Equol is a metabolite of isoflavone daidzein and has an affinity to estrogen receptors. Although equol is produced by intestinal bacteria, the association between the status of equol production and the gut microbiota has not been fully investigated. The aim of this study was to compare the intestinal bacteria responsible for equol production in gut microbiota between equol producer and non-producer subjects regarding the intake of daidzein. A total of 1044 adult subjects who participated in a health survey in Hirosaki city were examined. The concentration of equol in urine was measured by high-performance liquid chromatography. The relative abundances of 8 bacterial species responsible for equol production in the gut microbiota was assessed using 16S rRNA amplification. There were 458 subjects identified as equol producers. The proportion of equol production status and the intake of daidzein increased with age. Daily intake of daidzein was larger in equol-producer. The intestinal bacteria, which convert daidzein to equol were present in both equol producers and non-producers. However, the relative abundance and the prevalence of Asaccharobacter celatus and Slackia isoflavoniconvertens were significantly higher in equol producers than those in equol non-producers. The intestinal bacteria that convert daidzein to equol are present in not only the equol producers but also in the non-producers. The daidzein intake is associated with the equol production status through an increase of A. celatus and S. isoflavoniconvertens in the gut microbiota.

Altered amino acid levels have been found in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). However, it is not clear whether this alteration is due to altered hepatic metabolism or insulin resistance. The aim of this study was to clarify the association among amino acid levels, fatty liver, and liver fibrosis while eliminating the influence of insulin resistance. NAFLD and liver fibrosis were diagnosed using transient elastography and subjects were divided into three groups: normal, NAFLD, and liver fibrosis. To exclude the influence of insulin resistance, the subjects were matched using the homeostasis model assessment of insulin resistance (HOMA-IR). The amino acid serum levels were compared among the groups. Of 731 enrolled subjects, 251 and 33 were diagnosed with NAFLD and liver fibrosis. Although significant differences were observed among the groups in the serum levels of most amino acids, all but those of glutamate and glycine disappeared after matching for HOMA-IR. The multivariate logistic regression revealed that glutamate, glycine, and HOMA-IR were independent risk factors for liver fibrosis. The altered serum levels of most amino acids were associated with insulin resistance, while the increase in glutamate and the decrease in glycine levels were strongly associated not only with insulin resistance, but also with altered liver metabolism in patients with liver fibrosis.

The Japanese diet is a healthy dietary pattern, and the oral or gut microbiota have been identified as the main factors underlying the beneficial effects of the Japanese diet. However, epidemiological studies on Japanese dietary patterns calculated from daily eating habits in the general population yielded inconsistent findings. This study aimed to determine the association between the 12-component modified Japanese Diet Index (mJDI12) and the oral and gut microbiota in the general population of a rural area in Japan. After propensity-score matching, 396 participants (198 each in the low and high mJDI12 groups) were picked out. One year after the follow up survey, we reclassified the subjects and compared the low and high mJDI12 groups again. Participants with a high mJDI12 had a higher relative abundance of butyric acid-producing bacteria in their gut microbiota. Moreover, the significantly higher dietary fiber intake in the high mJDI12 group suggested that the high intake of dietary fiber contributed to an increase in butyric acid-producing bacteria in the gut. In contrast, in individuals with a high mJDI12, only Allpprevotella was decreased in the oral microbiota. Thus, the Japanese dietary pattern can have beneficial effects by improving the oral and gut microbiota.

Background/Objective: This study investigated the relationship between the composition of oral microbiota and metabolic dysfunction-associated steatotic liver disease (MASLD) in the general population. Methods: In total, 712 participants in a health check-up project were divided into four oral microbiota patterns by principal component analysis and cluster analysis; they were included in Neisseria, Streptococcus, Fusobacterium, and Veillonella groups. The Neisseria group had the largest number of patients and was used as a reference group to compare the incidence of MASLD and cardiometabolic criteria with the other groups. Results: In a multivariate analysis, the Veillonella group was a risk factor for MASLD independent of cardiometabolic criteria compared with the Neisseria group. The correlation between oral bacterial species and MASLD-related items showed that Neisseria was negatively correlated with controlled attenuation parameters, body mass index, waist circumference, hemoglobin A1c, alanine aminotransferase, and fatty liver index. Veillonella showed a positive correlation with controlled attenuation parameters, waist circumference, body mass index, blood pressure, triglycerides, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, and fatty liver index, and a negative correlation with high-density lipoprotein cholesterol. In contrast, the Streptococcus and Fusobacterium groups were not clearly associated with MASLD. Conclusions: Maintaining oral hygiene and preventing periodontitis may contribute to preventing MASLD and extending a healthy lifespan.

Surgery avoidance is an important goal in Crohn’s disease (CD) treatment and predicting the risk of subsequent surgery is important to determine adequate therapeutic strength for patients with newly diagnosed CD. Herein, we aimed to construct a prediction model for the risk of subsequent surgery based on disease characteristics at the patients’ initial visit. We retrospectively collected disease characteristic data from 93 patients with newly diagnosed CD. A logistic regression model with a brute force method was used to maximize the area under the receiver operating characteristic curve (auROC) by employing a combination of potential predictors from 14 covariates (16,383). The auROC remained almost constant when one to 12 covariates were considered, reaching a peak of 0.89 at four covariates (small-bowel patency, extensive small-bowel lesions, main lesions, and the number of poor prognostic factors), and it decreased with increasing covariate size. The most significant predictors were small-bowel patency, extensive small-bowel lesions, and age or major lesions. Therefore, this prediction model using covariates may be helpful in determining the likelihood that a patient with newly diagnosed CD will require surgery, which can aid in appropriate treatment selection for high-risk patients.

The association between liver fibrosis and oral or gut microbiota has been studied before. However, epidemiological studies in the general population are limited owing to the difficulty of noninvasive liver-fibrosis assessment. FibroScan–asparate aminotransferase (FAST) scores can be used to accurately and non-invasively evaluate liver fibrosis. This study aimed to determine the association between liver fibrosis and oral or gut microbiota using the FAST score in the general population. After propensity score matching of 1059 participants based on sex, age, body mass index, homeostasis model assessment of insulin resistance, and triglyceride levels, 125 (non-liver-fibrosis group, 100; liver fibrosis group, 25) were included. The diversity of gut microbiota differed significantly between the two groups; however, no significant differences were noted in their oral microbiota. The liver fibrosis group showed an increase in the relative abundance of Fusobacteria strains and a decrease in the relative abundance of Faecalibacterium, with the presence of Fusicatenibacter in the gut microbiota. Feacalibacterium was not identified as an independent factor of liver fibrosis in adjusting the fatty liver index. In the general population, gut microbiota may be more involved in liver fibrosis than oral microbiota.