A human life support system based on environment regeneration by plant photosynthesis has been developed and investigated. The system matter turnover involves humans not as an object to be sustained only, but also as a component whose metabolism provides for reliable and steady operation of the entire system. Experiments that lasted for several months demonstrated feasibility to completely regenerate atmosphere, water and 93% of the plant part of human diet in such a system. Self-sustained operation of the system requires the human to control all processes running within the system. Long-standing (many years) observations of health of a large group of people who took part in experiments revealed no pathological changes proving the adequacy of the system habitat to human requirements.