The effect of carbohydrate ingestion on plasma interleukin-6, hepcidin and iron concentrations following prolonged exercise

Abstract

The aim of our study was twofold, firstly to examine the relationship between plasma concentrations of IL-6, hepcidin and iron following prolonged exercise and secondly, to assess the effect of carbohydrate ingestion on circulating hepcidin concentration post-exercise. The study was a randomised double-blind cross-over design, with participants consuming either a carbohydrate (CHO) or an isovolumetric placebo drink throughout the trial. Nine healthy, trained males completed a treadmill run at 60% v V ˙ O 2 max for 120 min followed by a 5 km time trial. Plasma concentrations of both IL-6 and hepcidin significantly increased post-exercise following both trials ( p < .05) and returned to baseline by 24 h post ( p > .05). A positive correlation between hepcidin and IL-6 was demonstrated immediately following exercise during PLA while there was a trend for a moderate correlation during CHO (PLA trial rho = 0.81, p < 0.001; CHO trial rho = 0.36, p = 0.07). Plasma iron was unaffected immediately post-exercise but significantly reduced by 24 h post-exercise compared to baseline. CHO ingestion significantly reduced post-exercise IL-6 ( p < .05) but this had no effect on plasma hepcidin or iron concentration. Our data demonstrate CHO supplementation does not alter the rapid hepcidin response associated with exercise and does not prevent a subsequent fall in plasma iron concentration. This finding adds further support to the theory that an exercise-induced, up-regulation of hepcidin activity is a mechanism causing iron deficiency in endurance athletes.