Dietary Acid Load and Blood Pressure in Healthy Adults

Abstract

Mild metabolic acidosis, as influenced by dietary intake, has been the topic of many epidemiological studies as a contributing factor to developing high blood pressure (BP). Diets that include an abundance of fruits and vegetables are marked by a high potassium intake that contributes to a decreased renal acid load. In contrast, a Western diet, which is typically deficient in potassium and higher in protein and phosphorus, is characterized by a higher acid load that may negatively alter acid-base balance and contribute to future cardiovascular events. The purpose of this study was to investigate the relation between dietary acid load and BP in healthy adults. Healthy adults aged 18-79 years old were included in this retrospective analysis. Dietary acid load was approximated using the Potential Renal Acid Load (PRAL), which is strongly influenced by dietary intake of protein, phosphorus and potassium assessed from a 3-day diet record. The average of three seated BP measurements was used for our analysis. Associations between PRAL and BP were determined using bivariate and partial Pearson correlations. One hundred and fifty-four subjects (78M/76W; 39 ± 2 yrs; BMI 25 ± 0.3 kg/m²) were included in this study. Men had a higher BMI (26 ± 1 kg/m² vs. 25 ± 1 kg/m²; p=0.03) and BP (119 ± 1/70 ± 1 vs. 111 ± 2/67 ± 1 mmHg; p<0.05) than women. Average PRAL was 13.4 ± 1.6 mEq/day and is consistent with a high protein and low potassium diet. PRAL values were also greater in men than women (18.6 ± 2.6 mEq/day vs. 8.1 ± 1.8 mEq/day; p<0.05). Total energy intake was 2089 ± 48 kcals/day, with men consuming more energy than women (2340 ± 70 kcals/day vs. 1835 ± 51 kcals/day; p<0.001). PRAL was positively associated with systolic BP (SBP) and pulse pressure (PP) (SBP: r=0.171, p=0.034; PP: r=0.261, p=0.001) but not with diastolic BP (DBP: r=-0.050, p=0.539). When sex and age were included as covariates, PRAL was positively correlated with both SBP and PP (SBP: r=0.205, p=0.011; PP: r=0.234, p=0.004) but not DBP (DBP: r=0.007, p=0.936). In conclusion, these findings indicate that a higher dietary acid load, correlates with a higher SBP and PP. This relation remains even after accounting for age and sex.