Podcast episode 88 (in German)
The alkaline bath – an old ritual, a look inside the cell and what warm water can really do
September 26, 2026
Alkaline baths have a long tradition, from the bicarbonate springs in Bad Ems to the bath salt from the drugstore. The episode takes the ritual seriously, looks into the cell, where acid and base drive energy metabolism, and shows what warm bathing demonstrably achieves.
What it is about
In an alkaline bath, the bath water is brought to a pH of about 8.5 with alkaline salt; neutral would be 7. Users report velvety skin, genuine relaxation and fixed rituals during alkaline fasting, often two to three times a week. The episode explains what acid and base mean in and around the cell: why the interior of the mitochondria is alkaline, why lactate tends to act as a brake rather than causing acidosis, and what research says about mild acidosis in old age. Then it turns to the well-studied effects of a warm bath on sleep, heart and mood. It ends with a ritual for the evening and the reminder that bases get into the body via the plate.
Key points
- An alkaline bath salt has almost 3,000 ratings on Amazon, averaging 4.7 stars; the common thread is soft skin and relaxation (user reports, not evidence of efficacy).
- Blood keeps its pH between 7.35 and 7.45; inside the mitochondria it is around 8 – there the proton gradient drives the production of ATP.
- A much-cited review sees lactate not as the cause of acidosis during exercise but rather as a brake; good mitochondria are the best acid buffer.
- Alkaline minerals lowered the pain score of 82 people with chronic back pain by 49 percent in 4 weeks – a strong signal, but without a comparison group.
- A meta-analysis of 17 studies found that a warm bath or shower 1 to 2 hours before bedtime improves sleep.
- In a Japanese cohort of more than 30,000 people, those who took a tub bath almost daily had 28 percent less cardiovascular disease than those who bathed at most twice a week.
- In depression, 2 hyperthermic baths a week at 40 °C improved symptoms after 2 weeks markedly more than a sham treatment.
Where the data stop
That acids are drawn out of the body through the skin has not been shown; there is no controlled study on the alkaline bath itself. The acid-base balance is regulated by the lungs and kidneys, and bases get into the body mainly through vegetables and fruit. The hypothesis of mild acidosis in old age is also research in flux: for potassium citrate and bone density there is one positive double-blind study and one that found no difference.
The demonstrated effects belong to the warm water: sleep, circulation and mood. The studies on this mostly ran at around 40 °C, i.e. warmer than the classic body-temperature alkaline bath. With dry or sensitive skin, shorter baths and moisturizing afterwards are worthwhile, because healthy skin is slightly acidic. Anyone with cardiovascular problems or who is pregnant should discuss long hot baths with a doctor; alkaline preparations in kidney disease belong in the hands of a physician.
Listen (in German)
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Published on September 26, 2026.
The topic in the database
- Hours in warm water. The rationale on the pack does not hold up – the effect exists anyway, just by a different route.Long alkaline bathing
Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-26.