When rats swallow a special kind of big molecule labeled with a traceable marker, most of it comes out in their poop within two days — like 9 out of 10 pieces or more.

When rats and dogs swallow a big molecule called hyaluronan, their bodies absorb it and it shows up in places like their joints, spine, and saliva glands—and it stays there for almost two days.

When rats were given a special version of hyaluronic acid by mouth, almost all of it left their bodies within a week through breathing, pee, and poop—very little stayed inside, so it didn’t build up.

When rats were given a special version of hyaluronic acid by mouth, their blood showed the highest level of radioactivity after 8 hours, which means the substance took a long time to get from their stomach into their bloodstream.

When rats were given a special version of hyaluronic acid by mouth, scientists found traces of it in their skin two days and four days later—and even more was in the skin than in the blood, which means the substance traveled through the body and reached the skin.