The Effects Of Exercise And Dietary Iron Contents On Iron Status

Many studies have indicated that exercise can affect the iron metabolism, and argued if the iron supplement is necessary to athletes due to the inconsistent standpoints to the developmental mechanism of the effects of exercise to iron status. On the other hand, the dietary iron contents can affect the iron status in the body. In this study, the difference of the sensitivity of iron status to low dietary iron supply between the growing period and after the sexual mature was firstly explored by observing the variations of the blood iron indicess and the non-heme iron (NHI) contents in the liver and spleen in the rats who were given a low dietary iron supply for 4 weeks. Then, in the rats after the sexual mature, the possible effects of exercise and dietary iron contents and their interactional effects were explored by observing the variations of iron status indices both in blood and in the tissus NHI contents in the rats whose diet was given the different iron contents during their swimming period of 3 months. The results will provide experimental and theoretical evidence for scientific body building and reasonable dietary iron supplement.Both the 4-week old and the 9-week old female Sprague-Dawley (SD) rats were randomly divided into their corresponding low dietary iron groups and their iron sufficient groups, including the growing iron deficient group(GID), the growing iron sufficient group(GIS), the adult iron deficient group(AID), the adult iron sufficient group(AIS). The growing rats were fed a modified AIN-93G diet, and the sexual mature rats were fed a modified AIN-93M diet, both of which were modified with a slightly low iron content (18．9mg/kg) and a sufficient iron content (86．9mg/kg). After 4 weeks, the blood indices of iron status and the NHI contents in the liver and spleen were determined.Female SD rats after the sexual mature (9-week old) were randomly assigned to the corresponding dietary iron deficient groups, the iron sufficient groups and the iron supplement groups. Each group was sub-divided into an exercise group and a sedentary group. Thus, a total of six groups was formed, including the iron deficient groups (exercise, IDE; sedentary, IDS), the iron sufficient groups (exercise, INE; sedentary, INS), and the iron supplement groups (exercise, IHE; sedentary, IHS). These rats were fed a modified AIN-93M diet, which were modified with a slightly low iron content (18．9mg/kg), or a sufficient iron content (86．9mg/kg), or a higher iron content (497．6mg/kg). The rats in the exercise groups swam for 3 months. The blood iron status indices (RBC,Hb,Hct,MCV,MCH,MCHC,RDW,PI,TIBC,TS) and the contents of NHI in the liver,spleen,kidney,myocardium and gastrocnemius were determined at the end of the desired period.The results of the study:(1) As compared to the GIS, the variations of blood iron indices and the contents of NHI in the liver and spleen in the GID were as follows: the contents of NHI significantly decreased both in the live and spleen, and the variation in the liver was extremely significant, there were no significant variations of erythrocyte series and PI.As compared to the AIS, the variations of blood iron indices and the contents of NHI in the liver and spleen in the AID were as follows: the contents of NHI significantly decreased both in the live and spleen, the variation in the liver was extremely significant, and the content of PI decreased significantly, while the MCV and RDW increased significantly.(2) As compared to the IDS, the variations of blood iron indices and tissus NHI contents in the IDE group were as follows: the MCH and TS decreased significantly, while the TIBC increased significantly, although there were no significant variation of the NHI in the spleen and gastrocnemius, it decreased to some extent.As compared to the INS, the variations of blood iron indices and tissus NHI contents in the INE group were as follows: the TIBC increased significantly, and the TS decreased significantly, the content of NHI significantly increased in the liver, while significantly decreased in the myocardium, although there were no significant variation of the NHI in the spleen and gastrocnemius, it decreased to some extent.As compared to the IHS, the variations of blood iron indices and tissus NHI contents in the IHE group were as follows: the RBC,MCV,RDW and the contents of PI and TIBC all increased significantly, and the variation of the RBC,PI and TIBC were extremely significant, meanwhile, the TS decreased significantly, although there were no significant variation of the NHI in the spleen and gastrocnemius,it increased to some extent.(3) As compared to the INS, the variations of blood iron indices and tissus NHI contents in the IDS group were as follows: the MCHC increased extremely significantly, while the contents of PI and NHI in the spleen,kidney and myocardium decreased extremely significantly, although there were no significant variation of the NHI in the liver, it decreased to some extent.As compared to the INS, the variations of blood iron indices and tissus NHI contents in the IHS group were as follows: there were no significant variation of the blood iron indices, the content of NHI significantly increased in the liver and gastrocnemius, and the variation in the liver was extremely significant.As compared to the INE, the variations of blood iron indices and tissus NHI contents in the IDE group were as follows: the MCV significantly decreased, while MCHC significantly increased, the TIBC and the content of NHI in the liver significantly decreased.As compared to the INE, the variations of blood iron indices and tissus NHI contents in the IHE were as follows: the contents of PI and the NHI in the liver,spleen and gastrocnemius all significantly increased, while the TIBC significantly decreased, and the variations of PI,TIBC and the NHI in the gastrocnemius were extremely significant.The main conclusions of the study:(1) The sensitivity of iron status to nutritional iron deficiency is different between the growing youth and the adult after the sexual mature. The adult individuals after the sexual mature could have the higher sensitivity of iron status to nutritional iron deficiency than the growing youth.(2) Both the exercise and dietary iron content can affect the iron status, and the two factors would interact with each other. However, the effects of exercise on different dietary iron status are distinctive, and the the effects of dietary iron status are distinctive too between the sedentary and exercise state. Under the low dietary iron supply, exercise can improve iron status, and makes it approach to the normal status. While exercise could augment the iron loading in body, and intensify the iron over load due to the excessive iron supply. Therefore, the iron supplement to the crowd who exercise frequently must be prudent.