By Lew Kizer — 2026-10-21 — Health & Nutrition
The short answer
A study published October 20, 2026 in Nutrients tested 98 orders of French fries and tortilla chips cooked in shared fryers at restaurants in 14 states. 92 samples (93.9%) measured under 20 ppm gluten, the FDA gluten-free labeling limit. All six samples above 20 ppm were French fries, measuring 29.6 to more than 80 ppm. The authors say the results are not a recommendation to eat from shared fryers.
Key facts
- 98 samples: 55 French fry orders and 43 tortilla chip orders from 14 U.S. states.
- 92 of 98 (93.9%) tested below 20 ppm gluten; 6 (6.1%) tested above.
- All six samples above 20 ppm were fries, ranging from 29.6 ppm to more than 80 ppm.
- All 43 tortilla chip samples tested below 5 ppm, the test's limit of quantification.
- Fryers with daily oil changes: 0 of 39 samples over 20 ppm. Weekly oil changes: 4 of 35.
- Testing used the R5 ELISA method at an ISO 17025-accredited lab, Bia Diagnostics.
KINGSPORT, Tenn., Oct. 21, 2026 — For years, the standard advice to people with celiac disease has been simple: skip anything from a shared fryer. A study published this week puts real numbers on that risk for the first time at this scale.
The paper, published October 20 in the journal Nutrients, was led by Vanessa Weisbrod of the Celiac Disease Foundation with researchers from Children's Hospital Colorado, Columbia, Mass General Brigham for Children, the University of Chicago, Vanderbilt and Bia Diagnostics.
This article reports research news and is not medical advice. Talk with your clinician before changing your diet or medicines.
What the researchers tested
The team collected 98 orders of naturally gluten-free foods cooked in fryers that were also used for breaded or battered items: 55 orders of French fries and 43 orders of tortilla chips, from restaurants in 14 states. Each order was blended whole and tested with the R5 ELISA method, the official method used to check gluten-free claims.
| Food | Samples | Above 20 ppm |
|---|---|---|
| French fries | 55 | 6 (about 11%) |
| Tortilla chips | 43 | 0 (all under 5 ppm) |
| Total | 98 | 6 (6.1%) |
The six samples above the limit ranged from 29.6 ppm to more than 80 ppm.
Oil changes mattered, as far as the data can show
Restaurants that changed fryer oil daily had no samples above 20 ppm (0 of 39). Restaurants that changed oil weekly had 4 of 35 above the limit. The difference was statistically significant, but the study was observational, so it cannot prove the oil schedule caused it.
“This study is not a green light to eat from any shared fryer.” — Vanessa Weisbrod, Chief Programs Officer, Celiac Disease Foundation
Co-author Edwin Liu, MD, of Children's Hospital Colorado put it plainly: “These findings don't tell us that every shared fryer is safe.”
How it fits with earlier restaurant data
A 2019 study in the American Journal of Gastroenterology used readings from a consumer gluten sensor and found detectable gluten in 32% of restaurant dishes labeled gluten-free, including 53% of gluten-free pizza and 51% of gluten-free pasta tests. That device detects gluten below 20 ppm, so those results overstate risk in some cases and miss fermented gluten in others. Together, the two studies point the same way: restaurant risk depends on the specific kitchen and its habits.
What it means for your next meal out
The researchers suggest a conversation with your dietitian rather than a new rule. Our new guide to eating out with celiac disease lists the questions to ask a server, starting with what else goes in the fryer and how often the oil is changed.
“When you order from us, you don't have to ask. You don't have to wonder. You don't have to guess. The answer is always yes — everything is gluten-free.” — Lew Kizer, Founder, SmashMeals
Read how our dedicated gluten-free kitchen works and what our gluten-free standards cover. Then see this week's meals.
Commentary, not medical advice
The SmashMeals perspective
This is useful data, and the people who did it were careful to say what it does not prove. Six fry orders out of 55 came back above the limit, and a diner cannot tell which basket those came from. We built our kitchen so that question does not come up: SmashMeals operates a dedicated gluten-free kitchen, so there is no wheat basket next to the gluten-free one. Gluten is not the only allergen, so check each meal's ingredients and ask us anything before you order.
Frequently asked questions
Are French fries from a shared fryer gluten-free?
Not reliably. In the October 2026 Nutrients study, about 11% of fry samples from shared fryers measured above 20 ppm gluten. Most measured below it, but a diner cannot tell which result they will get.
Does changing fryer oil daily make shared fryers safe?
The study found no samples above 20 ppm from fryers with daily oil changes, compared with 4 of 35 from weekly changes. Because it was observational, the authors say it does not prove oil-change frequency caused the difference.
Should people with celiac disease eat from shared fryers now?
The researchers do not recommend it as a routine practice. They say the data can support individual decisions made with a dietitian or physician, and that avoiding shared fryers remains a reasonable choice.
Sources and credits
Follow the original sources for context and verification. A reference is not an endorsement of SmashMeals.
- Shared Fryers May Not Always Be as Risky for Gluten Cross-Contact in Celiac Disease as Dietary Guidance Suggests (opens in a new tab)
Nutrients (MDPI)
Why it matters: The peer-reviewed study, with methods and full results.
- How Risky Are Shared Fryers? New Study Offers Real-World Data for People with Celiac Disease (opens in a new tab)
Celiac Disease Foundation
Why it matters: The foundation's summary and the researchers' own cautions.
- Study Measures Gluten in Gluten-Free Labeled Restaurant Food (opens in a new tab)
Columbia Mailman School of Public Health
Why it matters: Earlier restaurant data: 32% of gluten-free-labeled dishes tested positive on a consumer sensor.