Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan.
OBJECTIVE
To determine the extent to which interpopulation (between-population) variance, relative to intrapopulation (within-population) variance, contribute to the total variability in nutrient intakes.


METHODS
Cross-sectional study.


METHODS
Five Public Health Center districts in Japan.


METHODS
Two hundred and seven men and 183 spouses.


METHODS
A three-day weighed food record.


METHODS
The total variance in the consumption of 17 nutrient variables was partitioned by analysis of variance into its inter- and intrapopulation components separately for men and women.


RESULTS
The percentage contribution of the interpopulation to total variance differed according to the nutrient; it was notable (8-17%) for total energy, carbohydrates, phosphorus, and sodium in both men and women, but was negligible (less than 4%) for micronutrients such as retinol, carotene, thiamin, riboflavin, niacin and ascorbic acid. The ratio of intra- to interpopulation variance was estimated for 31 nutrients (17 in men and 14 in women). The point estimates of the ratio were larger than unity in all nutrients, and the lower limit of the 95% confidence intervals exceeded unity for all but 5 nutrients. Of the two sources of intrapopulation variation, intraindividual variance was larger than interindividual variance in most of the nutrient.


CONCLUSIONS
The relative magnitude of interpopulation variation in dietary data can be used to quantify the range of exposure in ecological studies and to examine the heterogeneity of populations pooled for individual-based analysis.
Tsubono
Y
Y
Epidemology and Biostatistics Division, National Cancer Center Research Institute, East, Kashiwa, Japan.
Fahey
M T
MT
Takahashi
T
T
Iwase
Y
Y
Iitoi
Y
Y
Akabane
M
M
Tsugane
S
S
D000328:Adult; D003430:Cross-Sectional Studies; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D006801:Humans; D007501:Iron / Q000008:administration & dosage; D007564:Japan; D008297:Male; D008875:Middle Aged; D010758:Phosphorus / Q000008:administration & dosage; D012727:Sex Characteristics; D012964:Sodium / Q000008:administration & dosage
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D010758:Phosphorus; D012964:Sodium; D007501:Iron