The short-term restriction of carbohydrate (CHO) can potentially influence iron regulation via modification of postexercise interleukin-6 (IL-6) and hepcidin levels. This study examined the effect of a chronic ketogenic low-CHO high-fat (LCHF) diet on iron status and iron-regulatory markers in elite athletes.
International-level race walkers (n = 50) were allocated to one of three dietary interventions: (i) a high-CHO diet (n = 16), (ii) a periodized CHO availability (n = 17), or (iii) an LCHF diet (n = 17) while completing a periodized training program for 3 wk. A 19- to 25-km race walking test protocol was completed at baseline and after adaptation, and changes in serum ferritin, IL-6, and hepcidin concentrations were measured. Results from high-CHO and periodized CHO were combined into one group (CHO; n = 33) for analysis.
The decrease in serum ferritin across the intervention period was substantially greater in the CHO group (37%) compared with the LCHF (23%) group (P = 0.021). After dietary intervention, the postexercise increase in IL-6 was greater in LCHF (13.6-fold increase; 95% confidence interval [CI] = 7.1–21.4) than athletes adhering to a CHO-rich diet (7.6-fold increase; 95% CI = 5.5–10.2; P = 0.033). Although no significant differences occurred between diets, CI values indicate that 3 h postexercise hepcidin concentrations were lower after dietary intervention compared with baseline in CHO (β = −4.3; 95% CI = −6.6 to −2.0), with no differences evident in LCHF.
Athletes who adhered to a CHO-rich diet experienced favorable changes to the postexercise IL-6 and hepcidin response, relative to the LCHF group. Lower serum ferritin after 3 wk of additional dietary CHO might reflect a larger more adaptive hematological response to training.
1School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, WA, AUSTRALIA;
2Australian Institute of Sport, Bruce, ACT, AUSTRALIA;
3Western Australian Institute of Sport, Mt Claremont, WA, AUSTRALIA;
4Research Institute for Sport and Exercise, University of Canberra, Canberra, AUSTRALIA;
5Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, AUSTRALIA;
6Department of Laboratory Medicine (TML 830), Radboud University Medical Center, Nijmegen, THE NETHERLANDS; and
7Hepcidinanalysis.com, Nijmegen, THE NETHERLANDS
Address for correspondence: David Pyne, Ph.D., F.A.C.S.M., Research Institute for Sport and Exercise, University of Canberra, Canberra 2601, Australia; E-mail: email@example.com.
Submitted for publication August 2018.
Accepted for publication October 2018.