Define Use of Isotopically Labelled Nutrients?

Nutrient Turnover Radioactive labelled nutrients are used to know the total body pool and the compartment in which it is stored. The pool that falls below a certain level shows deficiency. These are used ta estimate how much nutrient is lost on a daily basis. Let us consider an example of iron. Isotopically labelled iron has been used in estimating the iron requirements for different groups. Ingested iron is absorbed and incorporated into red cells; complete incorporation occurring in 15 days time. A small dose of radio labelled iron is mixed with the diet and two measurements are made; the basal radioactivity of the blood before ingesting, the radio labelled diet and radioactivity of red cells after 15 days of ingesting the diet. From the retained radioactivity, the amount absorbed and requirements are calculated.