Understanding and Assessing Nutrition

Abstract

Most countries collect short-term food consumption information of individuals on a regular basis. These data, after much analysis and interpretation, are used to assess the nutritional status of population subgroups, design food assistance programs, guide nutritional and food policy, and—in epidemiological applications—uncover associations between diet and health. In this review, we focus on surveillance, a broad term that includes, for example, estimation of nutritional status and evaluation of the adequacy of the diet. From a statistical viewpoint, dietary intake and evaluation questions pose tremendous methodological challenges. Nutrient and food adequacy are defined in terms of long-term intakes, yet we can only practically observe short-term consumption, perhaps over one or two days. Food consumption measurements are noisy and subject to both systematic and random error, and in addition, there are very large day-to-day differences in a person's food consumption. Observed distributions of food and nutrient intake tend to be skewed, with long tails to the right and (in the case of episodically consumed items) with a mass at zero that can represent a large proportion of the distribution. We review the literature on this topic and describe some of the newest questions and proposed methodological solutions. The focus is on the use of large national food consumption surveys to address public policy and research questions, but much of what we discuss is applicable in a broader context.