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Published on: February 6, 2020
Inverse Association between the Omega-3 Index and Neutrophil-Lymphocyte Ratio: Pooled Results from Four
Michael I McBurney1, Nathan L Tintle2, Jason Westra3
1Department of Human Health Sciences, University of Guelph, Guelph, ON, Canada; Fatty Acid Research Institute, Sioux Falls, SD, United States.
Background:
The Omega-3 Index [O3I, erythrocyte eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) content] has been inversely correlated with neutrophil-lymphocyte ratio (NLR) and red blood cell distribution width (RDW) in observational studies.
Objectives:
We evaluated the effects of omega-3 interventions (EPA+DHA) on O3I, NLR, and RDW values in healthy adults and tested the hypothesis that changes in O3I (ΔO3I) modified NLR and, separately, RDW.
Methods:
We performed a de novo, individual-level analysis of baseline (b) and post (p) intervention O3I, NLR, and RDW values from 3 randomized, placebo-controlled trials and 1 ω-3 supplementation trial, followed by an equivalent duration washout (combined n =436). Primary outcome effect estimates were obtained using linear mixed effects models with a statistical significance threshold set at 0.05.
Results:
EPA + DHA supplementation (mean dose = 1160 mg/d) increased O3I (ΔO3I = 3.28%, P < 0.001, n = 253), whereas O3I decreased (ΔO3I = -0.62, P < 0.001, n = 183) in the CONTROL group. NLR decreased in individuals treated with EPA + DHA (ΔNLR = -0.15, P < 0.001) compared with CONTROL (-0.02, 95% confidence interval: -0.10, 0.06), a statistically significant difference (P < 0.05). In contrast, EPA+DHA supplementation was not associated with changes in RDW (P = 0.62), whereas RDW increased by ∼1% in CONTROL individuals (ΔRDW = 0.09, P < 0.01). ΔNLR values were inversely correlated with ΔO3I in unadjusted (model 1, r = -0.08, P < 0.05) and models that adjusted for baseline NLR, age, and sex (model 2, r = -0.07, P < 0.05). There was no evidence of an association between ΔO3I and ΔRDW (model 2, r = 0.003, P = 0.37).
Conclusions:
In healthy adults, EPA+DHA increased O3I and reduced NLR. ΔO3I was inversely correlated with ΔNLR but not with ΔRDW. Further clinical trials are needed to determine if ω-3 supplementation causes biologically relevant changes in NLR, and possibly RDW, to affect clinical outcomes in individuals with elevated NLR and RDW, and their associated increased risk of morbidity and mortality.