Telomere Length and Its Relation to Human Health

Abstract

Telomeres are complex nucleotide sequences that cap the end of chromosomes from degradation, unwanted recombination-fusion, inappropriate activation of DNA damage response and play a critical role in cell division and chromosome stability. There is growing evidence that telomere stability can be affected by occupational and environmental exposure, as some of these factors have been correlated with increase in inflammation, oxidative stress, DNA damage, chromosome aberration, and epigenetic alterations. Both extremely short and long telomeres have been associated with neurodegenerative, cardiovascular diseases (CVD) and cancer risk. Occupational and environmental exposure to several synthetic and natural chemicals has been found to be associated with changes in telomere length, although the molecular mechanism is not fully understood. Telomeric DNA is relatively less capable of repair, resulting in accelerated shortening during the cell cycle and replicative senescence. It is recognized that diet plays an important role in telomere maintenance. Prevention of exposure to environmental and occupational hazards as well as psychological stressors can reduce the risk of telomere instability. This review provides a broad evaluation of the associated mechanism between human health and environmental and occupational exposure with telomere length, including recent findings and future perspectives.

Occupational Exposure to Pesticides in Tobacco Fields: The Integrated Evaluation of Nutritional Intake and Susceptibility on Genomic and Epigenetic Instability

“…Our study differs from this one because participants from the current work, whether exposed or not, had appropriate intake of folate and B 12 . This adds to growing evidence that, actually, there is a complex relationship of telomere length with B vitamins (reviewed by [ 24 ]). In the general US population exposed to cadmium, leukocyte telomere length was found to be decreased and a diet pattern was also evaluated.…”

“…In our study, there was no significant difference in folate between nonexposed and exposed groups; still, vitamin B 12 , measured in serum, was significantly elevated for farmers, and yet, a decrease in telomere length was found for the same group. In other study, folate deficiency leads to long but dysfunctional telomeres, associated with higher chromosome instability, probably due to DNA hypomethylation (reviewed by [ 24 ]). Paul et al [ 59 ] observed that levels of folate above the median have a positive correlation with telomere length.…”

“…In our study, we observed a positive correlation between telomere length and intake of lipids and an inverted correlation with fiber intake. Fiber is a dietary factor that can reduce lipids levels through absorption of fat (reviewed by [ 24 ]). A high-fat diet intake was inversely associated with telomere length in more than 2000 American women, and individuals making use of vitamin complexes may have telomeres ~273 bp longer than those not using (reviewed by [ 24 ]).…”

“…More recently, telomere length has been introduced as a new biomarker in occupational exposure evaluations, including pesticides (reviewed by [ 24 ]). Telomeres mark the end of chromosomes and play a critical role in genomic stability by preventing chromosome end fusions.…”

“…It is known that several micronutrients are involved in DNA synthesis and repair, prevention of DNA damage, and maintenance of DNA methylation [ 27 ]. More than that, the telomere maintenance in vivo has been linked to intake and/or restriction of different nutrients and foods ([ 24 ], reviewed by [ 28 ]). The accurate significance of these data is still unclear as they are results from single studies ([ 24 ], reviewed by [ 28 ]), but the separate association of telomere maintenance and nutritional intake with cancer is widely known and accepted [ 24 ].…”