[Biological age as an index of human health level, aging and ecological well-being]

Methodology of estimating the integral health and aging level is based on the system index of biological age (BA). The paper introduces the reader to the BA principles and structure, search for meaningful aging biomarkers, useful tests, and applications in present-day biomedicine. The concept of BA is directly linked with the theory of organism vitality. BA biomarkers must provide a detailed picture of the process of aging. Number of biomarkers cannot be large, while their changes with aging must be uniform in every population member and fairly distinct though with moderate interindividual variations. Prognosis of the vital trajectory requires estimation of risk factors, i.e. hereditary and acquired factors that affect lifespan, and also longevity factors, i.e. genetic and environmental factors crucial for clinical medicine and gerontological prophylaxis properly. At present, BA gains wide recognition in clinical and preventive medicine, physiology and biology as a method to evaluate the general state of health, ecological well-being, adaptation to extreme factors, as well as the rate and degree of organism aging.