The Gerson Institute of Ayurvedic Medicine

Scott Gerson, M.D., Ph.D. (Ayurveda) Medical Director, Jupiter Medical Center Dept. of Integrative Medicine Division of Education and Research

Jupiter Medical Center at The Calcagnini Center for Mindfulness
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The Myth of Alkalinization

One of the more common medical myths that I hear from my patients is regarding the health benefits of “alkalinizing” the body by eating and drinking alkaline foods.

Alkaline water and diets have been promoted since the 1950’s by numerous doctors and companies, claiming to balance the pH in the body and help maintain optimal health. Their theory is that the body's pH should be more alkaline than acidic and that increased acidity will cause decreased energy, body aches, weight gain and even cancer. The science offered to support these claims is sprinkled with enough factual information to create an illusion of credibility, but quickly descends ridiculous fictional versions of physiology and chemistry.

Though none of this is remotely true, this is one myth that just doesn’t seem to go away. Here is the truth: nothing you ingest can affect the pH of your blood or cells. Blood pH always remains between 7.35 and 7.45; a further deviation of even 0.1 in either direction would surely cause convulsions, coma or death. The human physiology is safeguarded against that happening. Intracellular pH is generally slightly more acidic and varies according to the organelle (i.e. mitochondria, golgi apparatus, etc) but remains within its own tight range. What can change is the pH of the urine, which is essentially compartmentalized away from the rest of the body. Urinary pH depends on many factors and is a useful clinical diagnostic only in the context of numerous other measurements of urine and blood chemistry. So unless you are under the care of a physician for nephritic disease, diabetes, kidney stones or a urinary tract infection, daily pH testing is a waste of time. Since low urinary pH promotes precipitation of uric acid, it is sometimes monitored in gout patients. For such patients, citric acid or a citrate salt, which are metabolized to bicarbonate, are often prescribed to alkalinize the urine. Be aware that pH testing of urine and saliva is used by dubious practitioners to prescribe dietary supplements or special diets.

What is pH and Why is it Very, Very Constant

Alkaline water is widely promoted by alternative-health charlatans who also market worthless “water ionizer” machines for this purpose. Acidic water is known to be corrosive to metal alloyed pipes; but it does not have this action in the human body. Consider that acidic water (pH~4.0-6.0) is far less acidic than the physiological normal hydrochloric acid already present in your gastric fluid (pH~1.0-2.0)! Normal, healthy skin has a pH of 4.5-5.5, moderately acidic.

About two-thirds of the weight of an adult human consists of water. About two-thirds of this water is located within cells, while the remaining third consists of extracellular water, mostly interstitial fluid that bathes the cells, and the blood plasma (rasa dhatu). The latter, amounting to about five percent of body weight (about 5 L in adults), functions as a medium for transporting chemicals between cells and the external environment and also contains the formed blood cells (rakta dhatu). It is basically a 0.15M solution of salt (NaCl) containing smaller amounts of other electrolytes, the most important of which are bicarbonate (HCO3) and protein anions.

All water contains both H+ and OH ions. If the quantity of H+ exceeds that of the OH, the water is acidic. If there are more OH ions than H+, the water is alkaline. Pure water, which contains equal numbers of both ions, is said to be neutral. Science uses the pH scale (0 to 14) to quantify the degree of acidity or alkalinity. Pure water, being neutral, has a pH (“potential of Hydrogen”) of exactly 7.0. Acidic solutions have pH values of less than 7.0, alkaline solutions more than 7. Each unit on the pH scale represents a ten-fold change in the concentration of H+ ions and a hundred-fold change in the ratio of the two kinds of ions; for example, if the pH is 8.0, there are 100 times as many OH ions than H+ ions (specifically, [H+] = 10–8, [OH] = 10–6.) Any substance that when added to water increases the concentration of hydrogen ions is called an acid, and will lower the pH below 7.0 (neutral). Any substance that reduces the concentration of hydrogen ions is called a base and will raise the pH. Finally some substances enable solutions to resist pH changes when an acid or base is added. Such substances are called buffers. Buffers are very important in helping living organisms maintain a relatively constant pH.

The concentration of hydrogen ions in a solution is very important for living things. Many chemical reactions in living cells involve exchanges of hydrogen ions. This is because hydrogen ions are positively charged and hence they react with other molecules and alter their structure and function. By exerting forces on molecules, they change shape from their normal conformation. This is particularly important for proteins in solution because the shape of a protein largely determines its function. In fact, proteins control almost all cellular processes in the human body. Consisting of amino acids that are joined like links of a chain, a protein folds into a highly complex, three-dimensional shape that determines its function. Any change in shape dramatically alters the function of a protein, and both acids and bases have the ability to do this, particularly H+ ions, which are highly reactive. Therefore nature has evolved effective buffer systems to prevent pH changes in cells and tissues.

Acid-Base Chemistry in Human Physiology

Acid-base chemistry plays a crucial role in physiology, both at the scale of the individual cell, the dhatus (tissues), and the total organism. Almost every important metabolic process involves the uptake or release of hydrogen ions. The very state of being alive constantly produces an unending fluctuation in the surrounding intracellular pH, usually making it more acidic. This acidic environment is required for many important enzymatic-associated reactions to take place; many enzymes function optimally at an acidic pH. In fact, the most important physiological activity of most cells, is an acid-producing process: carbohydrates provide life-sustaining energy by being broken down into carbon dioxide and water:

C(H2O)n + O2 → H2CO3 → CO2 + H2O

The stage of this reaction (i.e. the electron transport sequence) which takes place inside the mitochondria requires an acidic environment. However persisting acidity could eventually damage cells and the entire organism in the absence of buffering agents. The human physiology has a vast, diverse, powerful, and efficient supply of such buffers. Many of the major chemical components of an organism, especially proteins, can themselves act as acid and/or base buffers.

However unscrupulous medical quacks have been able to propagate two principle lies:  (1) that all and any acidity is harmful and (2) that we can modify the blood and cellular pH with foods, water, and supplements.

They utilize very marginal and transparent pseudoscience to convince a scientifically unsophisticated public of the need to “alkalinize” the body with foods, special water, and supplements. The claims for the health benefits for alkalinization range from the vague (“increasing energy”) to the incredulous (“preventing cancer”) and all are nothing more than deceptive nonsense.

Maintenance of Acid-Base Balance

It is remarkable that the pH of cellular fluids is maintained within such a narrow range, given the large number of processes that tend to upset it. This is due to the exquisite balance amongst a large number of interconnected processes operating at many different levels. Processes which maintain acid-base balance in the body can be divided into two general mechanisms: (a) selective excretion of acids or bases, and (b) the buffering action of weak acid-base systems.

Over a normal 24-hour period, the adult human excretes 20-40 moles of H+ as carbonic acid H2CO3 which breaks down into CO2 (excreted via the lungs) and H2O (excreted via the kidneys). In addition, the kidneys excrete additional acid if required, mostly in the form of H2PO4 and NH4+.

The major buffering system in the body is the carbonate system, HCO3. Secondary buffering action comes from phosphate, from proteins and other weak organic acids, and (within blood cells), from hemoglobin.

Acid-Base Homeostasis

Deviations of the blood plasma pH from its normal range of 7.35 to 7.45 by more than about ±0.1 can be very dangerous. These conditions are known medically as acidosis and alkalosis. They can be caused by metabolic disturbances such as diabetes or by kidney failure (in which excretion of H2PO4, for example, is inhibited). Respiratory abnormalities can also cause this.

Numerous other processes lead to temporary imbalances. For example hyperventilation causes loss of CO2, and thus alkalosis. On the other hand, retention of CO2 caused by hypoventilation can give rise to acidosis. Acidosis can also result from diarrhea (loss of intestinal HCO3) while vomiting of gastric contents promotes alkalosis (not due to direct loss of HCl, but rather to parietal cell secretion of HCO3 back into the blood in exchange for blood Cltaken up for HCl replacement). If you have any doubts about how strongly the body protects its narrow pH parameters, try holding your breath for a few minutes. Breath holding causes accumulation of CO2 and H+. This causes blood pH to fall into the acidic range. Despite your best effort, after 1-2 minutes chemoreceptors in the aorta, carotid arteries and medulla oblongata sense the increase in H+ concentration and send involuntary impulses to resume breathing and return pH to normal. Here’s the chemistry of how carbon dioxide increases [H+] and therefore pH:

CO2 + H2O H2CO3 HCO3 + H+ CO3 + 2 H+

The human body has many intelligent and intricate ways of maintaining physiologic pH which only become disturbed in severe and advanced disease states. Which emphasizes the absurdity of the idea, widely promoted by commercial outfits, that people need "alkaline" foods or water supplements to "balance body pH" or "neutralize" acidic foods. This concept has no scientific support. It is pure, deceptive sales hype. Your stomach is so acidic, and is designed to stay that way, that no food can change its acidity. Lemons, vinegar, vitamin C (ascorbic acid) or Coca Cola do not change the acidity of your stomach or your bloodstream. An entire bottle of Tums (calcium carbonate) or any other antacid would not change the acidity of your stomach for more than a few minutes; then continued antacid use will actually increase acidity of the stomach via a parietal cell rebound mechanism. Its true! And has been proven for at least forty years![1]

All foods are acidic as they leave your stomach. Food then enters your intestines where secretions from your gallbladder (bile juice pH ~7.6) and pancreas (pH ~7.6-8.4) neutralize the stomach acids. So no matter what you eat, in the absence of severe disease, the food in stomach is acidic and the food in the intestines is alkaline.

Dietary modification cannot change the acidity of any part of your body except your urine. Certain foods can leave end-products called ash (mineral salt residues) which can be either alkaline or acidic. Foods that produce alkaline ash include fruits and vegetables; acidic ash comes from meats, grains, beans, and seeds[2].

Your blood and tissues maintain pH in a very narrow range, unaffected by ingested substances. It bears repeating that if anything changed acidity in your body by as little as 0.1 (i.e. from 7.35 to 7.25) it would make you very weak, hypotensive, confused and could even kill you.

After bicarbonate, the next most important buffer in the body is protein, which includes hemoglobin. Proteins are everywhere. Recall that cell membranes are 50% protein by weight. Proteins are very versatile buffers. Due to the variety and complexity of the buffering groups available from protein, proteins have a linear buffering ability across the physiological range of pH. Because proteins are found throughout the entire body, in acidosis or alkalosis protein buffering neutralizes H+ changes over the entire body, so the effect of a pH change is less in any one tissue. Even with all that protein contained in all the membranes of all the cells of the body, hemoglobin in our red blood cells still accounts for the majority (75%) of the overall protein buffering capacity of the body.

Given the efficiency of our physiology in maintaining constant pH, alkaline water or supplements will not change the pH of your body nor should anyone even want to do this. Promoters of these products claim that cancer cells cannot live in an alkaline environment and that is true, but neither can any of the other cells in your body. If someone tells you that your body is “too acidic” and you should use their product or diet to make it more alkaline, you would be wise to politely head for the door and never return.



1 N Engl J Med 1968; 279:900-905, October 1968.

2 American Journal of Clinical Nutrition, Vol 21, 898-903, Sept. 1968