Like the rest of our bodies, our cells go through wear and tear as they age. Human cells are not able to replicate an unlimited amount of times. This is because, at the end of every chromosome, there are DNA segments called telomeres. Telomeres are believed to have two purposes. First, they are believed to protect chromosome from damage (such as translocations). Second, telomeres act as a form of cellular timekeeper – recording the number of times that a cell divides.
Like the rest of the chromosome, the telomere consists of DNA, except that in these regions the DNA is long repeats of nucleotides, the building blocks of DNA molecules. In humans (and mice), this DNA sequence is TTAGGG. So at the end of the human chromosome are long repeats of TTAGGGTTAGGGTTAGGG………. TTAGGG.
Unfortunately, every time the cell divides, the process the replicates the DNA in the chromosome in unable to replicate the repeats at the very end. Thus, with every cell division, the telomere shortens. When the telomere shortens to a predetermined length, it is not longer able to replicate and undergoes a form of programmed cell death. However, this is not the case in every cell. Some cells have an enzyme called telomerase that is able to copy the telomeres. Sperm and egg cells along with adult stem cells do contain telomerase and can rebuild their telomeres. However, since most cells cannot rebuild their telomeres, cell aging can be determined by telomere length.
This idea is supported by the fact that newborns often have between 8,000-13,000 base pairs making up their telomeres. As they age, this number decreases by about 20-40 base pairs every year. Telomere degradation is a natural process, but we can speed the process up with our own habits.
In a new study, it was found that soft drinks can speed up the cellular aging process by breaking down telomeres faster than normal. After putting into account different factors such as race, age, and daily exercise, scientists zoned in on the effects of soft drinks on telomere length. It was found that for every 8-ounces of soda consumed, 1.9 years of cellular aging resulted. Drinking soda is not the only way we can inflict wear and tear on our cells. The authors were careful to note that other factors may play a role in these findings. Previous studies have shown that telomere length is also affected by obesity, smoking, and even the age of the father at the time of conception. Our genetic makeup affects the length of our telomeres as well. Therefore, it may not be the soda directly, but a combination of life style habits.
But there is good news – other studies have shown that the Mediterranean diet has the ability to slow the loss of telomere length. A long term study of nurses indicated that those individuals who followed a Mediterranean diet had telomeres that were longer than those that did not follow the diet. The exact mechanism by which this occurs has yet to be determined, but it may have something to do with damage to the cells from components of non-Mediterranean diets.
Overall, the conclusion is that your diet does not just affect the health of your body systems, it can be felt in the DNA of every one of your cells.
- Can soft drinks speed aging? (Science and Society, November 2014)
- Getting Long in the Telomeres (23andMeBlog, May 2013)
- Leung C.W., Belinda L. Needham, David H. Rehkopf, Nancy E. Adler, Jue Lin, Elizabeth H. Blackburn & Elissa S. Epel (2014). Soda and Cell Aging: Associations Between Sugar-Sweetened Beverage Consumption and Leukocyte Telomere Length in Healthy Adults From the National Health and Nutrition Examination Surveys, American Journal of Public Health, 104 (12) 2425-2431. DOI: http://dx.doi.org/10.2105/ajph.2014.302151
- Mediterranean diet associated with longer telomeres. (Medical Express, Dec 2014)
- Crous-Bou M., J. Prescott, B. Julin, M. Du, Q. Sun, K. M. Rexrode, F. B. Hu & I. De Vivo (2014). Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study, BMJ, 349 (dec02 5) g6674-g6674. DOI: http://dx.doi.org/10.1136/bmj.g6674
Michael Windelspecht is an author, instructor of introductory biology and CEO of Ricochet Creative Productions. Theresa Koos is a sophomore at Clarke University in Dubuque, Iowa where she is studying to be a Physical Therapist with a major in Biology.
Telomeres (top and thumbnail): Darryl Leja, NHGRI (http://www.genome.gov/dmd/img.cfm?node=Photos/Graphics&id=85281)