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Can Oatmeal Cause Diarrhea? Yes, and More

Oatmeal is a globally known breakfast item. The comforting bowl of nutrients and fiber that is sure to provide you energy to start the day. Maybe you have noticed something after a few hours later, is your stomach churning? Can oatmeal cause diarrhea? The answer is yes! Read more to know the reason why.

What is an Oatmeal?

Oatmeal is made from processed oat grains which are more commonly called “groats”. Did you know that there are three types of preparation for groats? Yep, they can be milled, rolled or steel-cut.

There is also another meaning for oatmeal, and that is the popular porridge that is made from processed oats. We may all be familiar with two categories – the quick or the instant category. As the name suggests, they depend on the preparation time. There is also the Old-fashioned oat which takes the longest to prepare. You have to boil it to make porridge. 

Other Oaty Perks

Oatmeal is famous for containing fiber, and as a bonus, it also contains other vitamins and minerals. 

A 100-gram cereal, oats, regular and quick, unenriched and cooked with water contains the following: 

  • Calcium 
  • Magnesium 
  • Phosphorus 
  • Potassium 
  • Sodium
  • Zinc
  • Vitamin E
  • Folates
  • Iron
  • Selenium
  • Copper
  • Manganese
  • Carotenoids 
  • Betaine
  • Choline
  • Amino acids

… And many others

The Stars of the Show

For every 100 grams of oats, you get 1.7 grams of total dietary fiber. There are two types of fiber that we need in our day to day life. You guessed it! These are soluble and insoluble fiber. 

Soluble Fiber

This type of fiber gets dissolved in water and other gastrointestinal fluids. When it dissolves, it turns to into a gel-like substance which is then digested by the local gut bacteria

This gelatinous substance helps firm up and bind the stool by absorbing and trapping water in it.

Besides the effect on the gut, soluble fiber can also bring various health benefits to the body. One example of this is its effect on blood cholesterol. You see, soluble fiber does not only bind stool, but it also binds cholesterol molecules floating around the intestinal tract. This prevents said cholesterol from being absorbed by the bloodstream. By including oats in your diet, it may help in reversing high cholesterol in the body

Soluble fiber slows down digestion due to the gelatinous consistency. This may affect the stabilization of blood sugar or glucose levels in the body. 

Besides that, soluble fiber is also food for the local gut bacteria. It travels down south and then gets fermented in the colon. This local microbiota helps in digestion and the absorption of various nutrients and minerals in the body. 

Insoluble Fiber

Contrary to soluble fiber, insoluble fiber does not dissolve in the gastrointestinal tract. Water and other gastric fluids cannot break it so it pretty much remains unchanged throughout the digestion process. With that said, it cannot be a source of calories. 

But is that a bad thing? Nope. We need both types of fiber for a healthy digestive tract.

Insoluble fibers help prevent constipation or the slow transit of bowel through the gut. It sits and absorbs fluids and other byproducts of digestion meant to become a stool. It speeds up the stool formation and the movement of food in the gut. 

Fast bowel movement? Is that diarrhea?


Diarrhea. We hear it and we immediately feel uncomfortable and queasy.

It is the fast transit of stool in the gut. It leads to watery, soft and loose stool. It is usually accompanied by a rumbling stomach and pooping of more than three times a day. 

Can Oatmeal Cause Diarrhea?

Oatmeal contains both soluble and insoluble fiber, right? The thing is, fiber often causes diarrhea, particularly insoluble fiber.

Too much insoluble fiber in the diet usually leads to diarrhea instead of its normal effect on the body. Of course, other factors can be considered such as bacterial infection, allergy, and food intolerance. 

Excessive insoluble fiber or this type of imbalance is more common and can be the likely cause of diarrhea. What happens is that insoluble fiber attracts more water to the stool being formed. This leads to loose and watery poop.

More oatmeal in the diet

The daily recommendation for the fiber intake is 25-30 grams of dietary fiber per day. Now fiber is more commonly available than you’d expect. To get a healthy mix of both soluble and insoluble fiber, you would need to eat more cereals, veggies, and fruits. 

It is as simple as that. 

Certain conditions may prove to be problematic for some, such as having a gluten allergy, Irritable Bowel Syndrome or Chron’s disease. There are different options to choose from to make sure that we can avoid having diarrhea while getting that dietary fiber that we need. 

Most plant products contain both soluble and insoluble fibers. Most of the time, insoluble fiber is usually higher in concentration. You can also check the nutrition label of commercial food products. Some manufacturers purposely enrich their products with fiber to increase its health benefits. The best way to get your dietary requirements from food is by eating it the natural way. 

Avoid juicing fruits and vegetables. The pulp left behind is made of dietary fibers too. 

Food that are good sources of fiber include:

The Takeaway

Oatmeal is a wonderful breakfast item to start the day. It is versatile enough to be made into different food products and accessible enough that you can find it in different stores globally. 

Can oatmeal cause diarrhea? Yes, too much oatmeal can cause diarrhea possibly because of the insoluble fibers present in it. It is not a cause for concern because it can be easily solved with a dietary shift. If you are unsure as to what caused your diarrhea, you may try doing an elimination diet to help you identify what food item triggered it. 

Do you like to make oatmeal cookies?

[thrive_toggles_group”][thrive_toggles title=”References” no=”1/1″]https://www.livestrong.com/article/494743-is-oatmeal-good-for-constipation/ https://healthyeating.sfgate.com/oats-body-2593.html https://fdc.nal.usda.gov/fdc-app.html#/food-details/379482/nutrients https://www.wellandgood.com/good-food/foods-that-make-you-poop-immediately/ https://www.health.com/condition/digestive-health/the-20-best-foods-to-help-with-constipation-so-you-can-finally-poop-again?slide=f20da495-d869-4e26-b46e-bf94d9b06abc#f20da495-d869-4e26-b46e-bf94d9b06abc https://en.wikipedia.org/wiki/Oatmeal https://www.medicalnewstoday.com/articles/319176.php#what-are-the-benefits-of-fiber https://www.health.com/nutrition/types-of-fiber https://gutadvisor.com/is-fiber-a-prebiotic/[/thrive_toggles][/thrive_toggles_group]

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Nicole Castaneda - RND

Nicole is a professional Nutritionist-Dietitian who advocates for food variation, moderation and the effect of food choices on the body. She loves to write light and easy to understand articles about food and gut health.

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  1. Great Article!
    I can't believe you only got one comment. however the comment concerning Steel Oats causing the person to experience Diarrhea is interesting. I add 2 Teaspoons to my 3/4 cup multi grain Oatmeal. It is not related to my present Diarrhea, because I haven't had any oatmeal or Steel Oats for awhile. but I will test it. I will also test lowering the amount of Oatmeal I eat, to see if that is the problem, as you suggested could cause Diarrhea in your article. It will be 2 separate test.

  2. I like your post. It's very helpful.
    I like oatmeal but I cannot handle the bowel issues that oatmeal brings.

    What can I eat with oatmeal that reduces the 'action' I get from oatmeal?

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