause bloating and distention.

Bloating is also a side effect of indigestion, which can be triggered by the high acid content in tomatoes. Tomatoes and tomato-based products are high in acid, which can lead to indigestion, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Lectins refer to a family of proteins that bind to carbohydrates. They get a bad reputation for causing GI issues like nausea and bloating.

Lectins are found in most plants, especially legumes, grains, fruits and vegetables. Tomatoes contain higher amounts of lectins, according to the Mayo Clinic. Most of the lectins in tomatoes can be found where the fiber is — the skin — as well as the 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 high-lectin foods, according to the Harvard T.H. Chan School of Public Health.

Tomatoes are known for being a nutrient-rich food, so you shouldn't avoid them altogether if you notice abdominal bloating after eating them. This may be due to the high content of fructose, water, fiber, acid and lectins in tomatoes.

Certain meals are more tomato-heavy than others. For example, a tomato soup may cause more discomfort than snacking on a handful of cherry tomatoes. So, start slow — this gives your body a chance to adjust to the sudden increase in fiber.

"If you're someone who isn't used to consuming foods rich in fiber, introduce them slowly to help your body get used to fibrous foods," Brown says.

Peeling and cooking high-fructose fruits can help reduce bloating, according to the Cleveland Clinic.

Tomatoes are high in fructose and a significant amount of the fiber is in the skin, so peeling and cooking them can make them more tolerable.

Cooked foods also tend to be easier to digest than raw foods, and cooking is an effective way to reduce the number of lectins in tomatoes. Cooking your food thoroughly softens it, breaking down the fibers and making it easier on the gut.

If acidity is the issue, there are ways around this. "Combine tomato with other foods that are less acidic, such as in a tossed green leafy salad," says Brown.

Pairing highly acidic foods like tomatoes with foods that are more alkaline can balance out the acidity. High alkaline vegetables include cauliflower, Brussels sprouts, potatoes and carrots.

Tomatoes are full of flavor and nutrients, so avoiding them altogether should be a last resort.

This can also be challenging considering the popularity of tomato-based products, such as pizza sauce, pasta sauce and tomato soup. But there are always alternatives that may be more tolerable to you.

Bloating and other side effects of tomatoes may not be worth it if other health conditions are at play. Anyone with tomato allergies, gastroesophageal reflux disease (GERD) and kidney disease may be advised to avoid tomatoes by their doctor. Those with GERD and IBS are more likely to experience bloating from tomatoes.