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The Associations Between Habitual Dietary Fat Intake and Inflammatory Markers Among Marathon Runners: An Exploratory
Qi Jin1, David Aguilar1, Damon Joyner1
1Department of Exercise and Nutrition Sciences, Dumke College of Health Professions, Weber State University, Suit 302, Swenson Building, 1435 Village Dr., Ogden, UT 84408, USA.
Background:
Marathon running triggers a robust systemic inflammatory response. Whether habitual dietary fat composition modulates pre-race cytokine concentrations or the magnitude and recovery of the exercise-induced inflammatory response remains unknown.
Methods:
Thirty-one recreational marathon runners (58.1% female; mean age 38.4 ± 10.2 years) completed the Diet History Questionnaire III to assess habitual dietary fat intake-including chain-length-specific SFA, MFA, PFA, trans fatty acids, and CLA-over the preceding three months. Circulating IFN-γ, IL-1β, IL-4, IL-6, IL-10, and TNF-α were measured pre-race, immediately post-race, and 48 h post-race. Repeated measures ANOVA examined cytokine changes; multivariable regression models estimated fat-cytokine associations adjusted for 11 pre-specified covariates, with Benjamini-Hochberg FDR correction applied across all models.
Results:
IL-6 rose markedly post-race (p < 0.001, generalized η2 = 0.615) before returning to pre-race levels by 48 h. IL-10 followed a similar trajectory (p < 0.001, generalized η2 = 0.346). TNF-α showed a borderline non-significant trend (p = 0.056); IFN-γ, IL-1β, and IL-4 did not change significantly. MFA 20:1 was positively associated with IFN-γ concentrations at 48 h post-race (β = 13.66; 95% CI: 8.94, 18.38, p < 0.01, q = 0.04) and TNF-α (β = 9.14; 95% CI: 6.43, 11.86, p < 0.01, q = 0.02).
Conclusions:
Habitual intake of the long-chain monounsaturated fatty acid 20:1 was positively associated with IFN-γ and TNF-α at 48 h post-race. This pattern, emerging specifically at the 48 h post-race phase, suggests that the post-race period, once acute exercise-induced signaling has subsided, may be a window in which habitual dietary fat quality is most detectable in relation to circulating cytokines. Habitual fat quality may warrant consideration in future endurance recovery nutrition research. This exploratory finding calls for replication in larger cohorts.