## 4 Discussion
Excessive D-galactose intake (800 mg/kg in mice) has been shown to decrease expression levels of tight junction proteins, including occludin and claudin-1, which are crucial for maintaining the integrity of the intestinal barrier, and disrupt the balance of gut microbiota [37]. Furthermore, D-gal administration (150 mg/kg in mice) can lead to an imbalance in gut microbiota, resulting in a decrease in the production of important metabolites such as SCFA [38]. Further studies are necessary to elucidate whether the reduction in goblet cell number in the CD group is due to the damage of intestinal stem cells or other factors. In a previous study, we found that fermented glasswort contained a significant amount of minerals and free amino acids such as alanine, proline, aspartic acid, and lysine [17]. In addition, the fermentation process can significantly influence metabolic changes in glasswort compared to non-fermented glasswort [39]. Among these metabolites, phenolic compounds are recognized for their ability to scavenge free radicals, thereby functioning as antioxidants and exhibiting anti-inflammatory properties [20]. Numerous studies have demonstrated that phytochemicals can influence compositions of intestinal microflora and reduce intestinal permeability by preserving the integrity of the mucous layer [40]. Notably, compositions of intestinal microbiota in elderly individuals have been found to be influenced by diet, which in turn can affect their health status [41]. Many studies have revealed that butyrate is involved in mucin production by regulating MUC genes expression in intestinal epithelial goblet cells [42]. Our results revealed that trends of mucus layer thickness changes had a similar pattern to changes observed for butyric acid levels. Using an aging animal model, we demonstrated that consumption of fermented glasswort diet could enhance the production of butyric acid, a metabolite of intestinal microorganisms, ultimately improving barrier function of the intestine. This implies that fermented glasswort might have a beneficial effect on intestinal health in elderly individuals. Based on these findings, future studies should focus on profiling intestinal microbiota and investigating the underlying mechanisms associated with gut health through a fermented glasswort diet. Reactive oxygen species (ROS) have high reactivity and give damage to cellular components such as nucleic acid, lipids, and proteins. Oxidative stress induced by ROS can trigger inflammatory responses and accelerate the aging process, thereby playing a significant role in the development of diseases [29]. Under a normal physiological state, homeostasis of ROS is regulated by biological processes. Aging is characterized by chronic inflammation known as immunosenescence [43]. Inflammation is a physiological defense system that can repair tissues when they are damaged. It involves immune cells and molecular mediators. Therefore, there is a persistent effort in the development of food materials that demonstrate antioxidant properties. In our study, the fermented glasswort diet resulted in a reduction in the content of MDA, a marker of oxidative stress. Additionally, it effectively decreased protein expression levels of IL-1\(\beta\) and NF-\(\kappa\)B. In an animal model with adenine-induced kidney damage, administration of fermented glasswort extract resulted in reduced levels of blood urea nitrogen (BUN) and creatinine, both of which are indicators associated with oxidative stress [44]. Main phenolic compounds identified in glasswort were vanillic acid and \(p\)-comamic acid. These compounds exhibit anti-cancer effects in colon cancer cells [45]. These effects might be attributed to antioxidant and anti-inflammatory properties conferred by high mineral contents and phytochemical compounds present in fermented glasswort.