In response to a query about iron deficiency and asthma (on another thread) I have posted the following information which may be of some interest.
Whilst the extract does not directly link iron deficiency to asthma, it clearly links iron deficiency to both immune system dysfunction and fungal infection, both found to be common characteristics in asthmatics.
Iron metabolism and infection
The relationship between iron metabolism and infection has been the subject of numerous reports and it appears that both increased and decreased iron levels can predispose the host to infection (Bullen, 1981). The incidence of infection is increased in iron-deficient individuals. Shortage of iron leads to impairment of T cell and neutorphil function (Bullen, 1981). Low serum levels of iron are seen in familial chronic mucocutaneous candidosis (Higgs & Wells, 1972).
Extract from 2.3.7 Malnutrition p28., Fungal Infection in the Compromised Patient by DW Warnock & MD Richardson.