Alkaline water is the opposite of acidic water. It has a higher pH level than plain water.
Claims that it has various health benefits have helped increase the popularity of alkaline diets and sales of machines that turn water alkaline.
Ionizing machines are one example of these products. These can cost over a thousand dollars.
But what scientific evidence lies behind drinking alkaline water? Are there any proven health benefits?
The pH of water is neutral, around pH 7. Chemicals and gases can change this to make it more acidic or more alkaline.
Rainwater’s pH is slightly below neutral, because there is carbon dioxide from the air, and this increases acidity.
- Acidic substances have a pH of below 7.0, down to zero. The pH of vinegar is around pH 3, lemon juice around pH 2, and battery acid around pH 1.
- Alkaline substances have a pH up to 14. Baking soda’s pH is between pH 8 and 9, and milk of magnesia is between pH 10 and 11.
Water can be high or low in pH, but if it is too high or too low, it can have adverse effects.
Water that is too alkaline has a bitter taste. It can cause deposits that encrust pipes and appliances. Highly acidic water may corrode metals or even dissolve them.
Alkaline water has become popular in recent years due to a belief that it may benefit health.
Bone health and osteoporosis
Some research has been done on the effects of alkaline intake on bones. A study published in Bone found an effect on bone resorption. Bone resorption is the process where old bone cells are broken down and replaced by new ones.
Less bone resorption and more mineral density result in better bone strength.
The authors concluded that “a bicarbonate- and calcium-rich alkali mineral water decreased bone resorption more than a calcium-rich acidic mineral water.”
However, this was a small effect.
The scientists called for more research, to see if the benefit of less bone resorption was long-term and could improve bone mineral density.
Another study, published in Nutrition Journal, compared the impact of an acidic diet, rather than alkaline water, on osteoporosis, a disease marked by weak and brittle bones.
Reviewing the background to the study, the authors noted a high number of claims being made on the Internet. These claims suggested “that alkaline diets and related commercial products counteract acidity, help the body regulate its pH, and thus prevent disease processes.”
The review used high-quality evidence to conclude that acid from the modern diet does not cause osteoporosis. It also concluded that an alkaline diet or alkaline supplements or salts do not prevent osteoporosis.
A review of studies published in 2012 found that an alkaline diet resulted in urine that was more alkaline, and possibly less calcium in the urine.
However, the researchers did not expect this to reflect total calcium levels, and they found no evidence that this would improve bone health or help prevent osteoporosis.
A review of the effects of alkalis on cancer was published by Dr. Tanis Fenton and colleagues in the journal BMJ Open.
The review assessed thousands of studies, but the authors found only one proper, randomized test of acid in the diet and cancer of the urinary bladder.
They found no studies about alkaline water and cancer in humans.
The researchers note: “In our experience, patients with cancer are approached by salespeople who are promoting water alkalinizers as a way to treat their cancer.”
One study has suggested that an alkaline diet, but not specifically alkaline water, may enhance the action of some chemotherapy drugs used to treat cancer.
Acid reflux disease is when the contents of the stomach, which are acidic, splash back up the food pipe.
Acid reflux that keeps happening for a long time can cause damage and a disease known as gastroesophageal reflux disease, or GERD.
A study published in Annals of Otology, Rhinology & Laryngology found that drinking alkaline water might be worth further study as a supplement to other treatments for reflux disease.
It found that alkaline water at pH 8.8 stops an enzyme that is connected to reflux disease. It also appeared to reduce the acidity of the stomach contents.
The work was done in a laboratory rather than in humans. More research would be needed to support these findings.
Moreover, stomach acid exists for a purpose. It kills bacteria and other pathogens, and it helps our bodies to digest food and absorb nutrients.
Blood pressure and diabetes
Scientists in Shanghai found that 3 to 6 months after drinking alkaline water, people with high blood pressure, high blood sugar, and high blood lipids had lower measures in each of these factors.
In 2016, researchers found that a high-pH electrolyte water reduced blood viscosity in 100 adults, after exercising. This may help reduce cardiovascular strain due to dehydration.
However, the scientists point out that participants had different measures of whole blood viscosity at the outset, which could have affected the results.
It is worth noting that the study was sponsored by Essentia Water, who also provided the alkaline water used.
Recommended daily intake
As there is no evidence to support the health benefits of alkaline water, there is no recommended amount that improves health.
However, if you wish to start drinking alkaline water, start with a low intake and increase it gradually. This can reduce the corrosive effects of highly alkaline water.