Traditional Japanese Style Bathing May Contribute to Good Health and Longevity

Abstract

The objective of this study was to determine how traditional Japanese style bathing could promote good health. Using healthy volunteers, we assessed body temperature (core and cutaneous), red blood cells, white blood cells (WBCs), venous blood gas parameters (PO2, SO2, PCO2, TCO2, HCO3, and pH), weight loss (which may indicate sweat volume), and the time until sweating before and after bathing. We simultaneously conducted a double-blind clinical trial using a bath additive group and a control group to investigate the effect of a bath additive on the same parameters. We found that bathing increased the core and cutaneous body temperature, as well as PO2, SO2, and blood pH. All of the subjects also showed increases in heart rate and weight loss (sweat volume). After bathing, the number and ratio of granulocytes increased while the number and ratio of lymphocytes decreased. These results tended to be emphasized in the bath additive group; however, significant between-group differences were not detected. Our results indicated that bathing improved blood circulation and had a modulatory effect on the autonomic nervous system. This suggested that traditional Japanese style bathing might contribute to good health and longevity; however, additional larger-scale studies were needed to confirm or refute this conclusion.