Development of substituted fatty acid food composition table for the use in nutritional epidemiologic studies for Japanese populations: its methodological backgrounds and the evaluation

Results of dietary assessment are influenced by quality of food composition tables used for nutrient calculation. The Japanese food composition table has considerable missing values for fatty acid compositions. Substitution is often used for filling missing values. We examined reliability of the following 4 major substitution methods using available values of arbitrarily selected 83 sets of foods from the published fatty acid composition table of Japanese foods: by a different part of the same specie, by a similar specie, by a same specie in the United States' Department of Agriculture food composition table, and by recipe. The mean correlation coefficients of food pairs were 0.97, 0.96, 0.84, and 0.80 respectively. Next, we substituted fatty acid compositions for the 794 missing foods using the 4 substitution methods, and developed the table with 1245 foods including those listed in the original (non-substituted) fatty acid composition table. Lastly, we calculated fatty acid intake levels with the original (non-substituted) and the developed (substituted) tables using 28- or 14-day dietary records of 211 men and women as a sample data, and compared the results. The intakes of all five fatty acid groups increased. The increase was most marked in saturated fatty acids (26% in men and 31% in women in crude values). As a consequence, polyunsaturated to saturated fatty acid ratio decreased from 1.15 to 1.01 in men and from 1.13 to 0.96 in women. The use of the developed fatty acid food composition table may increase the reliability on nutrition-disease association in future nutritional epidemiologic studies for Japanese populations.