The Influence of dietary sodium on circulating inflammatory cytokines in healthy young female adults
Authors: Robinson Austin T , Babcock Matthew C , Migdal Kamila U , Watso Joseph C , Farquhar William B 
Published: June 2021

Purpose

Rodent studies demonstrate that excess sodium (Na+) from high‐salt diets can promote tissue inflammation and autoimmune disease. However, the evidence for dietary Na+ modulating inflammation in humans is scarce, particularly in females. Therefore, the purpose of this study was to determine if dietary salt influences levels of circulating inflammatory cytokines in healthy young female adults.

Methods

Twelve non‐hypertensive, non‐obese female adults (age: 26±7 years, height: 160±10 cm, weight: 64±8 Kg, BMI: 25±8kg/m2, blood pressure: 112/67±8/3 mmHg) participated in this randomized, controlled feeding trial. Participants consumed three isocaloric diets containing low‐ (LS; 1,000 mg/d), medium‐ (MS; 2,300 mg/d), or high‐ (HS; 7,000 mg/d) Na+ in random order separated by 3four weeks. Participants collected their urine for the final 24 hours of each diet for measurement of urinary Na+ excretion to verify diet adherence. On day 10 of each diet, participants underwent a venous blood draw. Plasma samples were obtained following centrifugation and used to determine circulating levels of the inflammatory cytokines: interleukin‐6 (IL‐6), interleukin‐17 (IL‐17), and tumor necrosis factor‐α (TNFα) via enzyme‐linked immunosorbent assays (ELISA; R&D Systems, Inc.). Blood pressure was also measured in triplicate at each visit via oscillometry (GE Dash 2000) after at least 15 minutes of supine rest. Potential differences in urinary Na+ excretion, blood pressure, and plasma cytokines were assessed via one‐way repeated measures ANOVA. Cytokine data were not normally distributed, so a log transformation was performed prior to parametric testing. After log transformation, TNFα was still not normally distributed, so a non‐parametric (Wilcoxon) test was used. Data are presented as mean ± standard deviation.

Results

Urinary Na+ excretion increased in a step‐wise manner going from the LS diet to the MS diet to the HS diet (LS=48±27, MS=110±46, HS=257±69 mmol/24h, p<0.01) suggesting participants complied with the controlled feeding. There was an effect of diet on mean arterial blood pressure diet (LS=74±5, MS= 75±6, HS= 79±7 mmHg; p=0.02). Circulating levels of IL‐6 were not influenced by dietary Na+ manipulation (LS=1.0±0.7, MS=1.1±0.7, HS=1.1±0.8 pg/mL; log‐transformed RM ANOVA, p=0.65). IL‐17 was undetectable in the samples from these participants although we were able to detect IL‐17 using manufacturer provided assay controls. This would suggest IL‐17 concentration was very low in these healthy young participants. Circulating levels of TNFα were not influenced by dietary Na+ manipulation (LS=2.9±2.9, MS=3.6±3.8, HS=4.2±5.0 pg/mL; Wilcoxon nonparametric test, p=0.56).

Discussion

Our preliminary data suggest that dietary salt does not influence levels of circulating inflammatory cytokines in healthy young female adults, despite high dietary salt eliciting a modest increase in their resting blood pressure.

Support or Funding Information

Supported by: NIH Grant 1R01HL128388 and NIGMS P20GM113125; ACSM Research Endowment Award #16‐00213

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.