Why do people age?

Dr. Michael Roizen, MD
Internal Medicine
The best scientists have been able to do is to offer several theories for why we age (and all of them have at least some credibility). One theory is that the body is programmed to die -- that our genes program the cells to divide a certain number of times, and once that maximum number has been reached, the body begins to fail. This is known as the telomere theory. (Telomeres are genetic elements that control the number of allowable cell divisions.)

Another is that our neurologic and hormonal systems wear out over time, making us more susceptible to a variety of diseases.

A third hypothesis is the "wear-and-tear" theory - that living itself makes us old.

A fourth theory is that over the years the body eventually accumulates so many toxins and waste products that its systems begin to shut down.

You might know the fifth theory as the "free radical theory of aging": The body builds up free radical "oxidants" that damage the organs and DNA (deoxyribonucleic acid), causing us to age.

A related theory is the glucose toxicity theory, which also involves waste buildup in the body.

The seventh theory of aging derives from the law of entropy: Within the universe there is continual movement from order to disorder, and, in our bodies, that movement is marked as aging.

The eighth theory, the mitochondrial aging theory, relates to the energy sources of our cells and to the second collection of DNA that you and I have in most cells. Most cells have DNA, both in their nucleus and in another structure in the cell. Simply stated, our cells are in a constant state of division and renewal, during which mistakes can occur. And mistakes in the cellular (non-nuclear) DNA, which are called mitochondria and which govern an energy transformation process, may have a big effect on our health and rate of aging. For example, our DNA is continually being replicated, and when we don't have enough folate -- vitamins B6 and B12 -- the replication can occur with errors and abnormalities (which can possibly lead to cancer). The great news is that some genes, drugs, or supplements may be able to keep the mitochondrial DNA much younger.
The RealAge Makeover: Take Years off Your Looks and Add Them to Your Life

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The RealAge Makeover: Take Years off Your Looks and Add Them to Your Life

Why not live at 60 feeling like you did at 35?Thousands of Americans are younger today than they were five years ago. How is that possible? By following the specific recommendations that reverse...
Sharine Forbes
Geriatric Medicine

People age due to the lack of equilibrium in the body's mechanisms. For example, the production of collagen slows down as one ages due to the mechanisms working so hard during ones "youth". So as the collagen producing mechanisms get older the production of collagen slows down. Thus, ones face does not seem as "youthful" because it no longer has the same amount of collagen present. 

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.