Objective: To describe the rationale, design and methods for a nutrition surveillance study with special reference to vitamin B6 and other micronutrients.
Rationale and design: Several studies in the Netherlands have shown that differences in dietary intake and in nutritional status indicators are relatively small among various socio-demographic groups, so that the relevance of this traditional risk group identification in terms of public health and nutrition policy is limited. Therefore, it was decided to use the diet itself as primary selection criterion for a study on the adequacy of the vitamin B6 supply. The first Dutch national food consumption survey in 1987/88 showed, among other things, that mean vitamin B6 intake (per gram of protein) was substantially below the adequate level for all age-gender groups studied. Since the potential impact on public health of this observation may be relatively large, intake of vitamin B6 was chosen as first selection criterion. A study design that creates the largest possible distinction in vitamin B6 intake would be most efficient to study the health risks as a consequence of a low vitamin B6 intake. Several arguments, such as the need to estimate the prevalence of an inadequate status of vitamin B6 and other micronutrients, led to the decision to use a random population sample as a reference group for comparison with the group with low habitual vitamin B6 intake. Other major arguments underlying the study design and the selection of the nutritional status indicators, as well as the framework of the Dutch Nutrition Surveillance System, are discussed. Finally, the design and methods of the study are described in detail (except food consumption methods).