Meta-analysis finds higher circulating stearic acid associated with lower CKD risk in 18,193 adults

This meta-analysis examined the association between circulating saturated fatty acids (SFAs) and incident chronic kidney disease (CKD) by pooling data from 13 prospective cohort studies within the Fatty Acids Outcomes Research Consortium. The analysis included 18,193 participants from 9 countries who had baseline estimated glomerular filtration rates (eGFR) greater than 60 mL/min/1.73 m², representing a population with normal kidney function at study entry. The weighted median follow-up across cohorts was 7.6 years, during which 2,554 participants (14.0%) developed incident CKD, defined as an eGFR decline to below 60 mL/min/1.73 m² accompanied by at least a 25% decrease from baseline.

The exposure of interest was circulating concentrations of specific saturated fatty acids measured in different lipid fractions across the included cohorts. Seven cohorts measured SFAs in phospholipids, five measured them in serum or plasma total lipids, and one cohort used cholesterol esters. The analysis focused on five specific SFAs: palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0). The study did not report a specific comparator group but rather examined associations across continuous concentration ranges using interquintile ranges for effect size calculation.

For the primary outcome of incident CKD, the meta-analysis found a statistically significant inverse association with circulating stearic acid (18:0). The relative risk per interquintile range was 0.87 (95% confidence interval: 0.80, 0.95) with a P-value of 0.003, indicating a 13% lower risk of developing CKD with higher stearic acid concentrations. The heterogeneity between studies for this association was low (I² = 14.7%). In contrast, the analysis found no significant associations between incident CKD risk and circulating concentrations of palmitic acid (16:0), arachidic acid (20:0), behenic acid (22:0), or lignoceric acid (24:0). The authors did not report specific effect sizes, confidence intervals, or P-values for these non-significant associations.

The study did not report safety or tolerability findings, as this was an observational analysis of biomarker associations rather than an interventional trial. No adverse event data, serious adverse events, or discontinuation rates were provided. The analysis focused solely on epidemiological associations between circulating biomarkers and clinical outcomes without examining the effects of dietary interventions or pharmacological treatments.

These findings contribute to a growing but inconsistent body of literature on fatty acids and kidney health. Prior studies have yielded mixed results regarding SFA associations with kidney disease, with some suggesting harmful effects of certain SFAs and others showing neutral or potentially protective associations. This meta-analysis provides more precise estimates than individual cohort studies due to its larger sample size and standardized analytical approach across multiple populations. The specificity of the finding to stearic acid rather than SFAs as a class adds nuance to the understanding of how different fatty acid subtypes might relate to kidney function decline.

Several methodological limitations warrant consideration. As an observational meta-analysis, the findings demonstrate association rather than causation. Residual confounding from unmeasured factors such as diet quality, physical activity, or other lifestyle variables could influence the observed associations. The use of different lipid fractions for SFA measurement across cohorts introduces potential measurement heterogeneity, though the consistency of the stearic acid finding across studies suggests robustness. The outcome definition relied solely on eGFR decline without incorporating albuminuria or clinical endpoints like kidney failure, which may limit clinical relevance. The study did not report funding sources or author conflicts of interest, which is important context for interpreting findings.

For clinical practice, these findings suggest that circulating stearic acid concentrations may serve as a biomarker associated with lower CKD risk in adults with normal kidney function. However, clinicians should interpret these results cautiously and avoid making dietary recommendations based solely on this observational evidence. The study does not establish whether modifying stearic acid intake would affect CKD risk, and the biological mechanisms underlying the observed association remain speculative. The finding that only stearic acid showed a significant association—while other SFAs did not—highlights the potential importance of considering specific fatty acid subtypes rather than broad categories in nutritional epidemiology.

Important questions remain unanswered. The biological mechanisms through which stearic acid might influence kidney function decline require investigation through experimental studies. Whether dietary intake of stearic acid-rich foods correlates with circulating concentrations and subsequent CKD risk needs clarification. The generalizability of findings to populations with existing kidney disease, different age groups, or specific comorbidities is unknown. Future research should examine whether these associations persist when using more comprehensive CKD definitions that include albuminuria and clinical endpoints. Intervention studies would be necessary to determine whether modifying stearic acid intake affects kidney disease progression.