Casomorphins and Gliadorphins: The GAPS Explanation

A gluten-free label and a lactose-free label answer different questions. Gluten is a protein; lactose is a sugar. The GAPS discussion of casomorphins and gliadorphins concerns protein digestion, which is why removing lactose does not settle the casein question. Understanding that difference makes the grain and dairy guidance much easier to follow.^[1]

In Dr. Natasha Campbell-McBride’s explanation, incomplete digestion can leave opioid-like fragments of gluten and casein. She connects their absorption with the condition of the gut lining and its enzymes. The aim of GAPS is broader than removing two proteins: it also addresses digestion, the microbial community and nourishment.^[1]

What the Names Mean

• Casein is a milk protein. Casomorphins are opioid-like peptide fragments derived from it.
• Gluten is a grain protein. The GAPS books call its opioid-like fragments gliadorphins or gluteomorphins.
• Peptides are short chains of amino acids. Amino acids are the smaller building blocks into which proteins are broken during digestion.^[1]

The words “opioid-like” describe the peptides’ structure and activity in this discussion. They do not mean that a glass of milk contains heroin or that every person eating bread has the same neurological response.

How Protein Digestion Normally Continues

The 2020 book follows protein digestion from the stomach and duodenum to the intestinal surface. Proteins reach the intestinal cells, called enterocytes, as peptide chains. Enzymes on the cells’ brush border then break those chains into single amino acids for absorption. Producing peptides during digestion is normal; completing their breakdown is the important next step.^[1]

The stomach acid and pepsin guide explains the beginning of that process. The low-acid and peptide guide follows Campbell-McBride’s account of what can happen when digestion gets off to a poor start, including her earlier discussion of infant feeding. These stages belong to one digestive sequence, rather than three unrelated problems.

What GAPS Says Goes Wrong

Campbell-McBride describes abnormal gut flora, unhealthy enterocytes and a damaged gut wall. In her explanation, enzyme production becomes impaired, protein breakdown remains incomplete and peptides can pass through the gut wall into circulation. She links gluten- and casein-derived opioid peptides with effects on brain function.^[1]

The earlier book names reports involving schizophrenia, autism, ADHD, postpartum psychosis, epilepsy, Down syndrome, depression and autoimmune conditions including arthritis. That is the range of conditions she discusses, not a statement that these diagnoses are identical or that every person with one of them has the same peptide finding.^[2]

DPP-IV Is One Part of the Explanation

The earlier book highlights dipeptidyl peptidase IV, or DPP-IV, as one enzyme involved in breaking down these peptides. Campbell-McBride also stresses that the intestinal surface carries many enzymes, so adding one studied enzyme does not address the whole condition of the enterocytes and their microbial support. The DPP-IV and peptidase guide develops that point.^[2]

The earlier book also notes that people apparently absorb some protein as peptides or even unchanged. Its concern here is an excessive incoming load, rather than the mere existence of a peptide. She describes another proposed effect: an excessive incoming load of food peptides can inhibit peptidases that help clear the body’s own active substances after they have done their work. The peptidase and signaling guide keeps that explanation separate from the direct effects attributed to casomorphins and gliadorphins.^[2]

The Research Behind the Discussion

Campbell-McBride names Dohan, Reichelt, Shattock and Cade among the researchers who shaped this argument. Reichelt and colleagues’ 2012 paper reports identifying exorphins in urine using mass spectrometry and fragmentation analysis. The Cade research guide follows a different part of the history, including his animal work, university interview and human reports.^[2][3]

Keep a reported laboratory finding, a proposed mechanism and an individual response to food separate as you read. A person’s diagnosis or preference for certain foods cannot tell you which peptides are present. The gut-brain guide and celiac-disease guide explain the related questions in their own context.

Why GAPS Is Broader Than Gluten-Free and Casein-Free

The earlier book says the gluten-free, casein-free diet helped some autistic children substantially, while many did not improve on that change alone. Campbell-McBride’s explanation is that GAPS involves more than these two peptide groups. Removing their dietary sources does not, by itself, address every microbial, digestive and nutritional problem she describes.^[2]

That distinction matters when looking at dairy. GAPS excludes grains, but it does not impose a permanent ban on every dairy product for every person. The 2020 book permits appropriately prepared homemade fermented dairy where tolerated and uses a separate Dairy Introduction Structure for people who need it. Fermentation changes the food; an ordinary lactose-free milk label is not the same preparation.^[1]

Tolerance still matters. Campbell-McBride says some people need to avoid dairy proteins indefinitely, particularly in long-standing mental illness, epilepsy, autoimmune disease, severe asthma or severe eczema. Even ghee, which contains very little milk protein, is not tolerated by everyone with a severe dairy allergy. Use the milk and dairy guide and seven-step dairy introduction guide for the full distinctions.^[1]

Can Gluten or Casein Be Introduced Again?

The books describe people regaining tolerance as digestion improves, but that is not permission to reintroduce foods as soon as one symptom changes. The 2020 coming-off guidance calls for at least two years of strict GAPS for the majority and at least six months of normal digestion before introducing excluded foods. Individual conditions can require longer. The coming-off-GAPS guide follows that sequence.^[1]

Make the Food Rules Easier to Use

My family began GAPS in July 2024. When I explain the protocol here, I want the food rules to make sense together. Knowing whether a question concerns milk sugar, milk protein, fermentation or the stage of introduction is more useful than treating “dairy” as one undivided category.

Start with the guide closest to your question. For the other compounds mentioned in the book, continue with the wider neurotoxin guide or deltorphin and dermorphin. My Care Team Log is listed in the WFLI Shop. A notebook can keep dated observations and questions together.

References

1. Campbell-McBride N. Gut and Physiology Syndrome (2020), “Foods to avoid: Proteins,” “Milk and dairy products,” the Dairy Introduction Structure and “Coming off the GAPS Diet.”
2. Campbell-McBride N. Gut and Psychology Syndrome, expanded second German edition (2015), “Die Darm-Hirn-Achse,” particularly “Opiate aus Gluten und Kasein” and “Andere Toxine.”
3. Reichelt KL et al. Peptides’ role in autism with emphasis on exorphins. Microbial Ecology in Health and Disease. 2012;23:18958. doi:10.3402/mehd.v23i0.18958.