What Are Free Radicals?

Oxidative Stress

In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons. Highly instable and extremely short lived, free radical intermediates have a lifespan measured in trillionths of a second or less. Their presence in biological systems was first reported in the 1960s when scientists observed exceedingly short-lived events in enzyme-controlled oxidation-reduction (redox) reactions similar to those that take place inside our cells. Unlike ions, free radicals generally do not carry a net charge on the molecule, so their reactivity is different from the reactivity of similar ions. However, the unpaired electrons of a free radical create an activated energy state, making the molecule highly reactive chemically. Consequently, free radicals are aggressive participants in chemical reactions within the cell, reacting with other biomolecules at the instant of their creation.



During their fleeting existence, highly unstable free radicals can inflict considerable damage to the cell. Like sparks from a spitting fire that burn holes in your living room carpet, these supercharged particles leave a virtual killing field of destruction in their wake. For example, when a free radical interacts with a lipid molecule in the cell membrane, it sets in motion an autocatalytic raction that is self-perpetuating. Once oxidized, a lipid molecule interacts with and damages its neighbouring molecule. This newly formed lipid peroxide (oxidized lipid) then attacks its neighbour and the process repeats unless quenched by a membrane-active antioxidant. Lipid peroxidation is extremely damaging to the cell because it seriously impairs the selective permeability of the cell membrane and, with this, the ability of the cell to control its internal environment- nasty stuff, with nasty consequences for the cell.





Antioxidant are chemicals (both naturally occurring and man-made) that can prevent or slow cell damage. An “antioxidant” is actually not a substance; it’s a behavior. Any compound that can donate electrons and counteract free radicals has antioxidant properties.

Antioxidants are one of the first lines of defense that the body employs to keep free radicals in check and prevent them from causing a domino effect of damage on other cells. Antioxidant compounds can “donate” electrons to unstable free radicals so they don’t have to snatch electrons from unsuspecting nearby cells. Antioxidants can also help repair cell damage caused by free radicals.

Natural antioxidants are mainly found in fruits and vegetables, marine plants, and some seafood that eat marine plants. There are thousands of antioxidant compounds out there, but the most common dietary ones are vitamins A, C, and E, beta-carotene, and lycopene. Antioxidants can also be produced artificially and consumed in supplement form.