Explanations by Spring Quality

"Hot spring for women" that reaches to the core of the body

Hot spring with more than 20 mg of Total Iron Ion (Iron Ⅱ + Iron Ⅲ) in 1 kg of hot spring water. ※Total Iron Ions [Fe²⁺（ferroion）＋Fe³⁺（ferriion）]
“Iron containing Springs” is said to be called "Hot spring for women". This is because it has long been said to be effective for symptoms often seen in women, such as anemia, menopausal disorders, menstrual disorders, and sensitivity to cold.
Also, it warms up well when bathed, and is said to be effective for rheumatic diseases, menopausal disorders, uterine dysplasia, chronic eczema, lichen planus, and others.
In the 2014 revision of the Hot Springs Law, however, the Indications for spring quality for bathing is "None".
This is apparently because of the revision that emphasized scientific evidence, but before the revision, the Indications were determined based on experience.
Also, the iron of “Iron containing springs” is rarely absorbed into the body through the skin. Furthermore, the high iron content of the springs is highly irritating to the skin and may instead cause skin problems, which is why the indications for bathing may have been dropped. However, “Iron Springs” by itself, but when combined with "Chloride Springs", it definitely warms the body to the core. As the name suggests, drinking “Iron containing springs” can be effective against Iron-deficiency anaemia, which is caused by a lack of iron in the body. It is expected to stimulate the production of red blood cells by increasing the secretion of stomach acid and the absorption of iron. One thing to note, you should avoid consuming drinks that contain tannins, such as tea or coffee, immediately after drinking it. The reason is that iron and tannin are bound together and block the absorption of iron. “Iron containing springs” are clear and colorless at the time of gush, but when exposed to air, the iron gradually oxidizes and turns reddish brown (dark reddish brown) in color. “Akayu (red hot water)” is the name given to this type of spring. Iron containing springs are rare in Japan, and are definitely one of the rarest spring types, as well as “Carbon dioxide springs”, “Iodine containing springs”, and “Radioactive springs”. Note that it is the divalent iron that is effective for the body, and the effect decreases as it oxidizes to trivalent iron. Incidentally, “Iron containing springs” are classified into the following two types
(1) “Hydrogen carbonate type (Iron carbonate type)” which is combined with anionic hydrogen carbonate ion
・・・This type has the characteristics described above.
(2) “Sulfate type (Iron sulfate type)” which is combined with anionic sulfate ion
・・・The old name of this type was “Vitriol springs（Iron–sulfate springs）”. It is called “Hot springs for skin diseases”. It is highly acidic and has high sterilizing and heat-retaining effects.
In the case of simple iron springs (sulfate type), the water is often pale green in color.

• ■Old name of spring・・・Iron springs (Iron carbonate springs / Vitriol springs)
• ■Color of water・・・
  Hydrogen carbonate type: Reddish brown (Dark reddish brown)
  Sulfate type(Vitriol springs): Pale green
• ■Taste & Smell・・・
  Hydrogen carbonate type: Iron astringency, Iron rust smell
  Sulfate type(Vitriol springs): Sourness like astringent persimmon, Metallic smell
• ■Water texture・・・Chloride Ions are mainly: Sticky texture
  Hydrogen carbonate type: Smooth texture
  Sulfate type(Vitriol springs): When strongly acidic tingling texture
• ■Major hot spring inns・・・"Taketoritei Maruyama" Arima Onsen, Hyogo prefecture ※Chloride ion is the main component／"Unzen Fukudaya" Unzen Onsen, Nagasaki prefecture ※Sulfate type
List of inns with this spring quality