Free radicals attack other beneficial molecules in the body in a process known as oxidative stress.

Free radicals are highly reactive molecules and are harmful to cells and their various components.  They are produced naturally or can be induced by exposure to things like radiation, certain chemical pollutants, or other sources.  Free radicals attack the structure of many cell components, particularly DNA, proteins, and lipids, causing considerable damage.

Free radicals normally enter your body from environmental sources such as air pollution, tobacco smoke, medications, pesticides, toxic waste and alcohol. Factors such as aging, disease and stress promote your body's free radical production.

The body is normally able to handle the damage created by oxidative stress, but if you have an elevated level of free radicals, cellular damage can result. Antioxidants are nutrients that target and neutralize these damaging free radicals.

When free radicals come in contact with healthy cell membranes, they can cause damage to the membrane and may cause the cell to die.  As a cell ages, it can accumulate tens of thousands of lesions caused by free radical hits.  These hits or wounds lead to alterations in the structure of DNA and contribute to tumor formation.

A free radical is an atom or group of atoms that has at least one unpaired electron. Because another element can easily pick up this free electron and cause a chemical reaction, these free radicals can effect dramatic and destructive changes in the body.

Free radicals are activated in heated and rancid oils and by radiation in the atmosphere, among other things.

Some antioxidants have been shown to have cancer-protecting potential because they neutralize free radicals.