We scope space exploration beyond the low Earth orbit, such as manned activities on Moon and Mars. The advanced life support system is required to create and maintain living environment in outer space by providing foods, cloths and habitat. We shall prepare effective measures for promoting health and preventing illness, as well. Since astronauts would be exposed to various stressful situation, it is highly requested to feed them healthy meal with a good balance of its nutrients, which maintain inner environment of digestive organ at its proper condition. It is also important to prevent diarrhea and constipation, or to enhance willpower and physical strength of astronauts, by feeding them with good nutritious and ingestible materials. The lactic acid bacterium beverage (containing 80 billion Lactobacillus casei shirota) was given, every day for one month, to 10 healthy female subjects (20.4 ± 0.51 years old) who suffer constipation, together with another 10 subjects for the control with dead bacteria in the same beverage. Status of their constipation was examined by their reporting of number of evacuation, shape of the evacuation, their self awareness on their status. The average stool frequency increased in both the experiment and the control group from the first week of administration. In the experiment group, six among ten subjects showed improvement of clear constipation. Since seven out of ten control subjects did not show improvement in their constipation, administration of live lactic acid bacterium is effective for improving constipation. The L-casei shirota lactic acid bacterium stock helps the action of Bifidobacterium bifidum to keep bowels in normal state. Without proper population of Bifidobacterium bifidum, such conditioning is not effective. Administration of both bacterium species is required in such case. In the future space missions, intake of the lactic acid bacterium would be one of effective measures to maintain astronaut's bowel in good condition and contribute to enhance their health and productivity in their task of space exploration.
