Acute carbohydrate ingestion does not influence the post-exercise iron-regulatory response in elite keto-adapted race walkers

J Sci Med Sport. 2019 Jun;22(6):635-640. doi: 10.1016/j.jsams.2018.12.015. Epub 2019 Jan 4.


Objectives: Adhering to a low carbohydrate (CHO) high fat (LCHF) diet can alter markers of iron metabolism in endurance athletes. This investigation examined the re-introduction of CHO prior to, and during exercise on the iron-regulatory response to exercise in a homogenous (in regard to serum ferritin concentration) group of athletes adapted to a LCHF diet.

Design: Parallel groups design.

Methods: 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 standardised 19-25km race walk was performed while athletes were still adhering to their allocated dietary intervention (Adapt). A second test was performed three days later, where all athletes were placed on a high CHO diet (CHO Restoration). Venous blood samples were collected pre-, post- and 3h post-exercise and measured for interleukin-6 (IL-6) and hepcidin-25.

Results: The post-exercise IL-6 increase was greater in LCHF (p<0.001) during both the Adapt (LCHF: 13.1-fold increase; 95% CI: 5.6-23.0, CHO: 8.0-fold increase; 5.1-11.1) and CHO Restoration trials (LCHF: 18.5-fold increase; 10.9-28.9, CHO: 6.3-fold increase; 3.9-9.5); outcomes were not different between trials (p=0.84). Hepcidin-25 concentrations increased 3h post-exercise (p<0.001), however, they did not differ between trials (p=0.46) or diets (p=0.84).

Conclusions: The elevated IL-6 response in athletes adapted to a LCHF diet was not attenuated by an acute increase in exogenous CHO availability. Despite diet-induced differences in IL-6 response to exercise, post-exercise hepcidin levels were similar between diets and trials, indicating CHO availability has minimal influence on post-exercise iron metabolism.

Keywords: Ferritin; Hepcidin; Interleukin-6; Iron metabolism; LCHF diet; Race-walkers.

MeSH terms

  • Adult
  • Athletes
  • Diet, Carbohydrate-Restricted*
  • Dietary Carbohydrates / administration & dosage*
  • Female
  • Hepcidins / blood*
  • Humans
  • Interleukin-6 / blood
  • Iron / metabolism*
  • Male
  • Sports Nutritional Physiological Phenomena*
  • Walking / physiology*
  • Young Adult


  • Dietary Carbohydrates
  • Hepcidins
  • IL6 protein, human
  • Interleukin-6
  • Iron