It has long been known that bacteria existing in our intestinal tract affect our health and diseases. Because of difficult in cultivation, culture-based conventional methods have not provided detailed analysis of intestinal bacteria. However, development of genome-based analytical methods using next-generation sequencers allow the analysis of even difficult to cultivate intestinal bacteria. As a result, it has become clear that a greater number of intestinal bacteria are involved in our health than we had imagined, the identification of beneficial bacteria and its application to food and medicine. Furthermore, it has become possible to identify effective bacterial molecules by utilizing metabolome analysis. These technologies applied in various human studies reveal that there are large individual differences in the bacteria in the human intestine, and it is now possible to determine the dietary factors that define these differences, or conversely, to categorize their dietary effects based on the differences in intestinal bacteria. In this special issue, cutting-edge researchers will introduce the background and latest trends involving intestinal bacteria that are attracting attention both academically and socially.
Recent studies show that early-life gut microbiota are intimately associated with human health not only during infancy but also in later life. Immediately after birth, the neonatal gut is colonized by members of facultative anaerobic bacteria belonging to the Enterobacteriaceae family and Streptococcus and Staphylococcus genera. However, these bacteria are replaced with obligate anaerobic microbes such as bifidobacteria within a few weeks as the oxygen concentration of the intestinal lumen decreases. Breastfeeding markedly contributes to the formation of bifidobacteria-rich (up to 90 % of total bacteria) "healthy" gut microbiota. In this chapter, we describe how breastmilk mediates the interplay between gut microbes, especially bifidobacteria, and humans infants at the molecular level. Non-digestible oligosaccharides contained in human breastmilk (human milk oligosaccharides; HMOs), which are the third most abundant solid component and comprise over 100 molecules, promote the growth of several Bifidobacterium species (infant-type bifidobacteria) that possess varied enzymatic sets for HMO utilization. The infant-type bifidobacteria that proliferate in the gut in turn convert aromatic amino acids (breastmilk components) to aromatic lactic acids which have physiological relevance to the host e.g. immune system regulation and energy homeostasis. These findings provide the molecular basis underlying symbiosis and co-evolution between infant-type bifidobacteria and humans mediated by breastmilk components.
It is impossible to clearly answer the question, "What gut microbiota are necessary for extending life span (healthy longevity) in humans?" However, the pathological analysis of aging has rapidly advanced, with clarification of features such as genomic instability, shortening of telomeres, and cell aging along with active development of preventive and therapeutic agents affecting aging. Furthermore, the involvement of the gut microbiota in the pathophysiology of aging has been clarified, and important results have been reported showing that controlling aging of the gut may lead to prevention of lifestyle-related diseases and extension of healthy longevity. Furthermore, in addition to microbiota analysis, advances in analysis technology centered on mass spectrometers are revealing the existence of many microbiota metabolites that affect host immunity, inflammation, and metabolism. In this section, we explain ongoing health and longevity strategies focusing on the gut microbiota, and provide information that is being obtained from the Kyotango longevity cohort study.
Dementia is a substantial healthcare problem. In 2015, 47 million individuals worldwide were living with dementia. Recently, there has been a focus on the associations between gut microbiota and cognitive decline. Previous studies have suggested that disruption of the neuroinflammatory system, vascular inflammation, and remote relationships driven by various metabolites are mechanisms underlying cognitive decline caused by the gut microbiome. However, knowledge regarding the effects of gut microbiota on cognitive function remains limited.
We conducted an observational study that was originally designed to investigate the relationship between gut microbiota and cognitive function. In our previous study, gut microbial dysregulation was revealed to be associated with cognitive decline, vascular risk factors, and white matter hyperintensity.
In addition, gut microbial metabolites have been shown to be associated with both cognitive decline and adherence to a Japanese-style diet. These factors indicate the presence of a diet–microbiome–dementia cascade. We recently found that lipopolysaccharides, which are molecules in the outer membrane of gram-negative bacteria and induce release of critical proinflammatory cytokines that are significantly correlated with cognitive decline. However, gut microbial metabolites, as non-specific disease markers of neural damage, are not strongly correlated with gut microbial metabolites. These findings suggest a multiplex linkage among the gut microbiome, microbial metabolites, and cognitive function. Further studies are warranted to examine these associations in relation to the microbiome–gut–brain axis.
Newborn animals are immediately exposed to a diversity of microorganisms: vaginal and skin microbiota of mothers and other environmental microbes that colonize the gastrointestinal lumen and gradually establish gut microbiota during development. The premature microbiota in infancy develops into more stable microbial communities in childhood. Pertubations of gut microbiota early in life have been associated with susceptibilities to multiple immune and metabolic diseases, including asthma, atopic dermatitis, inflammatory bowel disease, and obesity, occurring later in life. Furthermore, administration of antibiotics during pregnancy increases susceptibilities to immunological and metabolic disorders of offspring. Thus, the prenatal and infant periods are regarded as critical time-windows for long-term health status. In this review, we describe our recent understanding of how the disturbance of early-stage microbiota cause pathological imprinting in immune and metabolic systems. We also discuss how microbial products shape host immune and metabolic configurations.
We have developed a new method for cultivation of green tea that contains highly functional theanine in high concentration, has excellent flavor, and reduces thermal energy costs. By applying organic fertilizer containing fish meal and shading with cheesecloth with a shading rate of 85-90%, it has become possible to cultivate green tea comparable to high-grade matcha (powdered green tea) with a theanine concentration of 2% or more. Using this method, freshly picked tea leaves were steamed, twisted, and dried using a primary drying tea roller in an air-heating furnace with a main shaft with press and stir arms. The tea leaves were then directly transferred to a tea dryer without transferring to a four-step rolling process typically used in the conventional crude tea making process in Japan. This unrefined tea was then preserved at 5°C and 15°C under nitrogen gas to carry out aging for seven months. In parallel, a part of this unrefined tea was refined and powdered with a crusher. This powdered green tea is also subjected to aging in the same manner. As a result, although we were not able to scientifically elucidate the aging effectiveness, we were able to develop a powdered green tea with a high theanine content that was as tasty as intermediate-grade matcha in sensory evaluation, at a low cost comparable to the production cost of commercially available high-grade sencha.
Nori (laver) is mainly made from the cultivated thallus of the red algae Pyropia yezoensis, and mostly is processed into dried sheets for consumption. It is a familiar food for us in Japan and is one of the indispensable foodstuffs in our daily diet. The origin of nori cultivation is believed to date back to the Edo period with subsequent development and improved cultivation technology in conjunction with the clarification of the life history of the algae resulting in peak domestic production of dried nori exceeding 10 billion sheets. Factors such as the shortening of the cultivation season, occurrence of diseases, and color fading of nori thallus have led to a gradual decline in nori production, and recent production has dropped to around 6 billion sheets per year. Saga Prefecture faces the Ariake Sea, the largest seaweed production area in Japan, and has been the largest producer of dried nori in Japan for 19 consecutive years in terms of both number of sheets and production value. However, the stagnation of nori consumption and the occurrence of low-quality and off-colored nori have become a concern in this prefecture. This paper focuses on porphyran, a polysaccharide unique to red algae such as nori, and eicosapentaenoic acid (EPA), a representative functional lipid, as characteristic components in nori. Carbohydrates are the main components, accounting for about half of the dry weight of seaweed, and most of the carbohydrates in nori are porphyran. Porphyran is a unique component of red algae and is a sulfated, viscous polysaccharide. Nori has a high lipid content (about 4% of dry weight) among edible seaweeds and is unique in that more than half of its component fatty acids are EPA. EPA and docosahexaenoic acid are typical n-3 polyunsaturated fatty acids and are found in abundance in fish. However, from the viewpoint of prevention of lifestyle-related diseases and metabolic syndrome, it has been pointed out that their intake in the population of developed countries is insufficient. Currently, the main source of these polyunsaturated fatty acids is fish, but algae are also attracting attention as an alternative source. This paper describes (1) analytical methods for polysaccharides including porphyran contained in nori developed by the authors and its application, and the relationship between polysaccharides and quality of nori, and (2) how to make effective utilization of EPA in nori by changes in the structures of EPA-containing lipids and porphyran by fermentation of nori with koji.
In September 2021, the application for genome-edited red sea bream was accepted as a food sanitation concept, making possible sale and distribute of red sea bream in the marketplace. A month later, genome-application for tiger pufferfish (Torafugu) was accepted. In Japan (as far as we know in the world), it was the first commercial application of genome editing technology for animals, marine products, and aquaculture species. The Ministry of Health, Labor and Welfare held five public online conferences in 2021 as social hearing activities discussing the practical application of genome-edited fish. At the meetings, there was discussion dealing with the breeding line of farmed fish having a genetic composition close to that of natural fish, how the genome edited fish are created, and when the food safety of genome edited fish should be confirmed. In addition, the concept of handling and labeling progeny hybrids of genome-edited fish was discussed.
Located in the south of Shikoku (Japan's smallest main island), Kochi Prefecture faces the Pacific Ocean with 713 kilometers of coastal line running from east to west. To the north of Kochi lies the Shikoku mountainside with densely packed woodlands boasting 84% forest area: the highest in Japan. Blessed by a warm climate and rich natural environment from the surrounding mountains, rivers, and sea, Kochi is a treasure trove of delectable dishes. The numerous varieties of su-mikan and sushi are distinguishing features of Kochi's culinary culture. Su-mikan refers to the highly aromatic and acidic citruses found in Japanese cooking. Most notably, Kochi Prefecture prides itself as Japan's number one producer of the yuzu citrus: holding 53% of the market share nationwide (as of 2018). Yuzu was imported to Japan from China during the Nara Period and has been used in cooking as a vinegar alternative and for medicinal purposes throughout the ages. When yuzu juice is added to sushi rice, this local delicacy is called "Tosa sushi" (or Tosa-zushi). Each region of Kochi has a different variation of Tosa sushi, making it possibly the most diverse type of sushi in Japan. Most popular among these is "Tosa inaka sushi" (or Tosa country sushi), eaten commonly in the mountainous regions of Kochi and consisting of mountainous ingredients such as myoga (Japanese ginger), takenoko (bamboo shoots), shiitake mushrooms, and konnyaku (a jelly-like food made from konnyaku potatoes). While not only healthy and visually appealing, this sushi is also unusual in that its ingredients make it acceptable for both vegetarian and vegan consumers.
Myanmar is known for its rich plant diversity due to the interactions of its geography, topography, and climate, along with its pattern of seasonal rainfall, and the presence of high mountains and major rivers. In this study, we highlight some information on agriculture, the use of wild edible plants, and the sustainable use of Amorphophallus in Myanmar. Agriculture is backbone of Myanmar's economy. The three main crop groups are paddy, beans, and oilseed crops. Home gardens are popular, and most of them are managed as places for cultivating vegetables and fruits and for growing cash crops. Home gardens also play an important role as a medicinal plants supply, and as an ex situ conservation area of rare species. Many wild plants are sold in the local markets and are used as edibles. Wild edible plants are used as vital ingredients for maintaining good health based on their traditional knowledge. Three Amorphophallus species are cultivated as cash crops in Myanmar: A. bulbifer Blume, A. muelleri Blume and A. krausei Engl, which have had economic importance in recent years. During the Japan International Cooperation Agency (JICA) grassroots program, to promote villagers' farming systems from shifting cultivation to continuous farming, we recommended green mulching for soil management in their initial stage and agroforestry system in their home gardens. While the villagers had employed Amorphophallus cultivation favorably, they benefited from this cultivation via the project for only three years. Amorphophallus cultivation exemplifies a case study of the sustainable use of plant resources. It is also expected that Amorphophallus spp. will be valued as a promising cash crop in the mountainous areas in Myanmar.