Alkaline Water and Cancer

pH scale, alkaline water is an 8 or 9 Photo©Alexey Bezrodny

Alkaline water has been touted to have benefits for people with cancer and for cancer prevention, but what does the research say? The theory behind alkaline water (or an alkaline diet) and cancer is that some cancer cells grow better in acidic environments. In addition, the tissue surrounding cancerous tumors tends to be, in fact, acidic.

While the literature is relatively scant, it's important to also look at what happens when alkaline water enters the tightly regulated milieu of the body. We will take a look at studies to date, the regulation of acid-base balance in the body, and current investigation into the use of alkaline water and diets.

What Is Alkaline Water?

Alkaline water is simply water (H2O) that contains alkaline minerals. While regular tap water has a pH that is around 7.5, alkaline water usually has a pH of 8 or 9. On its own, pure water is completely neutral. It is the minerals present (such as sodium, calcium, magnesium, an others) that can alter its pH.

Sources of Alkaline Water

Alkaline water can be obtained in a number of ways, including by adding bicarbonate (baking soda) to water, with filters or via ionizers, or by purchasing bottled alkaline water.

Tap Water

According to the Environmental Protection Agency, tap water should have a pH of 6.5 to 8.5, though in some regions it has been found to be lower than this.

Most water contains some minerals, and it's important to be aware of the presence of minerals in water when looking at potential benefits. For example, if alkaline water were found to have a positive benefit for someone, it could simply be that a trace mineral that was deficient has now been replaced.

An exception is water that is filtered by a reverse-osmosis system in which all of the minerals are removed. The importance of trace minerals can be seen by anyone who has watered their houseplants with only reverse-osmosis-treated water: they don't do well.

Alkaline Diet

Some proponents of alkaline water also recommend an alkaline diet (for similar reasons). Food components that are acidic or alkaline include the following.

  • Alkaline: Most vegetables, fruits, seeds, lemon juice (lemon juice is acidic outside the body, but is paradoxically alkaline due to the way it is metabolized in the body)
  • Acidic: Meats, beans, nuts, grains

In general, foods that are alkaline in nature tend to be healthier than those that are acidic. That said, there are exceptions, such as beans, nuts, whole grains, and carrots, which are acidic but very healthy.

pH Balance in the Body

To understand the potential benefits of alkaline water, it's important to discuss pH, how pH is regulated in the body, and what happens to pH throughout the digestive tract.

What Is pH?

pH is a scale that measures the acidity or alkalinity of a substance. On a scale of 1 to 14, 7 is considered neutral, with a pH of 0 to 7 considered acidic and a pH of 7 to 14 considered alkaline.

pH is measured on a logarithmic scale. What that means is that, for each increment in pH, there is a 10-fold difference in acidity or alkalinity (similar to earthquake or hurricane measurements).

For example, a substance with a pH of 3 would be 10 times more acidic than a substance with a pH of 4. On the other side of the scale, a substance with a pH of 11 would be 10 times more alkaline (or basic) than a substance with a pH of 10.

To put this in perspective, some examples of pH include:

  • pH 7: Battery acid
  • pH: 1.5-3.5: Stomach acid
  • pH 2.0: Lemon juice, vinegar
  • pH 3.3-4.2: Orange juice
  • pH 4-5: Tomato juice, beer
  • pH 5.0: Black coffee
  • pH 6.7-6.9: Milk
  • pH 7.0: Pure water
  • pH 8.0: Baking soda, sea water, toothpaste
  • pH 9.0: Borax
  • pH: 10.0: Milk of magnesia
  • pH 11.0: Ammonia
  • pH 12.0: Hair straighteners
  • pH 13.0: Bleach
  • pH 14.0: Drain cleaner

Normal Body pH

While different parts of the body may regulate their own pH (for example, vaginal secretions are more acidic), the pH of the blood is remarkably stable and slightly alkaline, with a systemic arterial pH that lies between 7.35 and 7.45.

This pH is optimal for the majority of enzymes (proteins) in the body, which would not function well (i.e., proteins denature) outside of this range. In fact. a pH lower than 7.0 (severe acidosis) or higher than 7.7 (severe alkalosis) is incompatible with life.

In contrast to blood pH, urine pH can change depending on diet and cellular processes. In other words, urine pH can change to maintain a constant pH of the blood. Healthcare providers measure blood pH by checking arterial blood gases and electrolytes.

pH Regulation

There are different mechanisms the body uses to maintain a pH within this range and maintain homeostasis.

  • Respiratory system: The lungs play a large role in regulating blood pH and are the greatest source of acid elimination. When the blood becomes slightly acidotic (when too much acid is produced by the cells of the body), excess acid is removed as carbon dioxide (CO2) via the lungs (by hyperventilating).
  • Kidneys: The kidneys can regulate blood pH by reabsorbing bicarbonate, by excreting ammonia (NH+), or by forming titratable acids. The kidneys play a secondary role in acid regulation and do so much more slowly than the lungs.
  • Extracellular and intracellular buffers.

Due to the body's regulatory mechanisms, it is extremely difficult to alter the pH of the blood.

In one study in which subjects were treated with bicarbonate enriched mineral water (alkaline water) plus an alkaline diet, blood pH changed on average only 0.014 units. This was less than the normal daily variation in pH among the subjects. Urine pH, however, did change by roughly 1.0 unit.

In a different study, it was again found that people given alkaline supplements or an alkaline diet had changes in their urine pH, but no appreciable change in their blood pH.

Acidosis and Alkalosis

There are medical conditions in which the normal pH of the blood may be altered, becoming acidotic or alkalotic.

This can be due to some respiratory conditions.

Metabolic conditions can also result in acid-base abnormalities in the blood.

When an abnormal blood pH occurs in these settings, a number of treatments are available.

pH and the Digestive Tract

When looking at alkaline water, it's helpful to consider what happens when it enters the digestive tract. The normal pH of the stomach in young, healthy subjects is 1.5 to 3.5.

This pH can be somewhat higher in premature infants and the elderly, and is associated with an increased risk of bacterial infections in the stomach and small intestine.

If a person drinks alkaline water or takes an antacid, it may increase this pH, but only very transiently. When food passes through the stomach into the small intestine, it is neutralized by enzymes and digestive juices so that the contents all have the same pH.

Since most uptake of water occurs in the intestines, the water that enters the bloodstream will have the pH of the small intestine digestive juices rather than the pH present at the time of drinking.

After food is digested and metabolized, there are end products present. These "leftovers" may be either acidic or alkaline and are referred to as "ash."

Alkaline Water and Cancer

Studies looking at alkaline water and cancer demonstrate the difficulty of predicting what will happen in the body based on studies in a dish in the laboratory.

When cancer cells are grown in a dish (in vitro) they grow faster in an acidic environment. In contrast, they are inhibited in an alkaline environment (as are normal cells).

It has been noted that the area surrounding cancerous tumors (referred to as the tissue microenvironment) tends to be acidic. This acidity is thought to be, at least in part, due to the differences in metabolism between cancer cells and normal cells. An acidic environment, in turn, is thought to play a role in both the progression and spread (metastasis) of tumors.

As noted, consuming alkaline water has little effect on changing the pH of the blood, but a few studies have also looked at the effect of alkaline water (or diet) on the development or progression of cancer.

In a large systematic review (combining 252 abstracts) looking at alkaline water and cancer, there did not appear to be any evidence that consuming this water had any effect on the initiation (development) or treatment (progression) of cancer. In only one of the studies was any significant association found, and that, in turn, was slight (between pH and bladder cancer).

A Finnish study looking specifically at men with bladder cancer and an alkaline diet, however, found that a lower urine pH (reflective of the alkaline measures) did not significantly reduce the risk of developing bladder cancer.

Alkaline Water and Other Conditions

There is one setting in which alkaline water may demonstrate a health benefit for some people, although studies to evaluate this in humans have not yet been done. In a 2012 in vitro study, it was found that alkaline water with a pH of 8.8 was able to inactivate pepsin in the stomach.

Pepsin is a digestive enzyme which, when it enters the esophagus (such as in a person who has gastroesophageal reflux disease), may cause irritation to the esophagus. Certainly, antacids may have a similar effect (at a lower cost).

There are also some very early ongoing studies looking at the possible effect of alkaline water on longevity. These studies are lab-based, and it's impossible to know whether they will translate to studies in humans at all.

For example, a 2020 study looked at the length of telomeres in mice fed with alkaline water. Telomeres are the regions of DNA found at the end of chromosomes, a shortening of which is correlated with aging.

In this study, the mice fed alkaline water had an increase in telomere length (an estimate of molecular aging). There are many steps that would need to be taken to know whether these changes actually correlate with aging, let alone would also occur in humans.

Finally, if any studies eventually find that alkaline water plays a role in health, it will be necessary to see if any effects were actually due to the alkaline water, or to the replacement of trace deficiencies that were alleviated by the minerals in the water. Likewise, alkaline foods may be beneficial due to the phytonutrients they possess rather than anything related to their pH.

Potential Side Effects of Alkaline Water

For those who are considering the use of alkaline water despite little evidence that it plays a role in cancer prevention or treatment, there are relatively few side effects, at least for people with normal kidney function.

However, side effects of alkaline water consumption could potentially include symptoms of metabolic alkalosis, such as nausea, vomiting, dry, itchy skin, tingling, or confusion.

Conditions related to a change in stomach pH must also be considered. For example, as noted above, the elderly and premature infants who may have an elevated stomach pH may also be predisposed to bacterial infections (bacterial overgrowth) of the stomach.

This makes sense if you consider that one of the functions of stomach acid is to remove bacteria present on the surface of foods. In addition, since the acidic environment of the stomach is important in the breakdown of some foods, an excess of alkaline water could theoretically interfere with digestion.

For many people, the greatest "side effect" may be the expense. Bottled alkaline water is quite expensive, especially if you consider that water with a similar pH could be obtained by adding a little baking soda. On the other hand, the ionizers that are sold for manufacturing your own alkaline water can run upwards of a thousand dollars.

Cautions and Contraindications

Anyone who has kidney disease, heart failure, or gastrointestinal conditions should drink alkaline water with caution, and talk with your healthcare provider before doing so. Likewise, for those living with cancer, it's important to talk to your healthcare provider about any dietary regimens you are considering.

For those with bladder cancer who are considering alkaline water, another concern may arise. The action of the drug ciprofloxacin (an antibiotic used to treat urinary infections and to help prevent bladder cancer recurrence), may be greatest at a low urine pH. As noted, urine pH would be likely to increase with alkaline water.

A Word From Verywell

Overall, based on studies to date, alkaline water appears to have little effect on the development or progression of cancer. Considering the cost of alkaline water, some of the simple but proven methods of reducing cancer risk (such as eating healthy diet and exercising) may be more worthwhile.

As far as an alkaline diet, many of the foods considered alkaline are healthy relative to those considered acidic. But several acidic foods, such as beans, are also important in a balanced diet focused on reducing risk. While it would be nice to have a "quick fix," such as switching over to alkaline water, the tried and true methods to reduce cancer risk remain our best bet.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."