VIP shows up in this category's description and I realized I barely understand it beyond the name. My rough understanding is that it's an endogenous signaling peptide with roles in gut motility, secretion, and some immune/anti-inflammatory signaling, and there's research interest around it in conditions involving inflammation and the gut-immune interface.
Can anyone with a better handle on the literature sketch out what's genuinely being studied here versus what's just online extrapolation? Not asking about use — just trying to build an accurate mental model of the biology and the state of evidence.