Nutrient intakes and demographic characteristics of under-reporters, accurate-reporters and over-reporters of total energy intake in the cache county study on memory, health, and aging

Abstract

To increase the awareness of methodologic issues of importance when using food frequency questionnaires to estimate usual dietary intake in elderly populations. We compared energy-adjusted nutrient intakes and other characteristics among under-, accurate-, and over-reporters of energy intake (EI) in the Cache County Study on Memory, Health and Aging (CCMS) in Utah. The CCMS is a prospective study of 5092 resident men and women who were 65 years of age or older in 1995. Usual energy and nutrient intakes were estimated using a 140-item food frequency questionnaire. Basal metabolic rate (BMR) was estimated using the Harris-Benedict equations and used to calculate the EI:BMR ratio. Participants with EI:BMR<1.27 were classified as under-reporters and participants with EI:BMR>1.7 as over-reporters. Pair-wise multiple comparisons in ANOVA were used to examine differences among the three groups. Under-reporting of energy occurred in 53% of men and 38% of women; 19% of men and 32% of women over-reported energy intake (p-value<0.001). Under-reporters were younger and had a higher body mass index compared to accurate- or over-reporters (p-values≤0.001). Over-reporters scored lower on a test of cognitive function compared to under-reporters (p-value<0.001). We observed few differences in estimated mean energy-adjusted (EA) nutrient intakes among the three groups. Among both men and women, under-reporters reported less EA-fat intake than over-reporters and more EA-calcium intake than either adequate or over-reporters (p-values≤0.01). Among men, under-reporters also reported more EA-iron intake than over-reporters (p-value<0.006). Adjustment for energy intake appears to reduce bias in estimated nutrient intake and this adjustment seems especially important among elderly men and women who over- or under-report energy intake.