Since time immemorial, people have been trying to search for ways to eliminate diseases altogether, hoping to stumble upon some metaphorical elixir of life. Many believe that the concept of ‘acidic’ and ‘alkaline’ diets is a relatively new one. It has, in fact, been around for over a hundred years. However, in recent times, it has gained significant popularity and attention. The amount of speculation on the possible benefits of being alkaline led to extensive research as well. Despite so much attention, though, the question as to whether it actually works remains a controversial one. Proponents of the theory, including celebrities and prominent media personalities, swear by it. The medical world is still largely divided on whether it is necessary or not.
In order to probe into this question, it is important to first understand what the terms ‘acidic’ and ‘alkaline’ mean.
Que: How the human body works to maintain its pH, and why it is so important to maintain a strict pH control?
The answer to the last question, simply speaking, is that you’d drop dead (literally) if the body lost its pH control mechanisms.
pH, or the ‘potential of hydrogen’, literally means the ‘capacity of hydrogen’. It is a measure of the hydrogen ion concentration in a solution. With the concentration of hydrogen and hydroxyl ions being equal, water has a neutral pH of 7.0. Solutions with a pH below 7.0 are said to be acidic, while those with a pH above 7.0 are called alkaline.
The human body maintains a strict blood pH control between 7.35 and 7.45. Outside this range, both the vital intracellular (within cells), as well as extracellular (outside cells) functions of the body are adversely affected.
An excess of hydrogen ions in the blood produces acidosis, whereas a deficiency thereof results in alkalosis. Both can result in a reduction in the activity, as well as the stability of several vital proteins/organs in the body.
Since even minute changes in blood pH can spell the difference between life and death, several pH regulatory mechanisms exist in-vivo.
The two principal organs responsible for this homeostasis are the lungs and kidneys. The bones act as a backup or alkaline reservoir for pH regulation.
Hence, pH disturbances within the blood are also classified as being respiratory, metabolic, or mixed in nature.
pH control within the digestive tract is maintained mainly by the pancreas with pancreatic juices having a pH of 7.8-8.0. Alongside activating the endocrine (hormone-producing) pancreas, the intake of a large meal also activates the exocrine (production and excretion) part of the pancreas. The partially digested food from the stomach is highly acidic, owing to the hydrochloric acid produced by the stomach lining – pH 1.2-3.0. The pancreas, in turn, produces a bicarbonate (alkalizing) rich fluid to neutralize the pH of this partially digested food, and to provide an alkaline medium for the optimum activity of pancreatic enzymes.
CHEMICAL BUFFERS within the blood also play a vital role in pH homoeostasis. These buffers act according to the Henderson-Hasselbach equation (or the buffer equation), neutralizing both excess acids and alkalis up to a limit. Of these, the bicarbonate-carbonic acid buffer system is quantitatively the most important. Other chemical buffers include hemoglobin, plasma proteins and phosphates. Since bone contains a significant quantity of both bicarbonates and phosphates attached to either calcium or magnesium, it is hypothesized that it plays a major role in acute pH disturbances. This is important to the alkaline theory, as will be seen later.
Ventilation rate (the number of breaths per minute) in lung alveoli (sacs) is determined by changes in the blood concentration of carbon dioxide –which is detected in the medulla oblongata of the brainstem, and to a lesser extent by the chemoreceptive carotid bodies – in order to maintain a stable PCO2. These changes are rapid, and therefore, any respiratory disturbances in pH become quickly evident, and can also be corrected relatively quickly.
Respiratory alkalosis most commonly results from hyperventilation due to panic or anxiety. It can also occur in patients on mechanical ventilation.
Respiratory acidosis, on the other hand, is a result of hypoventilation, as can be seen with head injuries, for instance.
In contrast to respiratory changes, metabolic changes are rather slow to take place. An excess of nonvolatile acids (such as lactic acid and the by-products of fat metabolism in diabetic ketoacidosis), or a deficiency of bicarbonates due to renal or gastrointestinal bicarbonate loss results in metabolic acidosis. Excessive hydrogen ion losses – such as can occur with severe vomiting or diuretic use – can lead to metabolic alkalosis.
Primarily regulate pH by maintaining the bicarbonate concentration through reabsorption of bicarbonate ions, as well as the production of new bicarbonate ions by excreting excessive hydrogen ions – which means they excrete the acid in urine.
While the body maintains the blood pH within a very narrow range, the intracellular pH varies from cell to cell depending upon function and metabolism. E.g. The pH of muscle cells is 6.1 vs urine pH 4.5-8.0.
As with extracellular pH, there are mechanisms in place to maintain intracellular pH as well. These include:
1. intracellular pH buffers, adjustments in arterial PCO2.
2. Membrane channels responsible for the influx or efflux of ions.
Intracellular pH buffering mechanisms can broadly be divided into three categories:
1. Physiochemical buffering – using intracellular proteins and phosphate, similar to extracellular physiochemical buffers.
2. Metabolic buffering – Metabolic buffering refers to changes in the metabolism of intracellular acids in response to changes in intracellular hydrogen ion concentration, for instance, in response to a fall in intracellular pH, lactic acid can be converted into glucose, or to carbon dioxide and water making the cell more alkaline.
3. Organellar (organ) buffering – Some organelles are capable of releasing hydrogen ions in response to acute pH changes.
A tight pH control is important for the optimum activity of intracellular enzymes and ion channels, and for the processes involved in the cell cycle. Within skeletal muscle cells, it is also important to maintain the contractility of actin and myosin fibres. These fibres work best at a pH of 6.1 and even minor increases in acidity (= lowering pH) can dramatically reduce their activity. Although the accumulation of lactate during exercise was previously considered to be responsible for muscle fatigue, recent studies have shown the subsequent fall in pH to be a bigger culprit. Even among cardiac muscle cells, a significant amount of cellular damage during ischaemia (lack of oxygen) is a result of pH drop. A major intracellular pH drop results in the release of the dipeptide carnosine (β-alanyl-L-histidine). It is present in the greatest concentration in skeletal muscle cells, which lack the enzyme carnosinase, which is responsible for its breakdown.
Carnosine has been the subject of widespread research over the recent years due to its potential as a booster of muscle performance during high-intensity athletic activity. As well as being a buffer, it also serves as an antioxidant and a free radical scavenger in weakly alkaline environments. While supplementation with carnosine itself failed to produce any notable changes in muscle activity, supplementation with β-alanine – a non-essential amino acid and a precursor of carnosine – was observed to significantly improve performance among athletes in various clinical studies. It improved various exercise variables including improved time to fatigue on a maximal cycle test, delayed onset of muscular fatigue, and increased ventilatory threshold and time to exhaustion.
Since it is found in almost all vital organs, its role in preventing complications from many diseases including diabetes, cardiovascular diseases, and Alzheimer disease is currently being investigated. Thus far, it seems that a slightly more alkaline or balanced intracellular environment may be better for the overall health, vitality, and performance of cells.
Next, let’s probe into another popular theory of alkalization – the alkaline ash theory and alkalization of the body through diet.
What exactly do people mean when they talk about being alkaline? What is the basis for an alkaline diet?
This is determined by measuring the pH of urine. In terms of food, it refers to the pH of the ‘ash’ or residue that food leaves behind in vitro. It is believed that upon consumption these foods have the same effect on the human body.
E.g. even though lemons and other citrus fruits are acidic in pH, they fall into the category of alkaline foods based on the pH of the ‘ash’ that they produce.
This pH would determine the potential renal acid load (*PRAL) of the food, and consequently, how much effort the body (kidneys) would have to make in order to neutralize this acid load.
(*PRAL = mEq of Cl + PO4 + SO4 – Na – K – Ca – Mg)
The pH of the food we eat does affect the pH and calcium content of the urine to some extent. Proponents of the alkaline ash theory propose that by measuring the pH of urine – and less commonly saliva – it is possible to determine if a person’s body is overall acidic or alkaline. Strip tests are easily available over the counter to measure these pH values. They believe that an acidic body is a rich source for the development of diseases such as diabetes and arthritis, as well as for the growth of cancer cells. They also believe that people who consume a predominantly acidic diet suffer more rapid bone loss and have a greater risk of developing osteoporosis since calcium and magnesium will have to be drawn from their bones in order to maintain blood pH as they are bound to bicarbonates and phosphates (alkalizing). Among other proposed benefits of being alkaline are better cardiac, digestive and mental health, better sleep, and a stronger immune system.
Average western diet: consists of a large proportion of animal proteins (including poultry and dairy), is considered to be acidic since protein metabolism results in the production of phosphoric and sulfuric acids. Other acidic foods include grains and alcohol. Fruits, nuts, legumes and vegetables are the main components of an alkaline ash diet, while fats, starches, and some natural sugars are considered to be neutral.
Alkaline ash diet: recommends cutting animal proteins and grains out completely. Based on the premise of the alkaline ash theory, the urinary pH and calcium content should be reflective of the overall body pH and calcium metabolism, respectively. However, research has shown that this is not the case. Studies found the overall bone metabolism markers to be higher among people with vegetarian diets rather than in those with omnivorous diets. Some studies even found proteins – the main content of an acidic diet – to have a positive overall effect on bone health as bone has a large protein component.
In postmenopausal women, a diet that balances net endogenous acid production increases calcium and phosphate retention and reduces bone resorption markers, and increases markers of bone formation. I.e. a balanced diet that favoured minimizing net endogenous acid production lead to improved retention of calcium and phosphate … leading to better bone health in postmenopausal women.
Furthermore, while some research linked predominantly acidic diets with an increased cancer risk, no study was able to establish a cause-effect relationship between the two. In fact, cancer cells can thrive equally well in an alkaline environment as well.
Is the alkaline ash diet another fad diet?
Not entirely. Evidence linking westernized diets to an increased risk of metabolic disorders such as type-2 diabetes and hypertension does exist. Eating more fruits and vegetables undoubtedly is beneficial for overall health. However, there is no evidence to warrant completely cutting out all acidic foods from the diet. While the alkaline ash diet consists of healthy unprocessed food, and may immensely benefit a small subset of people (such as those with chronic renal disease, who are unable to handle a high PRAL). The alkaline ash diet is healthy, not because of its alkalinity but because it consists primarily of fruits and vegetables. A balanced diet may, in fact, be one that consists of a combination of both acidic and alkaline foods.
Despite being around for a long time, the concept of alkalinity being healthier is still under scrutiny and is being largely investigated. From the above discussion, it can be inferred that a more ‘alkaline’ intracellular environment does have benefits for people involved in high-intensity training and sports, and may also potentially be beneficial for those at risk of various metabolic disorders. And while the alkaline ash diet may not carry all the benefits that it boasts of, it may still be an overall healthy choice.
SUMMARY: The human body has very narrowly controlled homeostasis and the pH of urine is in no way reflective of the intracellular or extracellular pH of the body. It is being used to monitor the renal pH buffering mechanisms. With a diet of highly acidic foods being consumed, the urinary pH will reflect this accordingly.
Alkalizing urine has its use in medicine to reduce uric acid stone production, to improve elimination of toxic compounds (weak acids) in an overdose setting or there are those who swear by using to improve sports performance/recovery. An animal study showed a four-fold improvement in the excretion of ochratoxin A, a mycotoxin.
There may be ways to maintain an optimal pH intracellular environment, which may, in turn, have a number of protective effects on our vital organs. This concept seems promising, and probing further into it may, in fact, lead to breakthroughs in preventive medicine.
This article is written to give an overview of the subject to inform and educate. It is not to be used as a therapeutic guide for the treatment of self or others, or for diagnostic purposes.
Readers are advised to seek medical advice if they seek guidance for their health.