Health effects of functional food factors has prompted paradigm change in nutritional science. Randomized clinical trials with beta-carotene as a supplement, however, ended in the unexpected results. We tried to find a breakthrough for nutrional epidemiology, and made a database for calculating all phytochemicals consumed based upon the dietary survey. Application of FFF database to the field study made it possible to calculate intake of more than 50 phytochemicals, and correlation analysis between intake of certain phytochemicals and biochemical markers revealed both favorable and unfavorable effects. Such new approach could contribute to estimate safety of phytochemicals, and safety of isoflavones was considered from such approach.