What are telomeres and why should I be interested in them?
Have you heard of telomeres and do you know why we are interested in them in the context of lifestyle medicine? Recent studies indicate that telomere length, which can be affected by various lifestyle factors, can affect the pace of ageing and onset of lifestyle and age-associated diseases.
Telomeres are DNA–protein structures found at the ends of our chromosomes and they play an important role in preserving the genetic information. As part of our normal cellular processes, a small portion of telomeric DNA is lost every time the cell divides. The telomeres effectively act like genetic buffers and over time (with age) the telomere ends become shorter, until they reach a critical limit when the cell enters senescence (equivalent of old age for cells) and/or programmed cell death. Telomere length could therefore serve as a biological clock to determine the lifespan of a cell and an individual. Shorter telomeres have been implicated in genomic instability and oncogenesis; the multi-step process by which normal cells turn into cancerous cells, leading to cancer growth in the body.
Our lifespan and quality of life depend on complex interactions among genetic, environmental, and lifestyle factors. Older people with shorter telomeres have an increased risk of dying of heart and infectious diseases. Specific lifestyle choices and the agents associated with those choices may speed up the telomere shortening process by damaging our DNA in general or more specifically at the telomeres themselves. So certain lifestyle factors may adversely impact our health, pace of aging and ultimately our life expectancy by increasing the rate at which our telomeres shorten.
Stress, obesity, an unhealthy diet, lack of physical exercise, smoking and exposure to pollution all increase the rate of telomere shortening through oxidative stress and inflammation. To preserve telomere length for longer and reduce our risk of diseases and slow the pace of aging, we should consider trying to stay lean through eating less and following a healthy, plant based diet, rich in antioxidants, fibre, soy protein and healthy fats (e.g. derived from avocados and nuts). Foods high in vitamin C and E are a good source of antioxidants e.g. sprouts, broccoli, red grapes, kiwi, tomatoes, flax, chia and sesame seeds. We should also try to stay fit and minimise stress via regular exercise and meditation.
DNA damage, including to telomeres, largely due to high levels of oxidative stress, is also a leading cause of defective sperm function. Such damage might provide a common underlying cause of male infertility and recurrent pregnancy loss, in addition to complex diseases in later life such as congenital malformations and childhood cancers. Oxidative stress is predominantly caused by a range of lifestyle-related factors, the majority of which can be adjusted. Hence changes in lifestyle is a potential therapeutic approach to overcome this cause of male infertility. It is believed that yoga and meditation can substantially improve the integrity of sperm DNA by reducing levels of oxidative DNA damage, regulating oxidative stress and by increasing the expression of genes responsible for repairing the DNA, controlling the cell-cycle and anti-inflammatory effects.
Human tissues express the enzyme telomerase that deters the shrinking of telomeres. It is known that female fertility decreases with increased maternal age. Various adverse factors, including alterations in the activity of this enzyme, can contribute to age-associated infertility in women. Women experiencing recurrent miscarriages may have shorter telomeres as a consequence of a more rapid rate of aging, or as a reflection of an increased level of cellular stress.
Shorter telomere length in both male and female partners and downregulation of major components of the protein complex known to protect telomeres might play a critical role in idiopathic (unknown cause) recurrent pregnancy loss.
Interestingly, recent research published in the International Journal of Molecular Sciences revealed that pregnancy achieved by assisted reproductive technology is associated with shorter telomere length in newborns. Shorter telomeres at birth could potentially influence the prevalence of life-style related diseases in later life.
Telomere length is highly variable among newborns. Research suggests that the BMI of women pre-pregnancy is associated with shorter newborn telomere lengths (a biomarker for accelerated aging). This highlights the benefit of a healthy weight pre-pregnancy in promoting molecular longevity from birth onwards.