The objective was to conduct a critical appraisal of research conducted within one of the UK government's research programmes, Optimal Nutrition Status, and to place the findings of this work in the context of the international research effort, to assist policy makers and advisers. Nine nutrients are addressed within the programme; the findings for three of these are reported here: folate/folic acid, iron and copper.

To conduct the review, the researchers had access to all unpublished progress reports, submitted to officials, arising from the projects. The overall assessment criterion was whether the information generated by the research programme could be regarded as reliable experimental data of direct relevance to setting optimal dietary requirements for the particular micronutrients. However, findings were also assessed against specific scientific criteria concerning understanding of the bioavailability, interactions, development of functional markers and inter-individual variations in metabolism, for each of the nutrients scrutinised.

The results of the review indicated that many important questions are indeed being addressed by the UK government's research programme, and that the work is contributing to the overall research effort being conducted world-wide on this important subject.

Many major questions still need to be addressed before it will be possible to identify optimal intakes for various sub-populations. These priorities are summarised in the paper.