Methods of nutritional assessment and surveillance
This chapter deals with some of the methods used by nutritionists and dietitians to assess and monitor the nutritional status and nutritional well-being of individuals and populations; they are also at the heart of much nutrition research. Biochemical indices used to assess micronutrient status can often be measured with great precision but interpretation of those values is often problematical because of doubts about the threshold values used to classify a subject as deficient. Individual methods of assessing food intake may either involve the prospective recording of food as it is eaten or may assess intake retrospectively by the use of interviews or questionnaires. The weighed inventory requires that the subjects weigh and record all items of food, drink consumed over a pre-determined period. The operator must then translate this food inventory into nutrient intakes with food tables. The analytical methods used to determine the nutrient content of foods are often extremely precise with a very low level of measurement error.