Effects of macro- and micronutrients on exercise-induced hepcidin response in highly trained endurance athletes

Iron deficiency has ergolytic effects on athletic performance. Exercise-induced inflammation impedes iron absorption in the digestive tract by upregulating the expression of the iron regulatory protein, hepcidin. Limited research indicates the potential of specific macro-and micronutrients on blunting exercise-induced hepcidin. Therefore, we investigated the effects of postexercise supplementation with protein and carbohydrate (CHO) and vitamins D-3 and K-2 on the postexercise hepcidin response. Ten highly trained male cyclists (age: 26.9 +/- 6.4 years; maximal oxygen uptake: 67.4 +/- 4.4 mL.kg(-1).min(-1) completed 4 cycling sessions in a randomized, placebo-controlled, single-blinded, triple-crossover study. Experimental days consisted of an 8-min warm-up at 50% power output at maximal oxygen uptake, followed by 8 x 3-min intervals at 85% power output at maximal oxygen uptake with 1.5 min at 60% power output at maximal oxygen uptake between each interval. Blood samples were collected pre-and postexercise, and at 3 h postexercise. Three different drinks consisting of CHO (75 g) and protein (25 g) with (VPRO) or without (PRO) vitamins D-3 (5000 IU) and K-2 (1000 mu g), or a zero-calorie control drink (PLA) were consumed immediately after the postexercise blood sample. Results showed that the postexercise drinks had no significant (p = 0.05) effect on any biomarker measured. There was a significant (p < 0.05) increase in hepcidin and interleukin-6 following intense cycling intervals in the participants. Hepcidin increased significantly (p < 0.05) from baseline (nmol.L-1: 9.94 +/- 8.93, 14.18 +/- 14.90, 10.44 +/- 14.62) to 3 h postexercise (nmol .L-1: 22.27 +/- 13.41, 25.44 +/- 11.91, 22.57 +/- 15.57) in VPRO, PRO, and PLA, respectively. Contrary to our hypothesis, the drink compositions used did not blunt the postexercise hepcidin response in highly trained athletes.