"Many of my friends say I have gained weight again," the 83-year-old professor often complains. "I have been very strict with my diet, but my stomach starts to bulge every afternoon and sometimes I can't eat dinner. Even so, my stomach is getting bigger and bigger.

       Digestive experts quietly tell you that although you are always bulging belly, but you may not really fat, but the small intestine bacteria excessive growth! With the acceleration of the social rhythm, people are used to ordering takeout, eating hot pot, malatang, the whole family bucket, no spicy not happy, but "high salt, high sugar, high oil" eating habits make our intestines "very hurt". Did you know that the best longevity secret in the world is to maintain a healthy gut? In June 2020, a Harvard survey study suggested that the reason why staying up late for a long time causes sudden death is because of the accumulation of oxides, which leads to cell damage or death, and the location of this reactive oxygen species is not usually what we think of as the brain or heart, but in our intestines!

In addition to the functions of digestion, absorption, detoxification and defecation of the human body, the intestine also has a rich neural network and endocrine structure, forming gut-brain interaction with the brain, and its abnormality will affect the gastrointestinal function, immune balance and emotional state of the human body, which is called the second brain. It is particularly important to care for the gut, and the structure of the gut flora is closely related to intestinal health, and the key to intestinal health is to maintain the dynamic balance of intestinal flora. Small intestine flora is a part of digestive tract flora, and the clinical symptoms and diseases caused by its imbalance have attracted more and more clinical attention.

What is bacterial overgrowth in the small intestine?
   

Normally, the colonization level of bacteria in the small intestine is low, and when there are too many bacteria in the small intestine, causing gastrointestinal symptoms, small intestinal bacterial overgrowth (SIBO) is formed. These bacteria are usually coliform bacteria, mainly gram-negative aerobic and anaerobic bacteria, can ferment carbohydrates to produce gas. What are the clinical manifestations of bacterial overgrowth in the small intestine? 

SIBO is characterized by abdominal discomfort such as bloating, abdominal pain, diarrhea, excessive exhaust, constipation and, in severe cases, nutritional deficiencies, including vitamin B12, vitamin D and iron deficiency. In the elderly, SIBO is a significant cause of unexplained diarrhea and weight loss. Because the symptoms of SIBO lack specificity and are easily confused with or accompanied by other diseases, SIBO is easily overlooked, and these patients have persistent or recurrent symptoms that seriously affect their quality of life. 

What are the predisposing factors and causes of intestinal bacterial overgrowth?
   

Pathophysiologic risk factors for SIBO include anatomical abnormalities of the small intestine (diverticulum of the small intestine), changes in the anatomical structure caused by surgery (Type II gastrectomy, bariatric surgery, end-to-side anastomosis), stenosis (Crohn's disease, radiotherapy, surgery, etc.), blind ansas (ileocecal valve resection), and insufficient secretion of gastric acid and digestive enzymes (prolonged use of proton pump inhibitors, post-surgery, and organs Atrophy), intestinal motility disorders (diabetic autonomic neuropathy, nervous system diseases, scleroderma, hypothyroidism, idiopathic pseudoileus, gastroparesis, chronic opioid use, long-term spasmodic use), immunosuppression (immunosuppressive or hormonal use), and abnormal protective antimicrobial mechanisms. The elderly are more susceptible to SIBO due to the deterioration of physiological functions of the organs, the coexistence of multiple diseases and multiple drugs. 

  

What is the diagnosis of bacterial overgrowth in the small intestine?
   

1.    Enteric fluid bacterial culture: The gold standard for diagnosing SIBO, the latest guidelines recommend a bacterial colony count of > 103CFU/mL in duodenal/jejunal aspirate. However, this examination is an invasive procedure and takes a long time.

2.    Breath test: The concentration of hydrogen and methane in the exhaled gas is measured by taking a certain amount of carbohydrate substrate (such as lactulose or glucose) orally. The lactulose or glucose breath test is non-invasive, economical, simple and acceptable, especially for the elderly, and is the most commonly used method for diagnosing SIBO clinically.