Oat flour vs oat fiber, bowl of oat flour sitting on top of a pile of whole oats

Oat Flour vs Oat Fiber – And Are They Low Fodmap?

Oat flour vs oat fiber? What’s the difference? These may sound similar, but they are in fact, different. In short, oat flour is made from ground whole oats, whereas oat fiber is made from the outer portion of the oat grain only. And yes, they are both likely low fodmap… to an extent. Read on to find out more!

First, if you are not familiar with FODMAPS and want to know more about them, see my blog post link below – What are Fodmaps? Briefly, “fodmap” is an acronym and it stands for Fermentable Oligosaccharides, Disaccharides, Monosaccarides and Polyols. 

These are big fancy words but really, they refer to sugars and starches that our gut bacteria can ferment very quickly. In some individuals, these produce unpleasant symptoms for the digestive system and are avoided on the “low fodmap diet”. 

BUT, back to oats. Let’s start with the basics. 


According to Harvard School of Health, oats were previously named “Avena sativa”. Thank goodness the name eventually changed to “oats”, which is far easier to say! 

Oats are of the grass family and known for their high dietary fiber content. They are highly regarded for their health benefits, specifically both heart health and digestive tract health. 

We all know the benefits of getting enough fiber in our diet, but see below for a quick review: 

  • stabilize blood sugar levels
  • protect against heart disease
  • lower LDL cholesterol
  • aid in weight management
  • digestive health management

Type of Oats

You may hear several different terms in reference to oat products. These include oat groats, steel-cut oats, whole rolled oats, quick oats and oatmeal among others.

For the purpose of our topic today, we will briefly cover the differences between these. However, we will spend most of our time talking about oat groats, oat flour and oat fiber. 

Oat Groats – refers to the entire grain of oat after the inedible husk has been removed. The oat groat contains three parts: 

  • Germ
  • Endosperm
  • Bran

Steel Cut Oats – whole oat groats chopped into smaller pieces to allow for quicker cooking. 

Whole Rolled Oats – whole oat groats steamed and mechanically rolled and flattened to allow for even quicker cooking.

Quick Oats (or Instant Oats) – whole oat groats, rolled/flattened and then chopped into smaller pieces for even quicker cooking (notice the trend here). 

Now that we have the basics out of the way, let’s dive into oat flour and oat fiber specifically. 

Difference Between Oat Flour and Oat Fiber

Oat Flour

Again, oat flour is the entirety of the whole oat groat ground into a fine powder (flour). Oat flour is often used as an alternative to traditional flours in gluten free baking. 

Oats and Gluten

Worthy of note, oats are naturally gluten free. However, in the harvesting and processing of the oats, they are most often cross contaminated with some source of gluten.

Gluten is found in wheat, rye and barley. These crops are often grown close to oat crops or processed on the same equipment. 

If you have a gluten sensitivity and are following a gluten-free diet or low gluten diet, regular oat flour may be a great option. This does depend, however, on the severity of your gluten sensitivity.

If you have celiac disease and are interested in using oat flour in your gluten free baking en-devours, make sure that the oat flour is certified gluten free. This ensures the absence of gluten higher than 20 parts per million which is the testing requirement for gluten free labeling. 

Oat Fiber

Oat fiber is made from the oat hull, or outer shell, of the oat groat. This hull of the oat grain is removed and ground into a powder. 

Unlike oat flour, oat fiber is not used as a one to one flour substitute for traditional wheat flour. This is because it is essentially pure insoluble fiber. 

Rather, it is often added to baked goods for improved texture and added fiber content. It also provides a unique, nutty flavor that many appreciate. 

Nutrition Content of Oat Flour vs Oat Fiber

Since oat flour is made from ground whole oat groats, it has a higher carbohydrate content than oat fiber alone. 

As mentioned, since oat fiber is made from essentially only the husk of the oat, it is mostly just fiber and usually has close to zero net carbs. That said, each manufacturer may vary in their separating process. So you may notice some products have a small amount of net carbohydrates where some have none. 

How to Find Net Carbs

Side note – if you aren’t familiar with how to determine the amount of net carbs a product has, simply subtract the grams of dietary fiber listed on the nutrition panel from the grams of total carbohydrates in the product. The net carbohydrate is the amount of carbohydrate that is left after the fiber in the product has been subtracted. 

Below, you will find a comparison table of the nutritional value of oat flour vs oat fiber. 

How to Use Oat Flour vs Oat Fiber 

Oat Flour

As mentioned, oat flour is often used as a replacement for all purpose flour in gluten-free recipes. It is a very fine, light flour. In some products like cookies or quick breads, it is a wonderful replacement for all purpose flour. In this type of product, a typical conversion ratio is 1 1/3 cup of oat flour to 1 cup all purpose flour. 

However, oat flour does not work quite as well in products that need gluten to make the dough rise like regular bread or cinnamon rolls. You may need to do a little experimenting with using a blend of flours such as oat flour, almond flour, coconut flour, etc.

For best results, you will also probably need to add something like xanthan gum to help with the structure of the product due to the missing gluten. 

Oat Fiber 

Since oat fiber is not used as a one to one replacement to all purpose flour, many add it to baked goods to increase the overall fiber content of the product. Consequently, this will decrease the carbohydrate content of the product somewhat. This makes it an excellent choice for those doing some low-carb baking on the keto diet. 

Do note that oat fiber has a high water holding capacity. If you add oat fiber to baked goods, you may need to increase the liquid content a bit to achieve desired results.

Many people may use oat fiber blended into smoothies or even sprinkled on salads for an extra fiber boost. It would also be a wonderful addition to something like overnight oats, Though again, it’s a good idea to add a bit of extra fluid to items like this. 

FODMAP Content of Oat Flour and Oat Fiber

We are circling back to fodmaps now.

So are oat flour and/or oat fiber low fodmap products? Remember that fodmaps are very portion specific. 

Not all foods can be categorized as “low” fodmap or “high” fodmap. Many foods are dependent on the portion size consumed. Oat flour is like this. 

Oat flour is low fodmap in 60g or less according to the Monash University. This means that we must be careful of how much we are eating to stay within a “low” fodmap serving.

You may need to do a little math to figure out how much oat flour you would get in a serving size of whatever you are making. Based on that, oat flour may still be a wonderful low fodmap alternative flour to use. 

Oat fiber, on the other hand, has not been tested for fodmaps as of this writing. It is thought, however, to be low fodmap because it is mostly fiber and very little, if any, net carbohydrates. 

Hopefully this article has provided you with a better understanding of the differences, similarities and unique characteristics of both oat flour and oat fiber. They are both wonderful products derived from good old Avena sativa…. just kidding – oats. 

As always, thanks for reading!

Related Posts:

What are Fodmaps?

Healthy, Low Fodmap Grains

Best High Fiber, Low Fodmap Foods to Avoid Constipation