A Correlation Between Telomere Length and Weight-Adjusted Waist Index
Epidemiological researchers have for been slowly moving away from body mass index and towards measures that more directly reflect the burden of visceral fat tissue. Waist circumference and measures such as weight-adjusted waist index are now often used. Here, researchers show a correlation between shorter telomere length and larger weight-adjusted waist index; people who are more overweight tend to have shorter telomeres.
Telomere length taken from white blood cells in a blood sample correlates with aging, but only in large studies. It isn't a great measure of biological age, but in principle reflects some combination of (a) replication stress placed upon the immune system, as telomeres shorten with each cell division, and (b) the pace at which replacement immune cells with long telomeres are generated by hematopoietic stem cells. In the case of T cells of the adaptive immune system it also reflects the degeneration of the thymus, as T cells mature in that organ. Degenerative aging will tend to lead to worse stem cell function and greater stress placed upon the immune system, but there is a lot of variability from individual to individual.
Does being overweight accelerate aging? One can mount a good argument that it does, based on a survey of mechanisms involved in aging and how they are altered in overweight individuals. Certain, excess visceral fat tissue appears to increase the pace at which senescent cells accumulate. This is a noteworthy feature of aging, as lingering senescent cells disrupt tissue structure and function via pro-inflammatory signaling. Excess visceral fat tissue also generates chronic inflammation via a range of other mechanisms.
Telomeres, which are also known as the "protective caps" of chromosomes, are DNA-protein complexes located at the tip of chromosomes consisting of DNA repetitions and a small number of protective binding proteins. They protect chromosomal ends from genomic damage and instability. Telomeres shorten with each cell cycle, and when they become severely short, cells either enter senescence, cell cycle arrest, or undergo apoptosis. Telomere attrition is widely recognized as a prominent hallmark of aging. Telomere attrition has been linked to numerous ailments, including diabetes mellitus, Alzheimer disease, and major cardiovascular diseases (CVD) such as atherosclerosis, hypertension, and heart failure. Moreover, shortened telomeres are connected with an elevated risk of all-cause mortality among the general population.
Obesity poses a significant threat to public health worldwide. However, the most commonly used traditional metric to define being overweight, Body mass index (BMI), cannot distinguish between fat mass and lean mass, nor between central fat and peripheral fat. It is worth noting that weight-adjusted-waist index (WWI) has the potential to compensate for both of these deficiencies. WWI, which is standardized by adjusting the waist circumference (WC) based on body weight, was first proposed in 2018. The initial objective was to construct an obesity index that indicates WC, which exhibits a weak connection with BMI. The aim was to alleviate the obesity paradox of BMI versus mortality. Like telomere length, WWI was found to be directly proportional to age, suggesting its unique function to reflect the age-related alteration of body composition.
This article presents the results of the inaugural study on the relationship between WWI and telomere length in adult populations. The cross-sectional investigation analyzed data from 3479 participants from the National Health and Nutrition Examination Survey (NHANES) conducted from 1999 to 2000. To inspect linear and nonlinear correlations, we adopted weighted multiple logistic regression analysis and smooth curve fit, respectively. In addition, threshold effects and subgroup analyses were accomplished. In the fully adapted model, a significant adverse association of WWI with telomere length was detected. The adverse correlation remained consistent across all subcategories. We also discovered an inverted U-shaped curve linking WWI and telomere length, with a conspicuous inflection point. The inflection point suggests that controlling WWI within an optimum range might be essential for aging and health.