Do All Grains Have Gluten? Yes, But Not "That" Kind

There's a gluten-free urban legend that needs to be dispelled: the idea that people with celiac disease and non-celiac gluten sensitivity actually react to gluten in all grains, not just wheat, barley, rye and sometimes oats. 

This just isn't true, despite what you might have heard or read. People who react to the gluten protein found in wheat, barley and rye don't automatically need to avoid rice, corn, millet, sorghum and other grains. (Oats are a separate but related issue, as we'll see below.)

Sadly, this pervasive urban legend leads to people who are following the gluten-free diet unnecessarily cutting all grains out of their diet, instead of just gluten grains. And that means they wind up following a very restrictive diet devoid of some very healthy, fiber-providing foods.

The confusion over whether all grains have gluten stems from the fact that the term "gluten" actually has two different meanings. Bear with me, as this takes some explanation.

The Two Meanings of Gluten

When you hear the term "gluten," it most likely means this to you: a protein found exclusively in the gluten grains wheat, barley and rye that adversely affects people with celiac disease and gluten sensitivity. Whenever you see something is "gluten-free," it means the product is free of the gluten proteins found in wheat, barley, and rye. This is the definition of gluten that most people know.

However, the term "gluten" also can mean this: a storage protein found in all grains, not just in wheat, barley, and rye. "Gluten," in this second definition, refers to proteins all grains contain, not just those found in wheat, barley, and rye. The proteins known as "gluten" store nutrients intended to support the growth of the plant's seeds (which we know as grain). They also have various other uses in agriculture. This second definition can be used in agriculture and for scientific research.

People with celiac and gluten sensitivity don't react to all forms of gluten from all grains—only to the specific gluten proteins contained in the grains wheat, barley and rye (plus variants of these, which include spelt, Einkorn and kamut). These so-called "gluten grains" belong to a specific subfamily of grass plants, as do oats (which is why some of us also cannot tolerate oats).

What About Those Other Glutens?

Other grains—such as corn, rice, soy, millet, and sorghum—belong to a completely different subfamily of grass plants, and their gluten proteins are very different too (which is why they don't always work as well as wheat substitutes in gluten-free baking). Most people with celiac disease and gluten sensitivity don't have any problems consuming the gluten storage proteins from these grains.

For example, you might have heard of corn gluten, which is used in feed for livestock and in pet food. It also can be used as an herbicide in organic farming. Although it's not commonly used for human consumption, corn gluten is considered safe on the gluten-free diet, since it doesn't contain gluten from wheat, barley, or rye.

Where Your Reactions May Come From

Now, I'm not saying that it's impossible to react to other grains—you can be allergic or intolerant to anything, including specific grains. But most people who react to gluten grains don't have issues with those other grains (some of which, like quinoa and buckwheat, aren't even really grains at all).

If you find yourself reacting to all grains, it's actually far more likely that you're reacting to gluten cross-contamination in the grains, not to the various grains themselves. Grains can be surprisingly cross-contaminated, generally due to shared harvesting and storage equipment at the farm level.

A Word from Verywell

When you're following the gluten-free diet, you don't need to eliminate all grains—just wheat, barley, and rye, plus oats if you're sensitive to that close relative to wheat. Other grains—ranging from rice and corn to buckwheat, amaranth, and "pseudo-grains" like quinoa—should be fine for you as long as you buy brands that guard against cross-contamination.

If you do seem to be reacting to all grains, you first should take steps to protect yourself against the gluten in those grains. People who react to gluten grains can have very different sensitivity levels to trace gluten, and a grain-based food that works just fine for the majority of those with celiac or gluten sensitivity may not work as well for you.