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...

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 ate hyaluronic acid, only 16% of it made it into their bloodstream unchanged — the rest got broken down or didn’t get absorbed at all.

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 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 special kind of slippery molecule labeled with a tracking dye, the dye shows up in their skin, bones, and joints a day later—but a different tracking dye (technetium) doesn’t show up anywhere.