“Very few individuals, if any, reach their potential maximum life span; they die instead prematurely of a wide variety of diseases—the vast majority being ‘free radical’ diseases.”
— Denham Harmon, M.D., Ph.D., who in 1954 first proposed the Free Radical Theory of ageing.
The theory of free radicals and the damage they cause to the human body has given answers to various queries on ageing and diseases. In defeating free radicals, most experts and scientists believe, lies the solution to longevity.
 What are Free Radicals?
Understanding free radicals calls for a brief refresher course in chemistry.
- Structure of an atom: As we may remember from the science studied in school, the human body consists of various types of cells, which, in turn, are made up of different types of molecules. Molecules contain one or more atoms joined together by chemical bonds. Atoms consist of nucleus, neutrons, protons and electrons. Protons, the positively charged particles in the nucleus of the atom, defines how many electrons (the negatively charged particles) surround the atom. Neutrons have no electrical charge. Electrons move around or ‘orbit’ the central mass of the atom made up of protons and neutrons. They surround the centre in one or more shells. The innermost shell is considered full when it has two electrons and when the first shell is full, electrons move to the second shell. The second shell is full when it has eight electrons and the electrons move to the next shell.
- Chemical bonding: Electrons are responsible for chemical reactions and are involved in bonding atoms together to form molecules. An atom’s chemical performance is decided upon by the number of electrons it has in its outer shell. Any matter with a full outer circle tends not to get into a chemical reaction and is considered ‘inert’. An atom always tries to reach a state of balance or stability by trying to fill its outer shell. It does so by either gaining or losing electrons to fill or empty its outer shell or by sharing its electrons by bonding together with other atoms in order to complete its outer shell. By sharing electrons, atoms bond together and the molecules reach optimum stability.
 Formation of Free Radicals
Occasionally, an atom loses an electron, and is left with an ‘unpaired’ electron. The atom is then called a ‘free radical’. This happens when weak bonds are formed and leaves the atom very reactive because it starts looking for a replacement electron. They are unstable and try capturing an electron to gain stability. This is generally done by indiscriminately attacking the nearest stable molecule and appropriating its electron. This sets off a process whereby the ‘attacked’ molecule loses an electron and becoming a secondary ‘free radical’. A chain reaction is thus set off that eventually causes extensive cellular and biological damage.
During metabolism, some amount of free radical formation is normal. The body’s immune system purposely creates them sometimes to neutralise viruses and bacteria. But, often enough, environmental pollutants like cigarette smoke, pollution, radiation, insecticides and herbicides give rise to free radicals.
 Damage Caused by Free Radicals
According to Dr. Harmon's free radical theory of ageing, cells continuously produce free radicals, and constant free radical damage eventually kills the cell. When free radicals kill or damage enough cells in an organism, the organism ages. Free radicals cause various diseases.
According to healingdaily.com , cell membranes are made of unsaturated lipids. The unsaturated lipid molecules of cell membranes are particularly susceptible to this damaging free radicals process and readily contribute to the uncontrolled chain reaction. Oxidative damage, another name for the chemical reaction that free radicals cause, can lead to a breakdown or even hardening of lipids, which make up all cell walls. If the cell wall is hardened (lipid per oxidation) then it becomes impossible for the cell to properly get its nutrients, get signals from other cells to perform an action (such as firing of a neuron) and many other cellular activities can be affected.
In addition to the cell walls, other biological molecules are also susceptible to damage, including RNA, DNA and protein enzymes. Right from arthritis, cancer, heart ailments to ageing and wrinkles, free radicals have been a contributor and in defeating this lays the cure to diseases.
 References and Useful Websites
- Free radicals and your health
- Free Radicals: nature's way of saying NO or Molecular murder