Nowadays, many patients are suffering from rectal cancer, which is very painful and poses great danger to their health. Most people do not know much about rectal cancer in their life. So, is constant farting a warning of rectal cancer? What are the symptoms of rectal cancer? Non-stop farting is a common physiological reaction, which is the gas accumulated in the gastrointestinal tract and expelled from the anus. This gas mainly comes from the process of food being decomposed and fermented by bacteria in the human colon, but also from the air swallowed when eating and drinking, as well as some of the gas released by the blood circulation of the intestinal mucosa. The chemical composition of farts is as follows: nitrogen 20% to 90%, hydrogen 0% to 50%, carbon dioxide 10% to 30%, oxygen 0 to 10%, and methane 0 to 10%. The more gas-producing are foods containing polysaccharide compounds, including beans, dairy products, onions, garlic, green onions, leeks, kale, sweet potatoes, potatoes, cashews, oats, wheat, etc. Lactose intolerant people eat foods containing lactose, such as milk, in which undigested lactose is broken down by bacteria to produce large amounts of gas. Foods containing starch such as corn will mostly produce gas when they are digested and broken down in the large intestine, but rice will not produce gas and is the only exception. On the other hand, seaweed and some seasonings have the effect of reducing gas production in the intestine, such as cumin, coriander (cilantro), turmeric, etc. Beans fermented into tempeh or cooked for a long time can reduce gas production by destroying the polysaccharides in them, but there is a loss of nutrition. Most people who fart in the normal population are constipated, feces stay in the body for too long, sulfide in the intestinal gas content increases, farts will be full of bad smell. However, if there are no farts, no bowel movements and bouts of abdominal pain for several days, it is often a sign of intestinal obstruction. What are the symptoms of rectal cancer? Blood in stool Many patients who have blood in stool think it is caused by hemorrhoids and do not pay much attention to it. In fact, 80% of rectal cancer will have the symptom of blood in stool, and in serious cases, there will be sticky blood stool, but this is often ignored. Black stool In recent years, influenced by the trend of detoxification and skin care, many people abuse laxatives and thus cause a significant increase in colon black stool disease, in fact, the common explanation is that the colon becomes black, the disease with adenomatous polyps and intestinal cancer rate of up to 22%-55%. Diarrhea A continuous change in bowel habits, including sudden constipation, diarrhea or alternating between the two, and a significant increase in the number of bowel movements are some of the symptoms of rectal cancer.