[1] Digestive enzymes can break casein down into peptides that have some biological activity in cells and in laboratory animals though conclusive causal effects on humans have not been established.
[1] Although research has shown high rates of use of complementary and alternative therapies for children with autism, including gluten and/or casein exclusion diets, as of 2008[update] there was a lack of evidence that these diets had any effect.
[2] If opioid peptides breach the intestinal barrier, typically linked to permeability and constrained biosynthesis of dipeptidyl peptidase-4 (DPP4), they can attach to opioid receptors.
Elucidation requires a systemic framework that acknowledges that public-health effects of food-derived opioids are complex with varying genetic susceptibility and confounding factors, together with system-wide interactions and feedbacks.
[3] Also known as morphiceptin (Note: There is also a form of bovine β-casomorphin 8 that has histidine instead of proline in position 8, depending on whether it is derived from A1 (His) or A2 (Pro) beta-casein.)