The Compound in Spinach and Almonds That IBD Guts Cannot Clear
Every gut healing protocol on the internet tells you to eat more spinach, more almonds, more sweet potato. A new study out of the University of North Carolina just handed a specific group of readers, people with inflammatory bowel disease, a real reason to ask whether that advice was ever written with them in mind. The compound in question is oxalate, and it sits in nearly every plant food there is.
- People with Crohn's disease have significantly more oxalate in their stool than people without IBD, despite eating about the same amount of plant food, UNC researchers found.
- The likely reason: two proteins that normally move oxalate out of the gut, SLC26A2 and SLC26A3, are consistently underactive in IBD tissue, whether or not that tissue is currently inflamed.
- In mice with colitis, adding oxalate to the diet cut survival by 60 percent.
- This does not apply to healthy readers. Oxalate sits in nearly every plant food, including the spinach, almonds, sweet potato and beet that gut healing advice leans on hardest, and the researchers say it is not yet enough to support any formal recommendation, even for people with IBD.
What the UNC team actually found
Oxalate normally passes through most guts without incident. The UNC team, led by researchers at the School of Medicine, found that people with Crohn's disease carried significantly more oxalate in their stool than people without IBD, despite eating comparable amounts of plant food. They checked diet two independent ways, once with a validated questionnaire and once by sequencing the DNA in stool samples, and both methods agreed. The likely mechanism: two proteins responsible for moving oxalate out of the gut, SLC26A2 and SLC26A3, were consistently underactive in intestinal tissue from people with both Crohn's disease and ulcerative colitis. Crucially, this held whether or not the tissue was actively inflamed at the time, and the more inflamed the tissue, the lower the transporter activity went. So oxalate accumulates where it can make inflammation worse.
Nutty, fibrous, and squarely on the list of foods this research flags for one specific group of readers.
NIAIDCC BY 2.0
Illustrative. A food photograph of almonds, not imagery from the study itself, which measured stool oxalate and gut tissue rather than photographing food.
Why this looks like more than a coincidence
Correlation in stool samples is one thing. The researchers went further, testing the mechanism directly in two separate mouse models of colitis. Mice given an oxalate supplemented diet alongside a colitis inducing agent were 60 percent less likely to survive than mice without the added oxalate, and both colitis prone strains already carried lower oxalate transport gene activity before any oxalate was added, mirroring exactly what was seen in the human tissue. In the lab dish, oxalate intensified the inflammatory response in macrophages and dendritic cells, the immune cells that police the gut lining. As the lead author put it, this is not about what patients eat, something is different about how their gut handles it. One more thread worth flagging as exploratory rather than settled: low activity in a third, related transporter tracked with a more scarring form of Crohn's disease in this study, a finding the researchers themselves say needs confirmation in a larger group before anyone builds anything on it.
something is different about how their gut handles it
Honest caveat
The human side of this study is cross sectional, meaning stool oxalate and transporter activity were measured at a single point in time, not tracked forward. The causal evidence lives in the mouse models and lab dish work, which is exactly where causal claims should stay for now. The researchers state plainly that their findings are not yet sufficient to support any formal oxalate recommendation for people with IBD, and that the next real step is a longitudinal study following stool oxalate, diet and flares over time. Cohort sizes for the human arm were not stated in the coverage available. And again, none of this applies to readers without IBD. A varied, plant rich diet remains a good habit for the general population, and this study does not say otherwise.
What this means for you
If you do not have Crohn's disease or ulcerative colitis, nothing here should change what you eat. Keep the spinach, keep the almonds. If you do have IBD, this is a real, mechanistic reason to bring oxalate up with your gastroenterologist before assuming that every gut healing food on the internet is doing you favors, rather than a reason to start cutting foods on your own. The more useful long term angle may not be restriction at all. Certain gut bacteria, Oxalobacter formigenes chief among them, break oxalate down before it can build up, and these bacteria are measurably less abundant in people with IBD. That points at a microbiome based fix that would not require giving up any food group. No probiotic on the market is shown to do this yet, which is worth knowing before anyone tries to sell you one.
Primary sources
- Salvador AC, Khaled Z, Awad A, et al. Dietary Oxalate and Intestinal Inflammation: Evidence From Experimental Colitis and Inflammatory Bowel Disease Patient Cohorts. Cellular and Molecular Gastroenterology and Hepatology, 2026, article 101861. Published August 13, 2026.
- UNC Health. UNC researchers identify dietary oxalate as a hidden driver of gut inflammation. August 2026.
Common questions
Does this mean I should stop eating spinach and almonds?
No, not unless you have inflammatory bowel disease. The researchers studied people with Crohn's disease and ulcerative colitis specifically, and they say plainly that the findings are not yet enough to support any formal oxalate recommendation, even for that group. If you do not have IBD, nothing here changes what you already know, a varied plant heavy diet is a good habit on its own.
What is oxalate, and why would it build up in some people?
Oxalate is a natural compound found in nearly every plant food, and most guts move it through and out without trouble. The UNC team found that two proteins responsible for clearing oxalate from the gut, SLC26A2 and SLC26A3, are consistently underactive in intestinal tissue from people with Crohn's disease and ulcerative colitis, whether or not that tissue is currently inflamed. Less clearance means more oxalate sitting in the gut, where it can make existing inflammation worse.
Is there a way to clear oxalate without cutting out healthy plant foods?
Possibly, and this is the more hopeful half of the story. Certain gut bacteria, Oxalobacter formigenes chief among them, break oxalate down before it can build up, and these bacteria are less abundant in people with IBD. That points toward a microbiome route that would not require restricting food at all. No probiotic on the market is yet shown to do this, so it is a direction worth watching rather than a recommendation today.
Stay Curious.
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