Either they don't have enough or they have barely have enough to be in the normal range, but nothing extraordinary
-Aminobutyric acid production by culturable bacteria from the human intestine
Or think of a drain clogged with your hair in the shower.the water definitely flows through it more slowly theres plenty of water in the shower basin and it COULD go through faster IF the drain allowed it, but the only way out is THROUGH THE DRAIN so it has to then wait, hanging out with your ankles in the meantime
[DOI] [PMC free article] [PubMed] [Google Scholar] 42.Guan W.-J., Liang W.-H., Zhao Y., Liang H.-R., Chen Z.-S., Li Y.-M., Liu X.-Q., Chen R.-C., Tang C.-L., Wang T., et al