A Statistical Approach for Estimating the Distribution of Usual Dietary Intake to Assess Nutritionally At-Risk Populations Based on the New Japanese Dietary Reference Intakes (DRIs)

Abstract

SummaryThe health of individuals is not markedly affected by the nutrients ingested in a single day; rather it is influenced by dietary habits over a long period of time. However, it is impossible to survey usual intake directly because recording diet over a long period of time is burdensome for the subjects, so usual dietary intake is rarely measured directly. Instead, we estimated the distribution of selected nutrients in subjects' usual dietary intake using a statistical method (Best-Power method) described previously. And we assessed the proportion of nutritionally at-risk subjects in individual groups based on the new Japanese Dietary Reference Intakes (DRIs), the Estimated Average Requirement (EAR), or the tentative dietary goal for preventing life-style related diseases (DG) as cut-points. We collected the survey data from 208 men and 251 women, aged 50 to 69 y in 2004 and 2005. The survey was carried out on three non-consecutive days four times each year: in spring, summer, autumn, and winter. The distribution of nutrients in the usual intake was estimated from a dietary survey of 3 d using one-way analyses of variance. We found that the proportion of the population at risk for nutrient deficiency was overestimated in the 1-d intake distribution. On the other hand, the fraction that was nutritionally at-risk in terms of salt intake, according to DG as the cut-point, was underestimated in the 1-d intake distribution: 74.0% of men and 82.5% of women in the 1-d intake, and 90.5% and 93.2%, respectively, for the estimated usual intake adjusted for seasonal variation.

Nutritional intake of Korean population before and after adjusting for within-individual variations: 2001 Korean National Health and Nutrition Survey Data

“…Only calcium demonstrated the opposite result; the percentage of the population whose intake of calcium was below the recommended increased by 3.2%. These increased proportions of inadequacies after controlling for within-individual variations have also been reported elsewhere [25,26], especially for some nutrients for which the median intake lies far below the EAR, regardless of the statistical approaches or software used.…”

Seasonal Variation in the Daily Urinary Sodium Excretion in Outpatients from the Morioka Region of Northern Japan

“…This suggests that people increase their sodium intake in the summer to compensate for salt loss due to sweating. Indeed, a dietary survey performed across 4 seasons in 459 Japanese subjects (including 208 men) identified significant seasonal variations in the daily salt intake, with intake being higher in summer than in winter among both men and women ( 33 ). Alternatively, this suggests that sodium intake is similar in summer and winter if salt loss from sweating is assumed to be minimal.…”

An Improved Statistical Method to Estimate Usual Intake Distribution of Nutrients by Age Group

“…During each season, the survey was conducted on 3 non-consecutive days; 2 of which were weekdays and one of which was a weekend day. The interval between the first and the third day was less than 2 weeks during each season [28]. The ethics committee of the National Institute of Health and Nutrition in Japan approved this survey.…”