EFFECT OF ALIMENTRAL FACTORS ON URINE pH

V.P. Stus, N.N. Moiseenko, M.V. Zhbakov, V.V. Ehalov SI « DMA of the Ministry of Health of Ukraine »

Introduction. Modern medicine is moving towards minimization of invasiveness, improvement and development of prevention of the most common urological diseases that do not involve any surgical intervention. In the development of the most common both urological and general diseases, the alimentary factor is of great importance. It is possible to trace its effect on the body by many laboratory parameters, but this article will talk specifically about the acid-alkaline balance of urine.

The normal environment for the human body is neutral one: the intracellular pH is 6.8, and the blood plasma pH is 7.33 to 7.45. As a result of everyday chemical processes occurring in our body, acidic and alkaline metabolites are formed. In addition, acidic metabolites are formed 20 times more than alkaline metabolites. The body has protective systems aimed primarily at neutralization of acidic decay products and their elimination from the body.

Mechanisms for maintaining pH stability are divided into physical-chemical and physiological ones. The acidity of the blood is adjusted in the greatest way, therefore the buffer systems of the blood are the first link of the body's defense against acidity fluctuations. Buffer systems are alkaline and acidic substances that neutralize products and metabolites of the opposite nature that enter the blood [1].

The advantage of buffer systems is the ability to instantly react to pH changes and quickly neutralize a small amount of strong acids and bases. However, the buffer reserves in the blood are quite limited, and due to a strong acid load these reserves begin to be extracted from other organs and tissues, the acidity of which is less critical.

Accordingly, in case of a constant acid load, even though the blood pH remains stable, the tissues of other organs undergo pathological acidification causing many chronic diseases. In addition to the fact that buffer systems are able to correct pH shifts limited by their capacity, which is determined by the number of equivalents of a strong acid or base, there is a second drawback of the first line of defense, which lies in its inability to remove metabolic products from the body.
In this case, there are second and third physiological lines of defense (respiratory and urinary systems, the liver, gastrointestinal tract, and sweat glands) [2].

The respiratory system is the body's second line of defense against acidity fluctuations. It starts to act 3-12 minutes after the pH drop. The excretion of metabolites occurs quickly, but in case of a strong acid load, the respiratory mechanisms are able to remove only 50-70%, and they are ineffective in case of an excess of alkalis [2].

The mechanisms of the urinary system are the third link in the acidity regulation. In contrast to the buffer and respiratory mechanism, the renal mechanism is not able to affect the pH drop in a short time, but it acts for several days. However, at the same time, up to 500 mmol/day of acids or bases are excreted from the body in the urine, and the urine pH with a strong acid or alkaline load can vary from 4.5 to 8 [3].

In ordinary mixed food and normal drinking regime in a healthy person the excretion of acids exceeds the excretion of bases, therefore urine has a slightly acidic reaction (pH 5.3-6.5) and the concentration of hydrogen ions is about 800 times higher than in the blood. The role of the kidneys in compensating for metabolic and respiratory acidosis is to increase the excretion of hydrogen ions. The kidneys produce and excrete in the urine the amount of hydrogen ions equivalent to their amount continuously entering the plasma from the cells of the body, while replacing the hydrogen ions secreted by the epithelium of the tubules with sodium ions of the primary urine [3].

A stable deviation of urine acidity from the norm can be observed in some urological diseases, such as metabolic disorders, urolithiasis and
urothelial tumors [4].

Alimentary factor. The level of acidity of the biological environment of the body is most affected by the diet. All products in the disintegration process form acid and alkaline metabolites.