Our bodies naturally produce a range of chemical products called free radicals as a consequence of typical metabolic processes.

To deal with these reactive species, our bodies also produce enzymes with antioxidant properties, like superoxide dismutase.

But our environment can also be a source of free radicals. Absorbing pollutants, including cigarette smoke and toxic metals, can overwhelm our bodies' home-grown defenses and increase oxidative damage.

Oxidative damage occurs when an electron is stolen from an important biochemical structure, such as a base in a genetic code or the amino acids making up proteins. 

Simple changes to DNA can transform a base into something different,...