Here's why:

* Free radicals are atoms or molecules with an unpaired electron in their outer shell. This makes them highly reactive and unstable.

* To become more stable, they seek to gain an electron from another molecule.

* When a free radical takes an electron from a molecule, it oxidizes that molecule.

* This process can damage the molecule, potentially leading to cell damage and disease.

Think of it like this: A free radical is like a thief looking for a single shoe to complete their pair. They'll take it from any unsuspecting person they can find.