In mice, certain good bacteria in the gut called Bacteroides are needed to help the body soak up a substance called hyaluronan when it's swallowed.

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.

Some good bacteria in your gut can break down a substance called hyaluronic acid, and different strains do it in different ways—some even share the broken-down pieces with other bacteria, like one bacteria passing along a chemical called UDP4.

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.

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 things your body gets from those bacteria.

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.