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Your Body Isn't as Old as You Think

author image Deborah Day
Deborah Day is a lifestyle and entertainment writer and editor. Former editor in chief of and executive editor of, she has been published on,,, and other media sites, as well as in Maxim, Interview and Time Out NY magazines.
Your Body Isn't as Old as You Think
Your body parts regenerate at different rates. Photo Credit: Janaka Dharmasena/Hemera/Getty Images

The pieces and parts that make up your body update at different paces. In a race, your stomach lining wins, being replaced every two to nine days; while the lens of your eye and most of your brain are the same as when you were born.

Video of the Day

NPR's science blog Skunk Bear team produced a handy 3-minute video, "How Old Is Your Body, Really?" hosted by reporter Adam Cole to help explain how these processes take place:

"Certain parts of your brain add a few new neurons over the course of your life," Cole explains, "but the vast majority of your neurons developed before you were born. It's the connections between those neurons -- the circuits that store memories -- that are constantly changing."

In order of update:

2-9 days: Stomach lining – your gut epithelium regenerates relatively quickly because of its exposure to stomach acid and bile.

7 days: Taste buds – the taste buds have about 10 to 50 sensory cells each that are renewed every week.

2-3 weeks: Lungs

2-4 weeks: Outer layer of skin (epidermis)

4 months: Red blood cells – 100 million cells are born every minute, while 100 million others are destroyed.

Most of your brain is with you from birth -- take care of it!
Most of your brain is with you from birth -- take care of it! Photo Credit: kirstypargeter/iStock/Getty Images

6 months: Nails

2-7 years: Hair – 100 hairs fall out every day and are generally replaced.

10 years: Skeleton

15 years: Muscle

25 years: Fat cells – they may seem to multiply, but they actually expand and contract.

Life: The lens of your eye, most of your brain and about half of your heart, stay with you from birth to death.

Scientists have been able to track cellular regeneration, in part, because of nuclear bomb testing of 1945 and 1963, the Skunk Bear team revealed on its blog.

What Do YOU Think?

Does this surprise you? Did you think more of your body and cells remained constant? Does this change how you think about aging? Why or why not? Tell us in the comments!

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