Why Watermelon May Trigger IBS Symptoms and 9 Fruits to Try Instead

Watermelon is a nutritious, refreshing fruit to enjoy in the summer (or any time). But if you have irritable bowel syndrome (IBS), it may rev up symptoms such as gas, abdominal cramps, bloating, diarrhea, or constipation.

If you have IBS, there are still some fruits you can enjoy. Here’s why watermelon can sometimes aggravate IBS, the fruits and veggies you can eat, and the ones to avoid.

Why Is Watermelon Bad for IBS?

Watermelon may trigger IBS symptoms because it’s high in FODMAPs, says William J. Bulsiewicz, MD, a gastroenterologist and author of The ‌Fiber-Fueled Cookbook‌, who is based in Mount Pleasant, South Carolina.

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. They are specific types of carbohydrates, according to Cleveland Clinic.

More specifically, oligosaccharides include fructans and galacto-oligosaccharides (GOS); disaccharides contain lactose, like that in milk and dairy products; monosaccharides contain fructose; and polyols include sorbitol and mannitol, according to the International Foundation for Gastrointestinal Disorders (IFGD).

These particular carbs can be poorly absorbed in the intestines, Dr. Bulsiewicz says. When this happens, they travel to the colon, where bacteria ferment them, causing IBS symptoms.

Watermelon Contains Fructans, Fructose, and Polyols

What’s more, Bulsiewicz says watermelon is a triple threat for people with IBS because it’s high in fructans, fructose, and polyols, namely mannitol.

If you have a gastrointestinal disorder like IBS, your body may struggle to digest and process these FODMAPs, Bulsiewicz says. “As a result, you can have symptoms when your gut encounters an excessive load all at once,” he adds.

That’s a hard fact to swallow. Watermelon is not only delicious but also loaded with vitamin C and lycopene, and it has one of the highest water contents of any food, according to the Academy of Nutrition and Dietetics.

Serving Size of Watermelon

But do you have to avoid watermelon at all costs if you have IBS? Not necessarily. Bulsiewicz says it’s all about portion sizes.

“For each individual person, there is a threshold of how much you can eat,” Bulsiewicz says. “Some people can eat a whole watermelon and feel fine, and some can’t even eat a slice.”

A typical portion of watermelon for someone who does not have IBS is 280 grams, or slightly less than 2 cups. That provides about 84 calories, 256 grams of water, and 1 gram of fiber, according to the U.S. Department of Agriculture (USDA).

Other Fruits High in FODMAPs

Watermelon isn’t the only fruit high in FODMAPs. According to Mount Sinai, others include:

• Apples
• Pears
• Peaches
• Cherries
• Mangoes
• Apricots
• Grapes
• Dried fruit
• Plums

These fruits may upset your stomach when you eat them in large amounts. So, you may need to steer clear of them, or at least eat only a small amount at a time.

Vegetables to Limit or Avoid With IBS

Many vegetables are also high in FODMAPs, including the following, according to Mount Sinai:

• Sugar snap peas
• Cauliflower
• Cabbage
• Onions
• Garlic
• Brussels sprouts
• Leeks
• Summer squash
• Asparagus

9 Fruits Low in FODMAPs (IBS-Friendly Fruits)

If you have IBS, there are many delicious, healthy, low-FODMAP fruits that probably won’t trigger symptoms. According to Mount Sinai, IBS-friendly fruits include:

• Blueberries
• Cantaloupe
• Raspberries
• Kiwi
• Lemons
• Limes
• Passion fruit
• Papaya
• Strawberries

9 IBS-Friendly Vegetables

Several IBS-friendly vegetables can help add variety and nutrients to a low-FODMAP diet. According to IBSDiets.org, these include:

• Lettuce
• Carrots
• Cucumbers
• Spinach
• Potatoes
• Collard greens
• Bok choy
• Bell peppers
• Zucchini

While these low-FODMAP fruits and vegetables are not always available year-round, you can check your local grocers and farmers markets to see which produce is in season. You can also check the USDA Seasonal Produce Guide.

Should You Consider a Low-FODMAP Diet?

If you have IBS, a low-FODMAP diet may make sense, Bulsiewicz says, aligning with Cleveland Clinic.

For example, a systematic review and meta-analysis published in Gut in 2022 reviewed 13 randomized control trials involving 944 participants. Researchers found the low-FODMAP diet to be superior to the British Dietetic Association and National Institute for Health and Care Excellence’s dietary advice for bloating and distention when it came to alleviating symptoms such as abdominal pain and bloating.

Another review, published in 2023 in Nutrients, analyzed 17 clinical trials involving adults and children with IBS. Researchers found the low-FODMAP diet to be beneficial in relieving symptoms, especially pain, bloating, and diarrhea. Several studies also noted improvements in bowel movements and stool characteristics, according to researchers.

This doesn’t mean you can never eat high-FODMAP foods. Talk to your doctor or a registered dietitian about how to safely incorporate FODMAPs into your diet.

In general, you’re likely to start off by eliminating all FODMAPs from your diet, according to Johns Hopkins Medicine. You then add them back in slowly as you track your symptoms in a diary to see which foods are your worst offenders, Bulsiewicz says.

So, Can You Eat Watermelon if You Have IBS?

Bottom line: You can probably still enjoy watermelon in small portions even if you have IBS.

It’s likely, however, that large amounts of the fruit may cause symptoms like diarrhea, gas, and bloating due to its high fructose, fructan, and polyol content.

So, if you experience symptoms after eating any amount of watermelon, avoid or limit it, and talk to your doctor or a registered dietitian to see which fruits are better for you to enjoy.

You can also use resources such as Monash University’s FODMAP Diet app to see which foods are high and low in FODMAPs.