Alkaline Diet

Generality

The alkaline diet favors the intake of " alkaline foods " - such as vegetables, fresh fruit, fruit juices, tubers, nuts and legumes - limiting " acid foods ", such as cereals, meats and cheeses; alcohol, cola-type carbonated drinks and very salty foods are not recommended.

Alleged Benefits

The alkaline diet is based on the consideration that a diet rich in acid foods ends up disturbing the body's acid-base balance, promoting the loss of essential minerals, such as calcium and magnesium contained in bones.

Such alterations would favor the appearance of a mild chronic acidosis, which in turn would be a predisposing factor for some diseases and a sense of general malaise.

The alkaline diet recommends consuming 70-80% of alkaline foods and 20-30% of acidic foods every day. This food model is clearly closer to that followed by man until the discovery of agriculture than the current one.

How to determine when an element is acid?

The acidity of a food is not measured in the fresh state, but on the ashes (minerals) that remain after combustion. These inorganic substances, therefore not metabolizable, can behave as acids or bases, and as such participate in maintaining the normal organic pH.

Lemon, for example, has a very low pH, linked to the abundant presence of citric acid; it is however considered an alkaline food because its acidic components have an organic nature and as such they are easily metabolized by the body and eliminated by respiration, while the basic inorganic ones remain longer.

The elements that give rise to the formation of acids, decreasing the urinary pH, are sulfur, phosphorus and chlorine, while foods rich in sodium, potassium, magnesium and calcium are considered alkaline.

Main

A very used index to evaluate the acidifying or alkalizing characteristics of a food is the so-called PRAL (Potential Renal Acid Load).

From a practical point of view:

• foods with negative PRAL (PRAL -) are potentially alkalizing (eg vegetables and fruits)
• foods with positive PRAL (PRAL +) have an acidifying effect (eg meat, milk derivatives, fish and egg yolk).

In addition to the table below, we have prepared a practical online calculator to establish the PRAL of a diet

Acidity of the organism

Our blood is slightly alkaline and under normal conditions its pH varies between 7.35 and 7.45. The maintenance of these values ​​is given by the subtle balance between production and excretion of alkaline and acid substances, in which the kidneys and lungs participate in particular. The respiratory mechanism eliminates or holds carbonic acid in the form of carbon dioxide, increasing or decreasing the blood pH, while the renal one eliminates or holds H + and tampons.

Regardless of the diet, normal metabolism generates huge amounts of volatile acids (eliminated by breathing) and fixed (eliminated by the kidney) every day. In addition to the homeostatic systems already described, other biological mechanisms called buffer systems are involved, capable of effectively neutralizing part of the acids. Among these, the main one is the carbonic acid / sodium bicarbonate system. It is no coincidence that the latter is sometimes taken by athletes with the aim of buffering the acidosis induced by the anaerobic lactate mechanism and prolonging the tolerance to fatigue.

Nor is it the fact that during this effort the organism increases pulmonary ventilation with the aim of eliminating excess carbon dioxide, therefore indirectly of hydrogen ions given by the dissociation of carbonic acid.

Metabolic acidosis

Only in extraordinary circumstances, the production of acid metabolites can grow to such an extent as to cause acidosis; this happens, for example, during a severe anaerobiosis (for example following a cardiovascular collapse), which causes quantities of lactic acid so high as to make normal homeostatic mechanisms insufficient.

Another cause of acidosis is the so-called ketosis, which occurs following an excessive catabolism of lipids and some amino acids; this condition is typical of decompensated diabetes mellitus (diabetic ketoacidosis), but also of prolonged fasting and a diet chronically based on the extreme reduction of the carbohydrate intake in favor of fats and proteins (strongly ketogenic).

Acute acidosis symptoms include lethargy, palpitations, nausea, vomiting, headache, stupor and coma; chronic acidosis is accompanied by an increased risk of fractures and osteoporosis.

Metabolic alkalosis

The conditions of metabolic alkalosis are more rare, but still possible, accompanied by cramps, muscle spasms, irritability and hyperexcitability. They are generally due to vomiting or excessive ingestion of alkanes.

Blood pH values ​​below 6.8 and above 7.82 are not compatible with life.

Alkaline Diet and Health »