Is oatmeal good for IBS?

Is oatmeal good for IBS?  The quick answer is yes, most people with irritable bowel syndrome tolerate oats well.  But it depends on how much you eat, how you prepare the oats, and your diagnosis.

In this post I answer some common questions about oats and IBS, share my go-to overnight oats recipe that I swear has improved by BMs, and provide links to low FODMAP oat recipes at the end.

Oats vs oatmeal vs porridge – what’s the difference?

Oats are a grain that can be prepared as groats (ie. steel cut oats), rolled (ie old fashioned oats) or flaked (ie. instant oats or quick oats). 

Oatmeal is the cooked dish made from oats. 

Porridge is a dish made from boiling grains, typically oats.  In Canada, porridge is another word for oatmeal.

How do oats affect IBS symptoms?

Raw oats are high in resistant starch, which is poorly digested and thus ends up in the colon where your gut bugs ferment it.  Fermentation produces gas, which can trigger abdominal pain in IBS sufferers who naturally have a hypersensitive gut.

Cooked oats, on the other hand, are much lower in resistant starch because the cooking process breaks down most of the starch.  This means the gut microbiota ferment only a small amount of resistant starch, resulting in less gas build up.  As a result, cooked oats are less gas-inducing than raw oats.

Since overnight oats aren’t cooked, there’s a chance they’ll make you gassy.  But they’re such an easy and convenient breakfast, so if you want to see whether they give you gas issues, eat them for breakfast for a week and monitor your symptoms.  Since it takes 24-72 hours for food to reach the colon, raw oats will show their gassy effects in 1-3 days.

Because resistant starch is considered a prebiotic (ie. optimal food for gut microbes), overnight oats are a great way to promote gut health.  If you don’t tolerate overnight oats, don’t shrug off oats altogether because even cooked oats are good for gut health!

Is oatmeal good for constipation and diarrhea?

Oatmeal is special because it does double duty helping to alleviate both constipation AND diarrhea.  How does it do this?  Through the magic of soluble fibre.

Soluble fibre dissolves in water and forms a gel-like consistency.  You’ve seen soluble fibre at work anytime you’ve cooked oats in water and watched them transform into a thick sludge.  That thick sludge is your ticket to better bowel movements.

For diarrhea, the soluble fibre in oatmeal binds the liquid that would have otherwise made your stool loose.  That thick sludge I just mentioned – it helps firm up your loose stool.

For constipation, the soluble fibre in oats attracts water which will help to soften and bulk up stool that would otherwise be firm, dry and hard to pass.  Soluble fibre can also quicken gut transit time so you don’t have to wait so long between toilet visits.

Other benefits of oatmeal

Oats (including oatmeal) are a healthy whole grain that I believe should be part of a balanced diet. They are nutrient dense, containing fibre (as we’ve just seen), healthy unsaturated fats, protein, vitamin E, iron and B vitamins like thiamin. 

Not only are they good for your gut and full of nutrition, but they also prevent blood sugar spikes and contribute to heart health by lowering LDL (bad) cholesterol (1).

We often think of fruits and vegetables as sources of antioxidants but oats also contain these anti-inflammatory chemicals.  One unique antioxidant found in oats is called avenanthramides (AVAs).  Research has found AVAs to be 10-30 times more potent than other common antioxidants.

What about oat bran?

Whole grain oats have 3 layers: the bran, endosperm and germ.

The endosperm contains the resistant starch that can make you gassy.

Oat bran, often used to make hot cereal or added to muffins, is only made up of the outer bran layer of the oat grain.  Therefore, oat bran has much smaller amounts of resistant starch and thus less capacity to cause gas build up.

Oat bran is roughly half soluble fibre and half insoluble fibre.  And while it too is beneficial for the gut and cholesterol levels, it isn’t a whole grain because it’s missing the other 2 layers that make up whole grains. 

This means oat bran doesn’t have some of the wonderful nutritional components I previously mentioned.

So I stick with whole grain oats for breakfast, but still like to add oat bran to muffins and pancakes for a soluble fibre boost.

How much oatmeal can you safely eat?

If you’re in the elimination or challenge phase of the low FODMAP diet, or you’re sensitive to fructans and galacto-oligosaccharides (GOS), then you need to follow the low FODMAP serving size in the Monash University FODMAP app. 

Unfortunately, this isn’t as straight forward as it sounds. The Monash app has 17 entries for “oats” and 4 entries for “oatmeal”.  Some of the entries are for products like Quaker, and some are for country-specific oat products. 

Personally, I eat Quaker Old Fashioned Oats (yellow package) which has a green light serving size of 1/2 cup (40g).  But is this raw or cooked?

Monash often specifies ‘cooked’ or ‘raw’ for the foods in its app but some oat entries don’t have either.

So I contacted the Monash FODMAP Team to clarify. They said that if the app doesn’t indicate “cooked’ or ‘raw’, then the serving size is based on raw oats.  They also said they are working on updating entries that don’t specify ‘cooked’ and ‘raw’. 

Steel cut vs rolled oats vs instant oats – which one is best?

The key difference between these oats is the degree of processing that the oat grain undergoes.  As with any food, the more processed it is, the quicker you digest it. The quicker you digest it, the quicker you become hungry again after eating.

Steel cut oats were all the rage ten years ago. I, however, held fast to my rolled oats knowing they were plenty healthy and quicker to cook than steel cut oats.

The trend now is overnight oats, which typically utilizes rolled oats.

While you’ll get the same wonderful soluble fibre from any kind of oat, I generally recommend sticking with the rolled or steel cut oats so you feel satiated longer.

Annoyingly, many instant oatmeal products on the market are laced with sugar.  If you opt for plain oats and you need a bit of sugar, you can add your own and control the amount you use.  You can also sweeten your oats by cooking them in milk or adding fruit.

Oats and gluten

The topic of oats and gluten is pretty controversial. 

Decades-old research suggested that some patients with celiac disease developed intestinal inflammation after consuming oats. It was thought a protein called avenin, which is similar to gluten, was the culprit.

However, modern scientific literature suggests that people with celiac disease can safely consume oats assuming they are not cross-contaminated with gluten.

Oats can become contaminated with gluten when they’re processed in facilities that also process gluten-containing grains like wheat, rye and barley. People with celiac disease are advised to eat “gluten-free” oats which means they were processed in a gluten-free facility.

If you have gluten intolerance, you should tolerate regular oats just fine.  If you have celiac disease and are unsure about oats, it’s probably wise to work with a dietitian who specializes in celiac disease.

Oat recipes and links: How to add oats to your diet

• Enjoy cooked oatmeal or overnight oats (see below) for easy weekday breakfasts

• Add oat bran or oats to smoothies

• Bake oat bran muffins

• Use oats in granola mixes you can sprinkle on yogurt

• Make your own granola bars for a pre-workout snack

• Whip up some oat pancakes for a weekend brunch

• Swap your chocolate chip cookies for my low FODMAP oatmeal cookies with browned butter, coconut, cinnamon and chocolate

• Make oat energy balls for a quick on-the-go snack

Bottom line

Cooked oats, made from 1/2 cup raw oats, are low FODMAP and may help ease both constipation and diarrhea.

Raw oats are just as healthy but they’re high in resistant starch which can contribute to gas.

So consider testing your tolerance to raw oats using overnight oats and see how you fare.

At the end of the day, eating oats on a regular basis is likely to be a win both for your gut and your overall health.

xoAndrea