What Are Free Radicals?

By Jessie Szalay

The human body is under constant attack from oxidative stress. Oxygen in the body splits into single atoms with unpaired electrons. Electrons like to be in pairs, so these atoms, called free radicals, scavenge the body to seek out other electrons so they can become a pair. This causes damage to cells, proteins and DNA.

Free radicals are associated with human disease, including cancer, atherosclerosis, Alzheimer’s disease, Parkinson’s disease and many others. They also may have a link to aging, which has been defined as a gradual accumulation of free-radical damage, according to Christopher Wanjek, the Bad Medicine columnist for Live Science.

Substances that generate free radicals can be found in the food we eat, the medicines we take, the air we breathe and the water we drink, according to the Huntington’s Outreach Project for Education at Stanford University. These substances include fried foods, alcohol, tobacco smoke, pesticides and air pollutants.

Free radicals are the natural byproducts of chemical processes, such as metabolism. Dr. Lauri Wright, a registered dietitian and an assistant professor of nutrition at the University of South Florida, said, “Basically, I think of free radicals as waste products from various chemical reactions in the cell that when built up, harm the cells of the body.”

Yet, free radicals are essential to life, Wanjek wrote in 2006. The body’s ability to turn air and food into chemical energy depends on a chain reaction of free radicals. Free radicals are also a crucial part of the immune system, floating through the veins and attacking foreign invaders.

The danger of free radicals

According to Rice University, once free radicals are formed, a chain reaction can occur. The first free radical pulls an electron from a molecule, which destabilizes the molecule and turns it into a free radical. That molecule then takes an electron from another molecule, destabilizing it and tuning it into a free radical. This domino effect can eventually disrupt and damage the whole cell.

The free radical chain reaction may lead to broken cell membranes, which can alter what enters and exits the cell, according to the Harvard School of Public Health. The chain reaction may change the structure of a lipid, making it more likely to become trapped in an artery. The damaged molecules may mutate and grow tumors. Or, the cascading damage may change DNA code.

Oxidative stress occurs when there are too many free radicals and too much cellular damage. Oxidative stress is associated with damage of proteins, lipids and nucleic acids, according to an article in the Pharmacognosy Review. Several studies throughout the last few decades have suggested that oxidative stress plays a role in the development of many conditions, including macular degeneration, cardiovascular disease, certain cancers, emphysema, alcoholism, Alzheimer’s disease, Parkinson’s disease, ulcers and all inflammatory diseases, such as arthritis and lupus.

Free radicals are also associated with aging. “The free radical theory of aging states that we age because of free radical damage over time,” said Wright. Free radicals can damage DNA’s instructional code, causing our new cells to grow incorrectly, leading to aging.