Longitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort study.

Plain-language summary

This study set out to see if regular sauna use is linked to lower inflammation and oxidative stress over time. It tracked 2269 middle-aged men for 11 years, measuring markers like hsCRP (a key inflammation marker), fibrinogen (a clotting factor tied to inflammation), white blood cell count, and GGT (a liver enzyme that can signal oxidative stress). More frequent sauna sessions (4-7 per week) were tied to lower inflammation markers both at the start and a decade later, but had no clear effect on oxidative stress. The findings suggest that sauna might help curb systemic inflammation, which could partly explain its health benefits.

Key findings

• 4-7 sauna sessions per week (vs. 1) was linked to lower hsCRP (-0.84 mg/l at baseline, -1.66 mg/l after 11 years)
• Frequent sauna use was also tied to lower fibrinogen and white blood cell counts over time
• No association found between sauna use and GGT (a marker of oxidative stress)