Serum biomarker-based validation of a self-administered diet history questionnaire for Japanese subjects.

Although several self-administered dietary assessment questionnaires have been developed for Japanese subjects, they have seldom been validated with objective measures. We validated a recently developed self-administered diet history questionnaire (DHQ) with fatty acids in serum phospholipid fractions, alpha- and beta-carotenes and alpha-tocopherol in serum as a gold standard using 86 university workers (42 men and 44 women, age-range=24-67 y). The age-adjusted Pearson partial correlation coefficients between the intakes of marine origin n-3 polyunsaturated fatty acids (PUFA) (crude values, energy-adjusted values by residual method, energy density, and fat density) and the serum phospholipid concentrations (percentage of total fatty acids) were 0.49, 0.51, 0.52, 0.48, and 0.58, 0.69. 0.66, 0.69 in men and women respectively. The correlation coefficients between intakes (microg/d) and the corresponding serum concentrations (micromol/L) were 0.43 and 0.40 in men and 0.42 and 0.60 in women for alpha- and beta-carotene respectively. It was -0.23 in men and -0.22 in women for alpha-tocopherol. The intakes of major foods (g/d) of marine origin n-3 PUFA, alpha- and beta-carotenes showed a relatively high level of correlation with the corresponding serum concentrations, whereas the level was generally lower than those observed in the analysis with the nutrient intakes. The results suggest that DHQ ranks individual adequately for marine origin n-3 PUFA, alpha- and beta-carotene intakes.