Iron Physiological Requirements In Young Men And Women Of Childbearing Age Assessed By The Stable Isotope Tracer Technique

Objective1.To establish the assessment method of the iron physiological requirements in young men and women of childbearing age by the stable isotope tracer technique.(1)To explore the methods for assessing the physiological requirements of adults with stable isotopes 57Fe and 58Fe using a direct calculation method.(2)To get the stable period of the abundances after the isotopes 57Fe and 58Fe absorbed in the body.(3)To get the proportion of the amount of blood iron to the iron in the whole body which is also called the "utilization rate of circulating iron".(4)To compare the results get by formula calculation method and linear regression method,and deduce the iron DRIs of adults according these results.2.To get the iron physiological requirements in Chinese young men and women.(1)To get the iron physiological requirements of young men.(2)To get the iron physiological requirements of women with childbearing age.(3)To compare the difference between the iron adult DRIs derived from this study and the available data.Method1.Research designUrban young men and women:Male and female college students in the Bethune Military Medical College in Shijiazhuang Hebei were recruited according to the inclusion criteria.After informed consent,their basic data were collected and iron nutrition status were tested.We arranged their accommodation,gave them uniformed recipes and recorded(trials for 14 days).At the beginning of the trial,the subjects were given 3.25 mg 57Fe orally and 2.4 mg 58Fe intravenously.The venous blood samples of subjects was expected to be collected on 0 d,14 d,lm,2 m,4 m,8 m,12 m and once every 4 months after 1 year,respectively.The venous blood was stored at-80? refrigerator for measuring.Rural women of childbearing age:Two batches women of childbearing age in the Xingtang village in Hebei province were recruit according to the inclusion criteria.After informed consent,their basic data were collected and iron nutrition status were tested.At the beginning of the trial,the subjects were given 50 mg 58Fe orally.We arranged their accommodation,gave them uniformed recipes and recorded(trials for 14 days).After the metabolic test,we continued to track and collect the blood samples and pay close attention to the health status of the subjects,especially the iron metabolism and pregnancy.The venous blood samples of subjects was expected to be collected on 0 d,14 d,lm,2 m,4 m,8 m,12 m and once every 4 months after 1 year,respectively.All blood samples were collected and stored in the refrigerator at-80 ? refrigerator for measuring.2.Sample analysisThe blood sample was digested with 70%nutric acid and then measured by MC-ICP-MS for the abundance of 57Fe or 58Fe.Iron biochemical indexes in plasma were measured by the Automatic biochemical analyzer.The scatter plot was drawn to get the stable period combined with the repeated measurement analysis of variance.The utilization rate of circulating iron and iron physiological requirement were calculated by the formula and the liner regression method.Result1.The iron physiological requirements of urban young men and women.19 subjects were eventually included in the final analysis of iron physiological requirements.57Fe reached its peak at day 60 and reached a stable period on day 240.58Fe reached its peak on day 14 and reached a stable period on day 425.The average utilization rate of circulating iron in 40 subjects was 84.06%,and the results of male and female showed no significant difference.In the whole process,the indexes of iron metabolism were in the normal range.The total amount of iron physiological requirements between 2 genders showed no significant difference(1101.68 ?g/d for women,959.9 ?g/d for men).But when adjusted by body weight,iron physiological requirements per kilogram of body weight appeared significant differences in different genders,which of women was 20.69 ?g/d.kg and of men was 14.04 ?g/d.kg.2.The iron physiological requirements of rural women with childbearing age.In this part,78 subjects were recruited.The 58Fe reached its peak on day 21 and reached a stable period on day 376.The results of 21 women of childbearing age were calculated by the formula.The average utilization rate of circulating iron in 46 subjects was 80.4%.The average iron physiological requirement was 1550.97 pg/d,and 23.63 ?g/d.kg adjusted by weight.The result of 33 women was calculated using linear regression method,the average iron physiological requirement was 1293.05 pg/d,and 20.98 pg/d.kg adjusted by weight.The iron loss rate was 22.71%per year.The median of the regression coefficient is 0.9691.ConclusionIn this study,the theoretical hypothesis and calculation formula for assessing the iron physiological requirement with stable isotope 58Fe tracer method were put forward and verified in two parts of volunteers.Different iron markers,ways of giving,methods of determining the "stable periods" and calculating iron physiological requirements were discussed.This method was used for the first time to obtain data on iron physiological requirements of adults(including young men and women of childbearing age).The utilization rate of circulating iron was 80%?84%,and the stable period started from 1 year.The iron physiological requirement of young men was 959.9 ?g/d,and 14.04?g/kg.d,and the EAR and RNI calculated according this result were the same as the recommended values of 2013 version.The iron physiological requirement of women of childbearing age was 1101.68?1550.97 ?g/d,and 20.69?23.63?g/kg.d,and the EAR and RNI calculated according this were slight lower than the recommended values of 2013 version.The results obtained from this study are in good agreement with the relevant research results,which can provide reference and basis for the improvement of the research methodology of iron physiological requirement and the revision of iron DRIs in the future.