Ulcerative colitis (UC) is a chronic intestinal disease that affects the mucosa of the colon and rectum, with diarrhea, mucopurulent stools and abdominal pain as the main manifestations. In addition to genetic susceptibility and abnormal intestinal immune function, lifestyle changes are also a hot topic of research, among which dietary factors are considered as possible risk factors for the development of UC, and some components of the diet have some auxiliary therapeutic effects on UC. In this paper, we review the progress of research on the role of diet in the development and treatment of UC. 1, the relationship between diet and the development of ulcerative colitis Clinical epidemiological studies suggest that although it is not clear what kind of food causes UC, and there is no evidence that the disease is related to food allergies, many studies have shown that some components of the diet are related to the development and recurrence of UC, for example, excessive intake of milk products and reduced fiber intake may be related to the recurrence of the disease. 1.1 Relationship between dietary sulfides and the development of ulcerative colitis The toxic effect of sulfides on colonic cells may be an important mechanism for the formation of colitis. As the standard of living increases, the proportion of protein in the diet increases, so the intake of sulfur-containing amino acids (including methionine, cysteine, cystine and taurine) increases significantly. Through the degradation and fermentation of sulfur-containing amino acids by intestinal bacteria, various sulfur-containing compounds, such as hydrogen sulfide, are produced and accumulated in the intestine, which may have some direct toxic effects on colonic cells and may also indirectly alter their protein function and antigenicity. Studies have shown that the intake of meat (rich in protein), especially red meat and processed meat, increases the risk of recurrence of UC. In addition, non-organic sulfates (including sulfur dioxide, hydrogen sulfide, and sulfites) are widely used as preservatives in the storage and preservation of foods and beverages, such as white wine, hamburgers, concentrated beverages, sausages, beer, and red wine, and therefore, these foods and beverages also increase the risk of developing UC. 1.2 Relationship between dietary fat and the development of ulcerative colitis Excessive intake of fat or unsaturated fatty acids can damage the colonic mucosa. Reif et al [9] showed that increased fat intake, especially animal fat and cholesterol, preceded the onset of UC. The inflammatory changes in the colon caused by increased fat intake may also affect the absorption and secretion of cholesterol. Geerling et al found that excessive intake of monounsaturated fatty acids and polyunsaturated fatty acids may increase the probability of developing UC. Therefore, there is a relationship between fat intake and the development of UC. 1.3 Association of dietary sugars with the development of ulcerative colitis Many investigations have shown that high sugar intake may be associated with the development of UC. Reif et al [9] found that high sucrose intake may increase the prevalence of UC by investigating the pre-onset recipes of UC patients. Bianchi Porro et al found that people who ate foods high in sugar had an increased risk of developing UC compared to a normal diet group, while those who ate a combination of vegetables and fruits seemed to have a reduced risk of developing UC. In an epidemiological study, Russel et al found that regular consumption of sugary foods such as cola drinks and chocolate was positively associated with the development of UC, while regular consumption of citrus fruits was negatively associated with the development of UC. However, the pathogenesis of UC due to high sugar diet is not clear. 2, the role of diet in the treatment of ulcerative colitis diet can promote the intestinal healing itself, which is one of the new concepts of UC treatment. Diet can assist in the treatment of UC, relieve symptoms and prevent recurrence, and its role deserves attention. 2.1 The therapeutic effect of probiotics and their products on ulcerative colitis Many clinical and experimental studies have suggested that intestinal flora plays an important role in the pathogenesis of UC. Probiotics are preparations containing sufficient numbers of defined live bacteria that are transplanted or colonized in the host to alter its microbial system and produce beneficial health effects. Most probiotics belong to the normal flora of the human gut, such as bacteria of the genera Bifidobacterium and Lactobacillus. Some probiotic strains can regulate the balance of flora in the body, such as some foreign bacteria, such as Bacillus and non-pathogenic Escherichia coli. Currently, the most commonly used probiotics in clinical practice are monobacterium or complex preparations of Bifidobacterium and/or Lactobacillus. Probiotics are bioantagonistic, strengthen intestinal epithelial barrier function and regulate intestinal immune system function. It has been shown that probiotics and their products may be effective in the prevention and treatment of mild to moderate UC. As a safe and effective adjuvant therapy, probiotic preparations are promising for their clinical application in the treatment of UC. 2.2 Therapeutic effect of butyrate on ulcerative colitis Short-chain fatty acids (SCFA) in the intestine have the function of maintaining the epithelial barrier of the colon. Butyrate, a SCFA produced by microbial fermentation of food components, is the main source of energy for the colonic mucosa, especially the terminal colonic mucosa epithelium, and it has a protective effect on the colonic mucosa. The protective effect of butyrate on the colonic mucosa is diminished by nitrogen derivatives and sulfides in the intestine. Bamba et al developed a germinated barley foodstuff (GBF), rich in glutamine and hemicellulose, which can be converted to lactate, acetate and butyrate by bifidobacteria and fungi to regulate colonic motility and reduce diarrheal symptoms. The mechanism is that these foods increase the absorption of butyrate and bile salts, reduce the production of pro-inflammatory factors, and promote the proliferation of colonic epithelium. Therefore, the protective effect of butyrate on the colonic mucosa can be enhanced by the intake of foods such as bran, oats, soybeans and high-fiber cereals. Vegetables and fruits seem to have a protective effect on the intestinal mucosa, and dietary fiber, especially fiber intake from fruits, is negatively associated with the development of UC. Butyrate, produced by bacterial enzymes in the intestine, remains the main source of dietary fiber. 2.3 Therapeutic effects of polyunsaturated fatty acids in ulcerative colitis There is now a new understanding of polyunsaturated fatty acids and fish oil or flax oil, either in the diet or as supplements, have been used in anti-inflammatory therapy. Belluzzi et al reported that polyunsaturated fatty acids may have anti-inflammatory activity, reducing the leukotriene content of inflammatory mediators and suppressing the immune response and inflammatory process in UC. Meister et al performed colonoscopy in 7 patients with UC, and the biopsies were cultured in vitro in SHS medium (containing fish oil) for 24 h. After 24 h, the concentrations of IL-1ra and IL-1β were measured by enzyme-linked immunosorbent assay, and the results showed that the IL-1ra/IL-1β ratio was significantly higher in patients with UC. Therefore, fish oil may be beneficial in the treatment of UC patients. Barbosa et al studied the effect of ω-3 fatty acids on oxidative stress in UC patients and showed that the effect of salazosulfapyridine (SASP) and ω-3 fatty acids was better than that of SASP alone. This suggests that ω-3 fatty acids have the effect of scavenging oxygen free radicals and can improve the therapeutic effect of UC. Since the body cannot synthesize linoleic acid and linolenic acid, they must be supplemented from the diet. Therefore, it is recommended that patients eat foods containing ω-3 polyunsaturated fatty acids, such as nuts, flaxseed and fish oil, which are helpful for improving the condition. 2.4 Therapeutic effect of hot water processed cereals on ulcerative colitis Björck et al gave hot water processed cereals (HPC) and regular cereals to UC patients, respectively, and performed colonoscopy biopsy after 4 wk to detect plasma antisecretory factor ( After 4 wk, colonoscopic biopsies were performed to detect plasma levels of antisecretory factor (AF) and to record the clinical symptoms of patients before and after treatment. It was found that HPC significantly reduced the incidence of diarrhea, but the effect was not significant in the control group. The reason is that HPC is an inducer of AF, which can promote endogenous AF production and enhance its activity, thus preventing excessive secretion of inflammatory factors. Therefore, the intake of these active foods can significantly improve the symptoms of UC patients. 3, Conclusion In conclusion, dietary components play a role in the pathogenesis and treatment of UC. Factors such as increased sulfide content in the diet, high sugar and fat intake are associated with the development of UC. If a food can trigger or aggravate the development of UC, it should be avoided as much as possible. More importantly, it is important to distinguish between a real allergy to a certain diet, or intolerance or malabsorption of this food, such as lactose intolerance or malabsorption of lactose in some patients. Having the patient keep a food diary is a good way to not only pinpoint the foods that are causing the patient problems, but also to show whether the patient’s diet is providing the right mix of nutrients. Restoring and maintaining good nutritional status is an important principle in the treatment of UC. Many patients with UC are malnourished. A well-formulated diet can not only be an adjunct to treatment, but can also improve the nutritional status of patients with UC. It is important to note that there is no single diet or eating plan that is suitable for all patients with UC. It is important to note that there is no single diet or eating plan that is suitable for all patients with UC. The type of food that is appropriate or unsuitable for a patient must be individualized and should be adjusted according to the duration, location and degree of the disease. The structure of the diet of UC patients should be studied in depth to determine whether plant-based foods should be substituted for animal-based foods.