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CSA Library Series:

The CSA Library Series is a collection of articles pertaining to celiac disease and dermatitis herpetiformis. Many first appeared in CSA's member newsletter, Lifeline. Historic articles included in these resources may or may not include updated notes. Articles represent the work of the author.

 

On the Use of Oats in the Gluten-Free Diet

Leon H. Rottmann, Ph.D., Professor Emeritus, University of Nebraska-Lincoln
Lifeline, Winter 1996, Vol XIV, No 1, pp 1-2

[1996 article adds to the timeline of information on oats and amino acid sequences. Later studies have built upon the past.]

 

A recent study from the October 19,1995 issue of the New England Journal of Medicine has raised renewed interest in the clinical gluten-free diet, particularly to the use of oats. In the past, the oat grain has been excluded from the clinical diet for the celiac as one of the glutamine-containing grains on the basis of its amino acid sequence and reports from patients on problems with oats when included in the gluten-free diet. (Refer to the table at the end of this brief presentation which indicates similarities of amino acid sequences of some grains and the human intestinal adenovirus 12.)

The Finland study found that oats taken in moderate amounts (50 grams per day) for six months was not associated with any damage to the small intestinal mucosa in adult celiacs who were in remission. Remission may be defined as being in a non-active or inactive phase of celiac sprue as any disease. The conclusions of the article and an accompanying editorial state that moderate amounts of oats are safe to eat over six months to a year for the celiac patient.

The protein from oats, known as avenin, (from the classification of proteins by composition) is in the category of prolamines with wheat (gliadin); corn (zein); rye (secalin); barley (hordein). These proteins have the general characteristic of being insoluble in water and absolute alcohol; soluble in 70% alcohol; high in amine nitrogen and proline; and occur in grain seeds. Zein protein, as found in corn and most maize grains, is non-toxic and does not contain the similar amino acid sequences as found in other mild reactive and toxic grain proteins which relate to the specific needs of the clinical gluten-free diet. Similarly, the oryzenin protein of rice does not contain amino acid sequences which are toxic to persons with celiac disease.

Many celiacs and their physicians have raised several concerns about the conclusions of the Finland study. Some of the skepticism centers around the following concepts:

  • the apparent disagreement of this study with food chemistry research studies from the U.S. on prolamines and amino acid sequences which support the toxic definition of avenin protein for the clinical gluten-free diet.
  • the purity of oat products, especially in the U.S.; the claim that oats and oat products are often contaminated with wheat.
  • the possibility that damage from oats takes longer to show up in patient monitoring and evaluation than in the six-month period of this particular study. And related, that the symptoms may be sub-clinical and not readily apparent to the patient or through routine monitoring and/or evaluation.
  • the potential that children under the age of 8 whose immune systems are not yet fully-developed and persons over the age of 55 or 60 whose immune systems are beginning to break down may be expected to have a higher cross-sensitivity to oats in a select group of celiac patients.
  • the difficulty for the self monitored celiac patient to be able to make the decision that the celiac condition for them might be in remission or in an inactive (non-active) phase.

So where does this study and these reactions leave the self-monitoring celiac in relation to following a gluten-free diet which omits all oats and oat products?

Physicians, celiacs and celiac organizations such as CSA are going to be reluctant to change the guidelines and restrictions of the present gluten-free diet for any patient who is doing well. In addition and of critical importance, celiacs need to take heed of U.S.-based research studies which have evaluated avenins in oats as toxic.

As defined earlier, there are two protein groups which compose gluten. First are the gliadins which are soluble in alcohol/water solutions. The second group are the glutenins which are not soluble in alcohol/water solutions, but are soluble in some salt solutions.

The gliadin proteins are separated into Alpha, Beta and Gamma gliadins which contain intramolecular disulfide bonds. These bonds link one part of a polypeptide chain to another. The Omega proteins do not contain disulfide bonds which means that they do not contain cysteine (or probably methionine) in their primary structure. (see pp 638-639, Skerritt, Devery and Hill, "Gluten Intolerance: Chemistry, Celiac Toxicity, and Detection of Prolamins in Food," The American Association of Cereal Chemists, July 1990). Thus, the Alpha, Beta and Gamma gliadins are defined as toxic to celiacs whereas the Omaga gliadins are regarded as non-toxic to celiacs.

There are two amino acid sequences that have been found to be toxic in the Alpha, Beta, and Gamma gliadins: Pro-Ser-Gin-Gin and Gin-Gin-Gin-Pro. [Pro-proline, Gin-glutamine, Ser-serine]. The Omega gliadins do not contain these sequences. See the following table as referencing these details in an outline format.


Similarities of Amino Acid Sequences of Some Gains
and the Human Intestinal Adenovirus 12.

Prolamin Amino Acid Sequence
Alpha, Beta & Gamma gliadins (Wheat, toxic) -Pro-Ser-Gin-Gin-...-Gin-Gin-Gin-Pro-
IIMW glutenines (Wheat, toxin) -Pro-Ser-Gin-Gin-...
LMW glutenines (Wheat, toxic) -Pro-Ser-Gin-Gin-...-Gin-Gin-Gin-Pro-
Avenin (Oats, toxic) Gin-Gin-Gin-Pro-
Secalin (Rye, toxic) -Pro-Gin-Gin-Gin-
Gamma hordein (Barley, toxic) -Pro-Ser-Val-Gin
Zein (Maize, nontoxic) -Gin-Gin-Gin-Gin-
Ad 12 E1b (Virus, toxic) -Pro-Ser-Gin-Cys-


Note: Rice does not contain any similar amino acid sequences.
[Pro=proline, Gin=glutamine, Ser=serine, Val=valine, Cys=cysteine.]

Sources:

John Skerritt, Jannine Devery, and Amanda Hill, "Gluten Intolerance: Chemistry, Celiac Toxicity, and Detection of Prolamins in Food," The American Association of Cereal Chemists, July 1990, 35:638-639.

G.L. Mantzais, et al, "Cellular Hypersensitivity to a Synthetic Dodecapeptide Derived From Human Adenovirus 12 which Resembles a Sequence of A-gliadin in Patients with Coeliac Disease," Scandinavian Journal of Gastroenterology, 1991, 26:393-398.

Michael N. Marsh, "Celiac Sprue: Gluten, MHC, and Intestinal Immunopathy," New England Journal of Medicine, Dec 12, 1991, 102:333.

Donald Kasarda, "Toxic Cereal Grains in Coeliac Disease," unpublished paper, 6.

(Prepared by Leon H. Rottmann, Editor in consultation with members of the CSA Medical Advisory Board. 1996)

 


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