Sunday, October 25, 2009

The Fountain of Youth

The Fountain of Youth
Almost every cell in your body is being continually regenerated, some at faster rates than others. The cells lining the stomach are replaced about every five days. The epidermis, or surface layer of skin cells, recycles about every two weeks. Red blood cells last about four months while liver cells are replaced every 300-500 days. Even the human skeleton renews itself about every ten years.
So, if the body is in a constant state of renewal, replacing old cells with new ones, that begs the questions; how and why do we age?
Theories of aging fall into two basic categories.
  1. Programmed-based: which says that aging is a genetically regulated predetermined process, occurring on a fixed schedule.
  2. Damage-based: which says that aging is the result continuous damage accumulation as a result of interaction with the environment, exposure.
In my opinion, these theories are not mutually exclusive, and both are at play in the aging process.
In essence, all living organisms are genetically programmed for three things: survival-growth and reproduction. After reproduction, and a period of nurturing of the progeny, nature has very little use for the aging. As humans, we are done physically growing and developing by the age of 25. Then, consistent with the programmed-based theory, we begin aging, the decline towards death.
The rate of aging is strongly influenced by our exposures, consistent with the damage-based theory. Consider the reproduction and replacement of cells analogous to photocopying. However, instead of making all copies from the original, we make each subsequent copy from the preceding copy. Along the way we lose some quality, resolution, create imperfections, and progressively degrade content from the original, with time and the number of copies made. Therefore, in our analogy, the rate of aging is directly related to the rate at which copies are made.
Again, in my opinion, programmed and damage-based aspects of aging also influence each other. Detrimental exposures (poor diet, smoking, sedentary lifestyle, environmental toxins, etc) may cause programmed aging to begin earlier, and accelerate the effects of damage-based aging. On the other hand, damage-based aging can, to a greater extent, be delayed and slowed by fewer detrimental exposures, especially when combined with more positive exposures (healthful diet, regular exercise, positive mental attitude, a life’s purpose, community, decreased stress, etc).
The link is allostatic load, the amount of work/effort your body has to expend to maintain homeostasis, your set-point, and to keep you alive.
Allostatic load is a product of your genes and their response to environmental exposures. These exposures may have their roots in your grandmother’s and your mother’s health, at the time of pregnancy (epigenetics), and includes all of your lifetime, lifestyle habits.
The healthier you are, the less your body has to work to maintain homeostasis, the less the allostatic load, the slower the rate of photocopying, the slower the rate of aging. And, obviously, vice-versa with poor health

In addition, if disease creating lifestyle behaviors start in childhood, resulting in obesity and diabetes, for instance, than programmed-based aging may be triggered earlier and damaged-based aging will likely be more pronounced at younger ages.
Ultimately, your genes (25-30%) + your exposure (70-75%) = your state of health and your biologic age.


yobro said...

I just attended my 40 year high school reunion. The variations in how my classmates had aged over the past 4 decades was astounding. Some had remained youthful, others appeared to be a generation older. I'd like to think that to a significant extent, including good genes, and good luck, our condition is a reflection of our respect for our "selves."
Take Care.

Anonymous said...

Your clear thinking on subjects relating to health always amaze me...thanks for the insite. My family and I really need to start eliminating the detrimental exposures in our environmetal again. Believe or the biggest challenge.