Preface: The following information was supplied originally in 1991 in the form of a letter to Phyllis Brogden, Chairperson of the Greater Philadelphia Celiac Sprue Support Group, by Donald D. Kasarda, who was a Research Chemist with the US Department of Agriculture at that time. Copies were sent to four other major celiac patient groups in the US. Dr. Kasarda retired from the USDA in 1999, but updated the information in February of 2000. Dr. Kasarda wishes to add the following disclaimer to the information: These are my opinions based on quite a few years of research in the area of proteins as they relate to celiac disease. They do not necessarily represent those of the Agricultural Research Service, U. S. Department of Agriculture. If you have any questions or comments regarding the piece, you can address them to Don at: email@example.com
The only plants demonstrated to have proteins that damage the small intestines of people with celiac disease are those from wheat, rye, and barley (and the man-made wheat-rye cross called triticale). Although oats had generally been considered harmful until 1996, several high quality studies published since then indicate that oats are not harmful either in celiac disease or dermatitis herpetiformis. Some physicians choose not to accept these findings or else point out that there is some potential problem of contamination of oats by wheat. The contamination question has not yet been adequately researched, but may be overemphasized. The three harmful species are members of the grass family and are quite closely related to one another according to various schemes of plant classification (taxonomy). However, not all members of the grass family damage the intestines of celiac patients. Rice and corn, for example, are apparently harmless.
The scientific name for bread wheat is Triticum aestivum var. aestivum--the first part of the name defines the genus (Triticum) and the second part, the species (aestivum). Species falling in the genus Triticum are almost certain to be harmful to celiac patients. Grain proteins of these species include the various types characteristic of the gluten proteins found in bread wheats (including the alpha-gliadins) that cause damage to the small intestine in celiac disease. Durum wheats (Triticum turgidum var. durum) used for pasta are also harmful to celiac patients. Some Triticum species of current concern include Triticum aestivum var. spelta (common names include spelt or spelta), Triticum turgidum var. polonicum (common names include Polish wheat, and, recently, Kamut), and Triticum monococcum var. monococcum (common names include einkorn and small spelt). I recommend that celiac patients avoid grain from these species. Also, given their very close relationship to bread and durum wheats, I think it is unlikely that these grains would be safe for those with classical allergic responses to wheat.
Rye (Secale cereale) and barley (Hordeum vulgare) are toxic in celiac disease even though these two species are less closely related to bread wheat than spelta and Kamut. They belong to different genera, Secale and Hordeum, respectively, and lack alpha-gliadins, which may be an especially toxic fraction.
There have been anecdotal reports suggesting a lack of toxicity in celiac disease for spelta and Kamut, along with anecdotal reports of the opposite, at least in the case of spelt-celiac patients who have been harmed by eating it. Controlled tests would be necessary to draw a firm conclusion, although they hardly seem necessary insofar as spelt and Kamut should be considered forms of wheat.
The diagnosis, sometimes self-diagnosis, of celiac disease is occasionally made without benefit of reasonably rigorous medical or clinical tests, especially intestinal biopsy. Individuals who are diagnosed in this way without rigorous testing may not actually have celiac disease. Claims that particular foods cause this latter group no problems in relation to their celiac disease could cause confusion.
Furthermore, celiac patients who report no problems in the short run with spelt or Kamut might experience relapse later. There is now adequate evidence that when celiac patients on a gluten-free diet (that is, a diet free of any proteins or peptides from wheat, rye, and barley) have wheat reintroduced to their diets, times-to-relapse vary enormously among individuals, ranging from hours to months, or even years. And this is for wheat, presumably the most toxic of all cereal grains to celiac patients.
Additionally, the relapse may not be accompanied by obvious symptoms, but be recognized only by physicians through observation of characteristic changes in the small intestinal tissues obtained by biopsy. The reasons for the enormous variability of response times are not known. It may be speculated that the variability has something to do with the degree of recovery of the lining of the small intestine on a gluten-free diet, the degree of stress that the patient had been experiencing (including infections), and individual genetic differences.
As I have indicated, all known grain species that cause problems for celiac patients are members of the grass family. In plant taxonomy, the grass family belongs to the Plant Kingdom Subclass known as monocotyledonous plants (monocots). The only other grouping at the Subclass level is that of dicotyledonous plants (dicots). Some other species about which celiac patients have questions actually are dicots, which places them in very distant relationship to the grass family. Such species include buckwheat, amaranth, quinoa, and rape. The seed of the last plant listed, rape, is not eaten, but an oil is pressed from the seeds that is commonly used in cooking. This oil is being marketed as canola oil. Because of their very distant relationship to the grass family and to wheat, it is highly unlikely that these dicots will contain the same type of protein sequence found in wheat proteins that causes problems for celiac patients. Of course, some quirk of evolution could have given rise in these dicots to proteins with the toxic amino acid sequence found in wheat proteins. But if such concerns were carried to a logical conclusion, celiac patients would have to exclude all plant foods from their diets. For example, buckwheat and rhubarb belong to the same plant family (Polygonaceae). If buckwheat were suspect for celiac patients, should not rhubarb, its close relation, be suspect as well?
It may be in order to caution celiac patients that they may have undesirable reactions to any of these foods--reactions that are not related to celiac disease. Allergic reactions may occur to almost any protein, including proteins found in rice, but there is a great deal of individual variation in allergic reactions. Also, buckwheat, for example, has been claimed to contain a photosensitizing agent that will cause some people who have just eaten it to develop a skin rash when they are exposed to sunlight. Quinoa and amaranth may have high oxalate contents-approaching those of spinach and these oxalate levels may cause problems for some people. Such reactions should be looked for, but for most people, buckwheat, quinoa, or amaranth eaten in moderation apparently do not cause problems. (Buckwheat is sometimes found in mixture with wheat, which of course would cause a problem for celiac patients.) It seems no more necessary for all people with celiac disease to exclude buckwheat from their diets because some celiac patients react to it than it would be for all celiac patients to exclude milk from their diets because some celiac patients have a problem with milk.
In conclusion, scientific knowledge of celiac disease, including knowledge of the proteins that cause the problem, and the grains that contain these proteins, is in a continuing state of development. There is much that remains to be done. Nevertheless, steady progress has been made over the years. As far as I know, the following statements are a valid description of the state of our knowledge:
- Spelt or spelta and Kamut are wheats. They have proteins toxic to celiac patients and should be avoided just as bread wheat, durum wheat, rye, barley, and triticale should be avoided.
- Rice and corn (maize) are not toxic to celiac patients.
- Certain cereal grains, such as various millets, sorghum, teff, ragi, and Jobs tears are close enough in their genetic relationship to corn to make it likely that these grains are safe for celiac patients to eat. However, significant scientific studies have not been carried out for these latter grains.
- There is no reason for celiac patients to avoid plant foods that are very distantly related to wheat. These include buckwheat, quinoa, amaranth, and rapeseed oil (canola). Some celiac patients might suffer allergies or other adverse reactions to these grains or foodstuffs made from them, but there is currently no scientific basis for saying that these allergies or adverse reactions have anything to do with celiac disease. A celiac patient may have an allergy to milk, but that does not mean that all celiac patients will have an adverse reaction to milk. Again, however, scientific studies are absent or minimal for these dicots.
A list of my publications with pertinence to celiac disease follows. Cross-references to the literature for most of the points discussed above can be found in these publications.
- Kasarda, D. D., and DOvidio, R. 1999. Amino acid sequence of an alpha-gliadin gene from spelt wheat (Spelta) includes sequences active in celiac disease. Cereal Chem. 76:548-551.
- Kasarda, D. D. 1997. Celiac Disease. In Syllabus of the North American Society for Pediatric Gastroenterology & Nutrition, 4th Annual Postgraduate Course, Toronto, Ontario, Canada, pp. 13-21.
- Kasarda, D. D. 1997. Gluten and gliadin: precipitating factors in coeliac disease. In Coeliac Disease: Proceedings of the 7th International Symposium on Coeliac Disease (September 5-7, 1996), edited by M. Mäkki, P. Collin, and J. K. Visakorpi, Coeliac Disease Study Group, Institute of Medical Technology, University of Tampere,Tampere, Finland, pp. 195-212.
- Srinivasan, U., Leonard, N., Jones, E., Kasarda, D. D., Weir, D. G., OFarrelly, C., and Feighery, C. 1996. Absence of oats toxicity in coeliac disease. British Medical Journal 313:1300-1301.
- Tatham, A. S., Fido, R. J., Moore, C. M., Kasarda, D. D., Kuzmicky, D. D., Keen, J. N., and Shewry, P. R. Characterization of the major prolamins of tef (Eragrostis tef) and finger millet (Eleusine coracana). J. Cereal Sci. 24:65-71. 1996.
- Kasarda, D. D. 1994. Defining cereals toxicity in coeliac disease. In Gastrointestinal Immunology and Gluten-Sensitive Disease, edited by C. Feighery, and F. OFarrelly, Oak Tree Press, Dublin, pp. 203-220.
- Shewry, P. R., Tatham, A. S., and Kasarda, D. D. 1992. Cereal proteins and coeliac disease. In Coeliac Disease, edited by M. N. Marsh, Blackwell Scientific Publications, Oxford, U. K., pp. 305-348.
- De Ritis, G., Auricchio, S., Jones, H. W., Lew, E. J.-L., Bernardin, J. E. and Kasarda, D. D. 1988. In vitro (organ culture) studies of the toxicity of specific A-gliadin peptides in celiac disease. Gastroenterology 94:41-49.
- Kagnoff, M. F., Patterson, Y. J., Kumar, P. J., Kasarda, D. D., Carbone, F. R., Unsworth, D. J. and Austin, R. K. 1987. Evidence for the role of a human intestinal adenovirus in the pathogenesis of celiac disease. Gut 28:995-1001.
- Levenson, S. D., Austin, R. K., Dietler, M. D., Kasarda, D. D. and Kagnoff, M. F. 1985. Specificity of antigliadin antibody in celiac disease. Gastroenterology 89: 1-5.
- Kagnoff, M. F., Austin, R. K., Hubert, J. J., Bernardin, J. E. and Kasarda, D. D. 1984. Possible role for a human adenovirus in the pathogenesis of celiac disease. J. Exp. Med. 160: 1544-1557.
Grains in Relation to Celiac (Coeliac) Disease by Donald D. Kasarda.
An annotated copy: http://wheat.pw.usda.gov/topics/