Today it is known that aging is caused by the progressive shortening of telomeres.
Researchers are looking to telomeres, the parts of chromosomes that control aging, for answers to the question of how we age. And for their possible link to Alzheimer's and Parkinson's disease, cardiovascular disease, diabetes and some types of cancer. The challenge is difficult
Now we must abandon phrases like 'You are only as old as you feel' or 'Age is just a number' and replace them with phrases like 'You are only as old as your telomeres are short'.
Telomeres are segments of DNA at the end of our chromosomes. Scientists often compare them to the plastic tips of shoelaces that hold shoelaces together. Telomeres function in a similar way, preventing chromosomes from fraying or becoming tangled with each other. When that happens, genetic information can get mixed up or destroyed, leading to cellular malfunction, increasing the risk of disease or even shortening life expectancies.
In essence, this is the way our body ages. As our cells lose their telomeres, without others taking their place, the body goes on and begins to break down. And telomeres don't go away (or shorten) silently. Their shortening process has been linked to aging, cancer and an increased risk of death.
The ticking of the biological clock at each telomere has the potential to alter our lives dramatically, but interestingly, it is not our age that determines when the clock will stop, it is the length of the telomeres.
One of the largest studies to date on telomeres sheds some light on the effect of telomeres on a person's health. Researchers collected saliva samples and medical records from more than 100,000 participants. Their results showed that shorter-than-normal telomere length is associated with an increased risk of mortality - even after adjusting for lifestyle factors such as smoking, alcohol consumption and education, which are linked to telomere length.
The study found that individuals with the shortest telomeres, approximately 10 percent of the study participants, were 23 percent more likely to die within three years than those with the longest telomeres. The results are more complicated than expected, however. Researchers are still unsure whether telomere length is just a marker of aging, like gray hair or wrinkles, or whether it is an active factor in whether a person is more likely to have a disease like Alzheimer's or to die.
There is also another key factor: telomerase.
Telomerase is an enzyme that lengthens telomeres and preserves them from being worn out too quickly or too early. But with constant cell division, telomerase levels become depleted, allowing telomeres to shorten. It stands to reason that if science finds a way to increase telomerase production, telomeres would remain long, extending life expectancy and possibly reducing the risk of some diseases.
In fact, a 2010 study on aging published in Nature conducted in rodents seems to confirm that theory. Mice engineered to lack telomerase aged prematurely and became decrepit. However, when the enzyme was replaced, they regained health. By reanimating telomerase in human cells where it has ceased to function, normal human aging could be slowed. "This gives rise to 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 as to whether reversing or slowing down aging through telomerase activity is the answer. For while telomerase lengthens telomeres, in humans with cancer, the enzyme helps existing tumors grow faster. At this stage, we don't seem to know enough about how telomerase is harnessed to ensure that it only works to lengthen telomeres and does not actually stimulate cancer.
There are many lifestyle changes we can make to lengthen telomeres.
Several studies have linked chronic stress to shorter telomeres.
A 2004 study compared healthy women who were mothers of healthy children (control mothers) with mothers caring for chronically ill children (caregiver mothers). On average, the caregiving mothers had telomeres that were 10 years shorter than the control mothers. That is, their cells behaved as if they were a decade older.
Another study examining African-American children found that those who came from stressful backgrounds had telomeres that were 40 percent shorter than their peers from stable homes
Chronic stress doesn't just put us in a bad mood; it contributes to aging in a real way. Exercising regularly, getting enough sleep and making time for ourselves every day are easy ways to help eliminate stress.
The benefits of exercise are well documented, from increasing happiness to providing an energy boost.
A recent study found that a person who does some form of exercise is about 3 percent less likely to have short telomeres than a person who does not exercise at all. Not only that, but the more a person exercises, the longer their telomeres are. The correlation between telomere length and exercise appears to be strongest among middle-aged people, suggesting that it is never too late to start exercising to keep telomeres from shortening.
Another study on how exercise keeps cells young found that middle-aged adults who were intense runners (we're talking 45-50 km a week) had telomere lengths that were, on average, 75 percent longer than their sedentary counterparts. This does not mean that we need to become marathon runners. What it does suggest is that regular participation in intense exercise can keep telomeres long and happy.
Vitamin-rich foods are believed to protect cells and telomeres from oxidative damage. A diet rich in antioxidant foods, such as berries and artichokes, may delay aging and help prevent or reduce cell damage.
In addition, taking a multivitamin supplement can lengthen telomeres as well. One study found that women who took a daily supplement had telomeres that were about 5 percent longer than non-users.
However, supplements still cannot mimic all the benefits of eating real, healthy foods. Oranges, bell peppers and kale are some of the top vitamin C foods. For vitamin E, almonds, spinach and sweet potatoes should be taken.
A 2008 study in men found that, after three months of a vegetarian diet, aerobic exercise and stress management, including yoga, there was increased telomerase activity. And a follow-up study from 2103 found that lifestyle changes are associated with longer telomeres.
Meditation has a form for each person, but it is clearly good for our minds and bodies.
While we wait for science to unravel all the mysteries of telomeres and how they work, we can make changes to lengthen them and positively affect the rest of our lives.
