We have reported that ingesting vegetable juices before meals might control postprandial blood glucose level for the prevention of diabetes. In this study, two human intervention studies were conducted under the hypothesis that sugar contained in vegetable juices was greatly involved in its action. Firstly, a 200mL of vegetable juice (①), vegetable and fruit mixed juice (②) or a sugar solution consisting of the same composition and concentration as ② (③) was served 30 minutes prior eating rice and compared the effect of each beverage on postprandial blood glucose with that by the same amount of water. As a result, intake of ② and ③ significantly suppressed the elevation in postprandial blood glucose level. In subjects with the top 50% maximum postprandial blood glucose level after ingesting water, the same effect was also observed by ingestion of ①. These results suggested that the suppressive effects of pre-meal ingestion of ① and ② were elicited via induction of insulin by the sugar in the beverages.

Next, we evaluated the changes in blood glucose and blood insulin concentrations after ingestion①, ②, ③ and a sucrose solution (④, sucrose water) with the same sugar concentration as in ③. As a result, Tmax, the time showing the highest concentration, of blood glucose level was significantly later in ① and ② than in ③ and ④, and Tmax of insulin was significantly later in ① than in ② and ③. We assumed that dietary fiber and/or other substances contained in ① and ② moderate the absorption of sugar, and presumed that the differences observed in this study affected the difference in the effects in the first intervention study. In addition, in the intake of ④, the Tmax of the blood glucose level was significantly faster than that of ① and ②, and Cmax, maximum concentration, of insulin was significantly larger than that of ①. This supposed that frequent ingestion of sugar water was considered to be a higher risk of diabetes than vegetable juices and vegetable fruit mixed juices containing the same amount of sugar.

As described above, the suppressive effect on the elevation in postprandial blood glucose level by the vegetable juice and vegetable fruit mix juice may be primarily due to the carbohydrates contained in these drinks, and the composition and concentration of carbohydrates might regulate the timing and strength of insulin induction and affect the effect.

We provided dietary education during lunchtime in elementary schools in Osaka City. The dietary education was provided under the theme of “let’s wash your hands thoroughly” for Grade 1 and 2 students, “let’s eat food to make bones strong” for Grade 3 and 4 students, and “let’s eat fish to spend every day energized” for Grade 5 and 6 students. Questionnaire surveys were performed before and after the dietary education to compare the effects of use of devised teaching materials between an intervention group that used the devised teaching materials and a control group that did not use them. In the survey after the learning, Grade 1 and 2 students in the intervention group showed higher positive answer rates for items about interests/concerns and knowledge/understanding than those in the control group, and Grade 5 and 6 students in the intervention group showed higher positive answer rates for items about interests/concerns and motivation/behavior than those in the control group ; significant differences were observed between these groups. In addition, in grade 3 and 4 students, the rate of choosing foods to make bones strong was significantly improved after the dietary education in the intervention group as compared with the control group. However, in practice and acquisition of knowledge, the effects of using devised teaching materials were not shown.

A self-administered questionnaire survey was conducted to find effective methods of providing food and nutrition education (shokuiku) for junior high school students by investigating their current breakfast eating habits and daily schedules.

Of the 336 participating students attending public junior high schools in Tokyo, there were 118 students in first grade (71 boys and 47 girls), 104 students in second grade (56 boys and 48 girls), and 114 students in third grade (55 boys and 59 girls). The survey was conducted in June 2016 to investigate daily schedules and dietary habits.

Students who ate breakfast in a co-eating situation had substantial side dishes and enjoyed their meals compared to students who did not have breakfast in a co-eating situation. On the other hand, there were differences in co-eating situations and bedtimes during the weekdays depending on the grade and gender. This suggested the need to provide food and nutrition education (shokuiku) based on individual characteristics.

In the future, to establish healthy dietary habits for life, it is important to provide a seamless and continuous food and nutrition education (shokuiku).