Healthy Foods and Diarrhea: What's the Connection?

It can be quite a shock when you're eating healthy whole foods like vegetables and fruits and your gut begins to rumble and ache, prompting an urgent race for the bathroom. If you pass loose, watery stools and have stomach pain after eating vegetables and fruits, there may be other things going on.

Read more: Why Can't You Digest Raw Vegetables?

The term "gut bacteria" is often used when talking about digestion, but instead of referring to the stomach, it actually refers to the intestines. Enzymes in the stomach are responsible for breaking down food, and bacteria in the intestines process it, according to Coral Dabarera Edelson, RD, a dietitian and nutrition coach based in Los Angeles. "There are more bacteria in our large intestine, also called the colon, than cells in our body," she says.

The time it takes food to travel from the stomach to the small intestine and then the large intestine and become an eventual bowel movement can vary from person to person, but it usually takes two to five days, according to the Mayo Clinic.

But, if you find you're having a bowel movement right after eating, that could be what's known as gastrocolic reflex, Edelson says. This process happens when food enters your stomach and your body automatically signals your colon to empty, to make room for more food.

If you're experiencing diarrhea after eating vegetables and fruit, fructose and fiber may be the culprits.

"The body can only absorb so much fructose at once," Edelson says. Eat too much in a short amount of time, like quickly slurping a big smoothie, and "it will cause too much water to enter your colon, causing watery stool," she says. "The fructose will be feeding bacteria in your gut and colon instead of you. That could throw your gut microbiome off balance by feeding 'bad' bacteria." Too many of these bacteria in your colon "can cause bloating, cramping and diarrhea," she says.

Vegetables and fruits are high-fiber foods, and eating a lot very quickly also can cause diarrhea, Edelson says. "Some fruits contain a lot of fiber, such as pear, which contains about 6 grams of fiber per medium-sized pear," she says. The daily value (DV) for fiber is 25 grams a day based on a 2,000-calorie diet, according to the U.S. Food & Drug Administration (FDA). Daily value reflects the amount to consume, or not to exceed, each day, the FDA explains.)

Adequate intake (AI), a metric used by the U.S. Department of Agriculture, approximates the amount of daily fiber intake presumed to be adequate for most healthy people. According to a November 2015 article in the Journal of the Academy of Nutrition and Dietetics, the AI for fiber for adult women is 25 grams, and the AI for adult men is 38 grams.

If you have irritable bowel syndrome (IBS), fiber may exacerbate your symptoms, according to a May 2016 article published in the Journal for Nurse Practitioners. Diet recommendations need to be individualized for people with IBS, it says, so talking to your doctor or a nutritionist about fiber and other dietary needs would be helpful.

Low-fiber foods like bananas and rice are great for helping to treat diarrhea right away, says Mascha Davis, MPH, RDN, a dietitian based in Los Angeles and author of Eat Your Vitamins. For long-term solutions, start by helping your body get used to larger-than-normal fiber amounts. "Instead of going from few fruits and veggies to many, increase your fiber intake gradually," she says. "This gives your gut, and the gut bacteria especially, time to adapt."

Knowing which vegetables are difficult to digest when raw can also help prevent diarrhea after eating them, Davis says. Examples of vegetables that can be difficult to digest when eaten raw include chard, spinach and other green vegetables. After the pain passes, Davis suggests talking to your doctor or dietitian about whether taking an enzyme or probiotic might aid your digestion.

Read more: A List of the Easiest Vegetables and Fruits to Digest