Taking good care of the intestinal flora is beneficial to our lifelong health

On December 1 this year, the international microbiome drug development field ushered in an important milestone, which attracted high attention from the industry
.
A novel fecal microbiome therapy has been approved by the U.
S.
Food and Drug Administration (FDA) to prevent recurrence of infection in adults with Clostridium difficile infection after antibiotic therapy
.
This fecal microbiome therapy aims to reintroduce live beneficial microorganisms into the patient's gut, restoring the "ecological balance" between microbes to curb harmful microbial overgrowth and ultimately help patients regain health
.

How much do you know about human gut microbes

In the human body, a large microbiome including bacteria, archaea, fungi and small protists, and microalgae is inhabited and inhabited, estimated to be 10 times or more
of the number of cells in the human body 。 According to Professor Huang Rui, an expert from the China Food Think Tank, vice chairman of the Colorectal Cancer Professional Committee of the Heilongjiang Medical Promotion Association, and deputy director of the Department of Colorectal Surgery of the Second Affiliated Hospital of Harbin Medical University, most data show that the number of human cells is about 10 trillion-100 trillion, while the number of microorganisms in the human body is estimated to be usually as high as 100 trillion-1000 trillion, and bacteria account for an overwhelming advantage in the human microbiota, exceeding other microorganisms hundreds or thousands of times
.

Whether viewed throughout the body or just from the digestive tract, colorectal is a major contributor to the total number of
bacteria.
Professor Huang Rui pointed out that normal people contain about 90 billion bacteria per gram of feces on average, and the volume of feces in a standard-weight adult male colorectal cancer is about 410 ml, which translates to about 36.
9 trillion bacteria
.
Women's colon contents are no different from men's, but women have lower somatic cell counts than men, so women have higher levels of bacteria
.

Scientists have found through metagenomic sequencing analysis that the human intestine contains 1000-1150 kinds of bacteria, and every adult has at least 160 kinds of bacteria in the intestine; The number of genes contained in the intestinal flora is more than 100 times the number of genes of the human body, which is called the "second genome of mankind", which shows the great
influence of intestinal bacteria on humans.
Professor Huang explained that as the largest and most complex intestinal micro-ecosystem in the human body, the intestinal flora presents significant individual differences
in structural composition.
But the gut microbiome also has its relatively stable side, with about 30 to 40 species making up 99 percent of gut bacteria
.
The human microbiome project has shown that 30 core bacterial genera in the intestines, such as Bacteroides, Pretiella, Bifidobacteria, and Klecratia, account for a relatively high proportion of the intestinal flora, which constitute the majority of the intestinal flora and play an important "role"
in the stability and function of the intestinal microecology.

Fecal bacteria transplantation can cure any disease

It is an indisputable fact that the intestinal flora is always involved in a person's
health activities throughout his life.
From the moment the baby is delivered from the mother, a rich intestinal flora begins to form and determines the future health
of the child.
Professor Huang introduced that the intestinal flora plays an important role in our body, including fermenting indigestible food components into absorbable metabolites, synthesizing essential vitamins, degrading toxic compounds into non-toxic compounds, inhibiting and defeating harmful pathogens in the intestines, strengthening the intestinal barrier function, and stimulating and regulating the immune system
.
In other words, "good" flora can help the body digest food and resist foreign invaders; And the "bad" flora can make the body uncomfortable or make people sick
.

With the continuous progress of medical science and technology, the term "fecal bacteria transplantation" has gradually entered the public's attention in recent years, and has greatly attracted the public's curiosity and attention
.
Huang Rui popularly explained that fecal bacteria transplantation is to transplant the beneficial microbiota in the feces of healthy people into the gastrointestinal tract of patients to rebuild the damaged intestinal microecological environment of patients, so that probiotics can be lost and recovered, and help people overcome diseases
。 At this stage, fecal bacteria transplantation has been trialed in clinical practice, and the treatment scope includes bacterial, fungal, viral and other infectious diseases; Intestinal diseases such as ulcerative colitis, irritable bowel syndrome, constipation; Hepatic encephalopathy, severe alcoholic hepatitis, non-alcoholic fatty liver, cirrhosis and other liver diseases; Metabolic diseases such as diabetes, obesity, metabolic syndrome, gout; and eight categories
, such as radiation enteritis and drug-induced colitis.

Colorectal cancer must be prevented

It should be emphasized that all of the above diseases tried to fight with fecal bacteria transplantation are closely related to intestinal microbial dysregulation, including the most common cancer, colorectal cancer
.
Professor Huang pointed out that intestinal flora is an important part of colorectal cancer risk factors, an adult intestine has about trillions of bacteria, intestinal flora dysregulation will change the physiological functions of the human body, and induce intestinal and extraintestinal diseases
.
Huang Rui said that the intestinal flora, including specific species of Escherella, Enterococcus, Bacteroides and Clostridium, can be induced and cause colorectal cancer
by chemical carcinogens in a synergistic manner.
Compared with the intestinal microbiota of healthy individuals, the intestinal microbiota of colorectal cancer patients is different, and it has higher species richness, among which the abundance of protective taxa such as Rochemycin is reduced, and the abundance of carcinogenic taxa such as Fusobacterium and Porphyromonas is increased
.

Professor Huang Rui explained that the occurrence process of colorectal cancer is complex, and the causes behind it, including inflammation, immune regulation, metabolism of dietary components, and the production of genotoxins, are "broken
" with the intestinal flora 。 Among them, N-nitroso compounds and hydrogen sulfide, products of bacterial metabolism, can cause cancer; Bacteria such as Fusobacterium nucleatus, Bacteroides enterotoxin, polyketogenic synthase + Escherichia coli, and Enterococcus faecali can cause inflammation and accelerate the course of colorectal cancer; Secondary bile acids produced by bacterial metabolism are inseparable from the high risk of colorectal cancer; Cell-lethal bulking toxins, colibactin, and Bacteroides fragilis can cause severe damage to DNA, which in turn can induce colorectal cancer
.

At present, large-scale epidemiological studies have identified multiple dangerous "drivers" behind colorectal cancer, including poor dietary patterns, obesity and other lifestyle factors
.
Professor Huang Rui believes that by correcting these lifestyles, at least half of colorectal cancer incidents can be prevented, and there is naturally the credit and dedication
of the intestinal flora behind this.
This is because dietary interventions can hinder the progression of colorectal cancer with the help of the gut microbiota; Weight control in obese individuals can profoundly alter the gut microbiota; In turn, obese people lose weight and help reduce the risk of
colorectal cancer.

Huang Rui said that at this stage, several probiotic bacteria, including Bifidobacterium and Lactobacillus, have shown anti-cancer properties in clinical studies, including inhibiting cell proliferation, promoting apoptosis of cancer cells, regulating host immunity, inactivating cancer-causing toxins and producing anti-cancer compounds
.
Despite in vitro and in vitro experimental support, direct evidence for probiotics for colorectal cancer prevention is in its early stages, and more clinical trials will help determine the clinical utility of probiotics in the prevention of colorectal cancer
.

Misuse of antibiotics with serious consequences

The intestinal flora gradually "takes root" in infancy to a more long-term stable state in adulthood, allowing people to benefit
from probiotics.
However, such homeostasis is susceptible to a variety of factors, including an individual's genetic characteristics, the body's immune response, infection, exposure to environmental microorganisms, circadian rhythms, dietary changes, and antibiotic abuse
.
Professor Huang explained that all kinds of intestinal bacteria have their own food preferences, some bacteria prefer high-fat, high-protein diet, when the body ingests such a diet for a long time, its intestines will "cluster in likeness" to condense such bacteria; There are also bacteria that prefer a high-fiber diet, and the body eats high-fiber foods for a long time, and these bacteria
are enriched in its intestines.
This suggests that if a person's diet is too single, the types of intestinal bacteria will become less, which is not conducive to the "harmonious symbiosis"
of the intestinal flora.

In addition, the rational use of antibiotics and the use of antibiotics with caution are also an important measure
to "maintain stability" of intestinal flora.
Huang Rui said that the discovery of antibiotics has cross-era significance, and its invention has saved the lives of
countless infected patients.
But the general use of antibiotics will kill innocents indiscriminately - while destroying pathogenic bacteria, it also accidentally injures probiotics or other unrelated bacteria; Even the cultivation of drug-resistant bacteria, even super-resistant bacteria, in our bodies eventually causes the microbiome imbalance in the body, bringing uncontrollable or fatal infections, or even facing a terrible situation
with no drugs available in the future.

Professor Huang warned that some common "small colds" in people's daily life may not be caused by bacteria, do not take antibiotics at will, and sometimes rely on autoimmunity to heal themselves; If it is caused by a bacterial infection, it needs to be applied
reasonably under the guidance of a doctor.

(Yi Xiaofeng, Ou Suwen, Ye Jinhua)

Preliminary review: Li Song Responsible editor: Zhang Jiazhen Review: Peng Zonglu