In the Ministry of Health, Labour and Welfare Notification No. 112, the purpose of use of alkaline ionized water apparatus (household-use electrolytic water generators) which are household-use medical devices is defined as “generation of alkaline electrolytic water for drinking to improve gastrointestinal problems”. (“Improvement of gastrointestinal problems” is the beneficial effect based on the experimental results verified through clinical testing. In clinical testing, stomach problems such as stomach heaviness or discomfort, etc. or intestinal problems such as bowel movement conditions, etc. were the subjects of the testing. An overview of the testing is provided in the research results pages.)
Conventionally, devices certified as medical apparatuses were those which were effective against chronic diarrhea, indigestion, abnormal fermentation in intestines, acid control, and acid indigestion.
On the other hand, since acidic water can be used for applications other than drinking, such as washing faces, washing, etc., it is expected to have an astringent effect.
For alkaline ionized water, activities for reverification of its safety and effectiveness are performed by the Alkaline Ionizer Review Committee established in 1993, and as a result of performing double-blind comparative clinical testing with gastrointestinal problems as the subject (the world’s first for drinking water), the conclusion “Alkaline ionized water is effective.” was stated.
However, although there are examples of use for the purpose of treating illnesses such as atopic dermatitis, diabetes, etc., the effectiveness of alkaline ionized water for such purposes has not been scientifically proven, and the beneficial effects are not currently recognized.
Further, the following cautions should be heeded regarding how to drink alkaline ionized water effectively.
In general, the pH should initially be set low (around pH8.0 to 9.0), and the amounts drunk should be increased gradually from 1 cup.
After drinking for around 2 weeks, the pH or amount should be gradually increased according to the body characteristics and conditions, and as far as possible just-made alkaline ionized water with pH around 9.5 should be drunk.
For children or elderly people, alkaline ionized water with low pH should be used at first, and as they become accustomed to it, the pH value should be gradually increased. In addition, for neonates (up to around 1 year after birth), since they mostly drink breast milk or milk, their intestinal movements are different from those of normal adults and so alkaline ionized water is not recommended, but when they start eating the same foods as adults, it is thought that there would be no problems.
Reference: Regarding the cause of the effects of alkaline ionized water
Regarding the cause of the effects of alkaline ionized water, although there are various hypotheses that have been put forth, the mechanism as to why alkaline ionized water has improvement effects for gastrointestinal problems has not been clearly explained at the current time.
According to pharmacology in Japan and overseas, the calcium hydroxide in alkaline ionized water is considered effective against acid indigestion, infant indigestion, and diarrhea, and it is a substance which has long been recognized as having that medicinal value.
However, the various effects which have been proven until now for alkaline ionized water are difficult to explain as being due only to the pharmacological effects of calcium hydroxide, and research is currently continuing.
Various other hypotheses such as those below have also been put forth.
| Cause of effect | Proof, hypothesis, etc. |
|---|---|
| Calcium hydroxide | Pharmacological effectiveness against acid indigestion, infant indigestion, and diarrhea |
| pH value | Stimulation of stomach nerve layer by alkaline pH |
| Hydroxide ions（OH－） | Changes in border surface activation power and surface tension (reduction in penetration pressure) |
| Clustering of water molecules (cluster theory) | Changes in water molecule aggregation (so-called “clusters”) |
| Oxidation reduction potential (ORP) | Acid control by reduction power |
| Hydrogen（H･／H2） | Hydrogen-driven reaction with activated oxygen / control of lipid peroxidation |
However, there are currently no reports of scientific proof of the cause of the effects. Currently, analysis of the physiological mechanism to back up the various efficacies are being conducted in several fields, and further research development is expected.
<About hydrogen(H•/H2)>
In alkaline ionized water, hydroxide ions (OH－) and negative ions (calcium ions, etc.) become more numerous due to electrolysis, and at the same time it contains hydrogen, but recently, the actions of this hydrogen has been gaining attention and fundamental investigations into its effects on living bodies have been proceeding.
In recent research reports, strongly-electrolyzed water contains “activated hydrogen”, and there is also a paper which announced that elimination of activated oxygen by this activated hydrogen had been confirmed.
At the same time, this is still in the research stage and clear conclusions regarding the hydrogen structure, how the activated hydrogen acts on the activated oxygen in living bodies, etc. have not yet been reached, and currently research from various aspects and angles is proceeding.
Further, when common tap water is electrolyzed, the hydrogen concentration in the alkaline ionized water is thought to be around 100 to 400µg/L (at pH9.5), but this varies greatly according to the electrolysis conditions. In addition, the suitable hydrogen concentration value (optimum concentration) has not been clarified and is not standardized. For alkaline ionized water with concentrations drastically higher than the hydrogen concentration stated above (for alkaline ionized water at pH9.5 generated by a medical device), scientific proof is considered insufficient, and particularly sufficient investigation of its safety and effectiveness is a problem. (Recently, equipment that have not received medical device approval/certification and promising higher hydrogen concentration have also appeared, but no members of this association are participating in such equipment.)
