When your body doesn’t absorb certain pieces of hyaluronan (a substance found in joints and skin), your gut bacteria break them down into tiny fatty acids—and in mice, these fatty acids are the only...

When mice eat certain types of hyaluronan, their bodies break down the parts they can’t absorb directly into tiny fatty acids, and those fatty acids are the only things their bodies can actually use from this substance.

When mice swallow hyaluronan, almost none of it gets into their bloodstream whole—just a tiny bit—so any effects they feel probably come from gut bacteria breaking it down, not from the original substance.

Your gut bacteria turn the hyaluronic acid you swallow into tiny pieces that your body can absorb; if you don’t have those bacteria, your body can’t absorb anything from it.

When mice swallow hyaluronan, only about 1 in 500 parts of it actually gets into their body without breaking apart—so most of it just passes through without being absorbed.

In mice, certain good bacteria in the gut called Bacteroides are needed to turn a substance from the mouth called hyaluronan into tiny pieces that the body can absorb.