A COMPARISON OF THE FOOD COMPOSITION TABLE-BASED ESTIMATES OF DIETARYELEMENT INTAKE WITH THE VALUES OBTAINED BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY - AN EXPERIENCE IN A JAPANESE POPULATION

In order to make quantitative comparison between food composition tabl e-based estimates and instrumental measures by inductively coupled pla sma atomic emission spectrometry (ICP-AES), total food duplicates were collected from 232 adult women in 10 study regions in 9 Prefectures i n Japan. Daily dietary intake of 5 elements, sodium (Na), potassium (K ), phosphorus (P), calcium (Ca) and iron (Fe), were estimated from the weights of food items in each duplicate by use of food composition ta bles. Parallel to this the intakes were measured by wet-ashing of food duplicate homogenates followed by ICP-AES analysis. Because the emiss ion intensity of K was significantly modified by Na co-present at vari ous concentrations, K was measured after Na concentration was reduced to the value 150 mg/L by dilution. The comparison of the two sets of t he results, the estimated values and the measured values, showed that the estimated values were significantly larger than the measured value s in the cases of Na, K, Ca and P (the ratio of the estimated to the m easured values: 118% for Na, 115% for K, 109% for Ca; and 130% for Fe) , whereas the two values essentially agreed with each other in the cas e of P (ratio: 93%). The differences were too large for any nutritiona l evaluation to be made when the method of Bland and Altman is applied . The significance of the differences in relation to nutritional evalu ation of element intake is discussed.