What is Potential Renal Acid Load?
Potential Renal Acid Load (PRAL) is a value calculated from a formula developed by Thomas Remer and other researchers at the Department of Nutrition and Health, the Research Institute of Child Nutrition, Dortmund, Germany, to assess the acidity of foods and diets.
PRAL = 0.49 x protein (g) + 0.037 x phosphorus (mg) – 0.021 x potassium (mg) – 0.026 x magnesium (mg) – 0.013 x calcium (mg)1
Today, there is a general consensus that diet can markedly affect acid-base status and that a person’s acid load can be specifically manipulated by dietary means.
In general, protein and cereal grains are metabolized to acidic residues, and fruits and vegetables are metabolized to alkaline residues. Current American diets are progressively more acidic in comparison to pre-agricultural diets (mean Net Acid Load of -88mEq/d vs. +48mEq/d)2. With the decline in renal function that occurs with aging, older persons are not able to excrete excess hydrogen ions, and they develop mild but slowly increasing metabolic acidosis1.
A study by Berardi et al. examined whether a plant-based dietary supplement, one marketed to increase alkalinity, impacts urinary pH4. Using pH test strips, the urinary pH of 34 healthy men and women (33.9 +/- 1.57 y, 79.3 +/- 3.1 kg) was measured for seven days to establish a baseline urinary pH without supplementation. After this initial baseline period, urinary pH was measured for an additional 14 days while participants ingested the plant-based nutritional supplement. At the end of the investigation, pH values at baseline and during the treatment period were compared to determine the efficacy of the supplement. Mean urinary pH statistically increased (p = 0.03) with the plant-based dietary supplement. Mean urinary pH was 6.07 +/- 0.04 during the baseline period and increased to 6.21 +/- 0.03 during the first week of treatment and to 6.27 +/- 0.06 during the second week of treatment. Conclusion: Supplementation with a plant-based dietary product for at least seven days increases urinary pH, potentially increasing the alkalinity of the body4.