During the last 5 decades research in intestinal flora made rapid progress: 1) development of comprehensive culture method; 2) establishment of classification and identification of intestinal anaerobic bacteria; 3) accumulation of microecological evidences as well as beneficial and harmful function of intestinal flora in human health. Thus, it is of great importance to promote beneficial bacteria such as bifidobacteria and to suppress harmful bacteria such as clostridia among the intestinal flora. Recent advances of research in intestinal flora are the background for the appearance of functional foods, which act directly or indirectly, through the modulation of intestinal flora, on health of the host. The functional foods enhance bioregulation such as stresses, appetite and absorption, bio-defence such as immunity and antiallergy, prevent diseases including diarrhea, constipation, cancer, cholesterolemia and diabetes, and suppress aging through immunostimulation as well as suppression of mutagenesis, carcinogenesis, oxidation processes, intestinal putrefaction and cholesterolemia. This lecture reviews progresses of the research in intestinal bacteriology and how such progresses had an influence on the development of functional foods focusing on our study.

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The immune system protects us from the invasion of pathogenic microorganisms and the generation of cancers. For the purpose of above biological defense mechanism, the gastrointestinal immune system, a largest and extremely elaborate biological defense system, produces immunoglobulin A and induce oral tolerance to inhibit the onset of allergic reaction by food allergens. This paper describes how intestinal microorganisms, probiotics and prebiotics interact with the gastrointestinal immune system and induce characteristic immune reactions.

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[in Japanese]

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The effects of locust bean gum intake at 5 g/day level for 2 weeks on defecation, fecal conditions and their metabolites were studied in 20 healthy volunteers. The fecal pH value was significantly dropped, and the fecal contents of putrefactive products, such as the concentrations of each ammonia and total amine, were also tended to decrease. Improvement of fecal consistency, change of fecal color from dark brown to yellowish brown, decrease of fecal odor and increase in defecation frequency of persons whose frequency was relatively low were observed after administration. The fecal contents of short-chain fatty acids (SCFA), especially acetic acid, butyric acid and propionic acid, were increased. These results suggested that the locust bean gum intake at 5 g/day level could improve the intestinal environment.

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