What do free radicals have to do with aging?

Imagine, if you dare, the world of high school dating. The big dance is rapidly approaching, and the head cheerleader has found herself without a date. The last thing this cheerleader wants to do is head off to the gym alone and stand around, hoping that some cute guy will ask her to dance. So she sets her sights on the football captain, despite the fact that he's already dating the student council president. The cheerleader successfully breaks up their relationship, leaving the student council president miserable and hunting for her own date. She starts spreading gossip about a girl in her math class, in an effort to woo the mathlete's boyfriend. In turn, the dumped brainiac lashes out against her best friend, and on and on. In the process of getting a date, the cheerleader has caused a chain reaction of damage throughout the entire school. Do you really think these stressed students will enjoy the dance now?

As awful a scenario as this is to consider, the same thing goes on in the human body. Just by breathing and breaking down food, our body creates free radicals, or molecules with unpaired electrons. Like our desperate cheerleader, these unstable molecules make their way through the body, scavenging our cells, trying to snatch up that missing part.

The free radical theory of aging holds that the damage that these free radicals do to our cells, particularly the oxidative stress that oxygen-free radicals cause, could be why our bodies age. When we're young, our cells have a defense system known as superoxide dismutase (SOD) that reins in those free radicals, but as we get older, SOD doesn't work as well. That leaves the free radicals to have their way with our cells, and when the damage gets to be too much, the cells die and so do we. Free radicals have also been implicated in a number of diseases and conditions that become more common as we age, including dementia, cancer and heart disease.

Not everyone agrees with this theory because it's hard to determine which came first, the free radicals or the aging. Perhaps the damage done by free radicals only begins after the aging process does. But even among those who subscribe to the free radical theory of aging are divided on how we could use this information to our advantage. Is taming free radicals the key to postponing aging?

Free Radicals and Aging: Are Antioxidants the Answer?

If one believes that free radicals bring about aging and disease, then it stands to reason that we could live longer, healthier lives by either eliminating their presence altogether or by investing in mechanisms that will make them disappear. Because free radicals are a natural byproduct of numerous bodily functions, including breathing, the former is impossible. We're doomed to have these molecules that could lead to our demise running around in our body. So what are scientists doing about the latter option?

The main point of defense for many years has been antioxidants, so much so that we might as well retire the phrase "an apple a day keeps the doctor away" and consider something along the lines of "a lot of antioxidants keep free radicals away." Antioxidants, such as beta carotene and vitamins C and E, help to clean up and neutralize free radicals. That's why you see antioxidants' presence touted on everything from dietary supplements to skin cream. The thinking goes that if you consume large amounts of these antioxidants, then you prevent oxidative damage and provide an important back-up for the superoxide dismutase (SOD) that weakens with age.

However, antioxidants haven't proven to be the fountain of youth that some scientists were hoping for. For one thing, antioxidants have failed to demonstrate consistent protective benefits in medical studies, particularly in the case of women [sources: Wanjek; Angier]. Additionally, the human body strives for a state of balance, or homeostasis, and by ramping up the antioxidants, particularly in a bulk supplement form, you could actually damage the natural mechanisms for dealing with free radicals [source: Angier].

Some researchers, in a study published in Science magazine in 1994, attempted to tweak those natural mechanisms directly. SOD keeps free radicals in check by converting them to hydrogen peroxide, and then another enzyme, catalase, converts the hydrogen peroxide to water, which is what much of the human body is made of [source: Kolata]. When researchers endowed fruit flies with the ability to produce excess amounts of both SOD and catalase, the flies lived longer, more vigorous lives than their non-enhanced counterparts [source: Kolata].

Of course, there's a huge difference between a fruit fly and a human, so more work needs to be done on the role of free radicals and aging. Scientists hope that eventually, we'll be able to take a pill that battles free radicals, but until then, we're stuck remaining healthy and fighting free radicals the old-fashioned way: regular exercise, no cigarettes and a healthy diet.

Lots More Information

Sources

  • Angier, Natalie. "Free Radicals, The Price We Pay for Breathing." New York Times. April 25, 1993. (April 27, 2009)http://www.nytimes.com/1993/04/25/magazine/free-radicals-the-price-we-pay-for-breathing.html?scp=5&sq=free%20radicals,%20aging&st=cse
  • Bryner, Jeanna. "Naked Mole-rats Hold Clues to Human Aging." LiveScience. Oct. 9, 2006. (April 27, 2009)http://www.livescience.com/health/061009_aging_rats.html
  • Cheung, Melissa. "Finding the Fountain of Youth." CBS News. June 13, 2003. (April 27, 2009)http://www.cbsnews.com/stories/2003/06/13/health/main558663.shtml
  • Kolata, Gina. "Theory on Aging is Tested, Adding 30% to Flies' Lives." New York Times. Feb. 25, 1994. (April 27, 2009)http://www.nytimes.com/1994/02/25/us/theory-on-aging-is-tested-adding-30-to-flies-lives.html?scp=1&sq=free%20radicals,%20aging&st=cse
  • Wanjek, Christopher. "Vitamin Mania: The Truth about Antioxidants." LiveScience. May 2, 2006. (April 27, 2009)http://www.livescience.com/health/060502_bad_vitamins.html
  • Wellcome Trust. "Antioxidants Are Unlikely to Prevent Aging, Study Suggests." ScienceDaily. Dec. 2, 2008. (April 27, 2009) http://www.sciencedaily.com­ /releases/2008/12/081201105711.htm
  • Wilcox, Kate. "Free Radical Shift." Scientific American. May 2009.