Iron is one of the most vital elements in humans as it plays a role in physiological functions such as transferring and storing oxygen, transporting electrons and catalysing numerous reactions, from oxidative metabolism to cellular proliferation. Iron deficiency can be attributed to poor absorption that leads to insufficient iron to meet body requirements. Oral iron supplements have been extensively used to treat iron deficiency and iron deficiency anaemia. However, the use of iron compounds in fortifying foods is one of the best practical approach to combat iron deficiency, while improving diet and food pattern involves long-term goal which can be challenging. Vitamin D has recently been shown to affect hepcidin levels, which in turn has effects on iron status but there are a limited number of studies investigating the hepcidin profile in humans following iron supplementation, and few data are available, especially in humans, despite its role as a primary iron absorption and homeostasis regulator. Although several studies have been carried out using iron fortified products, there is limited data on the potential effect of vitamin D on iron metabolism amongst iron deficient women in particular. Therefore, the present study aims to investigate the effect of vitamin D3 supplementation (1500 IU) consumed with iron fortified breakfast cereals on haematological indicators and hepcidin response in iron deficient women.