How Old Are Your Cells?

While you have one official birth date, your body is in a state of perpetual rebirth. Each second, millions of cells naturally die off and are replaced by brand-spanking-new ones. "The average age of a cell in an adult's body is only about seven to 10 years," says Jonas Frisen, MD, PhD, a stem cell biologist at the Karolinska Institute, in Stockholm. His team can back this up, thanks to a technique they've developed that pinpoints the age of specific cells in tissues and organs.

Frisen hopes his work will eventually provide the key to treating diseases and perhaps even slowing the aging process. "Some diseases, like anemia, are caused by the body's reduced ability to generate new cells," he says. Others, such as cancer, are caused by the production of too many cells. "Knowing the normal turnover rate of different cells in health and disease can help us understand if it is rational -- and realistic -- to modulate the process of renewal or perhaps replace cells that have been lost," Frisen notes.

For now, having a general chronometer for individual cells may help you stay healthy longer. "Despite cell renewal, the DNA mutates from one cell generation to the next, so cells become less efficient at renewing themselves," Frisen explains. That's where behavior and environment come in: "Smoking, the sun, and chemical exposure accelerate DNA mutation." Use the following body age map to help yourself look and feel as young as you can.

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