The epidermis is
the outer layer, which undergoes constant
renewal;
every 28 days
all cells are turned over as
the most superficial cells are replaced by
new ones.
The turnover is much faster for infants and slows down over
the course of
our lifetime.
The healing process also slows as we age.
The famous statistic, “
our body fully replaces itself
every seven
years,” probably came in part from studies that look at
the average age
of a cell in humans. Jonas Frisén published a paper in 2005 which showed, based on carbon dating, that
the average age
of a cell in
the human
body is between
7 and 10
years.
