DEBUNKED: Your Body Replaces Itself Every 7 Years

A common saying is “You’re a new person every 7 years.” Although it would be nice to have a fresh start and try a new life on, this claim is not telling the full story! Let's break down this myth by explaining where the myth comes from, why it’s biologically impossible, and what the harm that spreading the myth causes. 

The Origin 

Jonas Frisén, a professor of stem cell research, published a paper in 2005 titled Retrospective birth dating of cells in humans that showed the average age of a cell in the human body is between 7 to 10 years.⁽¹⁾  However, this got misinterpreted as every cell being replaced in 7 years. 

Why the Myth Is Biologically Impossible

→Your Body Constantly Renews Itself 

The lifespans of the various types of cells in our body are different and not on a neat 7-year cycle. For instance, our skin cells renew every 2 to 4 weeks as they are constantly shedding and renewing itself–think about whenever you get a cut or scrap.⁽²⁾  Similarly, your stomach lining cells regenerate every 2 to 9 days due to the constant exposure to stomach acid.⁽²⁾  On the other hand, bone cells regenerate every 10 years.⁽²⁾ 

→Some Cells In Our Body Are Never Replaced

Even though there’s some variability in the regeneration of cells, some cells don’t get replaced, such as heart, brain, or spinal cord cells. Neurons have a variety of important tasks and information to store, so it’s essential that some of these cells aren’t replaced frequently. For instance, spinal cord injuries lead to damaged nerves as they aren’t able to be repaired.⁽³⁾  However, there has been evidence about cell regeneration in the hippocampus, which is important for memory, and the striatum, which plays a role in motivation, motor control, and smell.⁽⁴⁾ 

Why the Myth Is Harmful (Beyond Just Being Wrong)

Click here to view Figure 2: Stem cell demonstration Source: https://www.news-medical.net/health/Stem-Cell-Therapy-for-Alzheimers.aspx  (Scroll down to find it)

The myth being spread has a variety of consequences. For instance, it can negate the field and practice of stem cell research. Stem cells have the ability to develop into different types of cells. This is because they aren’t specialized into being one type of cell like other cells, such as blood or skin cells. As a result, it’s possible for stem cells to repair or replace damaged cells.⁽³⁾  In the future, this research can be used to treat conditions or diseases such as Alzheimer’s disease, cancer, or heart disease.⁽³⁾  There has research findings on how transplanted stem cells can help improve cognitive impairment and memory deficits, which is important for Alzheimer’s disease.⁽⁵⁾ Dismissing the truth about cell regeneration can block this life-saving research that will help millions of people. 

Sources:

1. Elías (2020) Does the body replace itself every 7 years?

2. Landeros (2024) Does your body really ‘reset’ every 7 years? Here’s the deal on cell regeneration

3. Quest Diagnostics (2023) Do my cells really change every 7 years?

4. Kumar et al. (2019) ADULT NEUROGENESIS IN HUMANS: A Review of Basic Concepts, History, Current Research, and Clinical Implications

5. Qin et al. (2022) Stem cell therapy for Alzheimer’s disease: An overview of experimental models and reality