Recent research also turns on its head the long-held idea that antioxidants are helpful in fighting the effects of aging. This new theory is disturbing to many people, especially those who are involved in marketing antioxidants and those who take them to ward off the ravages of advancing age.
Oxidative stress is a condition that occurs when there is an abundance of free radicals and/or when the level of antioxidants in the body is low. Free radicals (collectively known as reactive oxygen species, or ROS) are highly reactive molecules that are a byproduct of normal metabolism.
Free radicals contain at least one unpaired electron, which causes them to constantly seek electrons from other molecules, a process that disrupts normal cell functions and causes damage to cells (oxidative stress). Antioxidants are substances, such as certain vitamins and other nutrients, that protect the body against free radicals and oxidative stress.
Dr. Siegfried Hekimi of McGill University’s Department of Biology notes that the older an organism appears, the more it seems to be the victim of oxidative stress. This observation has been the basis of the prevailing theory, which is that oxidative stress is a cause of aging. Researchers at McGill are proposing the opposite: that oxidative stress could be the result of aging.
They developed this theory for several reasons. One, they say clinical trials have not shown that antioxidant therapies provide statistically significant benefits in many cases, although improvements are evident in some studies. Two, their recent work shows that some organisms live longer when ROS and oxidative stress levels are elevated.
Dr. Hekimi and his associate studied worms (Caenorhabditis elegans, a commonly used model for aging) in which they disabled genes that are involved in the production of a potent antioxidant called superoxide dismutase (SOD). Although previous studies had shown that decreased production of SOD shortened an organism’s life, Dr. Hekimi’s work found that it did the opposite.
The researchers emphasize that their findings do not suggest that oxidative stress and ROS is good for the body. However, the study does indicate that they are not responsible for aging.
This is not the first study to arrive at this conclusion. A study conducted at the Institute of Healthy Aging at the University College in London found that removing SOD from the bodies of C. elegans did not reduce the lifespan of the worms. Similar results were found in a University of Texas study that used mice.