Variability of Total Energy and Protein Intake in Rural Bangladesh: Implications for Epidemiological Studies of Diet in Developing Countries

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Abstract
It has been recognized for some time that nutrient intakes show large day-to-day variations within the same individual in industrialized countries. However, little attention has been given to the quantification of within-and between-person components of the variation in developing countries. Within-person variability determines the number of measurements of dietary intake per person that will be needed to adequately represent the dietary intake of an individual over a period of time. A large within-person variation relative to the variation between persons in the intake of a nutrient decreases the strength of the observed association of the latter with an outcome of interest. This study quantified components of variation for 834 people of both sexes and various age groups and found that, although the diet in rural Bangladesh includes a limited number of food items-over 80% of calorie and protein intakes are provided by cereals, with rice being the main staple-the daily variability of nutrient intake in each individual over a year was as large as that reported for industrialized countries. The authors estimate that about seven days would be needed to assess total energy and protein intakes adequately, while much longer measurement periods would be needed for animal protein.