As the intestinal environment has a close association with the state of human health, we have examined whether certain agricultural food materials can help to improve the intestinal milieu. For this purpose, we developed an in vitro experimental model simulating the fermentation conditions within the intestine, allowing us to study intestinal fermentation characteristics in detail. This helped to clarify the influence of food materials on the time course of intestinal fermentation within a short period of time, and the results suggested that the in vitro conditions simulated by this particular model are similar to those in vivo. It was verified that resistant starch contained in red beans and kidney beans increases short-chain fatty acids in the cecum and improves cholesterol and lipid metabolism. Furthermore, chemically modified hydroxypropyl (HP) starch exhibited a distinct β-diversity in the intestinal flora that was different from native starch. Moreover, HP starch increased short-chain fatty acids in the cecum, and there were positive correlations with plasma GLP-1, mucin content, and IgA content. GLP-1 was also negatively correlated with both food intake and mesenteric adipocyte area. Although these findings represent basic evidence for the ability of agricultural food materials to improve the intestinal environment, we believe that they will contribute considerably to the maintenance and promotion of healthy human longevity.

This study investigated the effects of food factors on colonic microbiota, fermentation products, mucins, immunoglobulin A (IgA) and alkaline phosphatase (ALP) activity. Based on a study of glucomannan-containing lily bulbs, we demonstrated that the consumption of soluble dietary fibers, including glucomannan and non-digestible oligosaccharides, frequently increased colonic ALP activity by upregulating the expression of IAP-I in rats. We then investigated whether nutritional conditions influence these effects of non-digestible carbohydrates on colonic ALP activity. It was found that the types of dietary fat influenced the effects of dietary oligosaccharides on the colonic luminal environment, including ALP activity. Colonic ALP activity was positively correlated with colonic luminal variables such as the fecal mucin level, the ratio of Bifidobacterium spp., and the level of n-butyrate, which are associated with a more favorable colonic environment. We propose that the increase of colonic ALP activity induced by fermentable non-digestible carbohydrates may be important for protection of gut epithelial homeostasis.

The present study investigated the inhibitory effect of bread containing powdered Morus australis leaves on postprandial elevation of the blood glucose level. First, we assessed the 1-deoxynojirimycin (1-DNJ) content and α-amylase- and maltase-inhibitory activities of bread containing powdered M. australis leaves. Second, we investigated the inhibitory effect of this bread on blood glucose elevation in healthy individuals. Although the level of 1-DNJ was reduced during the bread-making process, 1-DNJ was still present in the bread containing powdered M. australis leaves. The powdered leaves exhibited no α-amylase-inhibitory activity. Although the median maltase-inhibitory concentration was higher in the bread containing the powdered leaves than in the powdered leaves alone, this bread retained its maltase-inhibitory activity. Moreover, consumption of the bread containing powdered M. australis leaves suppressed postprandial elevation of the blood glucose and insulin levels to a greater degree than consumption of bread without the powdered leaves. These findings demonstrate that bread containing powdered M. australis leaves has an inhibitory effect on postprandial blood glucose elevation.

Loss of appetite in the summer season leads to weight reduction, which subsequently affects sports performance. We investigated this issue in 94 high school freshmen baseball players at four high schools. The participants were divided into two groups: RICE (n＝38), receiving nutritional education with provision of rice; CON (n＝56), receiving nutritional education only. The study was conducted between May and August, which is considered the summer period in Japan. Analysis of covariance showed that body weight reduction in the RICE group was significantly diminished relative to the CON group (p＜0.001). In addition, the RICE group showed higher intakes of rice (p＝0.011), vegetables, and seaweed than the CON group (p＜0.05, respectively). These results suggest that nutritional education with provision of rice helped to attenuate the reduction of food intake in summer, thus maintaining body weight. On this basis we conclude that nutritional education with provision of rice can be a beneficial approach for maintaining and enhancing sports performance among high school baseball players.