Celiac Disease and Barley Malt

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Celiac Disease and Barley Malt

 

The following was written by Donald D. Kasarda who is a research

chemist in the Crop Improvement and

Utilization Research Unit of the United States Department of

Agriculture. If you have any questions or

comments regarding the piece, you can address them to Don at:

kasarda. More on malt can

be found on this site.

 

The connection with wheat (and rye and barley) wasn't recognized

until the 1950's…(a)nd it wasn't until the 1960's that

intestinal biopsies began to become commonly used in the diagnosis

of celiac disease. With regard to the

harmfulness of barley malt, the situation is complicated. I will

give you my best shot with the qualification that the

ideal experiments have not been done and a definitive statement is

not possible at this time.

 

Because barley malt is made from barley grain that has been

germinated it is reasonably certain to be less toxic than

barley itself. The hordein proteins and starch in the endosperm of

barley grains, like the equivalent gluten proteins and

starch in wheat, are there for storage purposes. In a sense, they

provide food for the new plant upon germination. In

order to use the hordein proteins, the grain releases and

generates enzymes upon germination that break down the

storage proteins into their constituent amino acids. The problem

is that the process is not complete during a short

germination, so some peptides (short pieces of the proteins)

remain intact in malted barley. There is experimental

evidence for this. The resulting mix of peptides is highly

complex.

 

We know from work described in the scientific literature that

relatively small polypeptide chains can still retain activity

in celiac disease and we know something about a few sequences that

seem to be harmful. But we probably don't

know all the sequences that are harmful and we haven't put our

fingers on the common theme that gives rise to the

activity in celiac disease. So the question arises as to whether

or not the remaining sequences in malted barley are

harmful.

 

The possibilities that come to my mind are:

 

1.There are sufficient remaining harmful peptides (with sizes

including approximately 12 or more amino acid

residues) to give a significant activity in celiac disease to

barley malt (remember though that barley malt is

usually a minor component of most foods in which it is used

and processing might decrease the amount of

harmful peptides in a malt product);

2.There are traces of these peptides, but they are sufficiently

minimal so as to cause no discernible harm; or

3.The key harmful amino acid sequences are completely destroyed

by the enzymes during germination (I can

speculate that there might be an important enzyme, very

active, in germination that clips a key bond in active

sequences, thus reducing the concentration of those active

sequences to almost nil while still allowing

non-harmful peptides to exist; no evidence exists for this

speculation, but it could be used as a working

hypothesis for experimentation).

 

There is no completely solid evidence for or against there being a

threshold of gluten consumption below which no

harm, or at least no lasting harm, occurs and above which definite

harm occurs (but see my previous post to the list

on starch/malt question). This is a difficult area to study where

zero consumption is being approached and the

arguments that come up are at least similar to those that have

arisen in regard to the question of whether or not there

is a minimal level of radiation exposure below which no harm is

caused, but above which there is harm that increases

with dosage. Accordingly, celiac patients must choose arbitrarily

the path they feel comfortable with.

 

Here are some references that deal with the question of peptide

toxicity. It is not a simple situation:

 

1.Shewry, P. R., Tatham, A. S., Kasarda, D. D. Cereal proteins

and coeliac disease. In Coeliac Disease, Ed. M.

N. Marsh. Blackwell Scientific, London 1992;pp. 305-348.

2.Kasarda, D. D. Toxic cereal grains in coeliac disease. In:

Gastrointestinal Immunology and Gluten Sensitive

Disease: Proc. 6th International Symp. On Coeliac Disease, C.

Feighery and C. O'Farrelly, eds., Oak Tree

Press, Dublin 1994;pp. 203-220.

3.Wieser, H., Belitz, H.-D., Idar, D., Ashkenazi, A. Coeliac

activity of the gliadin peptides CT-1 and CT-2.

Zeitschrift fur Lebensmittel-Untersuchung und-Forschung

1986;182:115-117.

4.De Ritis, G., Auricchio, S., Jones, H. W., Lew, E. J.-L.,

Bernardin, J. E., Kasarda, D. D. In vitro (organ culture)

studies of the toxicity of specific A-gliadin peptides in

celiac disease Gastroenterology 1988;94:41-49.

5.Fluge, 0, K. Sletten, G. Fluge, Aksnes, L., S. Elsayed. In

vitro toxicity of purified gluten peptides tested by

organ culture. Journal of Pediatric Gastroenterology and

Nutrition 1994;18:186-192.

6.Sturgess, R., Day, P., Ellis, H. J., Lundin, K. A., Gjertsen,

H. A, Kontakou, M., Ciclitira, P. J. Wheat peptide

challenge in coeliac disease. Lancet 1994;343:758-761.

7.Marsh, M. N., Morgan, S., Ensari, A., Wardle, T., Lobley, R.,

Mills, C., Auricchio, S. In vivo activity of peptides

31-43, 44-55, 56-68 of a-gliadin in gluten sensitive

enteropathy (GSE). Supplement to Gastroenterology