[Effects of head down bed rest or drinking water containing electrolytic silver-ion on intestinal bifidobacteria]

Objective. To investigate the effect of head down bed rest (HDBR) or electrolytic silver-ion on intestinal bifidobacteria in men and mice. Method. Three tests were conducted. Counts of bifidobacteria in feces were made in: 1) 5 male healthy volunteers after 21 d -6 degrees HDBR. 2) 4 groups of mice drank water containing no Ag+, 0.20, 0.40 and 0.60 mg/ L of Ag+ respectively for 1 month. 3) Seven male healthy volunteers drank water containing 0.20 mg/L of silver-ion for 16 days. Result. 1) The count of bifidobacteria after HDBR [8.08 +/- 0.82 (lgn/g)] was significantly decreased as compared with the control group [8.72 +/- 0.82 (lgn/g)] (P<0.01). It suggests that HDT -6 degrees bed-rest might reduce the number of bifidobacteria in the human colon. 2) The count of bifidobacteria in feces was negatively correlated with the silver-ion concentration in the water (r= -0.992, P<0.01). 3) The count of bifidobacteria in feces after test [7.83 +/- 0.71(lgn/g)] was significantly decreased as compared with that before the test (8.91 +/- 0.84) (P<0.05). Conclusion. It demonstrates that HDT -6 degrees bed-rest and electrolytic silver-ion all might reduce the count of bifidobacteria in feces.