Is deglutenized wheat starch safe for Celiacs?

If you have celiac disease, you know that eating gluten isn’t pleasant. Surprisingly, an ingredient now showing up in several blends of gluten-free flour mixes is deglutenized wheat starch (e.g. King Arthur GF bread flour, Caputo Fioreglut GF flour, etc.) Seeing wheat as an ingredient may cause concern for several of us. Deglutenized wheat starch is the product of a separation process, which removes the starch from the gliadin/glutenin proteins, leaving only traces amount of gluten.

A nutritional label for King Arthur gluten-free bread flour which shows deglutenized wheat starch as the first ingredient.

The FDA defines gluten-free as less than 20 ppm gluten. The bottom line is that as long as the wheat starch has a "gluten-free" label (like the above picture), it should be safe to eat if you have celiac disease. However, if you have a wheat allergy, that is not the case. Let's explore the difference.

Celiac disease

Protein digestion

Remember from my article about the chemistry of gluten: gluten is actually 2 proteins interacting together, gliadin and glutenin. Proteins are big molecules, and we don’t absorb them whole. Through digestion, our body breaks proteins down into their individual units: amino acids. They are small enough to be carried across the membrane of our cells through facilitated diffusion.

In the small intestine, where digestion happens, we have enzymes that are capable of cleaving proteins. Although glutenin is a large protein (up to 20,000 amino acids long!) our body can cut it down to single amino acids (or small chains of 2-4), which are then absorbed and used by our cells. However, our bodies cannot fully cleave gliadin.

Gliadin misbehaving

Gliadin is broken down into amino acids chains too large to be absorbed. This small complex attaches to enzymes inside the wall of our intestines. What I’ve described here with gliadin happens in all humans, not just celiac patients. Here is the difference.

White blood cells in our body are trained to look for chains of amino acids that are 8-11 amino acids long. This chain length is how most foreign proteins from viruses/bacteria present themselves. This amino acid chain that our immune system is on the lookout for is an epitope. In those of us with celiac disease, our immune system is recognizing the gliadin-enzyme complex (that we made through digestion!) as an epitope, and attacks. I created a meme to illustrate:

A meme comparing normal digestion where the white blood cell does not react to the gliadin epitope, but in celiac the white blood cell throws a bomb at the gliadin epitope.

And then we know the rest! Immune response means inflammation (brought on by the release of cytokine, to increase the blood flow to the small intestine). Bloating, diarrhea, cramps and a host of other discomforts accompany gluten ingestion. If we keep exposing our body to this gliadin-enzyme complex, the walls of our intestine can become permanently damaged by inflammation and hinder future nutrient absorption.

So, is gluten-free wheat starch safe for celiac? Deglutenized wheat starch does not contain gliadin, so it is considered safe for those of us with celiac disease to eat. Just make sure the product has a gluten-free label. And read the disclaimer at the bottom of this page!

Wheat allergy and deglutenized wheat starch

Celiac disease is a type of allergy that is non-IgE mediated (it does not involve an immediate reaction of the IgE antibodies in our bloodstream). However, a wheat allergy is IgE mediated; it triggers the immune system immediately after ingestion (think peanut allergy) and releases histamine. There is a long list of allergens in wheat that triggers this reaction, amongst the culprits are thioredoxin, and alpha-purothionin. So, if you have a wheat allergy, you cannot eat deglutenized wheat starch, as the molecules responsible for the allergic reaction are still present.

Here is a summary in this table:

Table summarizing the key takeaways between wheat allergy and celiac disease when exposed to deglutenized wheat starch.

I hope my beautifully drawn artistic meme helped you understand that it’s not necessarily gluten that’s bad, it’s the process of digesting the gliadin portion of it. Maybe there is hope for medicine, in the form of synthetic enzymes, that helps fully break gliadin down? Though for now, let’s just eliminate gluten from our diet.

Want to learn more? Check out the articles below! Have questions/comments, knowledge to contribute? Please leave a comment!

Attack of the Gluten - American Chemical Society (acs.org)

Wheat Allergy - StatPearls - NCBI Bookshelf (nih.gov)

Disclaimer: I am not a registered dietitian, only chemistry savvy. If you do not know whether you have a gluten or wheat allergy, please consult your doctor!