The Association Between Dietary Acid Load and Non-Alcoholic Fatty Liver Disease

Area of Science:

• Metabolic Disorders
• Nutritional Science
• Hepatology

Background:

• Global non-alcoholic fatty liver disease (NAFLD) prevalence is rising, linked to obesity and metabolic issues.
• Diet-induced metabolic acidosis, measured by dietary acid load (DAL) indices like potential renal acid load (PRAL) and net endogenous acid production (NEAP), is a potential NAFLD contributor.
• Existing research on DAL and NAFLD shows inconsistent findings.

Purpose of the Study:

• To systematically review and evaluate the association between dietary acid load (DAL) and the risk of non-alcoholic fatty liver disease (NAFLD) in adult populations.
• To synthesize current evidence from observational studies on the DAL-NAFLD relationship.
• To identify gaps in knowledge and suggest future research directions.

Main Methods:

• Comprehensive literature search of PubMed, Web of Science, and Scopus databases up to January 2025.
• Inclusion of observational studies assessing DAL and NAFLD in adults, with independent data screening and extraction.
• Methodological quality assessment using AXIS and Newcastle-Ottawa scales, followed by narrative synthesis due to heterogeneity.

Main Results:

• Five studies (four cross-sectional, one case-control) met inclusion criteria, published between 2015-2023.
• Three studies indicated a positive association between higher DAL (PRAL/NEAP) and NAFLD risk (adjusted ORs ~1.3-2.2).
• One study found no significant association, while another reported a U-shaped relationship with moderate PRAL inversely associated with NAFLD.

Conclusions:

• Current evidence suggests a potential association between higher dietary acid load and increased NAFLD risk.
• However, the findings are inconsistent, highlighting the need for further investigation.
• Well-designed longitudinal studies are crucial to establish causality and clarify the DAL-NAFLD relationship.