Free Radicals May Have no Role in Ageing

The Hindu

February 19, 2009

Canada

 Free radicals may have no role in ageing, as some organisms live longer, especially when their ability to rid themselves of such molecules is partially disabled. 

For more than 40 years, the onset of old age has been attributed to oxidative stress. Which implies that when molecules like free radicals, oxygen ions and peroxides build up in cells, they overwhelm the cells' ability to repair the damage they cause and the cells age. 

An industry of "alternative" antioxidant therapies -- such as Vitamin E or CoQ10 supplements in megadose format -- has sprung up as the result of this theory. However, clinical trials have not shown that these treatments have statistically significant effects. 

McGill University researchers are challenging the entire oxidative stress theory. Their results show that some organisms actually live longer when their ability to clean themselves of this toxic molecule buildup is partially disabled. 
Collectively, these molecules are known as reactive oxygen species, or ROS for short. 

Siegfried Hekimi of McGill's Department of Biology said most of the evidence for the oxidative stress theory is circumstantial, meaning oxidative stress could just as easily be a result of ageing as its cause. 

Hekimi and postdoctoral fellow Jeremy Van Raamsdonk studied mutant Caenorhabditis elegans worms. They progressively disabled five genes responsible for producing a group of proteins called superoxide dismutases (SODs), which detoxify one of the main ROS. 

Earlier studies seemed to show that decreased SOD production shortened an organism's lifespan, but Hekimi and Van Raamsdonk did not observe this. In fact, they found quite the opposite, said a McGill release. 

None of their mutant worms showed decreased lifespan compared to wild-type worms, even though oxidative stress was clearly raised. In fact, one variety actually displayed increased lifespan, the researchers said. The study was published in the February issue of PLoS Genetics. 

Copyright © Global Action on Aging
Terms of Use  |  Privacy Policy  |  Contact Us