Why do cells in older adults sometimes work less efficiently than cells in younger adults?

Cells in older adults often function less efficiently due to a combination of physiological and molecular changes that occur over the life span. This decline is driven by several key factors:

• Cellular Degradation: Organs experience a gradual loss of cells, which reduces the body's reserve capacity. Furthermore, the remaining cells may exhibit reduced activity in certain enzymes, requiring more time to complete essential chemical reactions.1
• Genetic Damage: The somatic mutation hypothesis suggests that aging results from the cumulative buildup of mutations in the DNA of body cells. These mutations can lead to the production of incorrect proteins, causing cellular malfunction or death.12
• Telomere Shortening: Each time a cell divides, telomeres—the protective segments at the ends of chromosomes—shorten. Once they reach a critical minimum length, the cell can no longer divide and may enter senescence or die.13
• Molecular Accumulation: Aging involves the cumulative loss and disorganization of vital molecules, such as proteins and nucleic acids, or the buildup of abnormal products within tissues.2