Death and taxes
have long been said to be the only two things guaranteed in life. Exactly when
someone will die, in most instances, remains a mystery. A new study, however,
identifies one possible predictor -- specifically, telomere length. This has
been linked to longevity, as well as the ability to bear children at an older
age. The study is being published online in Menopause, the journal of The North
American Menopause Society (NAMS).
What Are
Telomeres?
Telomeres are segments of DNA at the end of our
chromosomes. Scientists frequently compare them to the plastic tips of
shoelaces that keep the laces together. Telomeres function similarly,
preventing chromosomes from fraying or tangling with one another. When that
happens, it can cause genetic information to get mixed up or destroyed, leading
to cell malfunction, increasing the risk of disease or even shortening
lifespans.
Each time a cell divides, its telomeres become shorter.
After years of splicing and dicing, telomeres become too short for more
divisions. At this point, cells are unable to divide further and become
inactive, die or continue dividing anyway — an abnormal process that’s
potentially dangerous.
Essentially, this is how our bodies age. As more of our
cells lose their telomeres and go out of commission, without others to take
their place, the body follows and begins breaking down. And telomeres don’t
leave (or shorten) quietly. Their shortening process has been linked with
aging, cancer and a higher risk of death.
Each telomere’s ticking biological clock has the
potential to alter our lives in drastic ways but, interestingly, it’s not our
age that determines when the clock will stop — it’s the length of our
telomeres.
History of
Research
Discovered in 1938 by Hermann Muller, telomeres are DNA
structures at the ends of our chromosomes that are not coding regions, and thus
do not express any proteins. In the 1960s, researchers recognized the fact that
the ends of chromosomes, the telomeres, did not replicate fully during cell
division, and, in fact, shortened with each division. This observation led to
the understanding that these end caps served a critical function in cell
division and that their gradual disappearance was correlated with the
senescence of the cell. Telomeres were granted a biological clock function and
provided an explanation of the finite nature of cell division and ultimately
the unavoidable mortality of the host organism.
Further investigation in the 1970s and 1980s led to the
discovery of an enzyme whose sole purpose is to preserve the length of the
telomere end cap on replicating DNA. This enzyme, found by Carol Greider and
Elizabeth Blackburn, was dubbed “telomerase.” Telomerase elongates telomeres,
an activity critically important in cells that must preserve immortality, such
as germ cells and stem cells. Telomerase, once thought to be inactive in normal
somatic cells, is now known to have minimal, but detectable levels in various
adult cells including epithelial and endothelial cells, as well as fibroblasts.
The expression of telomerase may be modified by various lifestyle factors, such
as smoking and perceived stress. The emerging paradigm is that telomerase
activity is highly adaptive, and understanding influences on telomerase has
become an important avenue to understanding cellular health and longevity.
What Do Telomeres
Have to Do with Health and Aging?
One of the largest studies to date on telomeres shed some
light on telomeres’ effect on a person’s health. Researchers collected saliva
samples and medical records of more than 100,000 participants. Their findings
showed that shorter-than-average telomere length was associated with a boost in
mortality risk — even after adjusting for lifestyle factors like smoking,
alcohol consumption and education that are linked to telomere length.
The study found that individuals with the shortest
telomeres, or about 10 percent of the study’s participants, were 23 percent
more likely to die within three years than those with longer telomeres. The
findings are trickier than expected, however. Researchers are still unsure
whether telomere length is just a marker of aging, like gray hair or wrinkles,
or if it’s an active factor in whether a person is more likely to have a
disease like Alzheimer’s or die.
There’s also another key player in the game: telomerase.
Telomerase is an enzyme that lengthens telomeres and
keeps them from wearing out too fast or too early. But with constant cell
division, telomerase levels are depleted, enabling telomeres to shorten. It
stands to reason that if science found a way to increase telomerase production,
telomeres would remain long, lengthening life spans and possibly reducing the
risk of some diseases.
In fact, one 2010 study on aging published in Nature
performed on rodents seems to confirm that theory. Mice engineered to lack
telomerase aged prematurely and became decrepit. But when the enzyme was
replaced, they bounced back to health. By reawakening telomerase in human cells
where it’s stopped working, normal human aging could be slowed. “This has
implications for thinking about telomerase as a serious anti-aging
intervention,” said Ronald DePinho, a cancer geneticist who led the study.
However, there are still serious doubts about whether
reversing or slowing down aging via telomerase activity is the answer. Because
while telomerase does lengthen telomeres, in humans with cancer, the enzyme
helps existing tumors grow faster. At this stage, it doesn’t seem we know
enough about safely harnessing telomerase to ensure that it works only to
lengthen telomeres and doesn’t actually stimulate cancer.
Long Life Family
Study 2015
Several studies have already shown that late maternal age
at last childbirth is positively associated with maternal longevity. The Long
Life Family Study (LLFS) reported that the odds of living up to the top fifth
percentile were two times higher for women who had their last child past the
age of 33 years than for those who had their last child before the age of 29.
The study "Telomere length is longer in women with late maternal
age," used data from LLFS to show that certain factors associated with the
rate of aging and longevity, such as telomere length, are also associated with
later maternal age at the birth of the last child.
In this study, the proportion of women in the longest
telomere tertile was higher for women in the fourth quartile of maternal age at
the birth of their last child than in the first quartile (35.7% vs 20.2%).
Compared with women who had their last child at 29, women with a later age at
birth of their last child were found to have increased odds of being in the
longest tertile of telomere length.
"With longevity and the ability to bear children at
an older age associated with longer telomere length, this study suggests that a
higher maternal age of successful child bearing may be a marker of healthy
aging," says Dr. JoAnn Pinkerton, NAMS executive director. "However,
it's important to remember that personal and social factors often influence
childbearing age, and these factors may not have any relation to either a
woman's ability to bear children at later ages, longevity, or telomere
length."
More Facts
There are several indications that telomere length is a
good predictor of longevity. In newborns, telomere length varies from about
8,000-13,000 “base pairs” (DNA letters) in length, and declines by about 20-40
base pairs each year. Telomeres are also longer in women than men, mirroring
the difference in lifespan between the sexes. In elderly twins, the twin with
shorter telomeres is roughly three times more likely to die first.
The variability in telomere length between people of the
same age is not random, and has a genetic component that has interested
scientists for decades. In a recent 2013 study in the journal Nature Genetics,
scientists identified multiple markers that are associated with either shorter
or longer telomeres. The strongest of these resides near a gene named TERC.
Each copy of a “T” at this position is associated with an average 117 base pair
decrease in telomere length, equivalent to having the “biological age” of a
person about four years older.
How Can I Lengthen
My Telomeres and Slow Aging?
While science still isn’t 100 percent sure how telomere
length affects how we age, it’s clear that the longer our telomeres are, the
better. The good news is that there are a variety of lifestyle changes you can
make today to lengthen your telomeres.
1. Control and
Reduce Stress
Several studies have linked chronic stress to shorter
telomeres. A 2004 study compared healthy women who were mothers of healthy
children (the control moms) and those who cared for chronically ill children
(caregiving mothers). On average, the caregiving mothers had telomeres that
were 10 years shorter than the control moms. That is, their cells behaved as if
one decade older.
Another study that examined African-American boys found
that those who came from stressful environments had telomeres that were about
40 percent shorter than peers from stable homes.
The takeaway? Chronic stress doesn’t just put you in a
bad mood; it contributes to aging in a very real way. Exercising regularly,
getting enough sleep and carving out time for yourself daily are all easy ways
to help bust stress.
2. Exercise
Regularly
From boosting happiness to providing an energy boost, the
benefits of exercise are well documented. Now there’s another reason to hit the
gym.
A recent study found that a person who did some type of
exercise was about 3 percent less likely to have super short telomeres than a
person who didn’t exercise at all. Not only that, but the more a person
exercised, the longer their telomeres. The correlation between telomere length
and exercise activity seemed to be strongest among those in middle age,
suggesting that it’s never too late to start a fitness program and keep those
telomeres from shortening.
Another study about how exercise keeps your cells young
found that middle-aged adults who were intense runners (we’re talking 45–50
miles a week) had telomere lengths that were, on average, 75 percent longer
than their sedentary counterparts. Now, this doesn’t mean you need to become an
ultramarathon runner. It does, however, suggest that regularly engaging in
intense exercise, like HIIT workouts, can keep telomeres long and happy.
3. Eat a Range of
Foods for Antioxidant and Vitamin Benefits
Foods high in vitamins are believed to protect cells and
their telomeres from oxidative damage. A diet high in antioxidant foods, like
berries and artichokes, can slow down aging and help prevent or reduce cell
damage.
Additionally, taking a multivitamin supplement to bridge
the gap between the foods you’re eating and what your body needs might lengthen
telomeres as well. One study found that women who took a daily supplement had
telomeres that were about 5 percent longer than nonusers.
But supplements still can’t mimic all the health benefits
of eating real, wholesome foods. The same study found that, even after
adjusting for supplement use, participants who ate foods high in vitamins C and
E also had longer telomeres. Oranges, peppers and kale are among the top
vitamin C foods. For vitamin E, turn to almonds, spinach and sweet potatoes.
4. Practice
Meditation and Yoga
It’s time to unroll your mat and unwind. In a 2014 study
among breast cancer survivors, those who participated in mindful meditation and
practiced yoga kept their telomeres at the same length; the telomeres of the
control group, who did neither activity, shortened during the study time.
A 2008 study among men found that, after three months of
a vegan diet, aerobic exercise and stress management, including yoga, there was
increased telomerase activity. A 2013 follow-up study found that those
lifestyle changes are associated with longer telomeres.
Meditation comes in different forms for different people.
For me, it’s healing prayer and setting aside time to reflect. For others, it
might be setting an intention for their day, attending a regular yoga class or
spending time with loved ones without the distraction of technology or work.
Whatever your meditation looks like, it’s clear it’s good for our minds and
bodies.
While we wait for science to unravel all the mysteries of
telomeres and how they work for — and against — us, we can make changes to
lengthen them and positively affect the rest of our lives.
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