Can Hydrogen Water Improve Mood and Anxiety? What a 4-Week Trial Found

Stress and low mood are common, everyday complaints without a single obvious fix — which makes a small but well-controlled trial testing hydrogen water against a genuine placebo worth a look, even with a modest sample size.

What the research looked at

Published in Medical Gas Research in 2018, this double-blind, placebo-controlled crossover study enrolled 26 healthy adults (13 women, 13 men, average age 34). Participants drank 600 mL per day of either hydrogen-rich water or a visually identical placebo water for 4 weeks. Researchers measured psychological distress using the K6 questionnaire (a standard screening tool for mood and anxiety symptoms) and tracked autonomic nervous system activity, including sympathetic nerve activity linked to the body's stress response.

What they found

Compared with placebo, hydrogen-rich water produced a significantly greater improvement in K6 psychological distress scores and a significantly greater reduction in sympathetic nerve activity — a marker associated with the body's "fight or flight" stress response.

What this means in practice

This is a small trial (26 participants), so it needs replication in a larger sample before it can be considered settled evidence. It's also measuring general psychological distress in healthy adults, not diagnosed anxiety or depression, so it doesn't tell us how hydrogen water would perform as a treatment for a clinical mental health condition. Still, the crossover design (each participant served as their own control) and genuine placebo control make this a reasonably rigorous small study, and it's an interesting early signal for hydrogen water's effect on everyday stress — not a substitute for mental health treatment when that's needed.