Free radicals are buzzwords in the beauty industry. They are used to promote anti-aging creams, “superfoods,” and particular diets.
Free radicals do have a tangible impact upon human health, recent studies revealing that they can confer beneficial as well as negative effects. In this article we look at what free radicals are and examine their effect on the human body.
What is a free radical?
The human body is composed of many different cell types. These cells are made up of molecules. Molecules are comprised of one or more atoms joined by chemical bonds. An atom consists of a nucleus, protons, electrons and neutrons.
Protons are positively charged. They reside, along with neutrons, in the nucleus. Electrons are negatively charged. They orbit the atom, in its inner and outer shells. The inner shell of an atom has capacity for just two electrons. Once it is full, electrons start to fill the outer shells. Each of these outer shells can contain particular numbers of electrons before another outer shell is created.
The structure of an atom dictates its chemical behavior. Chemical stability depends on how many electrons an atom contains in its outer shell. The more electrons an atom has in its outer shell, the more chemically stable it is.
Atoms self-regulate their composition to attain maximum chemical stability. An atom can achieve this in one of two ways: by gaining or losing electrons to fill or empty its outermost shell; or by bonding with other atoms and sharing electrons to complete its outermost shell.
Sometimes bonded atoms split. They usually do this cleanly, keeping the electrons in pairs, maintaining both atoms’ structural stability. If the bond is weak, an uneven split may occur. An atom with an odd number of electrons is structurally very unstable. This is a free radical.
How are free radicals harmful to health?
Free radicals are quick to react to other compounds. Because atoms have the ability to regulate their own structure, if that structure is unsound, i.e. the atom is left with an unpaired electron, the atom will attack the nearest stable molecule in order to “steal” an electron.
The attacked molecule thus finds itself with an uneven number of electrons. It, in turn, will attack the next stable molecule it can find. Thus, a chain reaction begins. Once the process is initiated, it can spiral, damaging and depleting cells.
How do antioxidants protect us against free radicals?
Nutritional antioxidants, particularly vitamins C and E, protect against the destructive effect of free radicals. They do this by donating one of their own electrons to free radical, “scavenger” atoms. Antioxidants do not become scavengers themselves because they maintain their stability even with an odd number of electrons, so the chain reaction effectively ends.
We gain antioxidants through our intake of fruit and vegetables. Vitamin C is water-soluble, acting primarily in cellular fluid. Vitamin E is fat-soluble. If someone has a deficiency in these two vital vitamins, free radicals can cause damage. This damage accumulates with age.
How can free radicals have a positive impact on human health?
Not all free radicals are detrimental to health. Indeed, sometimes our bodies deliberately create them. Free radicals can aid metabolism. Sometimes the immune system purposefully creates free radicals to attack bacteria and viruses.
It is free radicals created outside of the human body that tend to have a negative impact on our health. Harmful free radicals are typically spawned by sources such as radiation, cigarette smoke, pollution and herbicides.
How has scientific opinion on free radicals changed?
For 40 years, scientists have attributed the aging process to “oxidative stress.” This is purportedly caused by the accumulation of free radicals, peroxides, and oxygen ions within cells. It overwhelms cells’ ability to regenerate and repair themselves.
A paper published by Canada’s McGill University in 2009 sparked a sea change in scientific opinion, placing the oxidative stress theory in doubt. McGill University studies revealed that some organisms actually live longer when their ability to clear themselves of free radicals is compromised.
Dr Siegfried Hekimi of McGill University’s Department of Biology worked with Jeremy Van Raamsdonk on an experiment on mutant Caenorhabditis elegans worms. The researchers disabled genes responsible for detoxifying reactive oxygen molecules. Rather than shortening the worms’ lifespans, a marked increase was found. In other words, although oxidative stress was clearly increased, the animals lived longer.
Hekimi and Raamsdonk’s findings indicate that while oxidative stress undoubtedly causes damage to the body, it does not appear to cause aging per se. Hekimi speculates that while free radicals can cause damage, their beneficial effect at normal levels is perhaps more important. Barry Halliwell, of Singapore’s National University, submits that we cannot live without free radicals, nor should we try to, but that they do have a detrimental effect in old age.
Hekimi’s research is ongoing. He hopes to test on more complex organisms, ultimately progressing to human clinical trials. Halliwell submits that such research could prove invaluable in the search for a cure for cancer as well as the treatment of a range of neurodegenerative diseases.