ARI Publication 40 – 2013 Version
Gut Treatments: Digestive Enzymes
Rationale: The body normally produces a variety of digestive enzymes to break large food
molecules into smaller ones that can be absorbed. Different enzymes are needed for different types
of protein, carbohydrates, and fats. Children with autism sometimes have low levels of certain
enzymes, or less active enzymes, or both – enzyme problems are especially common in children
with gut problems (chronic constipation or diarrhea).
One digestive enzyme, DPP4, is easily deactivated by small amounts of toxins including mercury and
organophosphates (pesticide sprays). DPP4 is needed to digest some peptides from casein and
other substances that can have an opioid-like effect.
Treatment: Take a digestive enzyme with each meal, usually at the start of the meal. Use
enzymes that are as complete as possible. Proteases are needed for protein, lipases for fats, and
disaccharidases and other enzymes for carbohydrates.
Note that we recommend digestive enzymes in addition to special diets, and they should not be
used instead of special diets. If a child has a problem digesting wheat or dairy products, it is best
to just avoid them, and use the digestive enzymes as a precaution against unknown exposures.
Symptoms of pain, gas, and discomfort after eating dairy products is a strong indicator of a lack of
digestive enzymes for milk, or a delayed-type food allergy to it.
If an endoscopy is conducted to investigate chronic gastrointestinal problems, it is highly
recommended to include a biopsy to test for digestive enzymes – this is a routine test in most
hospitals, and can easily be done as part of the endoscopy.
A Comprehensive Digestive Stool Analysis may reveal whether some types of foods are not being
digested well, suggesting a problem with specific digestive enzymes, but the reliability of the test is
Gut Problems are Common in Autism
There are many studies of gastrointestinal problems in children and adults with autism (see review
by Buie et al 2010), and most of the studies indicate that chronic gastrointestinal problems
(constipation, diarhea, abdominal pain, esophagitis, etc.) are common and should be evaluated and
Buie, T., et al. (201OJ. Evaluation, diagnosis, and treatment ofgastrointestinal disorders in individuals
with ASDs: a consensus repott. Pediatrics 125Suppl 1, 51-18.
Lack of Digestive Enzymes
Studies by Horvath et al. 1999, Williams et al 2011, and Kushak et al 2011 have found that many
children with autism and major gastrointestinal problems have low levels of enzymes needed to
digest sugars/carbohydrates, especially lactase, the enzyme needed to digest lactose (the sugar in
milk). Insufficient lactase would result in gas, pain, and diarrhea after consuming milk products.
Their studies involved tissue biopsies taken during an endoscopy, so these were from
children/adults with substantial gastrointestinal problems – problems with digestive enzymes are
probably less likely in individuals without obvious gastrointestinal symptoms.