You're Only as Young as Your Telomeres

One interesting area of longevity research centers on telomeres, which are the "tips" at the ends of our chromosomes, made up of sequences of non-coding DNA. Telomeres play a critical role in human health and the scientists who discovered them won the Nobel Prize in Physiology or Medicine in 2009.

When cells are about to divide, DNA must be replicated. The enzymes that perform the replication process start by latching on to the end of the chromosome.

The portion of the chromosome to which the replication machinery attaches cannot be copied, therefore with each cell division, the chromosome would theoretically become shorter. Telomere shortening is an indicator of cellular aging. Telomeres are the DNA segments at the ends of the chromosomes that provide a place for the replication machinery to attach, so that the DNA strand can be copied in its entirety. In order for another replication to take place, there must be enough of the telomere left to provide a place for the replication enzymes to attach, keeping the gene coding base pairs intact and available to be copied. If the telomere becomes too short, DNA replication is compromised, and the cell cannot divide. Cells have inherent mechanisms in place to maintain telomeres. The enzyme telomerase rebuilds telomeres, to compensate for the shortening that occurs with each cell division. 

Cellular Aging Leads to Cellular Senescence

Cellular aging, which includes telomere shortening and DNA damage, eventually results in senescence, a state of cellular growth arrest.  The cell is still alive, but not healthy and not capable of dividing. As more and more cells in a tissue become senescent, essentially the tissue is aging, its function becomes compromised.

Senescent cells are not able to carry out normal cellular processes, impair the tissue’s ability to repair damage, and secrete factors that negatively affect the function of neighboring cells and promote cancer development.

Shorter Telomeres are Linked to Disease

Telomere length and telomerase activity can be measured in human white blood cells, and this has given researchers the ability to investigate factors and disease states with ties to these cellular aging markers.

In human studies, shorter telomere length or lower telomerase activity has been associated with a number of chronic, preventable diseases, including hypertension, cardiovascular disease, insulin resistance, type 2 diabetes, depression, osteoporosis, and obesity.

Diet and Lifestyle Factors Affect Telomere Length

Telomere length and telomerase activity are affected by both genetic and environmental influences, including diet and lifestyle choices. Higher levels of vegetable and fruit consumption, fiber intake, vitamin and mineral intake, and exercise are factors associated with longer telomeres and greater telomerase activity.

Maintaining telomeres appears to be one of the many mechanisms by which these healthy lifestyle behaviors promote longevity.

Sources:

Burton DG, Krizhanovsky V. Physiological and pathological consequences of cellular senescence. Cell Mol Life Sci 2014, 71:4373-4386.

Cassidy A, De Vivo I, Liu Y, et al. Associations between diet, lifestyle factors, and telomere length in women. Am J Clin Nutr 2010, 91:1273-1280.

Deng W, Cheung ST, Tsao SW, et al. Telomerase activity and its association with psychological stress, mental disorders, lifestyle factors and interventions: A systematic review. Psychoneuroendocrinology 2016, 64:150-163.

Effect of comprehensive lifestyle changes on telomerase activity and telomere length in men with biopsy-proven low-risk prostate cancer: 5-year follow-up of a descriptive pilot study.

Marcon F, Siniscalchi E, Crebelli R, et al. Diet-related telomere shortening and chromosome stability. Mutagenesis 2012, 27:49-57.

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