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Posts Tagged ‘Biological Clock’

The Other Biological Clock

May 2nd, 2012 at 6:58 am by timigustafson

This year, I have a significant birthday coming up, nothing too dramatic by today’s standards of longevity, but still a good time to take stock. I’ve been reading lately a few books on the difference between chronological and biological age and have even taken some tests online, just out of curiosity (yeah, right).

Of course, I’m supposed to be as old as I feel, but what does that really mean? Am I in some ways younger on days I feel refreshed and energetic after a good night’s sleep. Does time catch up with me when I’m a bit under the weather?

One of the tests I’ve been taking was designed by Dr. Michael F. Roizen. In his book, “RealAge – Are You as Young as You Can Be,” he suggests that shaving off as much as a quarter of a century from your numerical age is a real possibility (so don’t take the test while you’re still in your twenties), provided you have good genes and stick to healthy diet and lifestyle choices. But seriously, taking the “RealAge” (sic) test was an eye-opener for me.

As Dr. Roizen points out, for the longest time aging was considered as a linear process. For example, all sixty-five plus year olds are categorized as seniors and as such, presumably, in a state of decline. This view may be helpful for census bureau statisticians, but it is not an accurate representation of today’s reality. “Not everyone ages equally,” says Dr. Roizen. Some of us continue to live active and fulfilling lives and pursue their goals with the same zest and energy they always had. Others are riddled with debilitating diseases, barely managing to get through the day. In other words, your ‘real age’ is not identical with the number of years you’ve lived according to your birth certificate.

Many people, including doctors, still believe that aging is mostly a matter of genetics. For this reason, everyone’s aging process, and ultimately life expectancy, is supposedly predetermined by his or her genetic makeup. Indeed, there is good scientific evidence that supports this assumption.

One of the symptoms of aging is the slowing of cell division. Cells in the body must continuously divide in order to reproduce and replace damaged tissue. How often cells are able to divide depends on the genetic information (DNA) embedded in them.

Each time a cell divides, its DNA strand, called chromosome, uncoils and genetic information gets copied into the new cell. When the copying process is complete, the strand coils up again and gets capped by a piece at the end called telomere (Greek for “end bodies”). This procedure can be repeated thousands of times over a lifespan, however, every time a DNA strand is replicated, a small portion of telomere gets cut off. Eventually, the telomere become too short (a.k.a. the Hayflick limit) for further DNA replications and cells stop dividing. They enter a period of so-called “cell senescence,” the cellular equivalent of aging, before they finally die. This also means that by measuring the lengths of telomere, we have effectively a way of estimating how far someone’s aging process has advanced. Or so scientists thought for a while.

In 1985, two researchers discovered an enzyme called telomerase. Dr. Elizabeth Blackburn and Dr. Carol Greider found that through telomerase the length of telomere can actually increase. In other words, its shortening is not an irreversible process.

While it is not yet fully understood how exactly telomerase helps telomeres, and in turn the health of cells, there is evidence that lifestyle and diet are important contributing factors. Besides aging, telomeres also seem to be affected by chronic stress, lack of exercise, sleep deprivation, obesity, low intake of essential nutrients and so on – in a nutshell, all the usual suspects that make people sick and wear them out.

On the other hand, if it turns out that positive lifestyle changes can in fact enhance telomerase activity, it may indeed be possible to slow down the aging process on a cellular level, if not reverse it.

Does that mean we can make ourselves biologically younger by eating right, exercising, getting more sleep and managing stress? Perhaps not. But there is ample evidence that diet and lifestyle choices do impact the way people age. I’m not just talking about the dramatic differences between the life expectancy of some villagers in remote places in Japan or the Mediterranean region and the rest of us. Extending longevity for its own sake is not necessarily progress. Maintaining good health and thereby one’s quality of life for as long as possible is the real goal.

So instead of counting my years and comparing myself to other members of my generation, I make sure I give my body what it needs to be well, knowing that when the time comes to let go, I have done my best. I can’t ask for more.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog, “Food and Health with Timi Gustafson R.D.” (, and at You can follow Timi on Twitter and on Facebook.

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About timigustafson

Timi Gustafson, RD, LDN, FAND is a registered dietitian, health counselor, book author, syndicated newspaper columnist and blogger. She lectures on nutrition and healthy living to audiences worldwide. She is the founder and president of Solstice Publications LLC, a publishing company specializing in health and lifestyle education. Timi completed her Clinical Dietetic Internship at the University of California Medical Center, San Francisco. She is a Fellow of the Academy of Nutrition and Dietetics, an active member of the Washington State Dietetic Association, a member of the Diabetes Care and Education, Healthy Aging, Vegetarian Nutrition and the Sports, Cardiovascular and Wellness Nutrition practice groups. For more information, please visit

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