PRAL

PRAL, or Potential Renal Acid Load, is a dietary metric used to estimate the net acid load a person’s diet would impose on the kidneys. Developed to quantify the acid-base potential of foods, it helps describe how dietary choices may influence urinary and metabolic acid load.

Calculation and interpretation rely on the mineral and protein content of the diet. Protein and phosphorus tend to increase acid production, while potassium, calcium, and magnesium tend to generate base precursors that can offset acidity. A commonly cited formulation is PRAL (mEq/day) = 0.49 × protein (g/day) + 0.037 × phosphorus (mg/day) − 0.021 × potassium (mg/day) − 0.026 × calcium (mg/day) − 0.012 × magnesium (mg/day). Some sources use slightly different coefficients, but the general pattern is the same: positive PRAL values indicate an acidifying dietary effect, while negative values indicate an alkalizing effect.

In practice, foods with high meat, dairy, and grain content tend to produce positive PRAL values, whereas fruits, vegetables, and many mineral-rich foods tend to produce negative values. Average daily PRAL values reported for diets in different populations vary, but many Western diets show a net positive PRAL, reflecting a tendency toward acidifying potential.

Limitations include reliance on estimated intake data, variation in individual metabolism, and the fact that PRAL is a proxy rather than a direct measure of urinary acid excretion. It does not account for all factors influencing acid-base balance, such as hydration status or non-dietary contributors. PRAL is commonly used alongside other measures, like NEAP, in nutrition research and diet planning.