Companies have started putting antioxidants in goods as different as face creams and soda, claiming that they clean out cells, prevent cancer and even stave off death. The idea is to prevent unstable oxygen molecules, which are normal by-products of metabolism, from damaging cells. But a recent study suggests that when it comes to living longer, those antioxidants may not be the answer.
The antioxidant theory of aging states that some of the oxygen molecules used by the body become negatively charged, making them reactive. As a result, they compromise health and age the body by damaging cell structures, proteins and DNA. Cells have a natural defense—superoxide dismutase (SOD), a special class of antioxidant that neutralizes the chemicals and prevents them from harming cells. According to the theory, proposed in 1956 by Denham Harman, now emeritus professor of medicine at the University of Nebraska, when the body gets older, SODs become less efficient at preventing oxidative stress. Over the past 50 years this widely accepted theory has held up in studies: when the SOD gene is knocked out in mice, flies or yeast, the organisms develop cancers and have shorter life spans.
But in the February PLoS Genetics, Siegfried Hekimi and Jeremy M. Van Raamsdonk, both at McGill University, report that removing SODs from tiny Caenorhabditis elegans soil worms has the exact opposite effect—they live longer. In the experiment, each of the worms’ five SOD genes, which primarily work in the mitochondria (the cells’ energy-producing organelles), was disabled in different combinations, hampering the worms’ ability to make the antioxidant. When the researchers turned off one SOD gene (namely, sod-2), the nematodes actually lived 30 percent longer. When four were disabled in follow-up work, the worms still had a normal life span.
Hekimi believes that the findings throw a wrench in the entire free radical theory of aging. Instead he claims that cell damage is a product of aging, not the actual cause. “It’s like the sun coming up every morning—they can’t prove that it will,” he says in reference to free radical proponents. “But I have to prove that it won’t.”
These modified worms are not healthy, though; they show evidence of oxidative stress. Without the antioxidants, their cells are left unprotected, and outside the lab the worms would have died from disease or cancer. But Hekimi separates such a condition from having a normal life span. The organism may be sicker, he observes, but it is living longer.
Other scientists doubt that the findings discredit free radicals entirely. “You can’t take a single paper studying a single gene in a single organism and make sweeping conclusions about a theory,” remarks John Phillips of the University of Guelph in Ontario, who has examined SODs in the fruit fly Drosophila melanogaster. Moreover, C. elegans has five SOD genes, whereas humans have two. “I think we need to know where the extra SODs are operating, like in tissues or muscles, and in which cellular compartments” to fully understand oxygen metabolism in C. elegans, Phillips says. Knowing the biological idiosyncrasies in the worm would elucidate how SODs work in general.
Hekimi proposes that his findings could bolster an alternative aging theory—specifically, the idea that a slower metabolism or lower temperatures decelerate the body and allow an organism to live longer. Several studies have challenged the rate of living theory of aging, but Hekimi thinks that “you have to take a broader version of the theory, that the rate at which things happen affects life span.” As he sees it, in SOD-deficient worms, free radicals damage the mitochondria, which produce less energy and thereby slow the organism down.
Hekimi’s idea stands in contrast with that of Bart Braeckman of Ghent University in Belgium, whose own 2007 experiments with C. elegans led him to rule out the metabolic theory of aging. But Braeckman also does not think that the free radical theory is the only answer. He notes that Hekimi’s work joins other recent studies that challenge the simplistic version of the theory. “The final conclusion was similar in all these papers: there is a problem with the free radical theory,” he states.
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Add CommentGreat title:
Reply | Report Abuse | Link to this"Antioxidants may not.. "
The syntax implies that "Antioxidants may ..."
So what exactly is trying to be said here?
My guess is: hey, we can't prove or disprove anything, and we've spent a lot of money studying this, so we are going to tell you what we know (NOTHING) in a lot of words.
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Reply | Report Abuse | Link to thisSOD is a defense mechanism for infection mostly. Antioxidants help quell the fire from things such as SOD, there has to be a balance for health. Without antioxidants, we would most likely die sooner, but with them, we won't necessarily live longer. Without SOD, many types of infections would kill us much earlier than a lack of antioxidants will. The key statement is synthetic antioxidants. Those don't work, many studies have shown that, but main stream researchers like to use those to prove antioxidants don't have health benefits. The body wears out to age, if you don't make hormones anymore (e.g. testosterone, estrogen, growth hormone, and others), it can't repair, build muscle and a function at its peak. The question is why do our hormone levels drop. That is the key to aging. Obviously genetically we our designed to die, otherwise there would be too many people, so it must be encoded in our genes. Someone will find out which genes turn off our protein building stuff, the you will have your answers.
Reply | Report Abuse | Link to thisHurry-up! .. I don't have much time left!
Reply | Report Abuse | Link to thisHurry Up, I don't have much time left!!!!
Reply | Report Abuse | Link to thisJBAIRDDO- THAT IS A HELL OF A GOOD ANSWER
Reply | Report Abuse | Link to thisAH YEH I DONT HAVE MUCH TIME EITHER. LOL BE GOOOD FOLKS
Reply | Report Abuse | Link to thisNot a scientist here -- but I want to know why people think that by smearing "antioxidant" cream on ones face, the antioxidants can get into the nucleus of cells where they could (in theory) neutralize free radicals. Has this been demonstrated? Same with eating foods with antioxidants. Will the get from the digestive tract to cells that need them?
Reply | Report Abuse | Link to thisTo heck with living longer, strive to live better. "I would much rather live until the day I am dead than to die until the day I am dead." You have no doubt seen a family member spend the last years of their life hooked up to machines, taking prescriptions, and having operation after operation all due to chronic degenerative disease. Significant lifestyle modifications that follow 5 simple pillars of optimal health in the name of prevention may be more beneficial than depending upon medical expertise to manage chronic degenerative disease once it manifests itself. Chronic degenerative diseases are created (some of it due to genetics, most likely), not caught!
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