Do Japanese take more folate from traditional Japanese dish than is conventionally estimated?-Actual folate contents in hospital diets and marketed lunch boxes.

Folic acid deficiency is very rare in Japan. However, recent concerns in relation to causal relationships between cancer and low folic acid levels necessitate information on actual folate intake by Japanese, which has hitherto not been well studied. We therefore evaluated folate contents of a hospital diet for 7 consecutive days and of 16 lunch boxes purchased at convenience stores. Dietary intake was assessed for weighed food items after cooking using our previously published data on folate contents of various foods and also by using Standard Tables of Food Composition in Japan (STFCJ). Mean daily folate intake from the hospital diet was 723.9 microg/day using our data but only 359.2 microg/day if calculated using the STFCJ. Twenty-nine % of the total daily folate intake was through rice. Mean folate intake through lunch boxes was 491.7 microg/day by our tabulation and 139.5 microg/day with the STFCJ. Folic acid intake of Japanese is far above the levels taken in other countries and over half of this amount is taken from rice. Levels of folic acid contents (especially in rice) listed in the STFCJ are too low and revision is strongly suggested.