How Fructans Could Be Behind Digestive Problems
By Jamie Bussin, featuring David Nelson
As the host of The Tonic, I spend a lot of time sorting through the latest wellness trends, claims, and emerging research. Every so often, something comes across my desk that stops me in my tracks, information that challenges what many of us think we know. Recently, that happened with an article about gluten sensitivity. I discussed the findings with frequent guest and friend of the show, David Nelson, a naturopathically-trained health researcher and educator on Episode #414 of The Tonic Talk Show/Podcast. This is a digest of that conversation.
The Three “Gluten” Problems We Often Confuse
Before diving into the new research, David made one thing absolutely clear: gluten intolerance isn’t just one thing. In fact, three completely separate conditions are often lumped together under the “gluten sensitivity” umbrella.
Celiac Disease: This is an autoimmune disease,meaning the body’s own immune system attacks the small intestine when gluten is consumed. It damages the intestinal lining and reduces nutrient absorption. It’s serious, lifelong, and confirmed through blood tests and sometimes biopsies.
Wheat Allergy: This is an IgE-mediated allergic reaction similar to allergies that cause hives or swelling. It can be identified through skin-prick testing.
Non-Celiac Gluten Sensitivity (NCGS): This is where things get murky. NCGS is diagnosed only after the two conditions above have been ruled out. It is more nebulous. Individuals consistently feel unwell eating gluten-containing foods, and better when they avoid them, but without an obvious immune marker or diagnostic test.
And as David pointed out, this group is large. Many people walk into health food stores or practitioners’ offices believing they’re gluten-sensitive, but without ever having been tested for celiac disease or wheat allergy.
The Big Twist: Maybe it’s Not the Gluten
Here’s where the research both David and I read becomes important, and perhaps a little shocking. In a controlled study involving people who self-identified as gluten- sensitive, researchers gave participants both gluten and fructans (a type of fermentable carbohydrate found in wheat, onions, garlic, and many processed foods). The results?
People reacted more strongly to fructans than to gluten. This suggests that a huge proportion of people who think they’re gluten- intolerant aren’t reacting to gluten at all, but to something else entirely.
Fructans belong to a category of compounds known as FODMAPs: fermentable carbohydrates that can cause gas, bloating, discomfort, and inflammation in people with digestive sensitivities. Monash University has done extensive work on the low-FODMAP diet, and clinicians frequently use it for irritable bowel syndrome (IBS) and related issues.
According to David, in naturopathic practice, many “gluten-sensitive” patients improve not because they’ve removed gluten, but because they’ve inadvertently removed fructans along with it.
The Gut-Brain Connection: Your Beliefs Matter More Than You Think
Another major finding in the study touched on the gut-brain axis, the two-way communication between the digestive system and the brain. Here’s the fascinating part: when people were told a food contained gluten, even when it did not, they reported stronger symptoms. This is not “faking it.” These participants genuinely felt worse.
The study suggests that expectations can influence digestive experiences. In other words, if your brain believes something will harm you, it may amplify signals from the gut, creating real, physical discomfort. As David put it, the gut can influence the brain, but the brain can just as powerfully influence the gut.
Only 16% to 30% Reacted to Actual Gluten
One of the most striking data points was this: Only 16% to 30% of self-identified gluten-sensitive individuals reacted specifically to gluten during controlled conditions. The rest reacted more strongly to fructans, or experienced symptoms driven by gut-brain interactions.This means many people may be avoiding gluten unnecessarily, without addressing the real cause of their symptoms.
So What Should You Do if You Think You Have Gluten Sensitivity?
Here’s where the practical advice begins.
1. Get Tested for Celiac Disease and Wheat Allergy: Before removing gluten entirely, confirm the diagnosis—especially if you experience chronic fatigue, nutrient deficiency, or longstanding digestive issues.
2. Look at the Bigger Lifestyle Picture: Our modern habits make digestive problems worse:
- High ultra-processed food intake
- Low fibre consumption
- Poor sleep
- Chronic stress
- Sedentary living
All of these impact the gut—and, through the gut-brain axis, your perception of symptoms.
3. Consider Whether FODMAPs are the Issue: Since fructans often ride along with gluten, a food journal can help determine whether foods such as bread, onions, garlic, certain cereals, or packaged foods are triggering bloating, gas, or discomfort.
4. Improve Fibre Intake: The average person gets only 13-15 grams per day. The minimum recommended amount is 30 grams daily, and fibre dramatically influences gut health and microbiome diversity.
5. Keep a Food and Symptom Journal: Patterns often reveal themselves after just a few weeks.
6. Work With a Healthcare Professional: A naturopathic doctor, dietitian, or physician can help identify whether gluten, fructans, stress, or gut-brain dysregulation is at the root of your symptoms.
This Research Is Brand New—Share It With Your Practitioner
The study David and I discussed is recent enough that many clinicians might not know about it yet. If you’ve been struggling with unexplained digestive symptoms, bringing this emerging research to your care team may open doors to a clearer diagnosis—and much better outcomes.
As always, we’ll include the study link in the show notes so you can explore it yourself.
