Why Watermelon Worsens IBS, and 11 Fruits to Try Instead

Watermelon is a refreshing fruit to enjoy in the summer (or any time depending where you live), but if you have irritable bowel syndrome (IBS), it may rev up symptoms like gas, pain, diarrhea or constipation.

If you have IBS and need to manage symptoms, there are still some fruits you can enjoy. Here's why watermelon is bad for IBS and lists of fruits (and veggies) you can eat — and ones to avoid.

Watermelon is bad for IBS because it's high in FODMAPs, says William J. Bulsiewicz, MD, a South Carolina gastroenterologist and author of ‌The‌ ‌Fiber-Fueled Cookbook‌.

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols — which are specific types of carbohydrates. 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 occurs, they feed bad bacteria in your gut and can cause the IBS symptoms that erode quality of life, like gas and abdominal pain, per the IFGD.

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

"If you have a damaged gut, you may struggle in your ability to digest and process FODMAPs like watermelon and, 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 because watermelon is not only delicious, but it's also loaded with vitamin C and lycopene and has one of the highest water contents of any food, according to the Academy of Nutrition and Dietetics.

But do you have to avoid watermelon at all costs if you have IBS? Not necessarily. It's all about portion sizes.

"For each individual person, there is a threshold of how much you can eat," Dr. Bulsiewicz says. "Some people can eat a whole watermelon and feel fine, and some can't even eat a slice." It may take some trial and error to see where you fall, he suggests.

A typical portion of watermelon for someone who does not have IBS is 1 cup, or 100 grams, with about 139 grams of water, 46 calories and less than 1 gram of fiber, per the USDA.

It's also important to know that watermelon isn't the only fruit that is high in FODMAPs. Others include, per Harvard Health Publishing:

• Apples
• Pears
• Peaches
• Cherries
• Mangoes

These fruits are high in fructose and polyols that may upset your stomach when you eat them in large amounts. So, you may need to steer clear of them.

Unfortunately, many healthful vegetables are high in FODMAPs, including, per the Cleveland Clinic:

• Broccoli
• Cauliflower
• Cabbage
• Asparagus
• Onions

These veggies are high in fructans, part of the oligosaccharides (i.e., the 'O' in FODMAPs).

If you have IBS, there are some fruits that are low in FODMAPs that will likely not cause you any symptoms like bloating or gas. IBS-friendly fruits include, per the Cleveland Clinic:

• Blueberries
• Boysenberries
• Cantaloupe
• Cranberries
• Grapes
• Oranges
• Lemons
• Limes
• Kiwi
• Strawberries
• Unripe bananas (Ripe bananas are typically high in FODMAPs, per Monash University, the developers of the low-FODMAP diet.)

IBS-friendly vegetables are available and will add variety and a great source of nutrients while on a low-FODMAP diet. These include, per the Cleveland Clinic:

• Eggplant
• Green beans
• Celery
• Carrots
• Spinach
• Sweet potato
• Yams
• Zucchini
• Squash

While the above low-FODMAP fruits and vegetables are not always available year-round, you can check your local grocer, farmers' market vendors and local farmers to see which produce is in season.

If you have IBS, a low-FODMAP diet may make sense, Dr. Bulsiewicz says.

In fact, an April 2016 study in ‌Gastroenterology‌ found that, of patients studied, more than 50 percent on the low-FODMAP diet showed major improvements in their abdominal pain, compared with 20 percent of those not following the diet.

There was also a greater improvement of other IBS symptoms like bloating, diarrhea and stool urgency.

This doesn't mean you can never eat foods that are high in FODMAPs. Talk to your doctor or a registered dietitian about how to safely remove or continue eating FODMAPs.

Bottom line, you ‌can‌ eat watermelon in small portions even if you have IBS.

It is 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, steer clear, and talk to your doctor or a registered dietitian to see which fruits are better for you to enjoy.