For decades, scientists theorized that aging was caused by oxidative stress, a phenomenon in which cellular damage is caused by free radicals and nasty oxygen-based molecules that build up over time as byproducts of normal biological processes.
According to the theory, the cellular defense against the culprits-which are enzymes known as superoxide dismutases-gets overwhelmed by the accumulating bad guys and the next thing you know, cells are looking like Methuselah.
From the theory sprung an entire industry hawking antioxidant therapies from Vitamin A to Coenzyme Q which supposedly boosted the body’s ability to water-cannon the free radicals.
Alas clinical trials have never shown them to work and now McGill University scientists are raising doubts about the validity of the oxidative stress theory itself.
Siegfried Hekimi and colleagues disabled one-by-one, 5 genes coding for superoxide dismutases in a worm that goes by the unassuming name C. elegans.
The successive gene deletions did not shorten the worms’ lifespan; in fact in one instance, the altered critters outlived the wild-types.
The report is in PloS Genetics.
Come to think of it, the evidence supporting the oxidative stress theory is circumstantial, Hekimi told BurrillReport.
And oxidative stress could be the result of aging rather than its cause.
“It is true that the more an organism appears aged, whether in terms of disease, or appearance or anything you care to measure, the more it seems to be suffering from oxidative stress. (But) people think correlation is causation,” he told BurrillReport.
Hekimi’s not saying oxidative stress is actually a good thing. It clearly interferes with normal cellular functioning. But it’s a stretch, he says, to say that oxidative stress causes aging.