The suitability of oats as part of the gluten-free diet has been a source of controversy, with some groups pointing to research suggesting oats are safe and others pointing to other research demonstrating oats are dangerous to those with celiac disease. Close inspection of available medical research clearly shows that oats, even “gluten-free” oats, should not be included in the gluten-free diet at this time.
Until the early 1990’s, oats were excluded from the gluten-free diet, along with wheat, barley and rye. Then, a few pilot studies suggested oats may not cause the harm previously thought. The idea was proposed that people with celiac disease would find their diet more palatable, and would benefit nutritionally, if they were allowed to eat oats.
Heavy contamination of many oat products with wheat, rye, and particularly barley, was a concern. Companies began to produce so-called “gluten-free oats.” These oats were tested for the presence of wheat, barley and rye. They are vigorously marketed as “safe” for celiacs. However, studies show that even “uncontaminated oats” (oats not containing wheat, barley or rye) are toxic to an unknown number of people with celiac disease.
Early studies proclaimed oats to be safe, but they have since been judged faulty with poor validity. Nevertheless, they opened the floodgates to oat enthusiasts.
Opposing research followed, showing that “uncontaminated” oats activated disease in some subjects and proved that oat itself contains toxic sequences that activate the immune system, although to a lesser degree than wheat, barley or rye. Some groups tried to refute the clear evidence of villous atrophy with the feeble idea that oats cause bloating and pain in some patients due to its high fiber content.
The controversy over oat safety is not resolved because neither the long-term effect or the actual percentage of people who are intolerant are known. Large scale studies consisting of thousands of subjects are needed to produce valid answers. Such expensive research has not been undertaken to date.
Meanwhile, oat growers, millers and manufacturers actively purvey the notion that so-called “gluten-free oats” are safe. Packaging does not contain the caveat that oats are not safe for everyone, that they should not be consumed in amounts larger than ¼ to ½ cup per day, and that the patient should be closely followed by a physician to monitor changes to their health.
RESEARCH ON OAT TOLERANCE
In 1995 a small pilot study from Sweden compared diet, with and without oats, in 52 adults in remission for 6 months and 40 newly diagnosed adult patients for 12 months.1 All the patients with new diagnoses were in remission at one year, except for one in the control group. Six patients in the oat groups and five in the control group withdrew from the study. Why did they stop eating oats? The study does not say, but concludes that “Moderate amounts of oats can be included in a gluten-free diet for most adult patients with celiac disease without adverse effects.”
In 2003, a study challenged 19 adults celiacs with 50 grams of oats over 3 months. One of the subjects developed partial villous atrophy and a rash during the first oats challenge. She subsequently improved on an oats free diet but developed subtotal villous atrophy and dramatic dermatitis during a second challenge. Five of the patients showed positive levels of interferon γ mRNA after challenge.2 Therefore, 31% of these subjects reacted to oats.
In 2003, a study showed that children with celiac disease have antibodies to oat proteins at significantly higher levels than reference children.3
In 2004, researchers studied the response to uncontaminated oats of nine patients with celiac disease.4 The nine patients were not a random sample. All patients had been eating oats, and four of them had shown clinical symptoms after oats ingestion. The goal of the study was to characterize the intestinal T cell response (immune system response) to oats in these patients, and to relate it to clinical symptoms and intestinal biopsy results.
The findings show that intolerance to oats exists at least in some patients with celiac disease, and that those patients have the same molecular reaction to oats that other patients have to wheat, barley, or rye. Of note: identical reactions to the subjects who had symptoms were also seen in two of the patients who did not have symptoms.
An article in WebMD advised physicians that oats are tolerated by most patients with celiac disease, but are not totally innocent. There are considerable differences between individual patients with respect to clinical and mucosal responses to gluten challenge.5
RESEARCH ON OATS
In 2007, a study showed that all the varieties of oats tested were immunogenic, with Lampton and Ava avenins inducing lymphocyte activation similar to that activated by wheat gliadin, while Astra and Nave avenins showed less immunogenicity, but still with a measurable effect.6
In 2011, a study showed that there is a wide range of variation of potential immunotoxicity of oat cultivars.7 It concluded some oat strains are more toxic than others.
RESEARCH SHOWING LONG-TERM EFFECTS OF EATING OATS IS WANTING
In 2007, a study sought to verify the group’s earlier findings in 22 subjects tested after 6-12 months that oats are safe after 5 years’ consumption of oats by the same subjects, but their validity failed because of the high drop-out rate. Only 12 subjects of the original 22 actually finished the 5 year study period. 10 dropped out because “they felt uncertain about the safety of long-term consumption of oats.”8
Individuals with celiac disease vary in their immune reactions and symptom responses to gluten in wheat, barley, rye and oats. It is clear that oats are not a safe grain for all patients.
Prudence dictates that oats should be avoided until large-sample, long-term tests on oats are performed, strains of oats that do not elicit immune reactions are discovered, and tests that can accurately determine whether a patient reacts to oats become available.
On a personal note, my broad experiences with the gluten-free community reveal a sizeable number of individuals with celiac disease who do indeed react to oats in the same way they react to wheat, barley and rye. In speaking to gluten-free support groups, I would estimate at least 10% of people say they react to oats. Here are 4 examples from hundreds of my own interactions:
- At the 2007 Food & Nutrition Conference & Expo in Philadelphia, an employee representing a popular so-called “GF oats” company appeared very ill and anxious. Her booth was across the aisle from our book booth where we were displaying my book, Recognizing Celiac Disease. During a lull in traffic, she approached me to speak. She described how, after having worked for this company the past 6 months and eating their oats, she felt the same as she did before her diagnosis. She said, “The only thing I changed in my diet is that I eat these oats.” Looking at the floor, she added, “This is my job.”
- Before giving a lecture In Tampa, a man came up to me to ask why he still needed blood transfusions after being strictly gluten-free for more than 2 years. His attentive wife vouched for him. After I spoke, during which I advised the attendees not to eat oats, the wife said to me, “He has something to tell you.” “I eat oats, but the package says gluten-free.” When I asked how much he was eating, he admitted to eating 2 cups of these oats every morning.
- A woman emailed to ask why her bloating and headaches continued on a strict gluten-free diet, eating only food labeled gluten-free. When she cut out the GF oats, these symptoms disappeared within the week.
- Leaders of 2 national celiac disease organizations positively told me they cannot eat oats. Many local support group leaders say the same.
Please add your own experience as a Comment below.
1. Janatuinen EK, Pikkarainen PH, Kemppainen TA, et al. A comparison of diets with and without oats in adults with celiac disease. N Eng J Med 1995 Oct 19;333(16):1033-7.
2. K E A Lundin,1 E M Nilsen,2 H G Scott et al. Oats induced villous atrophy in coeliac disease. Gut. 2003 November; 52(11): 1649–1652.
3. Hollen E, Hogberg L, Stenhammar L, Falth-Magnusson K, Magnusson KE. Antibodies to oat prolamines (avenins) in children with coeliac disease. Scand J Gastroenterol 2003 Jul;38(7):742-6.
4. Arentz-Hansen H, Fleckenstein B, Molberg Ø, et al. The molecular basis for oat intolerance in patients with celiac disease. PLoS Med.2004 Oct;1(1):e1. Epub 2004 Oct 19.
5. Ciclitira PJ Ellis HJ Lundin KE. Gluten-free diet what is toxic?
Best Pract Res Clin Gastroenterol. 2005 Jun;19(3):359-71.
6. Silano M, Benedetto RD, Maialetti F, et al. Avenins from different cultivars of oats elicit response by coeliac peripheral lymphocytes. Scand J Gastroenterol 2007 Jun 8;:1-4.
7. Silano M, Benedetto RD, Maialetti F, et al. Avenins from different cultivars of oats elicit response by coeliac peripheral lymphocytes. Scand J Gastroenterol 2007 Jun 8;:1-4
8. Comino I, Real A, Lorenzo L, et al. Diversity in oat potential immunogenicity: basis for the selection of oat varieties with no toxicity in coeliac disease. February 2011.
9. Kemppainen T, Janatuinen E, Holm K, et al. No observed local immunological response at cell level after five years of oats in adult coeliac disease. Scand J Gastroenterol. 2007 Jan;42(1):54-9 .