Popularized by celebrities and advertised for multiple health benefits, alkaline water is a controversial topic. Some practically see it as the elixir of life, while for others it’s just over-hyped snake oil. But is there a middle ground? Are any of its purported health benefits backed by science? Read on to find out.

What Is Alkaline Water?

In a nutshell, alkaline water is water that is less acidic than regular drinking water.

Water can be alkaline:

  • Naturally: when it comes from a well or spring rich in alkaline minerals. An example is the water from the Zamzam well in Saudi Arabia, with an average pH of 8 [R].
  • Artificially: when it’s made alkaline with additives, filters, or electric devices [R, R].

The potential effects of alkaline water are based on the same principles as the alkaline diet – the “acid-ash” hypothesis.

According to it, the protein- and grain-rich Western diet increases acid production in the body, which supposedly leads to osteoporosis and other health issues when the body attempts to compensate. Advocates hold that an alkaline diet based on fruits, vegetables, nuts, and legumes would decrease acidity and prevent these disorders [R].

Although the alkaline diet promotes eating several healthy foods, no scientific evidence backs up the acid-ash hypothesis. Additionally, this diet can reduce the acidity of urine but not of blood because the body has its own balancing mechanisms. Several reviews and meta-analyses concluded that the alkaline diet doesn’t prevent osteoporosis [R, R, R, R].

Alkaline water has been popularized by celebrities, athletes, and their trainers in recent years. Despite the shortage of studies, proponents of alkaline water claim that it can help:

  • Delay aging
  • Boost the immune system
  • Cleanse the colon
  • Improve hydration and recovery after exercise
  • Detoxify the body
  • Lose weight
  • Prevent cancer
  • Improve skin and hair health

What Does pH Mean?

PH Scale

Since we’re talking about the effects of alkaline water, it’s important to understand what pH – used to measure how alkaline or acidic something is – means.

pH (short for ‘potential of hydrogen’) is a measure of the acidity or alkalinity of a solution based on its concentration of hydrogen ions.

The pH scale ranges from 0 to 14, 7 being the neutral value. To get a bit more sciency, an increase of 1 pH unit reflects a ten-fold decrease of the hydrogen ion concentration.

Substances with a pH below 7 are considered acidic, while those above this value are alkaline. For instance, common acidic substances include vinegar (pH 3), lemon juice (pH 2), and battery acid (pH 1), while baking soda (pH 8), milk of magnesia (pH 10), and bleach (pH 13) are alkaline.

Your Body’s pH and Acid-Base Balance

Your body needs to maintain the pH of many of its fluids within an extremely narrow range (7.35 – 7.45) to ensure proper functioning. Outside this range, red blood cells can’t transport oxygen, proteins can’t achieve their proper shape, and many biochemical reactions don’t take place [R, R].

It’s important to tightly control the production and elimination of acids (mainly hydrogen ions and CO2) and bases (mainly bicarbonate) to stay within this range. Fortunately, your body has very efficient mechanisms to maintain its acid-base balance.

Breathing eliminates carbon dioxide (CO2) and lowers its concentration in blood. The kidneys take up bicarbonate from the urine into the blood and do the opposite with acids. Both the lungs and kidneys quickly respond to changes in blood pH and adjust your acid-base balance [R].

Imbalances in the production and elimination of acids and bases, often due to lung and kidney failure, shift the pH to values below 7.35 or above 7.45. The four main types of acid-base imbalances are:

What Is the pH of Drinking Water?

Pure water has a neutral pH of 7. Essentially, its alkaline (hydroxide) and acidic (hydrogen) ions balance out.

But drinking water comes from springs and wells. The minerals of rocks and soils are washed into the water as it flows through them. Some of these minerals raise the pH of water, while some others lower it [R].

Depending on their mineral composition, the pH of most drinking waters ranges between 5.6 and 8.5 [R].

What Does Alkaline Water Do?

Because alkaline water has a higher pH (ranging from 8 to 10) than plain drinking water, it may reduce the excess of acids in the body [R, R, R, R].

Ionized alkaline water is a mix of hydroxide ions and hydrogen. The hydroxide ions make it alkaline, while the hydrogen makes it antioxidant. Several suggested effects of ionized alkaline water seem to be related to its antioxidant activity rather than to its alkaline pH.

This type of water neutralizes free radicals and activates the enzymes that break them down, possibly reducing the damage these molecules can cause to cells [R, R].

The hydrogen of ionized alkaline water favors the growth of “good” gut bacteria (which can use it as a nutrient) over the “bad” bacteria (which are killed by it). This may improve digestive function while preventing microbiome imbalances and infections [R, R, R, R, R].

Snapshot of Alkaline Water

PROS

  • Few adverse effects
  • May help balance pH
  • Ionized alkaline water may be antioxidant
  • Rich in minerals if naturally alkaline or alkalized with electrolytes

CONS

  • Insufficient evidence for most benefits
  • Multiple fraudulent or over-hyped claims
  • More expensive than regular water
  • Filtered and ionized water may be poor in electrolytes
  • Ionized alkaline water may contain platinum particles
  • Bottled alkaline water is worse for the environment

Possible Benefits of Alkaline Water

1) General Wellness

In a clinical trial on 60 healthy people, ionized alkaline water (at least 500 mL/day) improved sleep quality and stool hardness better than purified tap water; it also improved an interesting measure of physical and mental fitness called whole body reaction time – how quickly someone can respond to a sound or image trigger [R].

Additionally, ionized alkaline water slightly increased longevity in mice but not in flies [R, R+].

2) May Accelerate Exercise Recovery

Intense physical exercise causes lactate buildup and raises blood acid levels, which may increase fatigue and delay recovery [R+, R].

In 2 clinical trials on 52 athletes, naturally alkaline water increased physical performance and lactate breakdown compared to regular water [R, R].

Similarly, an alkalizing supplement (Alka-Myte) increased power and reduced heart rate, oxygen use, and blood lactate levels after exercise in a clinical trial on 24 skiers [R].

In aged rats, an alkaline solution improved physical performance and accelerated lactate breakdown after physical exercise [R].

3) May Improve Hydration Status

In 4 clinical trials on almost 200 people, alkaline water improved some measures of hydration after physical exercise better than regular water. Specifically, it reduced the thickness and protein levels of the blood and increased the retention of water. As a result, it increased the production of less urine that’s higher in salt [R, R, R, R].

4) Conflicting Effects on Heart Health

Alkaline water is often advertised as a product that promotes heart health. Most claims are based on its higher potassium content; potassium can relax blood vessels, improve blood flow, and normalize heart rate. However, there is no evidence to back up the claim that alkaline water will have these benefits [R].

In 2 clinical trials on over 100 people, ionized alkaline water reduced blood thickness and blood pressure better than regular water, which may lower the risk of excessive blood clotting and heart attacks [R, R].

But animal studies warn us that alkaline water could be a dangerous fad. Ionized alkaline water increased heart tissue death and scarring in rats [R, R, R].

People with heart problems shouldn’t drink alkaline water before clinical studies determine its safety.

5) May Improve Gut Health

Gut microbiome imbalance may cause the bad bacteria to flourish, possibly triggering a host of metabolic and mental health disorders [R, R].

In animal studies, ionized alkaline water stimulated the growth of the bacteria that increase cholesterol use, protect the liver, and boost the immune system; it also lowered those that cause diarrhea and infections [R, R, R].

6) May Improve Digestive Issues

Adding to the benefit above, alkaline water (at least 1.5 L/day) reduced pain, heartburn, fullness, and bloating in a clinical trial on 18 people with indigestion; it reduced pain and discomfort in another trial on 27 people suffering from irritable bowel syndrome with diarrhea (IBS-D) [R+, R].

In rats with digestive issues, bicarbonate-alkaline water improved digestive function, stomach emptying, and bowel movements. In mice, it prevented stomach injuries caused by alcohol [R+, R, R].

7) May Improve Acid Reflux

It was long thought that only stomach acid is to blame for the esophagus damage people with acid reflux experience. However, the digestive enzyme pepsin seems to play a bigger role than previously realized [R].

Pepsin, however, is most active in an acidic environment. Alkaline water inactivated pepsin in test tubes. Together with a Mediterranean diet and reflux precautions, alkaline water also reduced reflux symptoms as effectively as conventional drugs (proton pump inhibitors) in 2 observational studies on almost 300 people [R, R+, R, R, R].

Due to its high pH, alkaline water may also neutralize stomach acid in a similar way to baking soda and antacids.

8) Removing Toxins

Regular water has to be filtered and treated with antimicrobial agents prior to drinking. Unfortunately, antimicrobials react with organic matter (such as algae or microbes) and produce byproducts that might be toxic. These byproducts have even been associated with diseases such as bladder cancer [R, R, R, R].

Naturally alkaline water theoretically contains fewer of these compounds, since many of them are more likely to form in acidic conditions (such as haloacetonitriles, haloacetamides, and halogenic acetic acids). However, other types of harmful compounds are produced under an alkaline pH (trihalomethanes) [R+, R+, R, R].

Using ionized alkaline water to wash foods – such as veggies and fruits – may be a good idea. This washing practice might break down and remove fungal toxins and pesticides, according to a couple of studies [R, R].

9) Insufficient Evidence for Cancer

The recommendation of eating an alkaline diet and drinking alkaline water for cancer is based on the misconception that tumors thrive under acidic conditions, when acidification is actually a consequence of their growth [R, R, R].

A systematic review of 252 studies on acid-base balance and cancer found only one that was relevant and well-designed. This study (on over 27k people) showed that urine acidity doesn’t increase the risk of bladder cancer. This means that reducing urine acidity by drinking alkaline water is probably ineffective for preventing cancer [R, R].

Similarly, a review of 13 non-clinical studies on the alkaline diet found no evidence for its anticancer potential [R].

The alkaline water from the Zamzam well is one of the complementary anticancer therapies most commonly used in Muslim countries. However, its use is due to religious rather than medical reasons since the well is believed to be blessed by God [R, R, R].

In very few animal and cell-based studies, alkaline water killed and stopped the progression of the following cancer types:

  • Lung [R, R]
  • Prostate [R]
  • Skin [R]

10) May Improve Diabetes

In a Chinese clinical study, ionized alkaline water lowered blood sugar levels. This study did not include a control group and we couldn’t access the study specifics, casting doubt on its implications [R+].

In diabetic rats and mice, ionized alkaline water reduced blood sugar and fat levels, increased response to insulin, and preserved pancreatic function [R, R+].

11) Bone Health

In 2 clinical trials on 69 women, bicarbonate-alkaline water (1-1.5 L/day) lowered two markers of bone calcium loss (blood levels of degraded collagen and parathyroid hormone) better than a more acidic water [R, R].

However, a meta-analysis of 55 studies couldn’t find any evidence that acid intake increases the risk of osteoporosis nor that alkaline diets and water protect the bones from this condition [R].

12) May Reduce Obesity

In mice and rats fed a high-fat diet, alkaline water reduced weight gain, blood fat levels, and fat buildup in the liver [R, R, R].

13) Metabolic Acidosis

In dogs and rats with metabolic acidosis due to kidney failure, ionized alkaline water raised blood pH (by increasing bicarbonate and reducing CO2 levels) [R].

Is Alkaline Water Really Good for You?

Since healthy people can naturally maintain their acid-base balance (contradicting the acid-ash hypothesis), the high pH of alkaline water may only benefit those with excess acids due to health issues or strenuous physical exercise.

It’s important to notice that acidosis often indicates serious conditions. People with suspected acidosis shouldn’t try to improve it with alkaline water but consult a doctor immediately.

Evidence suggests that alkaline water is more effective for hydration. There’s no doubt that staying hydrated is key to maintaining good health. But simply drinking regular water is sufficient in most cases. And people with severe dehydration due to intense physical exercise or heavy sweating will need to replace the lost electrolytes in addition to drinking water.

The hydrogen in ionized alkaline water may confer antioxidant activity and explain several of its purported benefits. Because most of these have only been tested in animals and cells, further studies in humans are needed to confirm them and evaluate if the real contribution of alkaline water to health justifies its higher cost.

Alkaline Water Side Effects

Theoretically, alkaline water in excess could raise the body’s pH too much and cause alkalosis. The main symptoms of alkalosis are [R, R]:

  • Nausea, vomiting, and stomach pain
  • Increased breathing rate
  • Irregular heart rate
  • Muscle tremors, twitching, and tingling
  • Confusion, seizures, and even coma

Drinking too much alkaline water may also neutralize stomach acid, which is required to digest food, absorb some nutrients, and kill infectious microorganisms [R+].

However, no cases of metabolic alkalosis or low stomach acid have been linked to drinking alkaline water. This is probably because the acid-base control mechanisms of the body are very effective.

If water is made alkaline by enriching it with calcium, it may increase the risk of developing kidney stones [R].

A potential danger of buying concentrated pH drops to alkalize water is that they can cause burns in case of accidental contact with the skin [R+].

Electrolyzers may release platinum particles into the water when their electrodes get old. Although platinum toxicity at the levels potentially found in ionized water is unknown, excessive exposure to this metal may cause skin allergies, respiratory issues, and kidney damage [R, R+, R, R+].

In rats, alkaline water caused heart muscle cell death and tissue scarring [R, R, R].

Alkaline water accelerated weight gain and development of the cubs in pregnant and breastfeeding rats, possibly due to an increased electrolyte (especially calcium) content in breast milk. However, it reduced growth in adolescent (6-week) rats [R, R, R, R, R].

Pregnant and breastfeeding women should avoid alkaline water due to the lack of clinical safety data.

Limitations and Caveats

Study Design

Except for its effects on hydration and physical recovery, the health claims linked to alkaline water have been tested in very few human studies or only in animals and cells.

Additionally, most human studies had a small number of participants. Therefore, more clinical trials with larger samples are required to validate these preliminary results.

Other limitations in the design of the studies include:

  • Obtaining the data mainly from subjective questionnaires [R]
  • Combining alkaline water with healthier diets and habits, making the contribution of alkaline water difficult to estimate [R, R]
  • Using control water with a totally different electrolyte composition [R, R]

Results

Different studies on the use of alkaline water for longevity, cancer, and heart and bone health had contradicting results. Further investigation is required to clarify them.

Funding and Conflict of Interest

Some studies were funded by companies selling alkaline water (Glacier Water Company, Uliveto, Danone, Essentia, and Evian) or electrolyzers (Asiagem). Others included workers or consultants of companies selling electrolyzers (Panasonic and Restech) among the authors [R, R+, R+, R, R+, R, R, R].

How to Make Alkaline Water

In addition to buying bottled alkaline water, it’s possible to make it at home from regular tap water and reduce the production of plastic waste.

The cheapest way is to add substances that make water more alkaline. You can add ⅛ tablespoon of baking soda or lemon juice (which is acidic but is broken down to alkaline byproducts when digested) per cup of water. Concentrated alkaline pH drops are also available.

You can also buy an alkaline bottle or pitcher. Bottles contain beads that release alkaline salts into the water. In turn, pitchers include filters claimed to remove not only acidic electrolytes, but also possible contaminants and chlorine (which changes the smell and taste of water).

A more expensive possibility is to install an alkaline water filter or reverse osmosis system in your home. It removes the salts that make water acidic and many impurities. Its price and the fact that it may also remove beneficial minerals from water are its main drawbacks.

Finally, you can use an alkaline water machine (water ionizer or electrolyzer). This expensive device uses an electric current to split water into an alkaline and an acidic solution. It’s normally attached to the faucet and has one hose for each solution. You can use alkaline water to drink and cook and leave acidic water to clean the dishes or wash your hands [R].

Alkaline Water Brands

Some of the main commercial brands of alkaline water are:

  • Flow: naturally alkaline water with a pH of 8.1
  • Icelandic Glacial: naturally alkaline water with a pH of 8.4
  • Evamor: naturally alkaline water with a pH of 8.8
  • Essentia: ionized alkaline water with a pH of 9.5
  • Perfect Hydration: with added electrolytes and a pH of 9.5
  • Phure: with added electrolytes and a pH of 9.5
  • Alkalife Ten: with added electrolytes and a pH of 10

Alkaline Water Reviews

Because users normally buy alkaline water expecting long-term benefits, most reviews (either good or bad) focused on the taste, composition, price, tested pH, packaging, and delivery service – as they would for regular bottled water – rather than on observed effects to rate the different water brands.

Only users with acid reflux experienced immediate benefits of alkaline water. In general, they were satisfied with the results and reported improved symptoms.

Those who bought a pitcher or bottle were generally happy that they could stop buying bottled water for a reasonable price. Issues with the filter and bad taste of the water were the negative aspects most commonly reported. In the case of bottles, some users also complained about their size and ergonomy.

Users of alkaline water machines were normally happy and those who weren’t mainly complained about the taste of the water, problems to install these machines, and (especially) about their high price.

In the case of Kangen electrolyzers, many people complained about the company. Bad customer service, unscrupulous sellers, and abusive fees where the most common issues.

Buy Alkaline Water

Take-Away:

Alkaline water is water that is less acidic than regular drinking water – either naturally or through alkalizing procedures. Currently a growing trend popularized by celebrities, alkaline water is often advertised as a miracle product that will increase your general wellbeing, detox your body, and improve several health conditions such as acid reflux, obesity, and even cancer.

Unfortunately, many of these claims haven’t been proven or are directly based on erroneous science interpretations.

Although healthy people can regulate their acid-base balance without any additional aids, this water may help those with excess acids due to health issues or strenuous physical exercise. In the case of ionized alkaline water, its antioxidant activity has some promising benefits that need further investigation.

About the Author

Carlos Tello, PhD (Molecular Biology)

PhD (Molecular Biology)

Carlos received his PhD and MS from the Universidad de Sevilla.

Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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