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Over the years many consumers have asked me about the “safety” of oat fiber for people with gluten related disorders and whether this ingredient is likely to be contaminated with gluten-containing grains. While I have some concerns about the use of this ingredient in labeled gluten-free foods, only one of the five single ingredient oat fibers tested by Gluten Free Watchdog tested at or above 20 parts per million of gluten.

Note: This article pertains to the ingredient designated as “oat fiber” or “oat hull fiber” in an ingredients list. It does not pertain to the ingredient “oat bran.”


According to the book, “Gluten-Free Cereal Products and Beverages,” the ingredient “oat hull fiber” or “oat fiber” is a primarily insoluble fiber derived from oat hulls, the outermost part of the oat kernel that surrounds the oat groat.

The ingredient “oat fiber” or “oat hull fiber” is allowed in foods regulated by the FDA. The word “fiber” is not allowed in the ingredients list of foods regulated by the USDA so the FSIS has suggested this ingredient be referred to as “isolated oat hull product” when used in a USDA-regulated food.

Oat fiber in multi-ingredient gluten-free foods

Oat fiber may be used in labeled gluten-free foods. It is found in products made by Crunchmaster , Chobani, Van’s, and Barbara’s (not a complete list). None of the manufacturers contacted expressly stated that the ingredient “oat fiber” used in their product was certified gluten-free.

Note: Gluten Free Watchdog has tested multi-ingredient labeled gluten-free products (including from manufacturers named above) containing oat fiber and they have tested below 20 parts per million of gluten.

Single ingredient oat fiber

Bags of single ingredient oat fiber are also available commercially. To the best of my knowledge, none of the suppliers of specially produced certified gluten-free oats are selling gluten-free oat fiber to consumers or manufacturers.

At Gluten Free Watchdog we have been in the process of testing as many “brands” of oat fiber that we can find. Brands tested are NuGrains Oat Fiber, LifeSource Foods Oat Fiber 500, Honeyville Oat Fiber, and Trim Fit Mama Oat Fiber. We have also tested oat fiber from Grain Millers, a supplier of this ingredient.

NuGrains: This brand of oat fiber is not labeled gluten-free. Product packaging does not include an allergen advisory statement for wheat. The manufacturer website does not include any statements regarding gluten-free status. The manufacturer stated the following to us in email correspondence “Cross contamination is possible in the fields (generally oats are grown close to wheat). NuGrains oat fiber is produced in a facility where products containing gluten are processed, although measures are in place to prevent cross contamination during processing. Ultimately, we do not test for gluten and thus do not label the product as gluten-free.”

LifeSource: This brand of oat fiber is not labeled gluten-free. Product packaging includes the allergen advisory statement: “Made in a plant that processes soy, wheat, eggs, and milk.” The seller website states the oat fiber is gluten-free but also states that the product may contain gluten due to shared equipment.

Honeyville: This brand of oat fiber is not labeled gluten-free. Product packaging does not include an allergen advisory statement for wheat. The manufacturer website states that the product may contain trace amounts of wheat.

Trim Healthy Mama: This brand of oat fiber includes the Certified Gluten-Free mark from GFCO on product packaging. This is the only brand of commercially available single ingredient oat fiber we have been able to find that is labeled or certified gluten-free. The manufacturer stated in email correspondence that they test their oat fiber for gluten contamination. We do not know who supplies THM with oat fiber.

Grain Millers: This ingredient supplier stated to me in email correspondence that they provide certificates of analysis for oat fiber self-certifying it as either under 10 or 20 parts per million of gluten. Gluten Free Watchdog was sent a sample for testing that was self-certified by the manufacturer at under 10 parts per million of gluten. Regarding their oat fiber, the manufacturer stated to us in email correspondence, “Our control, processing and testing has been rigorous for the oat fiber – however we have chosen to self-certify because of the still developing and limited market for gluten-free oat fiber; and the comfort level of our customers for our rigorous testing – right now we have every lot tested at FAARP …  We believe our oat fiber is quite homogeneous.  And it is finely ground and comingled.  And thus we believe that compared to larger particle materials, we have an excellent chance of success in maintaining the low gluten level throughout a pallet.”

Testing summary

One of the four brands of oat fiber tested well above 20 parts per million of gluten. The oat fiber sent to us by Grain Millers tested below 10 parts per million of gluten. Whether a manufacturer included an allergen advisory statement for wheat or gluten on the product packaging or the manufacturer website was not a good indication of gluten contamination.

Recommendations to manufacturers

1.     If at all possible source oat fiber from a supplier of specially produced gluten-free oats that adheres to a purity protocol.

2.     Test the oat fiber used in your products with the R5 ELISA even if the supplier also tests the ingredient.

3.     Let consumers know either on your website or product packaging that the oat fiber is properly sourced and tested.

Recommendations to consumers

1.     Contact manufacturers who use oat fiber in their products and ask whether they test this ingredient for gluten contamination.

2.     If the manufacturer does not answer your questions to your satisfaction, you may want to choose another product.

Oat fiber in Canada

Gluten Free Watchdog will be closely watching whether oat fiber is allowed in labeled gluten-free foods in Canada under Health Canada’s new proposed regulations for gluten-free oats. It is hoped that this new proposed regulation will provide those of us in the United States with some indication as to whether a truly gluten-free oat fiber from oats specially produced to be gluten-free is available.

As you may remember, Health Canada released a Notice of Intent to issue a Marketing Authorization (MA) to allow gluten-free claims for specially produced oats that do NOT contain more than 20 parts per million of gluten from wheat, rye, barley, or their hybridized strains, and for foods containing these “gluten-free oats” as ingredients when sold in Canada.

Specially produced oats are defined by Health Canada as, “Oats that are grown, transported, stored, prepared and/or processed in a manner that avoids cross-contamination by wheat, barley, rye, or their hybridized strains, or oats that are processed in a way that effectively removes cross-contamination by wheat, barley, rye, or their hybridized strains.”

For a food containing oats to be labeled gluten-free in Canada:

1. The food contains no oats other than specially produced “gluten-free oats.”

2. The “gluten-free oats” are clearly identified as such in all cases where ‘oats’ are referenced, including in the list of ingredients.

Note: In the United States, oats and oat ingredients used in labeled gluten-free foods do NOT have to be specially produced “gluten-free oats.”  In addition, the FDA has stated that the term “gluten-free” may be considered intervening material in an ingredients list because it is not part of the common or usual name for any ingredient. As a consequence it is very difficult for consumers in the US to know whether oat fiber (or any oat ingredient) is specially produced to be gluten-free.

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© Copyright February 2015 by Tricia Thompson, MS, RD for Gluten Free Watchdog. All Rights Reserved. This article may not be reposted or reprinted without the express written permission of Tricia Thompson. 


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