Acid - Alkaline Balance

When discussing the pH of foods it is always good to have a greater understanding of physiology that underlies the theories behind this type of diet.

The acid-base balance of the body is a state of equilibrium between acidity and alkalinity of the body fluids. Most of the metabolic processes that occur in the human body produce acids as their end products. These acids must be balanced (or buffered) so that the body may stay within a physiologically effective range. A somewhat alkaline body fluid is required as a medium for most of our vital cellular activities. Therefore, chemical exchanges of hydrogen ions must continuously take place in order to maintain this state of equilibrium. These hydrogen ion exchanges are partially what control the level of pH. An optimal pH (hydrogen ion concentration) between 7.35 and 7.45 must be maintained, or the enzyme systems and other biochemical and metabolic activities will not function as they should. If the pH drops below 7.30, the potentially serious condition of acidosis exists. If the pH goes above 7.50, the patient is in a state of alkalosis. ¹

The terms acidosis and alkalosis are medical definitions that are used to describe a condition that is secondary to some other underlying disease process.

Acidosis is the accumulation of acid and hydrogen ions or the depletion of the alkaline reserve in the blood and body tissues. This results in a decrease in pH levels. Some pathological conditions can result in acidosis. Acidosis usually occurs secondary to some underlying disease process. Two major types of acidosis are distinguished according to their cause. There is metabolic acidosis in which the acid-base status of the body shifts toward the acid side because of loss of base or retention of acids other than carbonic acid. There are many different subtypes of acidosis that fit under the broader category of metabolic acidosis. There is also a form of acidosis called respiratory acidosis. This form is due to excess retention of carbon dioxide in the body. This form is seen in chronic obstructive pulmonary disease and other conditions that interfere with normal lung function.

Alkalosis is also a pathological condition caused by excessive base in the body, including loss of acid without comparable loss of base in the body fluids. Alkalosis is the opposite of acidosis.

These types of acidosis and alkalosis are resultant from disorders that have overcome the natural buffer system of the body. The buffer system is a substance that increases the amount of acid or alkali necessary to produce a certain change in pH level. The bicarbonate buffer system in the blood maintains a balance between bicarbonate and carbon dioxide ions and determines the pH of the blood.

When it comes to the alkaline diet, this same buffer system works in part to maintain the normal pH levels of the body. Whether a diet that is too acid or too alkaline can actually result in true acidosis or alkalosis remains to be seen. A diet that too much one way or the other can shift the pH of the body fluid, but evidence that it can reach the criteria of pathological levels is doubtful.

 

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Food and pH

The pH forming properties of foods comes from how they are metabolized in our bodies. The pH of a food can be completely different when measured before it is eaten as to after it has been digested. These properties have to do with the components of the metabolized food.

An example of this idea would be in relation to some types of fruits. Certain fruits are acidic before they are eaten. Once these types of acidic fruits are digested the acids that they contain are broken down. Once broken down, the remaining nutrients contained in the fruit can effect the pH levels inside the body. The acidic fruits mentioned previously are broken down leaving a high concentration of potassium. Potassium is highly alkaline forming in the body.

On the other hand, vitamin C is acidic and is not broken down during digestion. Vitamin C will make the pH levels more acidic. As stated in an earlier article, one should not avoid all acidic foods simply because they are acidic. Many acidic foods contain valuable nutrients that our body's need. Balance and common sense need to be at play when deciding which foods are best to consume.

Common sense would come into play when it comes to carbon as well. Carbon is an acid forming element. Soft drinks contain carbon dioxide, which is what gives the drink its fizz. Consuming high amounts of acid forming carbon would lower ones pH levels. Soft drinks also contain phosphorus. Phosphorus is also acid forming in the body. Their are endless reasons NOT to consume soft drink, regardless of how acid forming it can be.

As an opposite example regarding the pH before and after consumption of foods, most meats and dairy have an alkaline pH measurement before they are digested. Once digestion takes place the high protein (amino acid) content will actually lower the pH value of the body fluids. Many dairy products are high in calcium and potassium, which has an alkalinizing effect, therefore these types of diary products could raise the pH of the body fluids. Foods containg high amounts of calcium, potassium, magnesium, and zinc are usually alkaline forming in the body. When it comes to supplementing with these minerals, it is important to take forms that ca be absorbed, such as those linked to citrate, picolinate, gluconate, orotate, and other amino acid chelates. Forms to aviod would be those linked to sulfates, carbonates, and oxides. If concerned about which form you are consuming, look the form up to make sure you are actually absorbing what you are consuming.

As one can see, the pH of a food before it is digested is completely irrelevant to what effect it could have on the body's pH balance. Pre-digestion pH is often times very different from post-digestion pH.

 

 

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Monitoring pH

The easiest and most typical way to self-monitor the body's pH levels is through saliva and urine pH testing. It is these two methods that closely respresent the pH status of the body. Testing kits for both saliva and urine are available through many sources.

Saliva

When a person is healthy the pH levels of the blood is near 7.4, the pH of the spinal fluid will be near 7.4, and the pH of saliva will be 7.4. This shows that the pH of saliva most closely parallels the values of extracellular fluid.

Urine

The normal pH of urine ranges from 4.6-8.0 in adults and 5-7 in newborn children. The urine pH levels are more tricky than saliva levels because of the changes that occur in the kidneys. The glomerular filtrate of blood (the blood that comes from the body into the kidneys) is usually acidified by the kidneys from a pH of approximately 7.4 to a pH of about 6 once it is excreted as urine.

The kidneys maintain normal body acid-base balance primarily through the reabsorption of sodium and the tubular secretion of hydrogen and ammonium ions. Urine becomes increasingly acidic as the amount of sodium and excess acid retained by the body increases. If the body's levels of acid are high then the kidneys will excrete more acid into the urine. This will result in an acidic urine when tested.

Alkaline urine, usually containing bicarbonate-carbonic acid buffer, is normally excreted when there is an excess of base or alkali in the body.

Secretion of an acid or alkaline urine by the kidneys is one of the most important mechanisms the body uses to maintain a constant body pH. This means that if the kidneys are to hold the blood pH levels at a normal range of 7.4, they must get rid of the excess alkaline.

Since urine pH is not a parallel of extracellular fluid like saliva, one can see how much more complex this regulatory system can be. The pH levels of urine can be reflective of many systemic problems.

For example, A highly acidic urine pH occurs in:

Acidosis, Uncontrolled diabetes, Diarrhea, Starvation and dehydration, Respiratory diseases in which carbon dioxide retention occurs and acidosis develops

A highly alkaline urine occurs in:

Urinary tract obstruction, Pyloric obstruction, Salicylate intoxication (aspirin excess),Renal tubular acidosis, Chronic renal failure, Respiratory diseases that involve hyperventilation (blowing off carbon dioxide and the development of alkalosis) .

Given this information, one can see the importance and benefit of monitoring the body's pH.

 

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References:

1. Dorland's Medical Dictionary for Healthcare Consumers.

 

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