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.

Visceral fat accumulation is a notable risk factor in the incidence of lifestyle-related diseases such as metabolic and circulatory disorders. In this study, we measured visceral fat area (VFA) and subcutaneous fat area (SFA) in rugby football players by using dual bioelectrical impedance analysis, as well as other metabolic and circulatory parameters. A total of 28 male players (15 forwards, 13 backs; mean age±SD: 23±4 years) participated in this study. VFA and SFA were significantly correlated with body weight. Thus, heavier players had higher VFA and SFA as well as higher body weight. In addition, VFA was significantly correlated with various blood parameters such as alanine aminotransferase, gamma-glutamyl transpeptidase, and triglyceride. Six of the 28 players met the criteria for visceral obesity, defined as both body mass index ≥25 kg/m² and VFA ≥100 cm². In some of these players, blood parameters such as high-density lipoprotein cholesterol <40 mg/dL, triglyceride ≥150 mg/dL, or systolic blood pressure ≥130 mmHg indicated elevated risk for metabolic syndrome. These findings suggest that in athletes like heavier rugby football players, abdominal visceral fat accumulation may indicate risk of lifestyle-related diseases.

Annual changes in age, age at onset, incidence of cases with steroiddependent intractable asthma, clinical asthma types and clinical efficacy rate were examined in 256 patients with chronic respiratory diseases, especially in 203 cases with bronchial asthma, admitted to Misasa Branch Hospital from 1982 to 1989.
1. A number of patients with respiratory diseases as well as asthmatics admitted each year, having spa therapy, increased from early year (1982) to later year (1989).
2. A number in cases with 40 year or over of age (also with 60 year or over of age) and cases with 40 year or over of age at onset showed a tendency to increase in later three years (1987-1989). A decreased frequency of cases with steroid-dependent asthma and of cases with type II (bronchiolar obstruction type) was observed in the later three years.
3. The clinical efficacy of spa therapy for bronchial asthma was Niger in the later three years than in early three years (1982-1984).