The Relationship Between Red Blood Cell Omega‐3 Fatty Acids and Inflammation in Post‐Menopausal, Obese Women Completing a Behavioral‐Based Dietary Intervention
Authors: Thompson Kylie , Orchard Tonya , Andridge Rebecca 
Published: November 2023

Objective

Determine the effects of a dietary intervention (LAS‐O3) aimed at lowering intake of added sugars and increasing intake of fiber and omega‐3 fatty acids (O3 FA) on biomarkers of marine O3 FA intake and inflammation.

Methods used

Sixteen post‐menopausal women with a BMI ≥30 (obese) were enrolled in a behavioral‐based pilot study. Fasting blood samples were collected at baseline, end of intervention (week 12) and follow‐up (week 24). Serum was analyzed for inflammatory cytokines (Interleukin‐6 [IL‐6], C‐Reactive Protein [CRP] and Tumor Necrosis Factor‐alpha receptor 2 [TNF‐αR2]). Red blood cells (RBC) were analyzed for relative fatty acid content (%FA/total detected FA) using gas chromatography; RBC eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as biomarkers of marine O3 FA intake. Paired t‐tests were used to test for changes in cytokines and RBC EPA and DHA over time. Linear regression was used to predict IL‐6, CRP and TNF‐αR2 based on RBC EPA and DHA separately for each time point. Linear regression was used to predict the change in IL‐6, CRP and TNF‐αR2 between visits based on change in RBC EPA and DHA between visits. All regression models were then adjusted to include percent weight change between visits as a covariate.

Results

In the 14 women who completed the intervention, mean baseline values for TNF‐αR2, IL‐6 and CRP were: 5982.5 pg/ml, 1.34 pg/ml and 1.6 mg/ml, respectively; mean EPA and DHA were 0.47% and 3.07%, respectively. There was a statistically significant reduction in mean TNF‐αR2 values from baseline to week 12 (−838.92 pg/ml; p=0.01), which was maintained through week 24. IL‐6 and CRP trended downward from baseline to week 12 and week 24, but not significantly. Mean RBC DHA increased significantly from baseline to week 12 (+1.25%; p=0.00) and was maintained through week 24. Mean RBC EPA increased from baseline to week 24 (+0.2%; p=0.02). Linear regression results suggested that RBC fatty acids were not significant predictors of inflammatory cytokines at any time point. The relationships at baseline were as follows: RBC EPA and IL‐6 (Slope=−0.73, p=0.22), RBC EPA and CRP (Slope=−11.18, p=0.13), RBC EPA and TNF‐αR2 (Slope= −1351.8, p=0.44), RBC DHA and IL‐6 (Slope=−0.12, p=0.44), RBC DHA and CRP (Slope=−1.53, p=0.44) and RBC DHA and TNF‐αR2 (Slope=−232.1, p=0.62). Changes in EPA and DHA were not significant predictors of changes in IL‐6, CRP and TNF‐aR2 at any time point. No appreciable modification of the results was made when adjusting for percent weight change. Percent weight change (week 12 to week 24) was a significant predictor of TNF‐αR2 change when individually adjusting for EPA and DHA change (slope=203.06, p=0.02 and slope=223.16, p=0.04, respectively).

Conclusion

A dietary intervention aimed at lowering added sugars and increasing fiber and O3 FA resulted in higher RBC O3 FA and lower inflammatory biomarkers in postmenopausal obese women. Testing this intervention in a larger sample with longer follow‐up is warranted to determine if these changes produce beneficial health outcomes.