Controversy on iron needs, intake levels, deficiency stigmata and benefits from iron supplementation.

At present there is considerable controversy over many aspects of iron nutrition, including: (1) iron needs and intake levels; (2) the bearing of iron intake on haematological levels; (3) iron deficiency anaemia and deficiency stigmata; and (4) iron therapy, prophylaxis, and the haematological and clinical benefits accruing. Differences of opinion prevail because of inadequacies of knowledge of the level of haemoglobin (or other parameter of iron status) below which unequivocal signs and symptoms of ill-health become manifest in the major proportion of those affected. Difficulties arise equally from lack of knowledge of the level of haemoglobin above which no clinical benefit, short-term or long-term, can be detected from iron supplementation. Clarification of the situation can be obtained only by carrying out the same meticulous and time-consuming procedures that have been used in respect of requirements and deficiency stigmata of other nutrients. Comprehensive iron depletion studies, real and simulated, and repletion studies, including the use of placebos, will be required. Epidemiological investigations bearing on haematological status and morbidity will also need to be undertaken, and include groups of subjects in both Western, and developing countries.