Take breathing—obviously, we could not survive
without oxygen, but oxygen is a catalyst for
much of the damage associated with aging
because of the way it is metabolized inside our
cells. Tiny parts of the cell, called mitochondria,
use oxygen to convert food into energy. While
mitochondria are extremely efficient in doing
this, they produce potentially harmful by-
products called oxygen free radicals. A variety
of environmental factors, including tobacco
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