What is the PRAL?
PRAL literally means Potential Renal Acid Load, that is to say renal acid loading potential.
The PRAL is a scientifically validated method, proposed by Remer and Manz, frequently used to calculate the chemical balance of the acidifying and alkalizing molecules of a food or a supplement. The PRAL does not simply establish the pH of a compound (which is easily measured by other methods), but estimates its ability to interact with human blood (of the pH range compatible with life: 7.38-7.42).
Simplifying, the PRAL determines the"acid-base chemical effect of a compound on the human organism, naturally absorbable and metabolizable by the healthy and functioning digestive system.
Variables of the PRAL
For the estimate, the PRAL takes into account the variables of:
- Total protein
- Sulfur of sulfur amino acids
- Phosphorus (P)
- Potassium (K)
- Magnesium (Mg)
- Calcium (Ca)
present in the food, e
- The production of endogenous acids and bases compared to the content of the individual minerals and amino acids involved.
NB: the PRAL is not the only system for assessing the chemical-nutritional impact, there is also another one called ash analysis; this technique is based on the DIRECT measurement of the alkalizing mineral salts present in a food residue following its combustion (it only estimates the pH and does not take into account the metabolic impact).
From a practical point of view, products with negative PRAL (PRAL -) are potentially alkalizing (e.g. vegetables and fruits), while foods with positive PRAL (PRAL +) have an acidifying effect (e.g. meat, milk derivatives) , fish and egg yolk).
The elements that determine the positive PRAL, therefore the lowering of the blood pH, are mainly sulfur (S) and phosphorus (P); on the contrary, the elements that determine the negative PRAL and raise the blood pH are: magnesium (Mg ), potassium (K) and calcium (Ca).
Impact of blood pH, therefore of food PRAL, on the organism: osteoporosis
Foods with PRAL + significantly increase the presence of hydrogen ions in the blood (H +) and the Net Acid Excretion (NAE - Net Acid Excretion), which is the correlating parameter the elimination of calcium in the urine (urinary excretion of calcium); this mechanism is decisively fundamental in the evaluation of a healthy and balanced diet, especially when some subjects at high risk of osteoporosis are considered (women, elderly people, those who are familiar with osteoporosis, former rickets, etc.). In fact, the "urinary excretion of calcium favors the depletion of skeletal density" regardless of the "nutritional intake of this mineral", consequently raising the "risk index for the onset of osteoporosis in old age.
It follows that, in order to obtain a balanced diet, it is essential to ALWAYS associate alkalizing foods with foods with PRAL + (or supplements, eg. Protein powder), with the aim of counteracting the lowering of blood pH and avoiding "possibility of increased NAE and urinary calcium excretion."
Recognize alkalizing foods
Alkalizing foods are mainly fruit, vegetables, legumes and whole grains (not refined); Below is a brief table illustrating the potentially alkalizing foods (in blue those with PRAL <-10), and the few exceptions of the two groups (highlighted in red):
Calculate the PRAL of your diet online "
