One of the hallmarks of ageing is the increase in probability to die within a given period of time. A substantial body of evidence suggests that several major causes of death including cardiovascular diseases, cancer, and ageing-related wasting share a conspicuous common risk factor, i.e. the oxidative shift in the plasma thiol/disulfide redox state (REDST). This review deals with the questions how the shift in REDST is generated and how it contributes to the major age-related diseases and conditions, which ultimately limit the maximum and/or average human lifespan. Methods to correct the plasma REDST in the elderly are now being developed to determine whether such methods may improve the quality of life in old age and to test the hypothesis that the shift in REDST may account for important aspects of the ageing process.