A fatty acid consists of the elements carbon (C), hydrogen (H) and oxygen (O) arranged as a carbon chain skeleton with a carboxyl group (-COOH) at one end. Fatty acids can be “saturated” and “unsaturated”. Saturated fatty acids have all the hydrogen that the carbon atoms can hold; they are saturated with hydrogen atoms. Unsaturated fatty acids are not saturated with hydrogen, and therefore, have double bonds (=) between the carbons atoms. While “monounsaturated fatty acids” have only one double bond, “polyunsaturated fatty acids” have more than one double bond. Fatty acids are frequently represented by a notation such as “C18:2”, which indicates that the fatty acid consists of an 18-carbon chain and 2 double bonds.
Free radicals are unstable molecules (e.g., oxygen) with an unpaired electron. They are very reactive, (e.g., reactive oxygen species) trying to capture the needed electron to gain stability. Generally, free radicals attack the nearest stable molecule, "stealing" its electron. When the attacked molecule loses its electron, it becomes a free radical itself, beginning a chain reaction. Once the process is started it can cascade, finally resulting in the disruption of a living cell. Some free radicals arise normally during metabolism. Sometimes the body’s immune system’s cells create them to neutralize viruses and bacteria. However, environmental factors such as pollution, radiation, cigarette smoke and herbicides can also generate free radicals.