Googled it and:

Gut microbiota: PAs can improve the diversity of gut microbes, and can increase the abundance of beneficial bacteria while decreasing the abundance of harmful bacteria.

Fecal odor: PAs can reduce the level of putrefactive substances in the feces, which can reduce fecal odor.

Fecal pH: PAs can decrease fecal pH.

Antimicrobial activity: PAs can have an antimicrobial effect on potentially pathogenic bacteria.

Prebiotic effect: PAs can have a prebiotic effect on beneficial bacteria.

Looks like I’m buying some seeded grapes for science!