High-intensity exercise and low dietary intake significantly alter iron metabolism involving hepcidin

Background and Objectives: The amount of food intake and digestive tract function is known to decrease during intense exercise, and many athletes consume high energy but do not consume food. However, there are a few direct studies on the relationship between the degree of malnutrition (mild to severe) and exercise-induced anemia. The purpose of this study was to observe changes in iron metabolism of rats due to high-intensity exercise during reduced food intake. Methods: Thirty-six, 4-wk-old male Wistar rats were divided into six groups after being acclimated to running: rested control, intense exercise, 80% feeding and rested, 80% feeding and intense exercise, 70% feeding diet and rested, and 70% feeding and intense exercise groups. Only three intense exercise groups underwent acute running sessions for 30 min (30 m/min) once a day for 7 d. Results: Rats did not develop anemia with exercise and food intake restriction. Serum iron levels, transferrin saturation, hepcidin-25, and hepatic iron levels in the exercise groups were lower than those in the respective resting groups. However, these values in the 70% diet groups were slightly higher than those in the 80% diet groups. Serum erythropoietin levels decreased as food intake decreased, but the serum erythropoietin level in the 70% feeding and intense exercise group was similar to that in the rested control group. Serum interleukin-6 levels were significantly lower in the groups with restricted food intake than in the free-fed group, and exercise had no effect. Conclusions: High-intensity exercise under restricted food intake may significantly alter the iron metabolism to maintain blood cell levels due to the strong promotion of metabolic iron utilization in response to dietary iron depletion, increased iron demand, and excretion.