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How Your Body Rebuilds Itself in Less Than 365 Days

The human body is a well-oiled machine capable of innumerable astonishing functions. One of the awesome abilities our body has is the ability to heal itself. We have inside us an innate capacity to replace, replenish and rejuvenate our own organs. No doubt you have heard the classic “urban myth” that every 7 years our body replaces itself. Although there is some truth to that claim, the exact time is relative to each organ. To answer the question how long it takes for the body to regenerate we must take it one organ at a time.



Our blood is mainly made of the fluid called plasma, which is basically water with clotting factors. The rest of the blood consists of red blood cells, white blood cells, and platelets. The average lifespan of red blood cells is around 115 days, while white blood cells’ life span depends on the type, ranging from 24 hours to years. Platelets, on the other hand, last around 8 to 9 days.  Due to the tremendous number of cells needed for our blood to work, the bone marrow replenishes these at a continuous pace.

The life span of the human red blood cell. (1946).



The outer layer of our skin is designed to be shed off and replaced. This keeps our skin in a state of constant repair, maintaining its ability to serve as a barrier to the outside world. Our skin keeps up with the job of protecting us by replenishing itself once every 2 to 4 weeks.

What is the Life Span of Skin Cells?



Our liver is one of the hardest working organs in our body. It detoxifies our blood, produces clotting factors, aids in our digestion, metabolizes medications, and helps in the regulation of carbohydrate, fat, and protein metabolism. Given the workload our liver faces daily, we need it to be replenished quite quickly. On average our liver cells have a turnover time of about 300 to 500 days.

 Liver regeneration.


Stomach and Intestines

Our digestive system is exposed to the harsh substances our body can produce. This includes hydrochloric acid and digestive enzymes. For our system to cope with such strong substances it must regenerate at a fast pace. The turnover time for these cells is around 2-5 days.



Our bones may seem completely static and unchanged when we reach adulthood – since we hardly notice any growth from the outside. However, inside our body it’s a whole different story. Our bones are made up of cells that constantly replenish the structure needed to make our skeletal system sturdy. On average the lifespan of these cells is about 6 to 9 months. Unfortunately, as we grow older, the turnover time begins to take longer. This results in the slowly increasing brittling of the bones seen in the elderly.

 Birth and Death of Bone Cells: Basic Regulatory Mechanisms and Implications for the Pathogenesis and Treatment of Osteoporosis. (2000).



An average person takes a breath around 30,000 times a day. Given that astounding number, you can just imagine the wear and tear our lungs face daily. Lucky for us our lungs regenerate every 2 to 3 weeks

Lung Cells Can Regenerate Themselves, Finding Could Bring New Disease Cures.



Putting a specific timestamp on the rate the brain regenerates itself is no easy task. In general, we are born with all the brain cells we will ever have and as we grow older we lose some of those cells. This should give you some added incentive to avoid neurotoxicity whenever possible, as the damage may be harder to repair. There are however a few exceptions. Our hippocampus, the part of the brain responsible for memory and emotions, has been found to have the ability to regenerate when damaged.  There is also some study indicating the potential some parts of the brain have for neuro-restoration – however research into this highly complex field is still ongoing.

Are you born with all your brain cells, or do you grow new ones?

Regeneration of Hippocampal Pyramidal Neurons after Ischemic Brain Injury by Recruitment of Endogenous Neural Progenitors. (2002).

 “Neuro-restoration” – Parkinson’s’ Related Disorders (2012).

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