It has been widely recognized that the drinking of strongly acid hot spring water often causes gastrointestinal symptoms. However, the research in this subject has been distinctly sporadic.
Fundamental and clinical experiments were undertaken to ascertain the effect of the drinking of Tamagawa Spa on the gastrointestinal mucosa. The property of Tamagawa Spa, Akita prefecture, is acid vitriol spring whose pH value is 1.2, and it contains a large amount of hydrochloric acid and hydrogen sulfide.
1. Studies in Man
The changes of gastric mucosa in 36 subjects after the drinking of hot spring water were observed by gastrocamera or gastrofiberscope.
Varying degrees of hyperaemia were found in all subjects administered non-diluted hot spring water, whereas these change were markedly reduced in subjects administered two times and over diluted hot spring water.
No instances of erosion or ulceration were seen in any of the subjects.
2. Experiments in Animals
Twenty three healthy rabbits, orally administered non-diluted or diluted hot spring water for seven days were autopsied.
The changes of gastric mucosa were similar to those in man, and no significant influence on the jejunal mucosa was seen. Microscopically the affected mucosa revealed degeneration of the epithelial cells of gastric gland and edema of the submucosa.
Based on the critical review of former studies, several important factors were suggested to explain the occurrence of gastric impairment after the drinking of Tamagawa Spa water.