Within- and between-person variation of nutrient intakes of older people in Korea

Objectives: (i) To examine the components of variation in nutrient intakes for older Korean adults; (ii) To calculate the level of accuracy with varying degree of precision in order tu achieve estimates of usual nutrient intakes. Design: Five or six 24 h recalls were made over a four month period on each individual. Setting: A senior school from a middle-income, urban community in Inchon, Korea. Subjects: Forty-seven males and 36 females over 60 y old with complete records for at least five dietary recalls. Results: The within-person variation of nutrient intakes (21.8-103.2%) was higher and differed more markedly by nutrients than the between-person variation (9.4-63.7%). Males (2.26-11.28) showed larger within-to-between person variance ratios than females (1.73-5.56). The variance ratios were different by nutrients for males, but no such pattern was observed for females. Depending on nutrients, 5-6 recalls over a four month period gave estimates of nutrient intakes within 30-50% of usual intakes. For most nutrients, 100-200 subjects were sufficient to obtain estimates with 10% deviation of group usual intakes. Achieving r = 0.9 between observed and usual intakes required 24-54 recalls for males and 8-23 recalls for females. Conclusions: The degree of precision achieved during assessment of elder Korean adults' usual nutrient intakes changes with gender and by the type of nutrients. Achieving similar level of accuracy of the estimates, older Korean adults may require more dietary recalls than the adults in western countries.