Wednesday, 21 April 2010

What to do about oats?

Oats in Australia is now Controversial


In Wilhem Dicke’s original studies showing that gluten from wheat, rye and barley is toxic coeliac disease, he also found that children with coeliac disease relapsed when fed oats (1, 2). Since that time, the argument has shifted back to blaming wheat, rye, or barley gluten contaminants for the toxicity of oats.
In Australia and New Zealand, commercial oats are generally regarded as toxic in coeliac disease because of gluten contamination.
In Europe, “gluten-free” oats are available and are used as part of the gluten-free diet. A small industry has evolved to cater for the gluten-free oats market, and oats provide an interesting addition to the gluten-free diet, especially for those with diabetes because of the favourable glycaemic index (GI) of oats compared to most other gluten-free cereals and grains.
Two influential studies, both published in the New England Journal of Medicine, one in 1995 (3) and the other 1997 (4), showed that addition of oats to glutenfree diet did not slow recovery or cause relapse of coeliac disease or dermatitis herpetiformis (DH). A follow-up of individuals enrolled in the former study found no harmful effects of oats when included in the gluten-free diet for up to five years (5). More recently, inclusion of oats in the gluten-free diet was again found to be non-toxic but quality of life assessment revealed oats were associated with more abdominal symptoms, similar to those in irritable bowel syndrome (6). The “dose” of oats in each of these studies was up to 70g/day.
Although important, the main criticism of these studies is that they may have missed the “rare” individuals who do react to oats because they may have been unwilling to volunteer for these studies. In fact, 11 from 102 of subjects withdrew from largest study (3) possibly because they had adverse reactions. Only ten subjects were included in the DH study. Hence, these studies did not exclude the possibility of uncommon reactions to oats in individuals with coeliac disease.

The oats debate was re-ignited by a study published in 2003 in which a series of19 individuals with coeliac disease were challenged with 50 g of oats daily for 12 weeks. Small intestinal biopsies performed before and after oats challenge identified one person with subtotal villous atrophy that evolved with oats exposure and resolved after oats were withdrawn. In five others, there were
subtle signs of intestinal damage following oats exposure (7). Around the same time, a Dutch group published the finding that oats contain protein sequences similar to those in gluten that stimulate the immune response to wheat gluten (Tcell epitopes) (8). In October 2004 it was reported that T-cells isolated from the intestinal biopsies of the individual who developed subtotal villous atrophy when
eating oats reacted to both wheat gluten and oats proteins sequences (9).
Hence, in principle, there may be people with coeliac disease with intestinal immune reactions that cannot distinguish between wheat gluten and similar oats proteins. We have recently, found that 1/5 individuals with coeliac disease eating oats have T-cells in their blood that react to a series of oats protein sequences including the one identified in earlier studies (10).
Toxicity to oats is present in a minority of people with coeliac disease. Identifying people who genuinely “react” to oats with worsening damage to the small intestine (i.e. a “coeliac” reaction) as opposed to irritable bowel symptoms without the inconvenience of a gastroscopy and biopsy is a major challenge.
Antibody-based blood tests are untested and may well be unreliable markers of intestinal damage when oats are the injurious grain.
In Australia and New Zealand oats will not be recommended as part of the gluten free diet until there is a reliable supply free from contamination by gluten from other grains. Some local manufacturers are soon to launch oat-based foods that are contaminate-free, and this should be a welcome arrival for the majority of people with coeliac disease, especially those with diabetes. Ignoring the issues of gluten-contamination, generalizations about the safety of oats (gluten-free or not) in coeliac disease should be tempered by the likelihood that occasional people do react to oats. Perhaps, the message for doctors and dietitians is that vigilance is needed when oats are included in a gluten-free diet and should be withdrawn if intestinal symptoms worsen or nutritional markers (e.g. iron levels) deteriorate. If there is a compelling reason to consume oats, it may be that a systematic challenge with oats and endoscopic biopsy before and during is the only definitive test for oats sensitivity.

Robert P Anderson PhD FRACP
Gastroenterologist
D.W. Keir Fellow, The Royal Melbourne Hospital, Parkville, Australia 3050
Cancer Council Fellow, Walter and Eliza Hall Institute, Parkville, Australia 3050
References:
1. Dicke WK, Weijers HA, van der Kamer JH. II. The presence in wheat of a
factor having a deleterious effect in cases of coeliac disease. Acta
Paetiatr. 1953; 42,34-42.
2. van de Kamer J, Weijers H, Dicke W. IV. An investigation into the
injurious constituents of wheat in connection with their action on patients
with coeliac disease. Acta Paediatr. 1953; 42, 223-31.
3. Janatuinen EK, Pikkarainen PH, Kemppainen TA, Kosma VM, Jarvinen
RM, Uusitupa MI, Julkunen RJ. A comparison of diets with and without
oats in adults with celiac disease. N Engl J Med. 1995 Oct
19;333(16):1033-7.
4. Hardman CM, Garioch JJ, Leonard JN, Thomas HJ, Walker MM, Lortan
JE, Lister A, Fry L. Absence of toxicity of oats in patients with dermatitis
herpetiformis. N Engl J Med. 1997 Dec 25;337(26):1884-7.

Try GF Uncontaminated Oats in Australia

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