The red blood cell proportion of arachidonic acid relates to shorter leukocyte telomeres in Mediterranean elders: A secondary analysis of a randomized controlled trial

Background & aims: Shortening of leukocyte telomere length (LTL) is a biomarker of aging. Epidemiologic studies of LTL in relation to dietary fatty acids have reported conflicting results. The red blood cell (RBC) fatty acid status is a valid objective biomarker of long-term dietary intake of C18:2n-6, C18:3n-3 and long-chain n-3 polyunsaturated fatty acids (C20:5n-3 and C22:6n-3). In healthy older individuals, we investigated whether LTL relates to the RBC proportions of the main dietary polyunsaturated fatty acids (PUFA), and to the RBC proportion of arachidonic acid (C20:4n-6), a fatty acid that can generate pro inflammatory lipid mediators once released from cell membranes. Design: Cross-sectional study in 344 subjects (mean age 68.8 y, 68.6% women) who participated in a randomized controlled trial testing whether a diet enriched in walnuts can delay the onset of age-related diseases (https://clinicaltrials.gov/ct2/show/NCT01634841). At baseline, we assessed LTL by high throughput quantitative fluorescence and determined fatty acids in RBCs by gas chromatography. Results: In multivariate models adjusted for age and gender, the RBC proportions of dietary PUFA were unrelated to LTL. In contrast, the RBC proportion of arachidonic acid inversely related to LTL (regression coefficient [95% confidence interval], 0.10 (-0.19 to 0.01), P = 0.023). Conclusion: An increasing proportion of C20:4n-6 in RBCs is associated with shorter telomeres. Further research is needed to investigate the role of this fatty acid and its derived lipid mediators in the aging process. (C) 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.