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Are breakdowns in our genetic repair system responsible
for aging?
Check the latest research |
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On Improving the Capacity for DNA Repair |
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Understanding the role that DNA damage and its repair, or lack of repair,
play in age-related disease is a first step. But some scientists are asking
how we can take the logical second step-that is, treating DNA damage, or
better still, preventing it. If our DNA repair systems are in fact the "guardians
of the genome,"34 can we strengthen those guardians?
As with any disease, we would do better to prevent DNA damage than to
treat it after it has already occurred. The most valuable action we can
take in preventing such genetic disruption is to avoid toxins, especially
cigarette smoke.
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Fighting Infection |
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Another major source of toxicity to our DNA is infection. Worldwide, one-third
of all cancers have been linked to chronic viral, bacterial or parasitic
infections. Some researchers theorize that DNA damage due to toxins generated
by these infections, or the body's defense against infectious agents,
contributes to the increased incidence of cancers and other chronic diseases.35,36
Better worldwide control of infection, therefore, might affect life span
in two ways, first by decreasing premature deaths due to the acute infection
itself, and second, by decreasing deaths due to late consequences of chronic
infection.
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Conflicting News on Antioxidants |
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Since much DNA damage occurs as the result of oxidative damage, scientists
have looked to administering antioxidants to try to prevent disease. A study
involving dosing laboratory rats with N-acetylcysteine, which is converted
by the body to glutathione, a potent antioxidant, resulted in the rats developing
fewer DNA adducts (large, disruptive molecules that muck up DNA).37
Unfortunately, results in humans have been more mixed. In one study,
male smokers were given supplements of beta-carotene, a form of vitamin
A, and an antioxidant. Surprisingly, their incidence of lung cancer was
slightly higher than in those smokers taking placebo.38 In
the Women's Health Study, taking supplements of beta-carotene neither
prevented nor promoted cancer in smokers.39 But while taking
beta-carotene supplements offers no demonstrated benefits in humans, eating
foods high in beta-carotene is associated with lower rates of disease,
including cancer.40 Other studies suggest that taking Vitamin
C and E supplements is associated with decreased rates of cancer, as well.
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Caloric Restriction |
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The only treatment shown definitively to slow aging in cells and certain
animals is caloric restriction, a reduction of total daily calorie intake
by about 35%. Some researchers speculate that caloric reduction works in
part by inducing more DNA repair.41,42 At this point, for humans,
caloric reduction remains an unpleasant (and unproven) way to promote healthier
DNA and increase life span, since people who practice it are often hungry,
cold, and uncomfortable.
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