Researchers from Kyushu University in Japan explored how hot spring bathing can influence the gut microbiome in healthy adults. The findings were reported in Scientific Reports.
The investigation looked at how different spa environments might shape the gut microbial community. A total of 127 volunteers across Japan participated. Each person selected a hot spring location and spent at least 20 minutes in the water daily for one week. Participants were advised to keep regular sleep and eating habits and to avoid alcohol and overeating during the study period.
Fecal samples were collected from every participant before and after the bathing period to assess changes in the intestinal microbiota. The results showed notable increases in various bacterial groups within the gut. In visitors to plain water hot springs, Oscillibacter and Parabacteroides became more abundant. For those exposed to bicarbonate-rich waters, increases were seen in Ruminococcus, Oscillibacter, and Bifidobacterium bifidum, while Alistipes rose with hydrogen sulfide sources. No significant changes were observed with chloride-based waters.
Some of the bacterial shifts observed are linked to health influences, including improved glucose tolerance, a reduced risk of constipation, stronger intestinal immunity, and better defense against enteropathogenic infections caused by harmful microorganisms.
The study also notes that certain bacteria may have dual effects on health. For instance, higher levels of Parabacteroides could potentially worsen amyotrophic lateral sclerosis symptoms in some contexts while contributing to longevity in others. This highlights the complex relationship between specific gut microbes and health outcomes, which may depend on host factors and environmental exposures.
Earlier discussions about the mental and physiological benefits of cold-water exposure are referenced in relation to menopausal well-being, illustrating how different water temperatures and mineral compositions might influence overall health and mood in diverse populations.