Does Oatmeal Cause Constipation? (Possible Causes)


Oatmeal doesn’t usually cause constipation. In fact, oatmeal usually relieves constipation due to its high soluble fiber content.

However, it is possible for oatmeal to cause constipation if someone is not used to eating it, or if it’s eaten alongside another food like dairy, which can be the root cause of digestion issues.

I’ll summarize everything you need to know about this topic in this short post.

How Fiber In Oatmeal Affects Constipation

Oatmeal, like other grains, has a lot of soluble fiber.

oats nutrition facts

Other good sources of soluble fiber include legumes (beans), apples, carrots, and barley.

Like the name implies, soluble fiber dissolves into water in your body and can’t be easily digested. In other words, it absorbs the water and bulks up, which typically improves pooping habits by having a pseudo laxative effect.

However, if you’re “blocked up”, adding extra bulk can make you feel worse.


While oatmeal doesn’t cause gas or constipation for most people, it is possible in some cases due to the high amount of soluble fiber. 

Dehydration Can Cause Constipation

One of the most common causes of constipation is dehydration.

If you’re not hydrated enough, that soluble fiber can’t bulk up, and it just sort of sits there. Water is important to keep things moving along.

This isn’t usually a problem with oatmeal since it’s cooked in a good amount of liquid. However, if someone is already dehydrated it could be an issue.

Research About Oats, Soluble Fiber, and Health

Current research supports that oats are generally quite good for your health (source):

Whole-grain foods such as oats may protect against colorectal cancer and have benefits on inflammatory bowel disease and coeliac disease.

In addition, soluble fiber has many benefits, including:

  • Helping to control body weight
  • Balancing cholesterol levels
  • Regulating bowel movements
  • Controlling blood sugar
  • Lower risk of colon cancer, breast cancer, and diabetes

The soluble fiber in oatmeal is generally healthy, but can take time to get used to. Eating rolled oats instead of steel cut oats can reduce the fiber content (steel cut oats are less processed).

Other Foods Eaten With Oatmeal Can Cause Constipation

If you’re experiencing constipation regularly after eating oatmeal, take a look at the other foods you’re eating with it, since oats are rarely eaten alone.

This could include:

  • Milk (dairy or non-dairy)
  • Chocolate
  • Sugar or other sweetener
  • Fruit

Dairy in particular commonly causes digestion issues, including constipation.

You can take out a particular ingredient for a few days in order to see if it’s the real issue behind your constipation.


While the oats themselves are sometimes the cause of constipation, oatmeal is often eaten alongside other foods that can be triggers for stomach issues.

Does Oatmeal Cause Constipation for Toddlers or Babies?

Oatmeal is generally healthy for children, just like everyone else. The fiber acts as a natural laxative and can help regulate healthy bowel movements.

However, many babies and young children can experience constipation when introduced to a new food. Oatmeal should be fed to them in small amounts at first. 

Finally, hydration is also important to avoid digestion issues.

Can Oatmeal Cause Bloating or Gas?

A common problem alongside constipation is excessive gas

I’ve written a detailed guide on why oatmeal can cause gas that you can refer to if you want more information, but I’ll give you the gist of it here:

  • Carbohydrates that don’t digest in the small intestine (i.e. fiber) can ferment in the large intestine, which produces gas as a side product.
  • Since oatmeal is relatively high in fiber (both types), it can cause gas if eaten in large amounts.

If someone is constipated, that leaves more time for fermentation, leading to more gas. In addition, the stool can essentially trap gas, leading to bloating as well.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. I've spent over 6 years as a freelance nutrition writer and researcher. During this time, I've tested over 50 vegan protein powders, and over 100 other types of vegan supplements.

Add comment