Human Cell Regeneration—A Whole New You

Illustration by Mads Abilgard

24 Hours: Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is clear fluid in and around the brain and spinal cord. In addition to cushioning these vital organs, CSF nourishes these structures of the central nervous system with glucose, proteins, lipids, and electrolytes. Each day humans make approximately half a quart (500 ml) of fresh brain fluid.

10 Days: Taste Buds

Sensory receptors on the tongue, roof of the mouth, and throat recognize the five tastes—sweet, salty, sour, bitter, and umami (savory)—and alert the digestive system that food is on its way. An average adult has around 10,000 taste buds, which slough off every 10–14 days and grow right back.

2 Weeks: Stomach and Intestinal Lining

Talk about rough work conditions. The intestinal tract labors almost nonstop in an acidic swamp. With all that wear and tear, these cells last up to only five days, requiring a new lining every two to three weeks.

27 Days: Skin

As the body’s first line of defense against damage and pathogens, the skin takes quite a beating. But don’t get too comfortable with the skin you’re in, because the epidermis (the top layer) renews itself roughly every 27 days.

13 Months: Liver

The liver is a filter, cleansing toxins from the body. It’s a strenuous job, so the liver must replace all its cells every 300–500 days. But even more incredible, if the liver is damaged, it is the only organ able to regrow from only 25% of its original mass.

10 Years: Bones

We think of bones as sturdy and unmovable; they are, after all, the body’s scaffolding. But their cells are always changing to adapt to needs, such as pregnancy or weightlifting. Throughout an adult’s life, some bone cells (osteoclasts, or “bone breakers”) remove bone material that’s no longer needed, while other bone cells (osteoblasts, or “bone makers”) build up the bone where it needs to be stronger. New bone forms throughout our life.

10 Years: Fat Cells

Fat cells play a major role in keeping our energy and glucose in balance. Too many or too few of these cells can cause serious problems. Humans renew about 10% of their fat cells annually.

Lifetime

A few body parts never regenerate, such as your tooth enamel, the neurons in your brain’s cerebral cortex, and the cells in the core of your eye lenses.