Dietary Acid Load and Human Health: A Systematic Review and Meta-analysis of Observational Studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 39899655 · doi:10.1093/nutrit/nuae222
What was done
A systematic review and meta-analysis of observational studies was conducted across Medline, EMBASE, Scopus, and Web of Science to evaluate associations between dietary acid load—measured via potential renal acid load (PRAL) and net endogenous acid production (NEAP)—and diverse health outcomes. Independent reviewers screened studies and assessed risk of bias. Evidence credibility for each outcome was classified into predefined classes based on pooled effect sizes, 95% confidence intervals, 95% prediction intervals, heterogeneity, small-study effects, and excess significance bias. The analysis included 118 observational studies (22 case-control, 65 cross-sectional, 31 cohort) covering 1,014,081 participants across 38 health outcomes.
What was found
Statistically significant associations were observed for 21 of 37 outcomes evaluated for PRAL and 20 of 38 outcomes evaluated for NEAP. For PRAL, evidence credibility was rated convincing (class I) for type 2 diabetes (T2D) and highly suggestive (class II) for overall cancer and systolic blood pressure. For NEAP, evidence was convincing (class I) for T2D and overall cancer, and highly suggestive (class II) for breast cancer. All other evaluated outcomes had suggestive (class III), weak, or non-significant evidence. Specific numerical pooled effect sizes were not reported in the abstract.
Why it matters
This review synthesizes large-scale observational data indicating that diets with higher acid-forming potential are linked to increased risks of type 2 diabetes and overall cancer, highlighting dietary acid load as a potential nutritional risk factor.
Limits
The included literature consists entirely of observational studies (predominantly cross-sectional and case-control), precluding causal inference and leaving open the possibility of residual confounding. Specific numerical effect estimates and heterogeneity values were omitted from the abstract. Most of the 38 evaluated outcomes had weak or suggestive evidence.
Cited by
- context Diets high in meat and dairy are acid-producing and increase systemic inflammation, which impairs athletic recovery.