Dietary acid load, blood pressure, fasting blood sugar and biomarkers of insulin resistance among adults: Findings from an updated systematic review and meta‐analysis

Objectives There is no clear summarised report of the association between dietary acid load components including potential renal acid load (PRAL) and net‐endogenous acid production (NEAP) with cardiometabolic risk factors. In the current meta‐analysis, we aimed to systematically review and summarise the eligible observational studies evaluating the association between PRAL and NEAP with blood pressure and hypertension and markers of glucose haemostasis among adults. Design and Setting In a systematic search from PubMed, SCOPUS, Web of Sciences and Cochrane electronic databases up to May 2019, relevant studies were included in the literature review. Observational studies evaluating the association between PRAL and NEAP with the systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose, insulin, homeostatic model assessment of insulin resistance (HOMA‐IR), haemoglobin A 1 C (HbA 1 C), HOMA‐β and quantitative insulin check index (QUICKI) and also prevalence or odds of hypertension, hyperglycaemia and diabetes were included. Results Total number of studies included in the 14 separate meta‐analyses were as follows: Mean (SD) of SBP (PRAL, n = 12; NEAP, n = 6), mean (SD) of DBP (PRAL, n = 8; NEAP, n = 3), mean (SD) of FBS (PRAL, n = 12; NEAP, n = 5), mean (SD) of HbA 1 C (PRAL, n = 6; NEAP, n = 4), mean (SD) of HOMA‐IR (PRAL, n = 7), mean (SD) of insulin (PRAL, n = 7; NEAP, n = 2); OR of type 2 diabetes mellitus (T 2 DM) (PRAL, n = 8; NEAP; n = 6), HTN prevalence (PRAL, n = 9; NEAP, n = 9), T 2 DM prevalence (PRAL, n = 7; NEAP, n = 6). According to our results, being in the highest PRAL categories was associated with higher SBP (WMD = 0.98; CI: 0.51, 1.45; P  < .001), DBP (WMD = 0.61; CI: 0.089, 1.135; P  = .022), insulin (WMD = −0.235, CI: 0.070, 0.400; P  = .005), higher odds of diabetes (OR = 1.19; CI: 1.092, 1.311; P  < .001), higher prevalence of T 2 DM (13% and 11% in highest vs lowest category). While, being in the highest category of NEAP was only associated with higher odds of diabetes (OR = 1.22; CI: 1.14, 1.31, P  < .001). In subgroup analysis for finding the possible source of heterogeneity, the continent, dietary assessment tool, sample size and gender were the potent sources of heterogeneity. No association between PRAL and NEAP with HbA 1 C, HOMA‐IR was reported. Conclusions In the current meta‐analysis, we found potent negative effects of high dietary acid load particularly higher PRAL scores cardiometabolic risk factors. Therefore, lower acidogenic food ingredients in the diets are suggested for the prevention of cardiovascular risk factors and diabetes.