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% vV˙O2max 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 less than .05) and returned to baseline by 24 h post (p greater than .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 less than 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 less than .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.