National Nutrition Survey in Japan--its methodological transition and current findings.

The National Nutrition Survey in Japan (J-NNS), an annual nationwide survey on nutrition and diet of the Japanese people, is reviewed. J-NNS was started in the Tokyo Metropolitan area in 1945 following the end of World War II. The survey area was gradually expanded and became nationwide in 1948. The current survey obtains data from more than 12,000 persons of approximately 5,000 randomly selected households. The survey consists of three parts: a physical examination, a dietary intake survey and a dietary habit questionnaire. The physical examination includes anthropometric measurements and a blood test, the dietary intake survey examines nutrient/food intake with a semi-weighed recording method, and the dietary habit questionnaire monitors nutrition/diet-consciousness and dietary habits. In this review, the aim and brief history of the survey are outlined in the first section. The following section, explains its administrative framework, target population, sampling method, annual schedule and question items, focusing on their historical transition. Then the findings of the J-NNS are summarized, which highlights annual changes in the intake of energy, macronutrients, micronutrients and food groups. The current findings of the dietary habit questionnaire are also given in brief.