Food Additives and Kidney Disease: A Critical Narrative Review of Exposure Assessment, Mechanistic Plausibility and Evidential Strength
Sivakumar Joghi Thatha Gowder *
College of Applied Medical Sciences, King Faisal University, Hufuf, KSA.
*Author to whom correspondence should be addressed.
Abstract
Industrial food additives are now near-ubiquitous constituents of the packaged food supply, and nephrology has treated them as a clinical problem for more than fifteen years, chiefly because inorganic phosphate salts deliver highly absorbable mineral to people whose capacity to excrete it is impaired. The literature that has grown around this concern is nevertheless fragmented. One body of work audits additive prevalence in the food supply, a second uses ultra-processed food intake as a proxy exposure and relates it to kidney outcomes, a third examines individual additive classes against non-renal endpoints in large dietary-record cohorts, and a fourth reports high-dose animal toxicology. These literatures rest on incompatible exposure constructs and are seldom appraised together. This critical narrative review evaluates the strength, consistency and limitations of evidence linking food additives to kidney disease across the general population, chronic kidney disease and kidney failure treated by dialysis. Literature was identified through structured searching of Europe PMC and Crossref Metadata Search, supplemented by institutional sources and citation searching, and appraised for exposure-measurement validity, confounding structure, outcome relevance and translational reach. The evidence is strongest, and closest to causal, for additive-derived inorganic phosphate raising serum phosphate in people receiving maintenance haemodialysis, where two randomised trials of additive avoidance produced concordant reductions. It weakens substantially in earlier chronic kidney disease and is largely absent for kidney endpoints in people with normal kidney function. Associations between ultra-processed food intake and incident kidney disease are consistent in direction but cannot identify additives as the operative agent, because ultra-processing co-varies with energy density, sodium, sugar and diet quality. Evidence on emulsifiers, non-sugar sweeteners, preservatives, colours and flavour enhancers is dominated by cardiometabolic, oncological or rodent endpoints, with kidney outcomes rarely measured. The central unresolved problem is exposure quantification: mandatory declaration of total phosphorus and additive-derived potassium would convert an unmeasurable exposure into a measurable one and is the precondition for informative trials. Current clinical advice should target additive-dense products rather than whole food groups.
Keywords: Phosphate additives, potassium additives, chronic kidney disease, ultra-processed food, food emulsifiers, non-sugar sweeteners, exposure assessment, food labelling