In his critical book entitled “Why We Age-and Why We Don´t Have To”, a genetics professor at Harvard Medical School Dr. David Sinclair defines telomeres as a cap that protects the end of the chromosome from attrition, analogous to the aglet at the end of a shoelace or a burned end of a rope to stop it fraying.[1] It is well established that as we age, telomere length shortens. After telomeres shorten to a certain length, a cell stops dividing and becomes senescent. Consequently, telomere length is a key biomarker of ageing.
Indeed, according to Dr. Sinclair, the attrition of telomeres is one of the hallmarks of ageing and the diseases that arise as a result of it. Many research papers have pointed to lifestyle factors that can accelerate the pace at which telomeres shorten. This is good news: it means that by modifying specific aspects of lifestyles for the better, we can significantly alter the rate of telomere shortening and thus increase lifespan.
Many lifestyle factors are strongly associated with an increased pace at which telomeres shorten. One of these major factors is smoking. According to Shammas, the dose of cigarettes smoked is positively correlated with accelerated telomere shortening. The mechanism behind why smoking has this detrimental effect on telomeres is via an increase in oxidative stress. Another lifestyle factor associated with an increased rate of telomere shortening is obesity. Obesity accelerates the ageing process; indeed, the telomeres in obese women have been shown to be significantly shorter than those in lean women of the same age group.[2] Other factors which speed up the rate of telomere shortening include exposure to pollution and stress (associated with the continuous release of glucocorticoid hormones, like cortisol).
On the other hand and on a different note, several lifestyle factors seem to have protective effects on the rate of telomere shortening. For example, diet (including what, how much and when we eat) appears to have a major effect on our telomeres and therefore on our longevity and vitality. Dietary restriction in general increases lifespan and is associated with longer telomeres. Indeed, the so-called “longevity hot spots” are all places where there is a strong fasting behaviour, which triggers an increased expression of your longevity genes (i.e. increased expression of sirtuins and down-regulation of the mTOR pathway). Intake of antioxidants (e.g. vitamin C, vitamin E, beta-carotene) can prevent accelerated telomere attrition. Also, dietary intake of fibre is positively correlated with telomere length. Another major lifestyle factor which prevents telomere attrition is exercise. To put it simply, and as stated in Dr. Sinclair´s book, those who exercised more had longer telomeres.[3]
Overall, caloric restriction, exercise, ingestion of antioxidants and fibre all slow down the rate of telomere shortening. Contrastingly, smoking, obesity, exposure to pollution and stress accelerate telomere shortening and hence the ageing process.
[1] Lifespan: Why We Age – and Why We Don’t Have To. Book by David A. Sinclair PhD.
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370421/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370421/
