Chapter 6
Abnormalities of the Digestive System:
Gluten and Casein, Peptides, Secretin, CCK, and Pancreatic Atrophy
By Dr. William Shaw

 Gluten and Casein Sensitivity

Numerous studies by Dohan, Reichelt, Shattock, Cade and others have established that children with autism and adults with schizophrenia have elevated levels of peptides in their urine resulting from the incomplete breakdown of certain proteins in milk and wheat (1-17). Removal of these proteins either through diet or dialysis causes improvement in the symptoms of these diseases. The major protein in milk is called casein while the major protein in wheat is called gluten and each of these proteins is made of a combination of amino acids. There are 20 amino acids that are commonly found in proteins. A protein can be thought of as analogous to a string of pearls each with as many as 20 different colors. The amino acids would be individual pearls on the string. The protein’s DNA or genetic code selects which particular amino acid (or which color of pearls) is present in each protein (string of pearls). When proteins are eaten, enzymes in the gastrointestinal tract first break them down to smaller pieces called peptides and then the smaller pieces are further broken down into individual amino acids. The individual amino acids are then absorbed through the intestinal lining into the bloodstream.

 Historical Perspective

Both cow’s milk and wheat are fairly new on the evolutionary scale to human beings and were probably first used as foods by many of our ancestors in the Mideast approximately 10,000 years ago, when the first sickles in Turkey were used to harvest cereals (18).  Up until this time, our ancestors ate a varied diet of wild plants, fish, animals, and insects. Civilization from the Mideast spread throughout Europe as these new farmers moved into lands just vacated by retreating glaciers that covered northern Europe, Asia, and North America. The milk cow and domesticated grain seeds moved in with these invaders. Many of the native people in Europe, including children, were not biochemically adapted to eating these foods, and as a result, they did not do well on such diets and many died. Consequently, the genes associated with gluten sensitivity became reduced in the population. In countries such as Ireland, which were invaded more recently (about 3000 years ago) by people subsisting on high wheat and milk diets, the incidence of sensitivity to these foods is higher than in any other country. Because the toxic effects of milk and wheat have not had very long to kill off the sensitive individuals in the population, western Ireland has the highest incidence of schizophrenia (19) and celiac disease (1 in 300) in the world (and the two are probably related). Dohan found that schizophrenia was essentially absent from primitive people in the East Indies until they adopted a Westernized diet with increased grains (2).

 Antibodies to Transglutaminase Cause Celiac Disease

What are the effects of gluten sensitivity? In the medical disorder called celiac disease, there is a reduced ability to digest wheat and there is often a direct toxic effect of gluten on the lining of the intestine called the intestinal mucosa. Symptoms may include diarrhea, failure to thrive, short stature, discolored dental enamel, depression, premature degeneration of the nervous system, seizures, arthritis, nutritional deficiencies due to malabsorption, and abdominal distension (20-23). Long eyelashes, premature balding and clubbing of the fingers are also commonly reported in this disease. In celiac disease, there is also an increase in the blood of antibodies to wheat, and also a marked increase in antibodies called endomysial antibodies. The exact nature of the endomysial antigen has recently been identified as the tissue transglutaminase enzyme (24, 25). Researchers in Norway (24) think that transglutaminase facilitates the physical linkage of the carboxamide group of an amino acid called glutamine in gluten to an epsilon-amino group of a lysine residue in transglutaminase in the intestinal tract. (The normal physiological function of transglutaminase is probably the repair of injured or inflamed tissue by cross-linking extracellular matrix proteins in the tissue, thus stabilizing the damaged tissue and protecting the surrounding tissue from further damage.) Since gluten has an abundance of the amino acid glutamine, it is especially vulnerable to this reaction with transglutaminase. This abnormally linked molecule is then perceived as a foreign antigen by the immune system and antibodies to transglutaminase begin to be produced, inhibiting the normal function of transglutaminase in repairing damaged intestinal mucosa. The test for antibodies to transglutaminase is now considered the most specific test for celiac disease with near perfect specificities and sensitivities for celiac disease and is now being offered by The Great Plains Laboratory. This test is invalid if the patient has been off wheat for several months.

I suspect that wheat and Candida sensitivity may be linked because of the pentosidine linkages discussed in the “Organic Acids” chapter in this book. I suspect that in autism, the arabinose from Candida, instead of transglutaminase, crosslinks the gluten molecule to other tissue proteins, leading to a different autoimmune reaction and gluten sensitivity.

In celiac disease, there is an increased incidence of certain antigens on the white blood cells called HLA (human leukocyte antigen). These HLA types are most commonly used to determine suitability for tissue transplants and for paternity testing. Patients with celiac disease have an increased frequency of the HLA-B8 and HLA-Dw3 types compared to the population as a whole (26). The HLA-B8 antigen is present on the white blood cells of about 85-90% of celiac patients compared to only 20% of the general population.

 Differences Between Wheat Sensitivity in Autism and Celiac Disease

In celiac disease, the cells of the mucosa (the lining of the intestinal tract) lose their characteristic features, do not function as well, and may have impaired ability to produce hormones like secretin that stimulate the pancreas to function properly. As a consequence, the absorption of food from the intestine is impaired and there may be severe diarrhea due to this malabsorption. Severe nutritional deficiencies may also occur due to this defective absorption of nutrients in damaged individuals with autism and schizophrenia. The intestinal cells do not appear to be as bad as in celiac disease and if a small piece of the intestinal lining is removed in a biopsy, the microscopic pattern of the tissue is not usually the same as in celiac disease.

Autism is also different from celiac disease in that patients with autism frequently have elevated antibodies against both wheat and milk. A major difficulty in both autism and schizophrenia appears to be the absorption of the incompletely digested pieces of the gluten and casein proteins called peptides. One of the reasons for the incomplete digestion may be a deficiency of enzymes that break down these small peptides. I have talked with numerous parents who had the biopsy done to test for celiac disease, and none of the tests indicated the microscopic pattern of classic celiac disease even though the child improved on a gluten-restricted diet. Most children with autism will be negative for the test for antibodies to transglutaminase but since celiac disease is such a serious condition, it may be worthwhile to test any child with autism positive for wheat allergy.  Such testing must be done before wheat is restricted.

Peptides from gluten and casein are important because they react with opiate receptors in the brain, thus mimicking the effects of opiate drugs like heroin and morphine. The peptide from wheat is called gluteomorphin (gluten + morphine) and the peptide from milk is called caseomorphin (casein + morphine).  Gluteomorphin (also termed gliadorphin) has been verified by mass spectrometry techniques to be present in urine samples of children with autism by Alan Friedman, Ph.D. in work done at Johnson and Johnson. Both casomorphin and gluteomorphin are composed of seven amino acids, which are abbreviated below. Both casomorphin and gluteomorphin start with the beginning N-terminal sequence tyr-pro (for tyrosine and proline) with additional pro residues (proline) in positions 4 and 6 of both peptides as indicated below. Similarities are indicated by bold print.

Figure 1

The inability to breakdown these peptides could indicate a possible genetic deficiency of dipeptidyl peptidase IV in children with autism according to Dr. Alan Friedman. Dipeptidyl peptidase IV is an enzyme that is also present on cells of the immune system called lymphocytes (27). The particular cells are termed CD4+ helper cells. It has been found that this particular enzyme is identical to a cell surface marker called CD26. (Proteins on the surface of cells are given the designation CD or cluster domain. Dipeptidyl peptidase IV has the job of breaking down peptides in which the amino acid proline (abbreviation pro) is in the second position of the peptide as it is in both casomorphin and gliadorphin shown above. Dipeptidyl peptidase IV is found in the immune system cells and in the linings of the intestine, kidney, and blood vessels (27).
Gliadorphin and casomorphin are important substrates for the enzyme DPP IV. Each molecule of casomorphin and gliadorphin is processed twice by DPP IV (Figures 1a and 1b). After two dipeptides are removed from gliadorphin and casomorphin, tripeptides with proline in the middle position remain. One might expect that DPP IV would then remove another dipeptide from these molecules; however, this is not the case. Instead tripeptides with proline in the center position are potent inhibitors of DPP IV that essentially inactivate DPP IV (27). By breaking down casomorphin and gliadorphin, DPP IV essentially embarks on a course of self-destruction. As a result, many of the other functions of DPP IV may be impaired. As a matter of fact, the inhibition of DPP IV breakdown of other important regulatory peptides (Table 1) by casomorphin and gliadorphin may be much more important than the opiate effects of these molecules.

Figure 1a
Breakdown of Casomorphin By DPP IV

Figure 1b
 Breakdown of Gliadorphin By DPP IV

At The Great Plains Laboratory, we found that the MMR vaccine is a potent in vitro inhibitor of DPP IV, presumably due to its hydrolyzed gelatin content (Figure 2). Gelatin is a byproduct of collagen from bones, tendons, and hooves obtained from animals at slaughterhouses. Whether this additive could be a factor in adverse vaccine reactions deserves further investigation. Gelatin is the major ingredient of Jell-O and Knox and gelatin is also the major ingredient of capsules for food supplements and drugs. Whether or not the small amount of gelatin in capsules, the gelatin in vaccines, or the large amounts of gelatin in Jell-O are significant in autism is unknown. The simplest way of finding out whether gelatin is a factor in causing autistic symptoms is to try a dietary challenge with a serving of unflavored Knox gelatin after restriction of all gelatin products for a week or more.

Figure 2
 Effect of MMR Vaccine on DPP IV Enzyme Activity In Vitro

Hydrolyzed gelatin is even a more potent inhibitor of DPP IV probably because hydrolysis releases peptides with proline in the third position of the peptides or tripeptides with proline in the second position (like the residual tripeptides from casomorphin and gliadorphin after DPP IV action). Such peptides are potent inhibitors of DPP IV (27). Hydrolyzed gelatin is a component of the combined current MMR and DPT vaccines as well as the single component vaccines at a concentration of 0.2 g per 100 ml (28).

One parent reported that her child did poorly in his ABA class consistently after he was given marshmallows as a treat in the afternoon. Suspecting gluten or casein contamination, she contacted the manufacturer who reported that the marshmallows did not contain any gluten or casein. Marshmallows do, however, contain gelatin. NAET testing indicated gelatin sensitivity. The day after NAET treatment for gelatin allergy, her child began to converse for the first time. Much more research needs to be done to determine if dietary gelatin is a problem for most children with autism or PDD.

I was especially interested in the possibility that the gelatin in the vaccines might cause an abnormal immune reaction in autism since numerous reports (28-32) have implicated gelatin as a major risk factor in children with severe immediate vaccine reactions to MMR, DPT, Varicella, and to vaccinations with single components of the MMR and DPT vaccines. Most of the children with these reactions had elevated IgG and IgE antibodies in serum to gelatin. At The Great Plains Laboratory, we tested the blood of 25 children with autism for the presence of IgG and IgE antibodies to intact gelatin using a commercial enzyme immunoassay and no abnormal results were found, indicating that the vaccine reaction in autism is different than the previously reported vaccine reactions involving gelatin. However, it is still possible that there may be antibodies produced against gelatin peptides (present in the hydrolyzed gelatin of many vaccines) in individuals with vaccine reactions and this should be separately tested. Investigators evaluating the autism vaccine connection should carefully scrutinize the dates that the hydrolyzed gelatin was first employed and see if the increased autism incidence occurs at the same time.

Table 1
Gastrointestinal and other peptides that are activated or inactivated by DPP IV


# of amino acids



Peptide YY


Small and large intestine

Causes intestinal constriction, inhibits motility of gastrointestinal tract, inhibits pancreatic secretion of enzymes and bicarbonate.

Neuropeptide Y


Sympathetic nervous system, gut, brain (hypothalamus and limbic system)

Kills Candida when N-terminal dipeptide removed by DPP IV. Inhibits effect of CCK. Inhibits glucagon and insulin secretion and renin release. Regulates hypothalamus in the brain. Increases blood pressure. Structure similar to Peptide YY. Increases thirst, drinking, eating. Facilitates memory.

Pancreatic polypeptide



Increases pancreatic secretion when stimulated by secretin.



Brain, intestine

Inhibits food intake.

Substance P


Brain, peripheral nerves, intestine, skin, sensory organs, lungs, urinary tract

Suppresses bile production and release and reduces pancreatic response to secretin. Causes flushing and diarrhea. Mediates pain, touch, and temperature perception and acts as a neurotransmitter. Releases histamine. Causes diuresis (increased urination).

Growth hormone releasing factor


Hypothalamus, pancreas, spleen, thymus

Releases growth hormone from pituitary gland. Increases feeding. Stimulates the immune system overall.



Para follicular cells of the thyroid gland

Storage form of calcitonin, a major hormone regulating calcium. Calcitonin lowers calcium in blood and is an antagonist of parathyroid hormone.

Glucose dependent insulinotropic polypeptide


Duodenal mucosa

Stimulates beta cells of pancreas to release insulin.

Glucagon-like peptide-1 (GLP-1)


Small and large intestine, brain

Part of proglucagon, which contains GLP-1 and GLP-2. Inhibits food and water intake. Decreases blood glucose.

Glucagon-like peptide-2 (GLP-2)


Small and large intestine

Part of proglucagon, which contains GLP-1 and    GLP-2. Increases intestinal growth.

Peptide histidine methionine (PHM)


Intestine, brain, nasal mucosa, stomach, genitals.
Highest in colon.

13 amino acids of PHM are similar to vasoactive intestinal peptide (VIP). Relaxes smooth muscle in lungs, gall bladder, and stomach. PHM is encoded in VIP gene and is secreted as part of ProVIP hormone.

Interleukins 1b, 2, 3,5,8,10,11,13


Cells of the immune system

Interleukins are potent regulators of the immune system



Pancreas, sweat glands

Activates pain receptors and causes smooth muscle contraction

It is significant that substance P, a peptide hormone that regulates the intestinal tract and many other polypeptide hormones, also have a proline in the second position of the peptide and are broken down by DPP IV. If DPP IV were inhibited by gliadorphin or casomorphin tripeptides, then substance P might accumulate to abnormally high levels if the enzyme is defective. Substance P is a neurotransmitter in the brain and nervous system (28) and it is also a mediator for the transmission of pain signals. The inability to break down substance P might cause prolonged painful stimuli that might account for the extreme sensitivity of children with autism to certain sounds as well as the gastrointestinal pain reported by Wakefield. Substance P is also a regulator of the immune system besides regulating pain, touch, and temperature (28). Several other proteins that regulate the red blood cells and immune system including IL-1b, IL-2, granulocyte-macrophage-colony stimulating factor, and erythropoietin also have the proline in the second position and could accumulate if dipeptidyl peptidase is defective (29). Table 1 lists a number of peptides that are acted on by DPP IV. Thus, DPP IV regulates peptides that influence many types of behavior and physiological functions including hunger, thirst, digestive function, food intake, growth, pain and touch perception, control of Candida, overall immune function, and calcium metabolism.

Low values for DPP IV in blood serum are found in patients with major depression (33) and in alcoholics (34), even when abstinent. In depression, the severity of depression is proportional to how depressed DPP IV is in the blood serum (33). High values are found in patients with schizophrenia (35) and low amounts of DPP IV are present in the intestinal cells of people with celiac disease (36). Low values have also been reported in people with rheumatoid arthritis (37) and anorexia nervosa (38). The Great Plains Laboratory has measured and analyzed DPP IV in blood serum of both children with autism and in normal control children and no significant differences were found. However, DPP IV levels in the intestine might still be decreased in autism and this should be evaluated because it is in the intestines and kidneys that amounts of DPP IV is present in the highest quantities.

Casomorphin and gliadorphin have been shown to react with areas of the brain such as the temporal lobes (39-41), which are involved in speech and auditory integration. Furthermore, the administrations of drugs like naltrexone (see chapter by Bruce Semon M.D. Ph.D.), that block the effects of opiate drugs, can lessen the symptoms of autism (42). Children with autism frequently improve overall after restriction of these foods and slip-ups can be catastrophic. One mother reported to me that her teenage son with autism, who was doing very well on a gluten-restricted diet, severely damaged her house in a rage after eating a few wheat crackers. I have personally been informed of so many cases of improvement after gluten and casein restriction that there is no doubt in my mind that this dietary restriction should be considered for every child with autism. I would be very cautious in changing the diet if it has been successful. Because the milk and wheat peptides function as opiates, a withdrawal reaction similar to that of a drug addict may occur when these foods are removed from the diet.

The withdrawal reaction from gluten and casein can sometimes be severe. Some parents have reported seizures and hallucinations during the withdrawal period. Sidney Baker M.D. describes the reaction of one child with autism to the removal of gluten and casein in his book Detoxification and Healing (43). The child refused to eat, lost 15 pounds, was extremely hyperactive, barely slept, increased biting and hitting behaviors, and had to have liquids forced on him to prevent dehydration. Repeated doses of Alka-Seltzer Gold provided temporary relief from the symptoms. At the end of the six weeks, the withdrawal ended and the child was significantly improved. Alka-Seltzer Gold is a bicarbonate that helps to neutralize stomach acid.

Warning! Other types of Alka-Seltzer are not the same as Alka-Seltzer Gold and could cause serious side effects if given excessively.

 Testing for Wheat and Dairy Sensitivity

Several different laboratory tests are available to evaluate gluten and casein sensitivity including tests for IgG antibodies to gluten and casein as well as antibodies to related grains such as rye, barley and oats; testing for the presence of antibodies to transglutaminase to confirm celiac disease, and testing for the presence of the peptides casomorphin and gluteomorphin in urine. Peptides in the urine may become normal within a week of dietary restriction of wheat and/or dairy products. Antibody tests will usually remain abnormal for three to twelve months after the start of dietary restriction of the specific food. Anyone in the world can obtain all of these tests from:

The Great Plains Laboratory Phone: 913 341-8949
11813 W. 77th St. Fax: 913 341-6207
Lenexa, KS 66214

 Restriction of Gluten and Casein from the Diet

Lisa Lewis, Pamela Scott, and Karyn Seroussi, and Bruce Semon deal extensively with dietary therapies and I will not cover them here except for two important topics: calcium deficiency due to milk and dairy restriction and soy sensitivity.

 Prevention of Calcium Deficiency on the Casein Free Diet

Calcium deficiency can be a severe problem in normal children on a milk free diet since milk is a significant source of protein, vitamin D, and calcium. Some physicians have reported rickets, a bone deformity in children with autism on the gluten and casein free diet. Calcium and vitamin D supplementation is essential to children on a casein free diet since most children with autism do not eat substantial amounts of other calcium rich foods.

Children with autism may have an even more severe problem with calcium deficiency. Mary Coleman, M.D. reported that children with autism who are calcium deficient are much more likely to poke out their eyes and a substantial number of children with autism have done so (44). This abnormal behavior is associated with low urine calcium because blood calcium levels were usually normal. Treatment with calcium supplementation prevents this behavior. This behavior may be due to increased eye pain resulting from high substance P in the eye and low calcium may act to intensify this pain. Subsequently, the child pokes at the eye in an attempt to relieve the pain. Dr. Coleman also found that speech developed very quickly after calcium supplementation in a portion of mute children with autism who had low urine calcium. Parathyroid hormone, calcitonin, and vitamin D were all normal in patients with low urine calcium. In one case, according to a parent who contacted me, her child with autism persisted in poking at the eyes even after one eye had been poked out and surgically replaced. Calcium supplementation stopped this behavior immediately.
I have talked to several parents of children with autism that began to touch their eyes after starting the casein-free diet. Calcium supplementation quickly eliminated this behavior. Calcium, magnesium, and zinc need to be balanced for optimal nutrition. Vitamin D supplementation may also be needed when milk is eliminated unless other sources of vitamin D are included in the diet. Recommended calcium and magnesium supplementation amounts are given below:

in yrs

of calcium

of magnesium

of zinc


600 mg

100 mg

2.5 mg


800 mg

200 mg

5 mg


1000 mg

250 mg

15 mg


1000-1200 mg

350 mg

25 mg

Do not exceed dosage recommendations because excessive magnesium can be fatal!

 Soy Sensitivity 

A review of IgG food allergy tests at The Great Plains Laboratory indicated that almost every child with autism or PDD who had been switched to soymilk or other soy products as a part of their gluten and casein restricted diet had extremely high allergies to soy. Frequently, the parent would indicate that the child had not responded well to the diet or responded favorably for a few weeks and then regressed. Restriction of soy in such individuals usually results in improvements in the behavior of the children according to the parents. The adverse reaction to soy is so common that I would advise against the use of this food. Soy has been shown to produce biologically active peptides (45). Furthermore, Dr. Lori White of the Pacific Health Institute in Hawaii found disturbing effects of soy. She found that Japanese-American men who ate tofu (soy sprouts) at least twice a week had a more rapid decline in mental abilities with age than those who did not eat tofu and that they also had significant brain shrinkage (46). A group of scientists has recommended that soy not be used in baby formulas because it inhibits mineral absorption and might cause fertility problems or alter sexual development due the high content of estrogen-like molecules called isoflavones. In addition, soy can cause abnormalities of the thyroid gland, and might be a factor in breast and pancreatic cancers (46).

 Use of Other Therapies to Control Gluten and Casein Sensitivity

Several other approaches have been evaluated to reduce sensitivity to gluten and casein. None of these approaches has been as extensively evaluated as dietary restriction of gluten and casein, which remains the “Gold Standard” for treatment. Nevertheless, all possible therapies should be investigated. Laboratory testing such as urinary peptides and IgG antibodies to gluten and casein should be able to document the degree of effectiveness of other non-dietary therapies.

 Other New Peptides That May Be Important in Autism

A chemist, Alan Friedman, Ph.D. has reported at several autism conferences the presence of increased amounts of other opiate peptides using mass spectrometry. Two of these opiates, deltorphin and dermorphin, are extremely potent and can bind to human granulocytes, a type of white blood cell. As a result, these opiates might alter the response of the immune system. Deltorphin has been isolated from the skin of frog species and Dr. Friedman believes that this compound is not being produced by the frogs themselves, but instead by bacteria or fungus on the skin. He suspects that the deltorphin, found in humans, has a microbial origin because of the presence of D-amino acids, which are not characteristic of human metabolism. However, recent information indicates that the frog genome does indeed code for these peptides and that the amino acids are modified to the D-form after the protein has been formed. Thus, it is possible that humans may also produce these peptides.

 High-Protease/Peptidase Enzyme Products Enhance Protein Digestion

In 1999, the first plant-based enzyme product targeted for children with autism was introduced.  Since then, other enzyme products with better specificities and higher potencies have made their way into dietary protocols.  Most physicians now agree on the use of digestive enzymes as a means of enriching the gut environment.  Dipeptidyl Peptidase IV (DPP IV), an enzyme found in the lining of the gut wall, is also found in certain protease blends.  This enzyme is responsible for degrading the exorphin peptides produced from certain proteins found in wheat, dairy, soy and many other foods.  Just as important is the use of other proteases that actually alter the manner in which these proteins are broken down, such that exorphin peptides are not produced.  This two-pronged approach of diminishing production of exorphins while also targeting the direct breakdown of any exorphins produced in the gut is the forefront of products such as Houston Enzymes’ AFP Peptizyde.  Many parents report that their child was able to use this product as an alternative to the GFCF diet.  Others found they could add back foods previously not tolerated, or found additional benefits beyond what the GFCF diet provided alone.  As every child presents differently with their particular digestive problems, care should be taken when using these products as a GFCF alternative.  These enzymes are highly purified proteins from Aspergillus oryzae, a non-pathogenic fungus, which is not related to yeast mold (Candida albicans).  Unless a specific allergy to Aspergillus exists, the enzymes should not be a factor even in those with mold allergies.

 Alpha-1-Antitrypsin Deficiency

Alpha-1-antitrypsin is a protein produced by the liver. Deficiency of this protein is associated with chronic obstructive lung disease (or emphysema), cirrhosis of the liver, and respiratory distress of the newborn. Alpha-1-antitrypsin is an inhibitor of enzymes that break down proteins (proteases). It inhibits the action of a number of naturally occurring proteases including trypsin, chymotrypsin, collagenase, white blood cell proteases, and plasmin and thrombin, which are released in inflammatory reactions of the lung. In the absence of sufficient alpha-1-antitrypsin, plasmin and thrombin may begin to digest the lung itself. Elevated values for this protein are found in patients who are genetically heterozygous deficient for alpha-1-antitrypsin, during infection, during pregnancy, in bacteria infection, following estrogen or steroid therapy, and in rheumatoid arthritis. In the gastroenterology department of a children’s hospital in Australia, it was discovered (47) that 8 of 15 children with autism had abnormally low values of alpha-1-antitrypsin. In children with celiac disease, there was also an increased incidence of low values of alpha-1-antitrypsin. The authors think that the low level of alpha-1-antitrypsin might predispose children to wheat sensitivity. The Great Plains Laboratory now offers testing for alpha-1-antitrypsin activity.

 Pancreatic Atrophy, Hypoglycemia, and Antibiotics

I reviewed the results of a very interesting case, which illustrates the possible damage of yeast byproducts. (I encountered many similar cases but this child, who was tested over an extended time period and extensively evaluated by many different medical specialists, had his biochemistry analyzed exhaustively.) At about 10 months of age, this normal child whom I’ll call Ralph, developed a Strep throat and was given antibiotics. The Strep throat cleared up but the conscientious parents were advised to be sure to finish giving the entire 14-day supply of antibiotics. When Ralph’s mom went to check on him, she found that he was having convulsive seizures. She rushed Ralph to the emergency room at the hospital where his blood glucose (blood sugar) was near zero. Ralph would have died if his mother had brought him in any later. Ralph was given an infusion of glucose into his vein and began to recover.

Because of Ralph’s extremely low blood sugar, the attending physician sent a urine sample to my organic acid laboratory to see if Ralph had one of the genetic disorders that caused low blood sugar. When I examined Ralph’s urine organic acid profile, he had none of the abnormalities associated with any of the genetic diseases that cause hypoglycemia (low blood glucose) such as fatty acid oxidation disorders. Ralph did have, however, very high levels of the sugar arabinose, which indicated a severe yeast overgrowth resulting from his antibiotic treatment for Strep. I reported my findings. A new physician at the hospital was sure Ralph had one of the genetic disorders and ordered a retest. Again, the only significant abnormality was the elevation of the same yeast-related compounds that I had found in children with autism.

When Ralph returned home, his parents became concerned because he began to stagger at certain times of the day. When tested repeatedly, his blood glucose was low again, testing between 30-50 mg per dl. Normal is about 100 mg per dl.  Many other endocrine tests revealed no cause for Ralph’s hypoglycemia. Ralph was referred to another specialist who suspected that Ralph might have a tumor of the pancreas, which would oversecrete insulin, therefore lowing blood sugar. However, repeated testing revealed only a slight increase in insulin at most and not a value high enough to indicate a tumor.

His parents were taught how to perform a blood sugar test and tested Ralph’s blood sugar several times a day. The child’s pancreas, where the insulin-secreting cells are found was examined by an imaging technique called MRI and it was found that there was a severe atrophy of the pancreas. In addition, the tail of the pancreas was completely missing, but a tumor secreting insulin was not found. Additional organic acid tests at later times revealed the same elevation of - byproducts.  Several times I recommended the use of an antifungal drug but my suggestions were ignored.

Instead, the parents of the child were instructed to give the child multiple doses a day of a food called cornstarch, which is broken down into sugar in the intestine. The idea here was that sugar derived from cornstarch would increase the child’s blood sugar.  However, the child’s blood glucose continued to be abnormal and the parents were reprimanded for not being diligent enough in giving enough cornstarchs throughout the day. More than likely, the excessive cornstarch was feeding Ralph’s untreated yeast overgrowth and just made his hypoglycemia worse. Low blood sugar is prevalent in fibromyalgia (48), a disorder in which yeast overgrowth is common (49, 50). Finally, at about the age of two and a half years, I learned that Ralph was being referred to a developmental pediatrics department with the diagnosis of a probable autistic-spectrum disorder. At this time, a trial of nystatin was introduced. Ralph’s blood sugar returned to normal in about a week and his organic acids were normal for the first time since he had started antibiotics as an infant. There is no doubt in my mind that I had witnessed and documented over a span of about two years, the transformation of a normal infant into a child with autism.

I have lost contact with the child’s parents and do not know what happened to him later on. Ralph’s story indicated to me that yeast overgrowth could cause severe hypoglycemia and that it might also severely damage the pancreas. Another parent of a child with autism reported to me similar hypoglycemia and even more pancreatic damage in her son. The hypoglycemia could be due to the yeast byproducts. I suspect that the damage to the pancreas was due to antibodies against the yeast that cross-reacted with the pancreas in an autoimmune reaction. (See the chapter on the immune system.) It is possible that protein crosslinks of pentosidines caused by abnormally high arabinose might also be responsible for some of the damage. (See the chapter on organic acids.) The pancreatic damage probably resulted in deficient production of digestive enzymes by the pancreas. This deficiency of digestive enzymes would also result in the incomplete digestion of wheat and milk proteins that would then be absorbed and cause their opiate effects on the brain.


Secretin is a small protein called a polypeptide produced by the cells of the small intestine and is made up of 27 amino acids (51). The function of secretin is to cause the pancreas to release bicarbonate after a meal. After a meal, the stomach secretes acid and the food passing through the stomach is very acidic. Next, the pancreas secretes digestive enzymes to digest the food arriving into the small intestine from the stomach. These enzymes will not be able to properly digest the food if the acid from the stomach is not neutralized by bicarbonate from the pancreas. Thus, if secretin secretion is deficient, no bicarbonate will be formed and foods will not be digested properly. Secretin is produced by certain cells in the intestine and is stimulated by the presence of stomach acid. Secretin has been used to assess the function of the pancreas and is derived from pig intestine. Synthetic human secretin is now available.

Human and pig secretin are very similar (Table 2) and the molecules differ in only 2 of the 27 amino acids (52). Furthermore, these amino acids, that are different in human and porcine secretin, are considered to be conservative replacements. Amino acids, which make up secretin, belong to certain families based on their chemical characteristics. These families are aromatic, aliphatic, acidic, basic, hydroxyl containing, and sulfur containing. The two amino acids that are different in porcine and human secretin belong to the same families. These similarities decrease the likelihood of an autoimmune response in a human using porcine secretin. However, elevated antibodies to secretin have been reported in children with autism treated with pig secretin. 

In order to assess pancreatic function, secretin in injected into the vein and is transported by the bloodstream to the pancreas. If the pancreas is functioning properly, then the pancreas will produce bicarbonate. The production of bicarbonate can be monitored through a tube down the esophagus and stomach while the patient is sedated.

Figure 3
 Comparison of Amino Acid Sequence in Pig and Human Secretin.
** Amino Acids That are Different in the Two Types of Secretin are Indicated with Bold Type.

Pig secretin –
27 amino acids
Human secretin –
27 amino acids

Figure 4
 Cholecystokinin (CCK 8)

Why are these children reacting to these infusions so dramatically? Several explanations are possible:

  1. Children with autism are not producing secretin in sufficient amounts and their digestive process is impaired as a result. The gush of bicarbonate after secretin might be due to the fact that the pancreas has not been stimulated adequately with the body’s own secretin and therefore it overacted to the external secretin administered intravenously. This is the most likely explanation. Reduced secretin production may be related to gluten sensitivity, Candida damage, or viral damage to the intestinal mucosa caused by the live virus vaccines such as the MMR. In celiac disease, the gluten damages the intestinal cells that produce secretin (51) and presumably, a similar mechanism is operating in autism.
  2. Children with autism are producing a defective type of secretin that is not capable of stimulating the pancreas.
  3. It is also possible that secretin has some direct beneficial effect on brain functioning.
  4. And lastly, the autoantibodies against the pancreas, induced by Candida, may be preventing the pancreas from responding to the normal amount of secretin produced by the child’s own body.

Dr. Horvath and his colleagues recently reported on additional gastrointestinal abnormalities in children with autism (54). It was found that 58% of children with autism had low intestinal carbohydrate digestive enzymes (lactase) and 75% had increased pancreatic fluid after secretin. Lactase deficiency was found to be the most common enzyme deficiency in these children. Nineteen of the 21 patients with diarrhea had significantly higher fluid output than those without diarrhea. Reflux esophagitis was found in 69% and inflammation of the duodenum was found in 67%. A particular type of duodenal cell called a Paneth cell was found to be present in much higher numbers than in control samples. Dr. Horvath’s work seems back up the work of Dr. Wakefield in confirming that there is a physiological basis for the stomach pain and abdominal distress commonly reported by parents of children with autism.

 Routes of Administration and Forms of Secretin

The most significant difference among secretin suppliers is whether the secretin is of human or porcine (of pig) origin. The routes of administration are oral (by mouth), intravenous, intramuscular, and transdermal (through the skin). Each of these routes may have certain advantages and disadvantages. Human synthetic secretin, which is identical to human secretin and is less likely to cause autoimmune reactions, can be obtained from Bachem, AG, CH-4416 Bubendorf, Switzerland. Repligen Corporation, a biopharmaceutical firm, based in Massachusetts, has been awarded a U.S. patent for the use of secretin in treating autism and is also developing synthetic human secretin.  Most of the secretin used in the United States to date has been administered by the intravenous route using porcine secretin. Porcine secretin is produced in the United States by Ferring Pharmaceuticals. At this time, it appears that Ferring has discontinued the production of secretin because they did not find it sufficiently profitable. The Japanese drug company Eisai also used to produce porcine secretin under the trade name, Secrepanâ. In Japan, secretin has been widely used to treat ulcers. The route of administration of secretin in Japan is the intramuscular route. There have been no significant reports of toxicity of secretin from Japan, but only adults have been treated with Secrepanâ until recently.

In Taiwan, Dr. Shin-siung Jung, a neurologist at the Springtide Foundation of Taipei City reported the results of the first double blind study of secretin on the Internet. They concluded Secrepanâ is a mild to moderately effective treatment of autistic symptoms in 75% of children with autism. The main improved symptoms included improved vocalization, stabilized emotion, improved socialization, decreased sleep disturbance, and improved eye contact. No improvement or worsening was found in 25% of the treated children.  Adverse side effects included irritability, sleep disturbance, hyperactivity, and poor appetite and these were observed in both placebo and Secrepanâ treatment groups. It was very difficult to differentiate adverse side effects of Secrepanâ from day-to-day fluctuation of autistic symptoms. No significant allergic effects were noted in the study. The Secrepanâ product has been reported to have significantly less secretin than the Ferring product. Ironically, it is possible that the lower purity of Secrepanâ may be one of the reasons this product was more effective in treating autism. Other hormones in the product may have produced additional benefits not produced by more highly purified secretin.

A trial of synthetic secretin done on a large group of children with PDD or autism was published in December 1999 (55). The trial was a single dose and no differences in improvement were found between the secretin and placebo groups. Another unpublished study also found no difference between placebo and synthetic secretin. In both studies of synthetic secretin and the Taiwan study, there was a significant placebo effect of around 50%, indicating to me that there is a critical need to develop better means of objectively assessing behavioral changes in autism in such trials.

The difference in results between the Taiwan studies and the studies using synthetic secretin may mean that other impurities in the pork secretin are causing the beneficial effects.  It is possible that the impurities enhance the effect of the secretin, or that the route of administration for secretin is critical for success. An alternate explanation is that the synthetic human secretin did not work because it was not dissolved in the optimum solution. The three-dimensional structures of peptides are highly dependent on the ionic strength, pH, and other factors in the solution. An anticancer peptide called endostatin that prevents angiogenesis, the development of a tumor blood supply, only was effective under certain stringent conditions and was ineffective under other conditions. I think it is premature to give up on synthetic secretin trials until many other factors are investigated. The use of insulin for treating diabetes would have been discontinued if the results of a single insulin injection were the only factor used to assess treatment effectiveness.

 Adverse Reactions to Secretin

Common side effects associated with secretin infusions include increased stimming and hyperactivity for up to two weeks after the infusion. More serious side effects have occasionally been reported. Some children have contracted childhood diseases to which they had been immunized, possibly due to the effects of secretin on the immune system. One child developed sores that covered the inside of the mouth shortly after the first infusion of secretin, making it difficult to eat. A seven-year-old girl began to develop breast buds after several secretin infusions. It is impossible to know if these side effects were due to the secretin treatment, or were simply coincidental. However, there are secretin receptors on the ovaries and it is possible that secretin may have stimulated these.

I personally talked to a parent whose child had The Great Plains Laboratory organic acids urine test a few days before his first secretin infusion. The test revealed an extremely high arabinose value (1600 mmol/mol creatinine), indicating a severe intestinal yeast overgrowth. The child was put on antifungals shortly before a scheduled secretin infusion, but antifungal treatment was stopped due to “Internet wisdom,” that anything taken by mouth might prevent secretin success. A few days after the secretin infusion, the child had grand mal seizures. This child had no previous history of seizures. Thus, it is possible that the seizures may have due to the severe yeast problem or may have been due to a yeast secretin interaction.

Side effects were even more severe in a second child. This child was a seven-year-old male with a normal EEG, no history of seizures or allergies, and he was not on any medications. Three prior infusions of Ferring Secretin had been well tolerated at 6-week to one-month intervals, and anti-secretin antibodies had remained consistently negative. Small test doses were given prior to each infusion to test for allergic reactions. Shortly after the infusion, the child began having generalized motor seizures and stopped breathing. The child eventually responded to treatment with Valium and oxygen and resumed breathing spontaneously. No further seizures occurred. This case indicates that parents should be sure that their physician is prepared to treat serious life-threatening reactions that might occur.

 Cholecystokinin (CCK)

Cholecystokinin (CCK) is another hormone produced by the cells of the small intestine. CCK has a 32 amino acid structure that is similar to the hormone gastrin.  CCK is produced initially as a prohormone with 58 amino acids and then is broken down into peptides with 33, 22, 12, or 8 amino acids. The 8 amino acid peptide, CCK8, is as biologically active as the 33 amino acid peptide. CCK stimulates the release of pancreatic enzymes, like secretin does, and also stimulates the release of bile from the gall bladder. As shown in Figure 4, a sulfate group is attached to the tyrosine in CCK. If sulfation is defective, as has been reported in autism, CCK may not be adequately sulfated. CCK, without the sulfate, loses almost all of its hormone function. The defective sulfation in autism would likely lead to defective sulfation of CCK, resulting in defective gastrointestinal regulation. Parents using over-the-counter CCK as an oral dietary supplement for their children with autism or PDD have reported beneficial effects similar to those of secretin. High doses suppress the appetite and the product is marketed as a weight loss treatment under the name Bodyonicsâ. CCK is available from GNC stores (800) 797-8828. For use in children, 1/8 to 1/4 of a 100 mg capsule of the CCK product is given exactly one hour after the first bite of food with each meal. The dosing and timing of administration are critical and should only be used under a physician’s supervision. Overdosage has caused panic attacks and appetite suppression. When given at the beginning of the meal, pancreatic enzyme secretion begins before the food reaches the small intestine and may cause rectal burning. This product is a beef extract so food allergy to beef could cause severe reactions.

 Abnormal Bile Secretion

Parents of children with autism often report abnormal color of their children’s stool. The stool is frequently described as clay colored, white or lightly colored. The brown color in normal stool is due to bile pigments. Light or uncolored stools probably indicate an inadequate flow of bile possibly due to inadequate stimulation of bile release from the gall bladder due to deficient CCK. Many parents report the presence of “sand” in their child’s stool. This “sand” is probably due to the presence of insoluble bile salts. The amount of “sand” is reported to increase dramatically after secretin infusions probably because secretin stimulates bile release. Bile salts containing taurine do not form this “sand” because they are more soluble. Supplementation with taurine might be useful since taurine is frequently low in the urine amino acid profiles of children with autism. The Great Plains Laboratory measures taurine and many other amino acids in its urine amino acid profile. Children with light colored stools may be significantly deficient in vitamin A, vitamin D, vitamin E, and vitamin K due to inadequate amounts of bile salts which aid in their absorption. Vitamin A palmitate, the prevalent form of vitamin A, may be especially difficult to absorb since bile salts are needed to remove the palmitate group before it is absorbed. A bile salt deficiency may be the reason that free vitamin A is needed for many children with autism.  The organic acid test gives some clue as to which children may have this problem. Reduced bile salts cause increased absorption of oxalic acid, which is frequently elevated in children with autism. The reason for this abnormality is that if taurine containing bile salts are not present, free fatty acids remaining in the intestinal lumen compete with oxalic acid in combining with calcium to form insoluble soaps that are eliminated in the stool. Free oxalic acid is absorbed from the intestine more readily than the oxalic acid salt combined with calcium, which is insoluble and is not absorbed from the gastrointestinal tract. Testing for vitamins A, D, E, and K may be useful in children with high urine oxalic acid or with light colored stools.

 Tests of Pancreatic Function

A common way to evaluate pancreatic function is to measure the concentration of pancreatic enzymes in the stool or blood and is included in the comprehensive stool test performed by The Great Plains Laboratory.

 Other Digestive Enzyme Supplements

While enhanced protein digestion through the use of high-protease enzyme supplements can produce significant benefits in addressing gut health, other areas of digestion are also of concern.  The function of different digestive enzymes is listed in Table 1.

AFP Peptizyde, previously mentioned in another section, addresses only protein digestion.  But many children also have problems with carbohydrates, fats, and certain fruits and vegetables high in polyphenolic compounds.  Enzyme supplements may help in these areas as well.

Many children suffer from gas, bloating, and loose stools.  Carbohydrase enzymes, which degrade complex carbohydrates such as starch to simple sugars, can provide help by reducing the tendency of large carbohydrate molecules to draw water into the gut.  Undigested carbohydrates are also a source of food for “bad” bacteria and yeast.  Once sugars are produced from the carbs, they are rapidly removed from the gut, taking water out as well. This results in a drier, more formed stool, as well as a more hospitable environment for probiotics and other “good” bacteria.  Houston Enzymes carries a formula known as Zyme Prime, a combination of many carbohydrase enzymes.  Many parents have noted better bowel movements and less “carb craving” when given on a consistent basis to their children.  Certain highly-colored fruits and vegetables cause behavioral and digestive problems in a subset of spectrum children.  These foods can be addressed in certain xylanase-containing enzyme products, such as No-Fenol from Houston Enzymes.  While the mechanism of action is still not fully understood, it is thought that the enzymes may remove certain types of sugar groups attached to polyphenols.  This removal may then allow the phenolic compound to be processed without the subsequent red cheeks and ears that are characteristic of such food intolerances.

 Behavior, Food Dyes, and Inactivation of Digestive Enzymes

Several studies have documented adverse effects of food colors on behavior (56-58). One possible mechanism for the negative effects of food dyes may be an inhibition of digestive enzymes by the food colors. In a study done in Germany (59), it was found that the biochemical function of the digestive enzymes amylase and trypsin were significantly inhibited by many common food colors. Thus, one of the best things you might do for your child is to remove food dyes from his diet. Children who may have pancreatic damage due to autoantibodies or intestinal damage due to toxic peptides do not need the additional burden of food colors to inhibit any functional enzymes that remain active.  The Feingold organization can be reached at

Table 2
Human Digestive Enzymes

Human digestive enzyme Function


Converts starches to sugar


Converts sucrose to simple sugars


Converts milk sugar (lactose) to glucose and galactose


Convert nucleic acids (DNA and RNA) to nucleotides


Converts fats (triglycerides) to fatty acids and glycerol


Converts phospholipids to fatty acids and glycerophosphate


Converts proteins to peptides


Converts proteins to peptides


Converts peptides to amino acids


Converts peptides to amino acids

Cholesterol esterase

Converts cholesterol esters to free cholesterol


Converts nucleosides to nucleic acid bases


Converts organic phosphates to free phosphates


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