Nutrient intake in schoolchildren: some practical considerations

The diet of schoolchildren has been a sensitive issue throughout this century.The observation that recruits to the army during the Boer War were below desirable growth standards opened interest in a topic which has never since left the agenda for discussions on nutrition policy in this country.In the last decade concerns have centred on the possibility that dietary habits of schoolchildren, notably their high levels of consumption of sugar and high-fat snack foods and low consumption of fruit, vegetables and fibre, contribute to the development of dental caries and to degenerative diseases later in life.More recently the possibility of inadequacy of the diet of schoolchildren has been brought to the attention of scientists and the public by the publication of a report suggesting that low vitamin and mineral intake may impair mental function (Benton & Roberts, 1988).It seems as important now as ever before to be able to assess the adequacy of schoolchildren's diets and to identify possible health risks associated with current dietary practices.In 1983 the Department of Health and Social Security (DHSS) carried out a survey of the dietary habits of 3591 children aged 10-14 years in England, Wales and Scotland (DHSS, 1989), using the 7 d weighed-intake method.This study provides a benchmark against which future studies will be compared.Other studies are likely to be based on smaller sample sizes and to have access to less resources and manpower than the DHSS survey.Practical aspects of the design and interpretation of such studies need to be considered to optimize the quality and validity of the data collected.We have recently carried out a survey of dietary intake in 12-year-old schoolchildren in Dundee which has highlighted some of the practical considerations and problems of small-scale dietary studies in schoolchildren.The survey was carried out as an assessment of nutrient intake before a randomized controlled trial of the effects of vitamin and mineral supplements on verbal and non-verbal IQ, the results of which have been reported elsewhere (Crombie et al. 1990).While the primary hypothesis under test did not relate to the level of nutrient intake in the children, the baseline dietary information was" seen as essential for the interpretation of the findings of a supplementation study.If a significant effect of supplementation were found, it is useful to know whether the intake of the nutrient under question is below recommended daily allowances (RDA) or whether these require upward revision.Whether an effect of supplementation is found or not, it is also necessary to know whether the intake of the nutrient(s) in question is unusually high or low relative to other groups of children to whom the findings might be considered relevant, and, if conflicting findings between similar studies are found, to determine whether the nutrient intakes of the different study groups explain the differences in the results obtained.