Telomeres are the caps at the end of each strand of DNA that protect our chromosomes, like the plastic tips at the ends of our shoelaces. Our cells replenish by copying themselves in a process called mitosis. Telomeres get shorter each time a cell copies itself, but the important DNA stays intact. When telomeres get too short, our cells can no longer reproduce, which causes our tissues to degenerate and eventually die. This is why humans visibly look older as they age.

We lose a third of our total telomere length in the nine months from conception to birth during our most intense cellular reproduction as we grow from an embryo into a baby. At birth, the average telomere length is 10,000 base pairs. We lose around 120 base pairs every year from then on. In a perfect world, that would make the average life expectancy 83 years, but the real number is 71. What happened to those 12 years?

We can shorten our own telomeres by the choices we make in life. Oxidative stress accounts for the loss of between 50-100 base pairs per cell division. The amount of oxidative stress in the body is thought to be affected by lifestyle factors such as diet, smoking and stress. Harvard researchers have recently shown that sleeping less than 6 hours a night reduces telomere length by 12%. This is equivalent to 9 years of cellular aging. What can we do to stop this?

Scientists from the University of California, San Francisco found a relationship between exercise and telomere length. Participants who walked at a moderate pace for 30 minutes a day for six days each week lengthened their telomeres about 10%. Consuming enough Omega-3 fatty acids and Vitamin D, eating a plant based diet while avoiding sugar and processed meats is another way to preserve telomere length.

While telomeres can be seen as the molecular clock that counts down a person’s life, it’s good to know that we can add more hours with the choices that we make.