Dietary acid load and cardiometabolic risk factors: a systematic review and meta-analysis of observational studies

Objective: Dietary acid load (DAL) might contribute to change the levels of cardiometabolic risk factors; however, the results are conflicting. The present review was conducted to determine the relationship between DAL and cardiometabolic risk factors. Design: Systematic review and meta-analysis. Setting: A systematic search was conducted in electronic databases including ISI Web of Science, PubMed/MEDLINE, Scopus and Google Scholar for observational studies which assessed cardiometabolic risk factors across DAL. Outcomes were lipid profile, glycaemic factors and anthropometric indices. Effect sizes were derived using a fixed- or random-effect model (DerSimonian-Laird). Also, subgroup analysis was performed to find the probable source of heterogeneity. Egger's test was performed for finding any publication bias. Results: Thirty-one studies were included in the current review with overall sample size of 92 478. There was a significant relationship between systolic blood pressure (SBP; weighted mean difference (WMD) = 1 center dot 74 (95 % CI 0 center dot 25, 3 center dot 24) mmHg; P = 0 center dot 022; I-2 = 95 center dot 3 %), diastolic blood pressure (DBP; WMD = 0 center dot 75 (95 % CI 0 center dot 07, 1 center dot 42) mmHg; P = 0 center dot 030; I-2 = 80 center dot 8 %) and DAL in cross-sectional studies. Serum lipids, glycaemic parameters including fasting blood sugar, glycated Hb, serum insulin, homeostatic model assessment of insulin resistance and waist circumference had no significant relationship with DAL. No publication bias was found. BMI was not associated with DAL in both cross-sectional and cohort studies. Conclusions: Higher DAL is associated with increased SBP and DBP. More studies are needed to find any relationship of DAL with lipid profile and glycaemic factors.