What are free radicals?

Dariush Mozaffarian, MD
Internal Medicine
Free radicals are a natural byproduct of energy metabolism and are also generated by ultraviolet rays, tobacco smoke, and air pollution. They lack a full complement of electrons, which makes them unstable, so they steal electrons from other molecules, damaging those molecules in the process.

Free radicals have a well-deserved reputation for causing cellular damage. But they can be helpful, too. When immune system cells muster to fight intruders, the oxygen they use spins off an army of free radicals that destroys viruses, bacteria, and damaged body cells in an oxidative burst. Vitamin C can then disarm the free radicals.

Free radicals are the loose cannons -- highly reactive forms of oxygen, to be exact -- that can damage cell membranes and other cellular structures in the body, but especially in the skin. Free radicals attack us from a variety of sources, both internal as an outcome to normal metabolism and respiration, as well as from external sources like pollution and UV rays. You can control free-radical damage through specific protocols that entail treatments to the skin, as well as nourishment from the inside.

From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.

Everybody knows that we need oxygen to live. In the body, oxygen is vital for many of the chemical reactions that keep us alive and healthy. But these reactions also produce "free radicals" -- highly unstable molecules that can damage cells. Free radicals are produced when the body breaks down foods for use or storage. They are also produced when the body is exposed to tobacco smoke, radiation and environmental contaminants.
Eric Olsen

Free radicals are highly charged or energetic particles produced by radiation from outside the body, by the body's own metabolism in the normal course of living, or taken into the body in the air we breathe and the food we eat. Free radicals, primarily highly energized molecules of oxygen, can attack the body's tissues by causing mistakes in DNA, thus disrupting the normal gene structure and producing mistakes in the information the genes carry.

Free radicals also cause damage to the body by interacting with unsaturated fatty acids in the membranes of cells; these highly energized molecules are oxidants that cause the body to "rust," as it were, literally turning the body's fats rancid.

Lifefit: An Effective Exercise Program for Optimal Health and a Longer Life

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Lifefit: An Effective Exercise Program for Optimal Health and a Longer Life

An easy-to-follow programme for lengthening and improving lives. More than an exercise guide, this text is an effective tool for making meaningful lifestyle decisions to benefit long-term fitness. In...
Emilia Klapp
Nutrition & Dietetics

A free radical is an unstable and destructive molecule -- unstable because it is an atom missing an electron. Some are formed during normal bodily functions such as breathing, eating, or drinking. Others form because of cigarette smoke, overexposure to smog or sunlight, and other factors.

Free radicals become bad for the body when the body produces too many for its natural processes to handle. This is because during the process of trying to pick up another electron to have a matched pair, the radical attaches itself to another molecule. This alters the structure of the other molecule, making it a free radical and creating a chain reaction of unstable molecules. These molecules cause continuous cell damage called oxidative stress, which eventually kills the cells. This oxidation is a major culprit in heart disease.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

Free radicals are unstable atoms or molecules (often oxygen) which react with cell membranes, mitochondrial DNA and proteins. These reactions lead to damage of a cell; after enough damage has occurred through a chain reaction created by contact with free radicals, the cell may die or mutate.


Free radicals are molecules with unpaired electrons. They are a natural byproduct of many bodily functions, including breathing. These unstable molecules make their way through the body, scavenging cells to try to snatch that missing piece. One theory is that the damage these free radicals cause to our cells could be why our bodies age.

Continue Learning about Wellness



Wellness is a difficult word to define. Traditionally wellness has meant the opposite of illness and the absence of disease and disability. More recently wellness has come to describe something that you have personal control over. ...

Wellness is now a word used to describe living the best possible life you can regardless of whether you have a disease or disability. Your wellness is not only related to your physical health, but is a combination of things including spiritual wellness, social wellness, mental wellness and emotional wellness. Wellness is seen as a combination of mind, body and spirit. Different people may have different ideas about wellness. There is no single set standard for wellness and wellness is a difficult thing to quantify.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.