Antioxidants are chemicals that interfere with oxidation.

In the context of a healthy diet, antioxidants are substances found in food items that help shield biological molecules such as DNA from this potentially destructive activity:

• These substances include vitamins like vitamin C and vitamin E, trace elements such as selenium and zinc, and other common plant compounds such as lycopene and flavonoids.
• A diet that includes a reasonable mix of fruit, nuts, vegetables, and mushrooms should contain sufficient antioxidants to guard our cellular machinery against oxidative stress. 

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, altering its behavior so it no longer spells out the same sequence.

While our bodies have repair mechanisms that can account for these damaging changes, as we age the problems can pile up. Mutations get missed, aggregations of proteins build, and risks of diseases like cancer or even neurodegenerative conditions like Parkinson's increase.