Amen to that. Restoration of the gut microbiome is key to life-long health, starting with infancy, where colonization by the "right" beneficial bacteria is really important.

Infact, milk does a remarkable job with that. One example: diverse group of complex oligosaccharides present in milk and reaching the colon intact serve as food for the beneficial bacteria, allowing them to dominate the infant gut and present a wide array of benefits.

Does pasteurization mess with this effect at all? Is raw milk better?

Hi! Pasteurization is not known to impact the structure or function of human milk oligosaccharides. But there are certain heat labile molecules that are impacted by it, and raw milk may retain those.

But there is a whole another story with raw milk and pathogenesis. If interested, check this article: https://pubmed.ncbi.nlm.nih.gov/32591006/

Since peptides is mentioned, BPC-157 is popular for certain gut/digestive problems.