Human health is related to various factors, including dietary habits(Ikeda & Collaborators, 2021; Przybylowicz & Danielewicz, 2022),environmental conditions(Beier & Arteel, 2021; Campbell-Lendrum & Woodruff, 2006), genetic factors(Nakanishi, Shimizu, Kumagai, Takai, & Marusawa, 2021), and more. Among these, nutritional factors are particularly crucial. People obtain the necessary nutrients for their bodies by consuming various foods, such as dietary proteins, lipids, cereal fibers, and vitamins, providing essential energy. Additionally, nutritional habits can also lead to human diseases, such as the prolonged consumption of certain specific foods. Studies have shown that long-term intake of high-fat foods may increase the risk of metabolic-related diseases such as obesity(Calder et al., 2011; Rasool, Geetha, Broderick, & Babu, 2018), hyperlipidemia(Bozzetto, Della Pepa, Vetrani, & Rivellese, 2020), and diabetes(Zhao et al., 2022). Interestingly, researchers have differing opinions on the effects of long-term capsicum consumption. Some scholars believe that eating capsicum long-term can burn body fat and energy(Shin, Yang, & Han, 2020). Therefore, most studies focus on the role of dietary capsicum or capsaicin in preventing and treating metabolic diseases(Panchal, Bliss, & Brown, 2018). However,some scholars argue that long-term capsicum consumption may harm the digestive system and, in extreme cases, may lead to health issues such as stomach and colon cancer(Chan et al., 2021; Chen et al., 2017). Despite the differing views on the potential impacts of long-term capsicum consumption, the specific mechanisms remain a mystery.
The purpose and innovation of this study lie in comparing the effects of two different dietary patterns, high-fat diet and capsicum diet, on the histomorphology of the digestive system (including liver, stomach, gallbladder, and colon tissues). It aims to observe how long-term intake of these two dietary patterns affects the digestive organs.
This study found that both high-fat diets and capsicum diets can potentially increase the levels of serum triglycerides, total cholesterol, low-density lipoprotein, and high-density lipoprotein in guinea pigs.
This study found that long-term consumption of capsicum significantly leads to gastric mucosal ulcers, gastric gland atrophy, and necrosis, inducing gastritis. The stomach is responsible for storing food and achieving mechanical and chemical digestion through gastric motility, secretion of gastric acid, and pepsin. Factors such as the gastric mucosal barrier and gastric acid also help prevent the invasion of pathogens and foreign bodies. Previous extensive studies have shown that a high-fat diet significantly increases the incidence of gastritis. Additionally, studies have found that a high-fat diet increases the number of ghrelin-expressing cells in the stomach, leading to obesity(François et al., 2016; Sato et al., 2014; van Loenen, Geenen, Arnoldussen, & Kiliaan, 2022). This study found that the gastric mucosa in the high-fat diet group was significantly damaged, ulcerated, and accompanied by gastric tissue inflammation. The above studies indicate that a high-fat diet can indeed lead to the occurrence of gastritis and gastric ulcers. Previous research has confirmed that Capsicum peppers can damage gastrointestinal tissues and cause significant inflammation in the jejunum, ileum, and colon. Combining the research views of the above scholars, our research team believes that long-term consumption of a high-fat diet or capsicum diet may induce gastric tissue damage, thereby triggering gastritis and gastric ulcers.
This study also confirms that long-term consumption of a high-fat diet can indeed lead to liver steatosis, fibrosis, and inflammatory responses, while long-term consumption of capsaicin can significantly cause liver steatosis and mild fibrosis, but the inflammatory changes are not significant. The liver is not only one of the main metabolic organs and digestive glands of the human body but also plays a key role in glucose and lipid metabolism and is responsible for the production and secretion of bile. Numerous research results confirm that long-term consumption of a high-fat diet can significantly lead to liver fat accumulation, liver fibrosis(Jia, Hu, Kimura, & Tanaka, 2021; Wu et al., 2008), and liver inflammation(Fonseca et al., 2020). Some scholars have confirmed that dietary capsaicin has potential benefits in treating cholestatic liver fibrosis and preventing hepatotoxic liver injury(Karimi-Sales, Mohaddes, & Alipour, 2024; Sheng, Zhang, Chen, & Yu, 2020). In addition, studies have shown that capsaicin inhibits liver fat accumulation in mice with non-alcoholic fatty liver disease induced by a high-fat diet(Shin et al., 2020). Other research has confirmed that capsaicin inhibits liver cancer by suppressing liver progenitor cells' stemness through the SIRT1/SOX2 signaling pathway(Xie et al., 2022). These studies suggest that dietary capsaicin may improve liver fibrosis, liver fat accumulation, and inhibit the occurrence of liver cancer. The above conclusions indicate that capsaicin has a positive effect on improving liver diseases. However, some studies have shown that the intake of different doses of capsaicin affects liver function differently. Specifically, doses of 5 mg·kg−1 and 15 mg·kg−1 of capsaicin are beneficial for liver digestive function and antioxidant capacity, while a dose of 20 mg·kg−1 of capsaicin is detrimental to liver digestive function and antioxidant capacity. Based on the conclusions of other scholars' research, our research team believes that both high-fat diets and capsaicin diets may induce liver tissue damage, leading to liver steatosis and fibrotic changes.
In this study, it was found that high-fat and capsicum diets can lead to gallbladder mucosal atrophy. The gallbladder has functions of storing, concentrating, and emptying bile. Studies show that bile is also involved in the cholesterol metabolism process. Moderate fat intake stimulates the normal contraction of the gallbladder, allowing bile to be emptied in a timely manner, reducing bile stasis, and preventing gallstone formation and exacerbation of cholecystitis. However, long-term high-fat intake can weaken the gallbladder's contraction function(Kim et al., 2023; Mathur et al., 2008). Research has confirmed that a high-fat diet can significantly increase the formation of cholesterol stones(Di Ciaula et al., 2019; Parra-Landazury, Cordova-Gallardo, & Méndez-Sánchez, 2021). Additionally, studies have shown that the excessive consumption of red capsicum peppers has been proven to be a cancer risk factor in Chilean women with gallstones(Báez et al., 2010; Tsuchiya et al., 2011). Based on the viewpoints of the aforementioned scholars, our research team believes that both high-fat diets and capsicum pepper diets may lead to gallbladder mucosal atrophy and impaired gallbladder contraction function.
This study found that both high-fat and capsicum diets can thin the colon tissue and induce inflammatory responses, while also causing a large number of fat cells to appear in the submucosa of the colon tissue. The colon plays a crucial role in the digestive system; it is not only the site for absorbing nutrients like vitamins, water, and inorganic salts, and for forming feces, but the bacteria and microorganisms in the colon also play a key role in maintaining the metabolic balance of the digestive system. Some scholars' research has confirmed that a high-fat diet induces oxidative stress in the colonic mucosa, which increases the permeability of the colonic epithelial barrier and triggers inflammation of the colonic mucosa(Li et al., 2019). Other studies have shown that long-term high intake of trans-unsaturated fatty acids is closely associated with an increased incidence of ulcerative colitis.According to the results of a study, the frequency of dietary chili diets is strongly associated with the incidence of colitis(Mi et al., 2022). Based on the viewpoints of the above-mentioned scholars, our research team believes that both high-fat and capsicum diets can cause damage to colon tissue and induce colitis.
In summary, long-term consumption of a high-fat diet and a diet rich in capsicum peppers has negative effects on the tissues of digestive organs such as the liver, stomach, gallbladder, and colon.
The shortcoming lies in the fact that the study only analyzed the tissue changes in digestive organs caused by a high-fat diet and a capsicum diet at the morphological level, without delving into the underlying mechanisms of related damage.