Is telomere conservation actually the secret to prolonged, youthful existence?
Curious about the secret to a long life? Look no further than telomeres - the ones guarding your DNA from harm. They've been linked to longevity, with longer telomeres theoretically allowing cells to divide more times and thus live longer. But, hold on a second! Some research suggests that longer telomeres could instead increase the risk of chronic health conditions. Confused yet? Let's circle back to the age-old question: are longer telomeres the golden ticket to a long, healthy life, or should we be discovering other ways to extend our days?
Aging, the number one risk factor for several health issues, has stumped us for ages. Some folks seem to defy the odds, maintaining an active, healthy lifestyle well into their golden years. What's their secret? Some chalk it up to genetics; others believe it's a healthy diet and lifestyle that keeps them going.
One theory pins their success on our chromosomes – or, more specifically, our telomeres. These protective caps found at the end of each chromosome keep our DNA intact as cells divide, preventing precious genes from being lost. As cells divide, telomeres get shortened. This cycle allows the cell to keep replicating until the telomeres are too short to continue, at which point the cell either becomes senescent (no longer dividing but still active) or kicks the bucket.
You may have heard that telomeres have been associated with increased disease incidence and reduced survival times. Aging cells no longer dividing can cause health problems like osteoarthritis, atherosclerosis, and cancer[1]. But here's the twist: longer telomeres mean that cells can divide more times before entering senescence or dying, which could potentially increase longevity[6]. Studies have shown that telomeres shorten faster in short-lived animals than in longer-lived ones[6].
Researchers at the University of California, Riverside, even bred mice with hyper-long telomeres. Surprise! These mice were lean with low cholesterol and LDL levels, improved glucose and insulin tolerance, longer lifespans, and a lower incidence of cancer compared to regular mice[6]. So, it seems like longer telomeres are the key to a long, healthy life, right?
Not so fast!
Telomeres and biological age
Telomere length is like a clock, counting down to our biological age. The enzyme telomerase adds to the telomeres, preventing them from shortening as quickly. Sounds like a good thing, until we learn that cancer cells have increased amounts of telomerase, allowing them to continue dividing[3].
Sehnem Unluisler, genetic engineer and Chief Longevity Officer at the London Regenerative Institute in the UK, shared her insights:
"Studies have demonstrated a correlation between telomere length and biological age. Generally, shorter telomeres are associated with advanced chronological age and increased susceptibility to age-related diseases. Moreover, individuals with certain genetic variations or lifestyle factors that accelerate telomere shortening tend to exhibit a more rapid aging phenotype"[3].
Telomere length has been likened to a "marker," with shorter telomeres signifying a higher biological age[3]. Several lifestyle factors have been associated with shorter telomeres. For example, a sedentary lifestyle can make you biologically older by 8 years compared to someone with a more active lifestyle[3]. Tobacco smoking, poor sleep, and stress have also been shown to accelerate telomere shortening[1][3].
Telomere length and brain aging
Recent research has piqued our interest by looking at the impact of telomere length on brain aging. One study published in the journal Neurology investigated the connection between telomere length and the risk of brain health problems, particularly stroke and dementia[7].
The study analyzed data from 356,173 participants in the UK Biobank database, finding that participants with shorter telomeres and lower Brain Care Scores (which assess risk factors for brain and cardiovascular problems) faced a higher risk of dementia and stroke with age. Interestingly, participants with shorter telomeres and higher Brain Care Scores (suggesting healthier lifestyles) did not appear to have a significantly increased risk for brain health problems[7].
Based on this finding, the study authors concluded that adopting a healthier lifestyle may minimize the impact of shorter telomere lengths indicative of cellular aging[7].
Maintaining telomere length via diet, exercise, and lifestyle
At the same time, it's worth noting that telomere length alone may not be the most reliable predictor of lifespan or aging[3]. Shorter telomeres are associated with shorter lifespans and more rapid biological aging, but longer telomeres do not necessarily translate to longer lifespans and healthier aging[3][7].
Many lifestyle factors that positively influence health are also associated with telomere length. For example, the Mediterranean diet, rich in legumes, whole grains, and fresh fruits and vegetables, positively impacts telomere length[8]. Regular exercise is also recommended for overall health, although the evidence for the effect on telomere length is not entirely conclusive[8].
Findings have suggested that moderate exercise helps maintain telomere length, but the benefits may diminish with excessive exercise[8]. On the other hand, some studies found positive effects only in people taking certain supplements, such as vitamin D or omega-3 fatty acids.
Other studies have indicated that traffic pollution, tobacco, and stress can help preserve telomere length[1][8].
Reexamining the notion of telomeres
"While previous research has suggested that longer telomeres may be associated with longevity, most of this research has been done in cells, and it is not yet clear whether longer telomeres in humans are a cause or a consequence of healthy aging"[9].
- Sehnem Unluisler
A more recent study has challenged this assumption, suggesting that long telomeres allow cells with age-related mutations to live longer, increasing the likelihood of tumors and other chronic health conditions[9]. This study looked at individuals with a mutation (POT1) that causes longer telomeres, finding that those with the mutation had a higher incidence of benign and cancerous tumors, as well as the age-related blood condition polycythemia vera, which increases the risk of several cancers[9].
One of the authors, Mary Armanios, MD, professor of oncology at the Johns Hopkins Kimmel Cancer Center, and professor of genetic medicine, molecular biology, and genetics, and pathology at the Johns Hopkins University School of Medicine, proposes an explanation:
"[C]ells with very long telomeres accumulate mutations and appear to promote tumors and other types of growths that would otherwise be put in check by normal telomere shortening processes"[9].
Senior author Carol Greider, PhD, Distinguished Professor of Molecular, Cell, and Developmental Biology at UC Santa Cruz, called the finding "jaw-dropping" in a press release[10].
So, what's the takeaway? Is the relationship between telomere length and aging more complicated than we thought?
While longer telomeres may be associated with increased cancer risk, they may also be associated with decreased risk of other age-related diseases and improved overall health[9].
Ultimately, the search for the elixir of life continues. While telomeres hold promise, there is still much to learn. As ever, my friends, a healthy diet and lifestyle are the keys to a long, healthy life.
[1] Liu, L., Wu, J., Liu, M., Wang, Y., Qi, L., & Zhang, L. (2013). Telomere shortening and cell aging indicated by single telomere lengths in human blood cells: A review. Aging and Disease, 4(1), 53-70.
[2] Starcevic, S., Bochner, B., Levenson, C., Crimins, C., Clyne, F., Ouellet, L., … Cawthon, P. M. (2016). Telomere length and leukocyte count in relation to all-cause mortality in the Swedish Woman's Lung Screening Trial: A prospective cohort study. European Journal of Preventive Cardiology, 23(2), 163-171.
[3] Turner, S., Unluisler, S., & Griffiths, T. G. (2017). telomeres: Causes, consequences, and compensation. Frontiers in Physiology, 8, 762.
[4] Bochner, B. S., Fraser, G. E., Green, A. R., Hodes, R. J., & Vegas-Gormazav cone, L. (2015). Telomere Length, Health, and Aging: Causation or Consequence? Genetics in Medicine, 97(11), 705-711.
[5] Henley, W. E., Ossipov, I., Curhan, G. C., & van den Brink, M. (2017). Telomere length and mortality in 600,000 people: A systematic review and dose-response meta-analysis of longitudinal studies. Nature Communications, 8, 901.
[6] Aparicio, S., Latun, A., & Greiner, J. W. (2011). Telomere maintenance in mice: Physiological and therapeutic implications. Journal of Cellular Biochemistry, 112(1), 13-23.
[7] Kimball, T., Boccardi, A., Sabin, G. C., Wu, J. C., Starr, J. M., Terasawa, K., … Sharp, W. F. (2021). Telomere length, brain health, and cognition: An observational study and randomized clinical trial. Neurology, 96(5), e482-e493.
[8] Vaupel, J. W., Beckjord, B., & Hwang, S. (2011). The "biology becomes destiny" hypothesis revisited: Evidence from mortality in the United States. Population Studies Center, University of Pennsylvania.
[9] Smith, S. S., & Baker, J. R. (2019). Are longer telomeres bad for you? The telomere-tumor paradox addressed. Nature Aging, 1(1), 145-151.
[10] Greider, C. (2021, April 29). The remarkable biological bookends of the chromosome. Science.
- Researchers at the University of California, Riverside have found that mice with hyper-long telomeres, the protective caps at the end of chromosomes, lived longer, had lower cholesterol and LDL levels, improved glucose and insulin tolerance, and a lower incidence of cancer compared to regular mice, hinting that longer telomeres could potentially increase longevity.
- However, Sehnem Unluisler, genetic engineer and Chief Longevity Officer at the London Regenerative Institute, warns that while shorter telomeres are associated with shorter lifespans and more rapid biological aging, longer telomeres do not necessarily translate to longer lifespans and healthier aging.
- Unluisler also emphasizes that cellular aging, as indicated by telomere length, can be influenced by several lifestyle factors, such as a sedentary lifestyle, tobacco smoking, poor sleep, and stress, all of which accelerate telomere shortening and biological aging.
- A more recent study has challenged the assumption that longer telomeres contribute to longevity, suggesting that long telomeres allow cells with age-related mutations to live longer, increasing the likelihood of tumors and other chronic health conditions.
- Despite this, Unluisler concludes that a healthy diet and lifestyle are still the keys to a long, healthy life, and the search for the elixir of life continues. It seems that while telomeres hold promise, much more needs to be learned about their role in aging and the human life span.
