An antioxidant is a substance that protects cells in your body from damage caused by harmful molecules called free radicals. Think of free radicals like tiny troublemakers that form naturally when your body breaks down food or when you're exposed to things like pollution or sunlight. These troublemakers can damage your cells over time, kind of like how rust damages metal or how an apple turns brown when you leave it out.

Antioxidants work like protective shields, stopping free radicals before they can cause harm. Your body makes some antioxidants naturally, but you also get them from foods like berries, dark chocolate, nuts, and colorful vegetables. Vitamins C and E are well-known antioxidants.

Scientists are still studying exactly how much antioxidants help people stay healthy as they age. You'll often see the word on food packaging, where companies advertise that their products are “rich in antioxidants” or have “antioxidant properties.”