It has become clear that food components, including micronutrients, and gut microbiota are involved in the control of health conditions. Further, there has been growing interest in food products and drug development targeting the gut environment. Particularly, precision nutrition, which proposes optimal diets based on an individual’s gut environment, genetic information, and lifestyle, has gained importance. In this article, we discuss the relationship between the gut environment, which is shaped in collaboration of diets and gut microbiota, and its immune functions and health, using examples such as vitamin B₁ and dietary oils. Furthermore, we explore the potential for developing a personalized nutritional guidance system through the advancement of precision nutrition and the utilization of gut environment databases, as well as the possibilities for drug development and healthcare targeting beneficial gut bacteria.

AIN93G diet without manganese carbonate was used as a simple low-manganese diet, and the extent to which manganese status is reduced when it is administered to growing rats was examined. Twelve 4-week-old male Wistar rats were divided into two groups, one of which received the AIN93G diet (manganese concentration, 10 μg/g) and the other the AIN93G diet without manganese carbonate (manganese concentration, 0.3 μg/g) for 4 weeks. There was no difference in rat growth between the two groups, and no clinical signs related to manganese deficiency were observed at all in the low-manganese diet group. Organ manganese concentrations were clearly reduced by the low manganese diet, with values in the low manganese group being 28.4% of the control group in the liver and 49.3% of the control group in the kidneys. Arginase activity in the liver was also significantly decreased in the low manganese group, but the decrease was not as pronounced as in the manganese concentration, as 79.2% of the values were maintained in the low manganese group compared to the control group. In serum biochemical tests, the low-manganese diet group showed slightly but significantly higher serum iron concentration and transferrin saturation than the control group. To induce manganese deficiency with a simple low-manganese diet, it may be necessary to administer a low-manganese diet immediately after weaning for multiple generations.

When consumed in appropriate amounts, caffeine stimulates the central nervous system, preventing drowsiness, recovering from fatigue, and improving concentration. It also has a stimulant effect, and consuming more than 1000 mg in a short period of time can overstimulate the central nervous system and heart. From 2021 to 2023, a questionnaire survey was conducted on 27 pregnant women and 146 female students regarding their caffeine purchases. When asked how they found out about caffeinated beverages, pregnant women saw them in stores, while female students were more likely to see commercials, advertisements, or TV. When asked whether they checked the caffeine content, pregnant women（74%）and female students（86%）did not. When asked whether they consumed caffeinated beverages, pregnant women and female students consumed more coffee and black tea, while female students consumed significantly more roasted green tea than pregnant women. Caffeinated beverages only list the amount of caffeine, and we believe that symptoms of overdose and precautions should be included.

We have previously studied the taste response of many kinds of dashi and soups, such as udon dashi, shirodashi, and shoga shoyu (soy sauce). In this study, the taste of “noodle soups” was scientifically analyzed using taste sensors. Thirteen types of noodle soups were used to measure taste responses in this study: five types of commercial dashi soy sauce (Koikuchi Shoyu),four types of dashi soy sauce (Usukuchi Shoyu),and four types of ramen soup. These samples were diluted with ultrapure water according to the respective manufacturers’ directions on package and multiple taste responses were quantified using the taste sensor, including bitter, sour, salty, umami and so on. In dashi soy sauce (Koikuchi Shoyu),differences in taste were observed among the products, with Koikuchi2 having less acidity and Koikuchi3 having more acidity and less saltiness and umami than Koikuchi1. In dashi soy sauce (Usukuchi Shoyu),the taste response of Usukuchi6 was comparable to that of Usukuchi7. Also, the taste response of Usukuchi6 was slightly more acidic and astringent than that of Usukuchi8,and less acidic, bitter, astringent, and bitter than that of Usukuchi9. In ramen soup10,the salt equivalent was low and the acidic and astringent taste stimuli were also weak. However, the taste was found to display high umami and salty tastes. On the other hand, the powdered ramen soup13 had different taste characteristics from the other soups. In addition, two ramen soups11 and 12 showed exactly the same taste response. From these findings, the taste sensor can scientifically clarify the differences in the taste response of noodle soups, and can be used for product development and quality assurance.

Iron biological parameters (hemoglobin concentration, hematocrit and serum iron concentration) are being used to check for iron nutritional condition. However, these parameters are changed by iron deficiency and other mineral deficiency, especially by zinc deficiency. We measured liver and spleen non-heme iron concentrations (supernatant and coagulum) in moderate zinc deficiency or with diet restriction. Thirty 3-week-old male Sprague-Dawley rats were randomly and equally divided to control group (Control), pair-fed group (PF) and moderately zinc-deficient group (ZD), and fed for 4 weeks. Non-heme iron fractions (supernatant and coagulum) were separated and measured by atomic absorption spectrometry. Differences between groups were statistically analyzed by the Brown-Forsythe ANOVA and post hoc Welch’s t-test. P value less than 0.05 was considered significant. Liver supernatant non-heme iron concen- tration was significantly increased by zinc deficiency and significantly decreased by diet restriction. Spleen superna- tant non-heme iron concentration was not significantly changed by ANOVA. Liver coagulum and spleen coagulum non-heme iron concentration were not significantly changed in all groups. These results suggest that iron accumula- tion in liver is remarkable by zinc deficiency per se, removing the effect of low food intake by paired-feeding technique.

We previously reported that dietary oyster (Crassostrea gigas) extract (OE) promoted fecal mucin excretion in mice fed a normal-fat (NF) diet. However, it remains unclear whether OE increases fecal mucin excretion and ileal goblet cell counts in mice fed a high-fat (HF) diet. This study examined the effect of OE intake on fecal mucin excretion and ileal goblet cell counts in mice fed NF and HF diets. Male C57BL/6 J mice were divided into four groups and fed an AIN-93G diet (NF diet), AIN-93G modified HF diet (HF diet), NF diet containing 5% (w/w) OE (NFOE diet), and HF diet containing 5% (w/w) OE (HFOE diet). After 28 days of experimental diet feeding, feces and distal ileum were collected. Fecal mucin content was quantified using a fluorometric assay kit that discriminates O-linked glycoproteins from N-linked glycoproteins. Goblet cells in the villi of the distal ileum were counted via staining with Alcian blue-periodate Schiff stain. Fecal mucin content and ileal goblet cell count were significantly increased by OE intake (p = 0.013 and 0.007, respectively). OE intake may enhance the intestinal barrier function by increasing the number of goblet cells and mucin secretion in the distal ileum.

We investigated the nutritional and health-promoting functions of oyster extract (OE) prepared by extracting and concentrating the nutritional and functional components of oyster (Crassostrea gigas) meat. We have reported the bioavailability of zinc^{1 ,2)}, hepatoprotective effect³⁾, prevention of colorectal precancerous lesions^{4 ,5)}, and prevention of renal damage⁶⁾ as the nutritional and health-promoting functions of OE intake. Regarding the gut environment, which has been actively studied in relation to health in recent years, OE has proven effective in increasing the proportion of Lactobacillus genus in the feces of rats and mice^{7 ,8)}. In addition, OE attenuates experimental colitis symptoms induced by dextran sulfate sodium, partly owing to improvements in the gut microbiota and short-chain fatty acid composition^{9 ,10)}. Because the gut is exposed to pathogenic bacteria and their toxins, it has a robust barrier function and immune system to protect the body from these factors¹¹⁾. Mucin is a key component of the gut barrier that prevents the entry of pathogenic bacteria and their toxins^{12, 13)}. Dietary OE enhances fecal mucin excretion in mice fed a normal-fat (NF) diet¹⁴⁾. However, it remains unclear whether the addition of OE to a high-fat (HF) diet used to induce obesity and hyperlipidemia in mice enhances fecal mucin excretion. In contrast, mucin is produced and secreted by goblet cells and scattered among absorptive epithelial cells. The number of goblet cells is affected by dietary components¹⁵⁾. However, the effect of OE on the number of ileal goblet cells has not yet been investigated. In this study, we fed mice two experimental diets (NF and HF) supplemented with OE and evaluated the effects of OE on fecal mucin excretion and ileal goblet cell counts.

We conducted a survey with the aim of identifying predictive factors for the risk of severe disease by determining the relationship between serum zinc levels and clinical indicators. The subjects were 124 patients who were diagnosed with SARS-CoV-2 nucleic acid or quantitative antigen levels and were hospitalized between April 1, 2021 and December 31, 2021. Average age was 52.1 ± 15.7 years, 77 men (62％)，47 women (38％)，Alb 3.9 ± 0.5 g/dL, CRP 5.9 ± 6.4 mg/dL, lymphocyte count 9.3 ± 4.3 million/ mm ³, serum zinc concentration was 57.6 ± 11.5 μg/dL, and PNI was 43.3 ± 5.4. A negative correlation was observed between serum zinc levels and CRP (r = -0.422; P< 0.001)，and a positive correlation was observed between serum zinc levels and PNI (r = 0.543; P< 0.001). As far as serum zinc concentrations were concerned, Alb and PNI were significantly lower in the zinc-deficient group than in other two groups, and CRP was higher in the zinc-deficient group than in other two groups. The results of this survey showed that abnormalities in CRP, lymphocyte count, serum zinc concentration, and PNI were observed as characteristics at the time of hospitalization COVID-19 infected patients. In conclusion, serum zinc levels may be closely related with inflammatory and nutritional biomarkers in patients with COVID-19.

Fucoxanthin (Fx) is a marine xanthophyll primarily found in brown algae, known for its anti-obesity, anti-tumor, and antioxidant properties. A previous study showed that alkali treatment alters the chemical structure of fucoxanthin, resulting in two main compounds: isofucoxanthinol (Iso FxOH) and fucoxanthinol hemiketal (FxOH HK). However, the physiological activities of alkali-treated Fx remain unclear. Here, for the first time, we investigated the physiological effects of dietary IsoFxOH and FxOH HK on obesity in mice, compared to Fx. Six-week-old male C57BL/6 J mice were fed a high-fat diet (HFD) as the HFD-cont group, an HFD containing 0.05% (w/w) of Fx, Iso FxOH, or FxOH HK as the experimental groups, or AIN-93G as the control group for 8 weeks. There were no significant differences in final body weight or white adipose tissue weight between the groups. However, in mesenteric white adipose tissue, the expression level ofLpl was suppressed in mice fed HFD containing 0.05% (w/w) FxOH HK. Conversely, the expression of Srebf1, which is involved in de novo lipogenesis, was upregulated by HFD supplemented with 0.05% (w/w) FxOH HK. Additionally, FxOH HK upregulated the expression of Cpt1a, which is involved in fatty acid oxidation. These results suggest that the products of alkali-treated Fx may alleviate obesity in mice fed a high-fat diet, primarily by reducing fatty acid uptake in adipose tissue.

High plasma levels of methylmalonic acid and total homocysteine are markers for vitamin B₁₂ deficiency, whereas high plasma levels of total homocysteine indicate folate deficiency in animals, including cattle. Although a combination of solid-phase extraction and derivatization is effective for analyzing plasma methylmalonic acid and total homocysteine, these procedures can be time-consuming, complicating large-scale analyses. To address this, we focused on automated solid-phase analytical derivatization (SPAD), because both solid-phase extraction and derivatization can be conducted automatically in a short timeframe. In the present study, we evaluated a gas chromatography–mass spectrometry- based quantitative method utilizing automated SPAD to determine plasma levels of methylmalonic acid, total homocysteine, and related metabolites in Japanese Black cattle. Compared to manual derivatization without solid-phase extraction, the SPAD demonstrated superior analytical quality for the quantification of methylmalonic acid, total homocysteine, and some related metabolites, possibly because of solid-phase extraction. Additionally, the SPAD requires less time. These results suggest that the presented quantitative method has the potential to precisely and practically evaluate folate and vitamin B₁₂ deficiencies in Japanese Black cattle.

In this study, we investigated the taste characteristics and antioxidant activity of Namba green onions (Allium fistulosum L.)，a traditional variety in Osaka prefecture, and green onions. The taste characteristics were evaluated by measuring taste responses using the taste sensing systems (electronic tongues)，total soluble solids (TSS, Brix), and sugar content. Antioxidant activity was evaluated by determination of oxygen radical absorbance capacity (ORAC) value, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and contents of total polyphenol total vitamin C, and carotenoids. Compared with green onions, Namba green onions had significantly higher initial tastes (acidic bitterness, umami, saltiness) and aftertastes (bitterness, astringency) (p < 0.05). In Namba green onions, TSS (Brix), sucrose content, total sugar content, and degree of sweetness were significantly higher (p < 0.05)，while d-fructose content was significantly lower (p < 0.05) comparing green onions. Namba green onions had significantly higher lipophilic and total-ORAC values and DPPH radical scavenging activity (p < 0.05). The total polyphenol, total vitamin C, β-carotene, and β-cryptoxanthin content of Namba green onions were significantly higher (p < 0.05) than that of green onions. This is the first study to report the taste characteristics and antioxidant activity of Namba green onions. In addition, Namba green onions have stronger umami, saltiness, and sweetness than green onions, and exhibit higher antioxidant activity.

Oyster (Crassostrea gigas) extract, which is obtained by extracting nutritional and functional components from raw oysters, contains zinc, glycogen, taurine, and so on. The extract is useful as a raw material for health foods. Oyster extracts harvested from oysters in different production areas by adjusting methods devised by each producer have a protective effect on the immune regulation and intestinal microflora. In particular, the effects of orally administered oyster extract on the composition ratio of intestinal lactic acid bacteria were up regulated in the cecal and fecal microflora. Furthermore, it has also been reported that oral administration of Lactobacillus plantarum ATCC8014 strain in rats may have a certain protective effect on the intestine by increasing the intestinal barrier function and preventing acrylamide from entering the tissues. Therefore, in this study, we used the lactic acid bacteria L. plantarum ATCC 8014 strain to examine the effect on lactic acid bacteria by directly adding oyster extract (OE) extracted from raw oysters to a nutrient medium.

When OE was added to the media, no significant difference was observed in either the 1.0% or 0.5% OE addition group, compared to the control group after 1.5 hours of culture. Rather, it showed a tendency of suppression. However, after three hours of culture, the growth-promoting effect abruptly appeared, and after six hours of culture, the growth-promoting effect of 1.0% and 0.5% OE containing groups were 114% and 113%, respectively, compared to the control group. In particular, in the 0.5% OE containing group, after culturing for nine hours and 12 hours, significant growth-promoting effects of 110% and 107% (p < 0.05), respectively, were observed compared to the control group. By the time 24 hours had passed, the changes compared to the control group had become 100% and 103% in the 1.0% and 0.5% OE added groups, respectively and the proliferation promoting effect had diminished. It was suggested that such a transient lactic acid bacteria growth-promoting effect caused by the consumption and depletion of the growth-promoting factor contained in the OE after six hours of culture.

If global warming, overfishing and ocean pollution continue at current rates, the world's fish stocks could be wiped out in less than 30 years. In other words, we may not be able to eat natural fish in the near future. Dashi (Japanese soup stock) is a globally used ingredient that evolved as a way to bring out the true flavor of ingredients. In Japan, the food culture has long been centered on vegetables and fish. Therefore, dashi was needed to add umami to these mild-flavored ingredients. In this study, we developed a plant-based dashi using only vegetable ingredients. The final plant-based dashi was made by adjusting the ratio of mushroom dashi, vegetable dashi and Kaeshi (boiled sauce, a mixture of soy sauce and mirin) . The vegetable dashi was supplemented with concentrated seaweed (kelp) dashi. The odor of the vegetables was reduced by adding fermented soybean flour. Compared to bonito dashi, the scientific characteristics of the plant-based dashi did not contain inosinic acid as a nucleotide umami component. However, a small amount of guanylic acid was detected. All amino acids, including glutamic acid and aspartic acid, were low as amino acid umami components in a plant-based dashi. The multiple taste response using the taste sensor showed a high value for bitter stimulus and bitterness, but a slightly low value for umami. However, the flavor and taste of the plant-based dashi was close to that of bonito dashi, and the overall taste was well balanced. This plant-based dashi was named "Veggie Dashi produced by dashi maker".