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The Alkaline Diet is Nonsense

The fake claims of the alkaline diet

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First published: 11.Oct.2018


The alkaline diet (also known as acid-ash diet) claims that our Western diet "acidifies" the body and that this acidity causes diseases such as osteoporosis, heart disease, arthritis, and cancer.

The alkaline diet is also promoted as a treatment for diabetes and hypertension, but its greatest claim is that it can prevent the appearance of cancer or, treat cancer once it has developed.

These claims are false.

This article will debunk these wild claims, criticize the lack of rigorous science behind this fad diet and point out its incongruencies.

In this Article (Index)

rubber stamp: Rejected
False or unfounded claims. Not based on scientific facts

What is the Alkaline Diet?

The alkaline diet is based on the false notion that you can alter the pH balance of your body and blood by modifying the food that you eat.

It assumes that ingesting more "alkaline" foods than "acid" ones will tip the balance of your body's pH making it more alkaline.

It also states (but offers no scientific evidence to support this notion) that alkalinity is better than acidity, and blames our "acidic" Western diet for a wide range of diseases and health conditions.

Acidic bodies are supposed -and again, these claims are not backed by evidence- more prone to arthritis, kidney, and liver disorders, heart disease, osteoporosis, and even cancer.

It classifies food according to their "ash" content, this "ash" is a residue formed when the food is burned. There are two types of ash:

  • Acidic-ash: meat, wheat, grains, sugar, dairy products, alcohol, processed foods, caffeine.
  • Alkaline-ash: fruits and vegetables (except prunes, plums, cranberries).

Let's look into each of these assumptions and learn the real science behind our body's "acidity", "alkalinity" and "pH balance":

Acids and Alkalis

Let's first understand what an acid and an alkali are: The distinction is based upon how certain substances behave when diluted in water.

Certain molecules split into atomic structures called "ions" in the presence of water. Ions unlike regular molecules possess an electrical charge which can be either positive (called a cation) or negative (an anion).


An acid is a substance that when it is mixed with water produces an anion and a positively charged hydrogen ion or cation. This cation is a hydrogen atom stripped of its only electron. It is written H+. The remaining part of the diluted acid forms a negatively charged ion.

For instance, hydrochloric acid which is the combination of one atom of hydrogen (H) and one of chlorine (Cl), when diluted in water, dissociates as follows: HCl → H+ + Cl-.

Substances the form H+ are acids.

Some examples of edible acids:

  • Acetic Acid (found in vinegar)
  • Citric Acid (found in lemons and oranges)
  • Lactic Acid (causes the distinctive tang of yogurt)
  • Ascorbic Acid (vitamin C)


Alkalis are also known as "basic" or "alkaline" substances; they behave differently in water: one of their components is a negatively charged hydroxyl ion: OH-.

The presence of the hydroxyl ion tells us that a substance is "basic".

For instance, sodium hydroxide (caustic soda) in water splits according to the following chemical reaction: NaOH → Na+ + OH-.

Some examples of clearly alkaline basic edible substances:

  • Milk of Magnesia
  • Baking soda

How we measure acidity or akalinity: pH

A scale is used to measure the acidity or alkalinity of a substance. It uses a value called pH.

It measures the concentration of hydrogen (H+ cations) or hydroxyl (OH- anions) to define how acid or basic is a given substance.

pH stands for "Potential of Hydrogen", and it uses a logarithmic scale that ranges from 0 (most acidic) to 14 (most alkaline). The midpoint value of 7 is that of a neutral solution.

As the scale is logarithmic and not linear, the difference between two units on the scale is not "one" (1), but "ten" (10). Let's explain this:

If a tomato has a pH of 4, and coffee a pH of 5 (both are acidic), tomatoes are ten times more acidic than coffee. As milk has a pH of 6, tomatoes with a pH of 4 are two units away, or 10 by 10 = 100 times more acidic than milk.

Vinegar with a pH of 3 is 10 times more acidic than tomatoes, 100 times more acidic than coffee, and 1000 times more acidic than milk.

Our body's pH

Evolution has shaped our biochemical processes over billions of years. Although some regions of our bodies are highly acidic (the stomach for instance uses HCl or hydrochloric acid to help us digest food) overall the body has a pH of approximately 7.4, which is slightly alkaline.
The reason for this is that the enzymes that catalyze (speed up) our body's biochemical reactions can only work within a very narrow pH range. Any shift in pH either towards a more acidic or a more alkaline environment will disrupt our body's biochemistry and cause our death.

Body Acidity and Alkalinity: a perfect balance

A stable pH range is critical for survival. Any changes in our body's pH are quickly adjusted back to its correct value. This process is known as "homeostasis" from the Greek words "homo" = "the same" and "stasis" = "standing still".

allegory of perfect balance: woman doing yoga pose at sunset
Perfect balance

The body has several self-regulating mechanisms to keep its pH within strict limits (7.35 to 7.45). These mechanisms are based on simple chemistry: the body removes excess ions by neutralizing them.

It uses ions or electrically charged molecules to bind to the positive hydrogen ions (acidic) or the negative charges (alkaline) and therefore removes them from circulation, adjusting the pH (1):

Protein Buffers

Proteins are long chains of amino acids that contain amino groups with a positive charge and carboxyl groups with a negative charge. Therefore they can act as buffers and bind to hydrogen or hydroxyl ions in the blood or inside our body's cells.

Buffer Solutions

A buffer solution resists changes in pH when strong acids or bases are added to it: it maintains a constant pH.

Our body uses these solutions to keep its pH within a narrow range:


Hemoglobin is a protein in our red blood cells that transports oxygen to the body's cells.

Our cells "burn" fuel combined with oxygen and generate carbon dioxide (CO2).

The carbon dioxide dissolves into the water that forms part of the bloodstream's fluid, forming carbonic acid, which in turn dissociates into a hydrogen ion and a carbonate ion:

CO2 + H2O → H2CO3 → H+ + HCO3-

Hemoglobin picks up the hydrogen ions removing them from the bloodstream, lowering its acidity, and this increases its pH.

Nerve cells detect the pH changes very quickly and this regulates respiration (more CO2 generated means more acidity and therefore you must breathe faster to eliminate it by exhaling it through your lungs).

When hemoglobin reaches the lungs the process is reversed and CO2 diffuses into the air sacs and is exhaled.

The opposite happens when you hyperventilate (deep and rapid breathing intaking more than you exhale): it removes carbon dioxide from the blood lowering the levels of carbonic acid and therefore alkalinizing the blood, hold your breath a few seconds and CO2 will build up again, balancing pH to its normal levels.

Phosphate buffering

Our blood contains two different types of phosphates, one is a weak acid (disodium hydrogen phosphate), the other is a weak base (sodium monohydrogen phosphate). The weak base will combine with hydrogen ions and revert into the weak acid form. This buffers blood pH reducing acidity. On the other hand, if the blood is more alkaline, the weak acid will react with the hydroxyl ion (and therefore reduce the pH) as it reverts to the weak base form.

Bicarbonate Buffer

It is similar to the phosphate buffering. In this case, sodium bicarbonate reacts with the hydrogen ion becoming a weak acid (carbonic acid). This uptake of H+ ions lowers blood acidity.

If on the other hand, a carbonic acid molecule encounters a hydroxyl ion (OH-), it reacts with it, removing it from the blood and lowering pH.

Our bodies have more bicarbonate than carbonic acid because most of our body's metabolic byproducts are acids (lactic acid or ketones) and therefore more hydrogen needs to be withdrawn from the blood.

The ultimate regulation of bicarbonate levels in the blood is controlled by our kidneys:

Renal regulation

Our kidneys maintain our acid-balance by reabsorbing bicarbonate from urine and excreting hydrogen ions into our urine (and making it acidic in the process).

About the acidic areas of our body

Although our body maintains the pH inside cells, and in the intracellular spaces constant, pH inside the digestive system can vary from an extremely acid 1.5 in the stomach to an almost neutral pH in the rectum. Fallingborg (1999) describes the different pH values of our digestive system as follows (2):

"... pH is rapidly changed from highly acid in the stomach to about pH 6 in the duodenum. The pH gradually increases in the small intestine from pH 6 to about pH 7.4 in the terminal ileum. The pH drops to 5.7 in the caecum, but again gradually increases, reaching pH 6.7 in the rectum."

So, pH conditions in blood and intracellular spaces is stable, but in our digestive system, it has a wide range of variation. But neither the pH of our bowels or the pH of the urine in our bladder can affect the pH of our bloodstream.

The Fake Science behind the Alkaline Diet

Acid-Ash and Alkaline-Ash

The "ash" theory dates back to the 1800s when different foods were incinerated and their ash analyzed. Of course, during combustion, all the carbon, nitrogen, and hydrogen that is present in food combines with oxygen to form carbon dioxide, nitrogen oxides, and water, that escape as gas and water vapor.

What is left behind are the minerals and metals contained in the food: sulfur, phosphorus, calcium, iron, etc.

These minerals are the ones that define the acidity or alkalinity of the ash:

  • Alkaline-ash foods have higher concentrations of calcium, magnesium, potassium, and sodium in their ash.
  • Acid-ash foods contain chloride, iron, phosphorus, or sulfur, minerals that form acid compounds.

This theory has two drawbacks:

It does not look into the actual acidity or alkalinity of the food before its incineration. For instance, lemon juice contains citric acid (C6H8O7) and is therefore an acidic food, but when it is incinerated, the hydrogen will combine with oxygen to form steam, the carbon will combine with oxygen to form carbon dioxide and the oxygen will be released or form oxides. The resulting "ashes" will be produced by the minerals that may be present in the lemon juice and these, according to an article published by the University of Arizona (3), are more alkaline than acidic!! so lemon juice would be classified as being alkaline, which is absurd since it is acidic.

The second problem behind this reasoning is that our bodies do not incinerate food and re-assemble the "ashes" into bases or acids. The proteins we ingest, regardless of their origin (from a vegetable or beef) are broken up into their building blocks, amino acids, and reassembled into new proteins by our body.

Other foods are not even acidic or alkaline: for instance, refined sugar, it has no minerals, it is a molecule composed of carbon, hydrogen, and oxygen: C12H22O11. If it is incinerated it will turn into steam and carbon dioxide, no ashes will remain other than the impurities from its processing. The same can be said about fats and oils (olive oil, butter, coconut oil, etc), whether vegetable or animal they are purely organic molecules with small residues of other elements.

You can't alter your body's pH through diet

The alkaline diet states that one can make the body more alkaline by eating alkaline foods. This is not possible.

Regardless of the original acidity or alkalinity of food, as it passes through our digestive system it is broken down into its molecular components.

The food is bathed in a highly acidic environment in our stomach and then neutralized with digestive enzymes from the pancreas and gallbladder before entering the intestines.

Nutrients and water that are released during the digestive process are then absorbed by the walls of the intestine, passing into our bloodstream.

The ionic compounds will dissociate in the blood and some hydrogen and hydroxyl ions will form. But, blood's pH, as we have seen further up, is one of the most tightly regulated variables in our whole body, it fluctuates within a slightly alkaline and very narrow range: pH 7.35 to 7.45.

So these ions will be quickly neutralized to maintain the normal pH balance.

Supplementation with alkaline minerals

Researchers from the University Hospital of Freiburg, Germany investigated the effects of ingesting supplements rich in alkaline minerals (a daily dose containing 65 mEq of alkalis) (4).

They found that the subjects' blood pH rose by 0.01 from 7.4 to 7.41, which shows how strong the body's homeostasis mechanism is. Of course, the excess alkalinity removed from the bloodstream had to be excreted, and this was reflected by an increase of urinary pH (it became more alkaline) from 5.94 to 6.57. This study shows that:

  • Blood pH is not modified significantly by supplementation with alkaline minerals
  • The surplus alkalinity is excreted.

Osteoporosis and an acidic diet

Supporters of the alkaline diet consider that our Western diet provokes a chronic subclinical acidosis, meaning it is not severe enough to display symptoms. This diet supposedly "acidifies" our blood and leaches alkaline calcium salts from our bones to maintain our acid-base balance.

This process weakens our bones provoking osteoporosis.

Below we mention two studies that found no relationship between dietary acid load and osteoporosis:

A Canadian research team from the University of Calgary reviewed 238 studies in a meta-analysis (a strict statistical evaluation) and concluded that (5):

  • There was no evidence for an adverse role of phosphate, milk, and grain foods (considered acidic foodstuffs) on osteoporosis.
  • There is no support for a casual association between dietary acid load and osteoporotic bone disease.
  • There is no evidence that an alkaline diet is protective of bone health.

They revisited the subject in 2017 (6), and once again reached the same conclusions: "There is no evidence from superior quality balance studies that increasing the diet acid load promotes skeletal bone mineral loss or osteoporosis (...) Promotion of the 'alkaline diet' to prevent calcium loss is not justified."

Furthermore, they didn't find any evidence that "phosphate intake contributes to demineralization of bone or to bone calcium excretion in the urine."

And the study gives a strong warning: "Dietary advice that dairy products, meats, and grains are detrimental to bone health due to 'acidic' phosphate content needs reassessment. There is no evidence that higher phosphate intakes are detrimental to bone health."

Excessive ingestion of Vinegar

At the other extreme of the pH fads, lies the risky ingestion of large quantities of vinegar (an acidic beverage).

Those who believe that "apple cider vinegar", or any other vinegar is good for their health should consider the following case reported by Lhotta (7):

A woman who had drunk, for a period of 6-years, half a pint (250 ml) daily of apple cider vinegar suffered severe health effects.

The excessive amounts of acid in the apple cider vinegar were converted into bicarbonate in the liver and excreted by the kidneys. So the woman's body pH remained unchanged, but the urine excretion that removed the bicarbonate also eliminated sodium and potassium ions. This altered her electrolyte balance and provoked osteoporosis.

Electrolytes are charged atoms or molecules (ions) that critical for many body processes that function by using electric current. If this balance is disrupted the consequences can be very serious and can even lead to death.

Read More

> > Apple Cider Vinegar side effects. The health risks of drinking too much vinegar.

Cancer and alkaline - acid conditions

Those marketing the alkaline diet promote the "fact" that alkaline foods are a way to prevent cancer and also to treat it. This creates confusion among oncological patients and may have serious health consequences. Let's check the scientific evidence:

Alkaline diet supporters claim that cancer cells and tumors proliferate in an acidic environment and that an alkaline diet will increase the body's pH, making it more alkaline and therefore unsuitable for the growth of cancerous cells.

The facts are quite different and quack claims often combine truths with fake claims to create a credible story. Let's go into the details:

Fact: Yes, Tumors create their own acidic microenvironment

The pH inside normal cells is slightly alkaline (pH 7.1) and the extracellular region that surrounds them is also alkaline, with a slightly higher pH of 7.35 (8).

But cancer cells behave differently: In 1930, Otto Warburg discovered that tumors consumed glucose to keep alive and released lactic acid which combined with carbonic acid produced by the tumors acidifies the spaces between cells (interstitial space), lowering the pH to values ranging from 6.3 to 7.0 (9, 10, 11).

The glucose metabolism of cancer cells creates highly alkaline conditions inside the cell (higher than that of normal cells), which promotes its aggressive behavior.

This acidification provoked by tumors is an advantage for them; Kato (2013) found that although "acidic pH is toxic to many cells, including tumors", tumors that have managed to adapt to an acidic condition then "use it for their own cellular activation, this increases drug resistance and leads to more aggressive behavior" (12).

Ibrahim-Hashim and Estrella (13) describe how this acidity helps tumors proliferate: "... by inducing genome instability, promoting local invasion and metastases, inhibiting anti-tumor immunity, and conferring resistance to chemo- and radio-therapies".

So here the half-truth of the alkaline diet seems logical: add alkalis to your diet to neutralize the tumors' acid surroundings and kill it.

The suggestion of neutralizing tumor acidity on a local level to help control metastasis sounds reasonable.
Therapy that would increase extracellular pH (making it more alkaline) and decrease intracellular pH (making it more acidic or neutral) should be effective.
But, Estrella and Ibrahim-Hashim report that the phenomenon is poorly understood and that this buffering therapy has not been effective against tumors. They recommend looking for "alternative approaches and agents that will directly or indirectly raise tumor pH to be used in combination with chemo or immune therapy."

Alkaline environments may promote some cancers

It seems that far from combating cancer, an alkaline enviroment may promote some types of cancer.

Khajah and his team (14), found that an alkaline microenvironment enhances their invasive potential of endocrine-resistant breast cancer cells. And caution that some "newer therapeutic strategies aimed at reversing or even alkalinizing pH of the extracellular matrix may be counter-productive for endocrine resistant cells," and wars "against indiscriminate application of alkalinising drug therapy."

A recent study (Ninna et al., 2020) using mice, found that consuming alkaline water (doped with baking soda) promoted cancer growth (16).

Acidifying the interior of tumors may be beneficial

Targeting the internal alkaline environment of a tumor with a drug is considered a more promising approach (9) this means making it less alkaline, or more acidic.

Another study by Harguinedey et al. (15) suggest that "the attempt to induce cellular acidification using proton transport inhibitors and other intracellular acidifiers of different origins is becoming a new therapeutic concept and selective target of cancer treatment."

An alkaline diet does not prevent cancer

Fenton and Huan conducted a meta-analysis in 2016 involving 252 studies to verify if there was any link between acid ⁄ alkaline diets and cancer. They found that (17):

  • Despite the promotion of the alkaline diet and alkaline water by the media and salespeople, there is almost no actual research to either support or disprove these ideas.
  • The promotion of the alkaline diet and alkaline water to the public for cancer prevention or treatment is not justified.

Closing Comments

There is no scientific proof to support or validate the claims put forward by the proponents of the alkaline diet.

Eating "alkaline" foods does not alkalinize your body, it does not reduce "acidity", whatever that may be, and does not modify the body's pH.

On the contrary, by banning healthy foods from your diet, it may cause more harm than good.

Furthermore, there is no evidence that it prevents or cures cancer.

References and Further Reading

(1) Anatomy and Physiology 26.4 Acid-Base Balance, Rice University

(2) Fallingborg J, (1999). Intraluminal pH of the human gastrointestinal tract, Dan Med Bull. 1999 Jun;46(3):183-96

(3) Fallahi, E. & Moon, J. W. Jr. (1988). Effects of Canopy Position on Quality, Photosynthesis and Mineral Nutrition of Four Citrus Varieties. Journal Citrus Research Report, Pub. College of Agriculture, University of Arizona (Tucson, AZ).

(4) Daniel König, et al., (2009) .Effect of a supplement rich in alkaline minerals on acid-base balance in humans, Nutr J. 2009; 8: 23. 2009 Jun 10. doi: 10.1186/1475-2891-8-23

(5) Tanis R Fenton et al, (2011). Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill's epidemiologic criteria for causality, Nutrition Journal201110:41

(6) Carol J Fenton Tanis R Fenton Tian Huang, (2017). Further Evidence of No Association between Dietary Acid Load and Disease, The Journal of Nutrition, Vol 147:2, 1 February 2017, pp272,

(7) Lhotta K., Höfle G., Gasser R., Finkenstedt G., (1998). Hypokalemia, Hyperreninemia and Osteoporosis in a Patient Ingesting Large Amounts of Cider Vinegar, Nephron 1998;80:242-243

(8) Tomas Koltai, Rosa A. Cardone,and Stephan J. Reshkin, (2019). Synergy Between Low Dose Metronomic Chemotherapy and the pH-Centered Approach Against Cancer. Int J Mol Sci. 2019 Nov; 20(21): 5438. doi: 10.3390/ijms20215438

(9) Grillo-Hill B.K., Choi C., Jimenez-Vidal M., Barber D.L. (2015). Increased H+ efflux is sufficient to induce dysplasia and necessary for viability with oncogene expression. eLife. 2015;4:4. doi: 10.7554/eLife.03270

(10) Shen-Han Lee and John R. Griffiths, (2020). How and Why Are Cancers Acidic? Carbonic Anhydrase IX and the Homeostatic Control of Tumour Extracellular pH. Cancers (Basel). 2020 Jun; 12(6): 1616. doi: 10.3390/cancers12061616

(11) Boedtkjer E, Pedersen SF.The Acidic Tumor Microenvironment as a Driver of Cancer. Annu Rev Physiol. 2020;82:103-126. doi:10.1146/annurev-physiol-021119-034627

(12) Yasumasa Kato (2013). Acidic extracellular microenvironment and cancer, Cancer Cell Int. 2013; 13: 89. 2013 Sep 3. doi: 10.1186/1475-2867-13-89

(13) Arig Ibrahim-Hashim and Veronica Estrella, (2019). Acidosis and Cancer: from Mechanism to Neutralization. Cancer Metastasis Rev. 2019 Jun; 38(1-2): 149–155. doi: 10.1007/s10555-019-09787-4

(14) Maitham A. Khajah, Iman Almohri, Princy M. Mathew, and Yunus A. Luqmani, (2013). Extracellular Alkaline pH Leads to Increased Metastatic Potential of Estrogen Receptor Silenced Endocrine Resistant Breast Cancer Cells, PLoS One. 2013; 8(10): e76327. Published online 2013 Oct 1. doi: 10.1371/journal.pone.0076327

(15) Harguindey S, et al. (2017). Cellular acidification as a new approach to cancer treatment and to the understanding and therapeutics of neurodegenerative diseases. Semin Cancer Biol. 2017;43:157-179. doi:10.1016/j.semcancer.2017.02.003

(16) Ninna C. S. Voss, Thomas Dreyer, Mikkel B. Henningsen, Pernille Vahl, Bent Honore and Ebbe Boedtkjer (2020). Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO3 Therapy in Murine Breast Tissue. Cancers (Basel). 2020 Apr; 12(4): 891. doi: 10.3390/cancers12040891

(17) Tanis R Fenton and Tian Huang, (2016). Systematic review of the association between dietary acid load, alkaline water and cancer, BMJ Open. 2016; 6(6): e010438. 2016 Jun 13. doi: 10.1136/bmjopen-2015-010438

About this Article

The Fake Claims of the Alkaline Diet, A. Whittall

©2023, 01 Sept. 2023. Update scheduled for 01 Sept. 2025.

Tags: Apple Cider Vinegar (ACV), acne, ACV side effects, acidity, alkalinity, cancer, osteoporosis

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