This study showed that the daily practice of Wim Hof’s method can help people with autoimmune disease reduce chronic inflammation, improve markers of disease status, and improve overall quality of life.
Heart rate variability biofeedback in chronic disease management: A systematic review (2021)
HRVB (and, hence, slow breathing) is a powerful adjunctive therapy for managing a wide variety of chronic diseases. To be effective, it should be practiced for a minimum of 10 min/day (but probably 20+ for best results—see next section). More broadly, this study supports using slow breathing at around 5-6 breaths per minute in people with chronic diseases.