The body has no means of excreting excess iron, thus control of the body iron burden is by regulation of iron absorption. The only way in which iron is lost from the body is from shedding of cells from skin and mucosal surfaces, sweat (0.2–0.3 mg/day), urine (<0.1 mg/day), and hair.
In healthy individuals, iron losses are thought to be approximately 1 mg/day in males and slightly more in women of child-bearing age because of additional losses due to menstruation, pregnancy and lactation. In premenopausal women, iron is also lost in menstruation.
It is assumed that only 15% of dietary iron is absorbed. As a result, the Reference Nutrient Intake (RNI) for men aged over 19 and women aged 19-50 is 8.7mg/day and 14.8mg/day respectively. The RNI falls down to 8.7mg/day for women of 50+ years.