It has been demonstrated adherence to a low carbohydrate (CHO) high fat (LCHF) diet can alter markers of iron metabolism in endurance athletes Purpose: To investigate the impact of CHO re-introduction in athletes previously adapted to a LCHF diet on subsequent inflammatory and hepcidin responses to exercise.
Methods: In the three weeks prior to the exercise trials, twenty-three elite race walkers adhered to either a CHO-rich (n=14) or LCHF diet (n=9). A 19-25 km race walking protocol was performed while the race walkers were still adhering to their allocated dietary intervention (Adapt). A second exercise test was performed three days later, where the LCHF consumed CHO 2 h prior to, and during the exercise protocol (in line with sports nutrition guidelines) for the first time in 3.5 weeks (CHO Restoration). Venous blood samples were collected pre-, post- and 3 h post-exercise and analysed for serum ferritin, interleukin-6 (IL-6) and hepcidin-25. Results: Serum ferritin concentration was similar between trials (p=0.48) and dietary groups (p=0.93). The post-exercise IL-6 increase was greater in LCHF (p<0.001) during both Adapt (LCHF: 13.1-fold increase; CHO: 8.0-fold increase) and CHO Restoration (LCHF: 18.5-fold increase, CHO: 6.3-fold increase); outcomes were not different between trials (p=0.84). Hepcidin25 levels increased 3 h post-exercise (p<0.001), however, they did not differ between trials (p=0.46) or diets (p=0.84). Conclusions: Strenuous exercise undertaken following chronic adaptation to a LCHF diet is associated with a greater post-exercise IL-6 response than when exercise is undertaken with
high CHO availability. The elevated IL-6 response in athletes adapted to a LCHF diet is not attenuated by an acute increase in exogenous CHO availability. Despite diet-induced differences in IL-6 responses, no differences in hepcidin levels were evident, suggesting IL-6 is likely not the primary factor determining the magnitude of post-exercise hepcidin levels. Baseline iron status may be a more dominant factor regulating this response. Increased IL-6 levels may negatively influence other body processes, and the long-term impact of adhering to LCHF on other health outcomes warrants further investigation.
Funded by the ACU Research Fund and the AIS High Performance Sport Research Fund.
Mckay, A. K. A., Peeling, P., Pyne, D. B.
, Welvaert, M., Tee, N., Leckey, J. J., ... Burke, L. M. (2019). Acute Carbohydrate Consumption On The Iron-regulatory Response To Exercise In Elite Keto-adapted Endurance Athletes
. Medicine and Science in Sports and Exercise
(6), 771-771. https://doi.org/10.1249/01.mss.0000562799.86566.1a