Difference and Variance in Nutrient Intake by Age for Older Adults Living Alone in Japan: Comparison of Dietary Reference Intakes for the Japanese Population

This study aimed to estimate the distribution of usual intakes in protein, sodium, potassium, and calcium by age group and assessed whether proportions of deficiencies/excesses of each nutrient would occur more in older age via a comparison with the dietary reference intakes for the Japanese population (DRIs_J). A cross-sectional analysis was conducted using a database of the 2-day nutrient intake of 361 Japanese people aged 65–90 years. The AGEVAR MODE was used to estimate usual intake. Percentile curves using estimated distribution by sex and age and usual nutrient intake were compared to those of the DRIs_J. The usual intake of protein (male and female) and potassium and calcium (female) were lower with older age. Within-individual variance of protein in female (p = 0.037) and calcium in male (p = 0.008) subjects were considerably lower with older age. The proportion of deficiencies in protein (male and female), potassium (female), and calcium (female) were higher with older age. However, the proportion of people with excess salt (converted from sodium; male and female) did not differ by age. The variances found herein could be important for enhancing the understanding of differences in dietary intake by age.