| Summary: | American Recommended Dietary Allowances (RDAs) and British Dietary Reference Values (DRVs) are used as the scientific benchmarks in a number of policies and surveys relating to food, nutrition and welfare. In the USA the RDAs have a number of statutory and regulatory involvements, particularly with respect to food assistance programmes and the definition of the poverty level. In the UK, although DRVs have no statutory role, they are the benchmarks against which diets of population groups are assessed or food supplies are determined, and hence they indirectly influence various policy decisions. Although RDAs and DRVs are often presented and used as if they were solely scientific standards, the thesis is premised upon the assumption that they are in fact a mixture of scientific, social and political factors. The thesis examines the way in which RDAs and DRVs are constructed, both the process and the products, by particular reference to the allowances for vitamin C in the USA and UK, and the controversy that surrounded the publication of the tenth edition of the RDAs in the USA in the 1980s. In particular, it focuses on what constitutes scientific evidence in the RDA arena, where and why boundaries are drawn between scientific and non-scientific evidence, and what are the judgements and interpretations included in the process and products of RDA and DRV construction. Research was carried out by means of a critical analysis of the literature to identify the relevant scientific evidence and areas of interpretation and selection. This was followed by in-depth interviews with key individuals who were involved in the most recent RDA and DRV report processes or in the disputed 1985 RDA report, or who have been advocates or critics of these standards over the years. The thesis shows that the science underlying the recommended figures is incomplete and the theoretical methods outlined for determining an RDA/DRV were not followed in practice. Even though the standards could be improved by strengthening the scientific evidence, they will always be subject to value judgements over the question of 'adequacy'. Influencing such judgements and also underlying the 1985 RDA controversy are the conflicting certainties and interests of different cognitive groups within science. With scientific credibility and scientific authority at stake, the boundary between science and non-science moves to suit the interests and beliefs of the different scientific groups. At the same time external groups align themselves with the cognitive evidence which reinforces their own position.
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