Good bacteria are lost and recovered Fecal bacteria transplantation brings a healthy turnaround

On December 1, a novel fecal microbiome therapy was approved by the U.
S.
Food and Drug Administration (FDA) to prevent recurrence of infection in adults with Clostridium difficile infection after antibiotic treatment
.
"This is a milestone in
the development of international microbiome drugs.
" Huang Rui, an expert at the Chinese Food Think Tank, vice chairman of the Colorectal Oncology Professional Committee of the Heilongjiang Medical Promotion Association, and deputy director of the Department of Colorectal Surgery at the Second Affiliated Hospital of Harbin Medical University, said that this fecal microbiome therapy aims to reintroduce live beneficial microorganisms into the patient's intestine and restore the "ecological balance" between microorganisms to inhibit the excessive reproduction of harmful microorganisms and ultimately help patients regain health
.

Gut bacteria have a huge impact on human health

In the human body, a large microbiota including bacteria, archaea, fungi and small protists, microalgae
, is inhabited and inhabited.
According to Huang Rui, 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 usually estimated to be as high as 100 trillion-1000 trillion.

In the human microbiome, bacteria are overwhelmingly dominant, hundreds or thousands of times
more than other types of microorganisms.

And both whole-body and just from the digestive tract, colorectal is a major contributor to the total number of
bacteria.
Huang Rui pointed out that normal people contain about 90 billion bacteria per gram of feces on average, and the volume of colorectal feces in a standard-weight adult male 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 in the human body, which is called the "second genome of human beings", which shows the huge
impact of intestinal bacteria on human health.
Huang Rui explained that as the largest and most complex intestinal microecosystem in the human body, the intestinal flora presents significant individual differences in structural composition.
At the same time, the intestinal flora also has its relatively consistent side, about 30-40 species make up 99% of the intestinal bacteria
.
The study of the Human Microbiome Project shows that 30 core bacterial genera in the intestine, such as Bacteroides, Pretiella, Bifidobacterium and Klescella, account for a relatively high proportion of the intestines, 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 against intestinal microbiobiosis

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.
Huang Rui introduced that the intestinal flora plays an important role in the human 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 intestine, strengthening 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, "fecal bacteria transplantation" has gradually entered the public's attention and greatly attracted the public's curiosity and attention
.
Huang Rui explained that fecal bacteria transplantation is to transplant the beneficial microbiota in healthy people's feces into the gastrointestinal tract of patients to rebuild the damaged intestinal microecological environment of patients, so that probiotics can be "lost and regained" to 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; Diabetes, obesity, metabolic syndrome, gout and other metabolic diseases, radiation enteritis, drug-induced colitis, etc
.

It should be emphasized that all of the above diseases tried to fight with fecal bacteria transplantation are closely related to intestinal microbiome, including the most common cancer - colorectal cancer
.
Huang Rui pointed out that intestinal dysbacteriosis is an important risk factor for colorectal cancer, which will change the physiological functions of the human body and induce intestinal and extraintestinal diseases
.
Specific species of the intestinal flora, including Escherichia, 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 had higher species richness, among which the abundance of protective taxa such as Rochemycin decreased, and the abundance of carcinogenic taxa such as Fusobacterium and Porphyromonas increased
.

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
.
Huang Rui said that by correcting these lifestyles, at least half of colorectal cancer incidents
can be prevented.
Naturally, there is also the credit of the intestinal flora behind this - the implementation of dietary interventions, which can hinder the development of colorectal cancer with the help of the gut microbiota; Weight control in obese individuals can significantly alter the gut microbiota; Conversely, weight loss in obese people helps reduce the risk of
colorectal cancer.

At this stage, several probiotic bacteria, including Bifidobacterium and Lactobacillus species, 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
.
However, despite in vivo and in vitro trials, 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.

The consequences of misuse of antibiotics are serious

The intestinal flora gradually "takes root" in infancy to a relatively 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 profile, the body's immune response, infection, exposure to environmental microorganisms, circadian rhythms, dietary changes, and antibiotic abuse
.
Huang Rui explained that all kinds of intestinal bacteria have their own food preferences, some bacteria prefer high-fat, high-protein diet, the body ingests such a diet for a long time, the intestine will "gather things" and 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 the intestines.
This suggests that if a person's diet is too single, the types of intestinal bacteria will decrease, 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 and even super-resistant bacteria in the body finally makes the microecology in the body out of balance, bringing difficult to control or fatal infections, and even facing the terrible situation
of no drug available.

Huang Rui 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)

China Food News(Version 03, December 21, 2022)

(Responsible editor: Luo Chen)