Abstract P105: Dietary Acid Load of a Low Versus a High Protein Diet and Its Effect on Blood Pressure: A Fully Controlled Dietary Intervention Trial

Background: Mild metabolic acidosis may result in elevated blood pressure (BP). Several formulas to estimate dietary acid load have been developed. However, studies in which these formulas have been validated are limited. Objectives: To validate and/or improve existing formulas for dietary acid load and to examine the association between dietary protein, acid load and BP. Methods: We performed a randomized 14d crossover dietary intervention involving 37 healthy subjects (age: 21±2 y) who consumed individualized, isocaloric diets that were either low or high in protein (0.5 versus 2.0 g protein/kg BW/d). Duplicate portions of the provided diets were collected and analysed for energy and nutrients. We used two measures to characterize dietary acid load (i.e. PRAL and NEAP). Urinary Net Acid Excretion (NAE; i.e. titratable acid + ammonium - bicarbonate) was analysed. BP was measured according to standardized procedures. Results: Mean dietary intakes significantly differed between the low and high protein diet, resulting in significantly different acid load values (Table 1, all p<0.001). The correlation between PRAL and NAE was 0.08 in the low protein diet and 0.62 in the high protein diet. For NEAP the correlations were 0.27 and 0.32. PRAL explained 69% of the variance of NAE, which could not be improved by adding other variables to the formula. Systolic BP was 108.4±7.5 and 109.5±8.0 mmHg on the low and high protein diet respectively (p=0.25). Conclusion: PRAL predicts NAE reasonably well in healthy adults for normal to high protein intake. PRAL can be influenced by diet, but this cannot be clearly attributed to protein intake alone. PRAL does not seem to influence short-term BP in healthy adults with normal BP.