Author: Karuna Meda
Institution: University of Pennsylvania
Nowadays, we are bombarded by all sorts of advertisements urging us to get as many antioxidants in our diet as possible. The list of must-eats' and benefits is quite overwhelming. Perhaps the most attractive feature of antioxidants is its supposed anti-aging properties. It turns out that these super nutrients might not be that magical after all. In a study published in the February issue of PLoS Genetics, researchers at McGill University have questioned the entire oxidative stress theory.
According to the theory, the build up of molecules known as reactive oxygen species (ROS) damage cells, and further hinder repair mechanisms, thus causing the cells to age. However, results from the study show that organisms may actually live longer due to this very build-up. The confusion arises because previous studies supporting the antioxidant theory are based entirely on correlative data.
Dr. Siegfried Hekimi of the McGill Biology department says "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." However, ROS accumulation cannot be termed a direct cause of aging.
In their experiments, Heikimi and his post doctoral student Jeremy Van Raamsdonk studied mutations in "Caenorhabditis elegans" worms. They knocked out five genes coding for proteins called superoxide dismutases (SODs) which are thought to prevent ROS-dependent toxicity. Contrary to previous studies showing that decreased SOD protein levels are associated with shortened life spans, none of Heikimi's mutant worms showed decreased lifespan compared to wild-type worms. Interestingly enough, even though they were under oxidative stress, there was one class of mutants that lived longer!
According to Heikimi and Raamsdonk, the mutation that is responsible for the anomalous longevity, disrupts the main SOD found in the mitochondria of the worm's cells. Heikimi remarks, "This is consistent with earlier findings that mitochondria are crucial to the aging process. It seems that reducing mitochondrial activity by damaging it with ROS will actually make worms live longer."
Even though Heikimi's study is very preliminary, it gives important insight into the aging process, even in humans, since the oxidative stress theory is conserved across species. In spite of their results, the researchers insist that increased oxidative damage is by no means a solution to aging,the evidence is entirely circumstantial. Much more research is needed to figure what exactly these antioxidants do in our bodies. Until then, it looks like the battle against wrinkles and white hair will continue.
Written by: Karuna Meda
Edited by: Jeff Kost (News and Features Editor) and Nira Datta (Professional Reviewer)
Published by: Hoi See Tsao