What are the gut microbiota and human microbiome?

What is the human microbiome? Every human being harbors between 10 trillion and 100 trillion microbial cells in a symbiotic relationship. Some research estimates that there are around 10 timesTrusted Source more microbial cells in the body than human cells, while other scientists claim the ratio is closer to 1:1. This symbiotic relationship benefits microbes and their hosts as long as the body is in a healthy state. Estimates vary, but there could be over 1,000 different species of microorganisms making up the human microbiota. The composition of the human biome can greatly varyTrusted Source between people. Different parts of the body will also host different microbial communities. For example, the oral cavity, genital organs, skin, gastrointestinal system, and respiratory tract all contain many microbial cells. Still, the types and levels and functions will vary between locations. What is the gut microbiota? The gut microbiota is a vast and complex collection of microorganisms that profoundly affects human health. Previously, people referred to the gut microbiota as microflora of the gut. The gut microbiota assists in a range of bodily functions, includingTrusted Source: harvesting energy from digested food protecting against pathogens regulating immune function strengthening biochemical barriers of the gut and intestine Changes in microbiota composition can affect these functions. While there are beneficial bacteria in the gut, there are also harmful bacteria that can enter the GI tract and cause infection.. These infections include food poisoning and other GI diseases that result in diarrhea and vomiting. Why is the human microbiota important? Microorganisms are integral to human life and carry out various vital functions. In fact, there are roughly 10 times moreTrusted Source bacterial cells than human cells in the gastrointestinal system. Research suggestsTrusted Source that bacterial population makeup and potential disturbances have links to: asthma autistic spectrum disorder cancer celiac disease diabetes eczema heart disease malnutrition multiple sclerosis obesity Nutrition As well as absorbing energy from food, gut microbes are essential to helping humans absorb nutrients. Gut bacteria help the body to break down complex molecules in meats and vegetables, for example. Without the aid of gut bacteria, the body cannot digest plant cellulose. Gut microbes may also use their metabolic activities to influence food cravings and feelings of being full. The diversity of a person’s diet affectsTrusted Source the diversity of their gut. Immunity Some researchTrusted Source suggests that the body’s first exposure to microbes may occur before birth. Without these early microbial guests, adaptive immunity would not exist. This vital defensive mechanism learns how to respond to microbes after encountering them. This allows for a quicker and more effective response to disease-causing organisms. A person’s gut microbiota develops from the first microbial exposure and typically reaches a full composition at 3-5 yearsTrusted Source. Disturbances to these early exposures can hamper the development of the microbiota. Behavior A person’s gut microbiota and brain constantly communicate with each other. The gut-brain axis primarily affectsTrusted Source intestinal function. However, researchers have also observed linksTrusted Source between the gut microbiota and psychological disorders, such as depression and ASD. Disease Research suggests that bacterial populations in the gastrointestinal system play a role in developing gut conditionsTrusted Source, including inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis. Low microbial diversity in the gut also has links to obesity and type 2 diabetes. The status of the gut microbiota also has linksTrusted Source to metabolic syndrome. Changing the diet by including prebiotics, probiotics, and other supplements may reduce these risk factors. Disturbing the microbiota with antibiotics can also lead to disease, including infections that become resistant to antibiotics. The microbiota also plays an important role in resisting intestinal overgrowth of externally introduced populations that otherwise cause disease – the “good” bacteria compete with the “bad,” with some even releasing anti-inflammatory compounds. Microbiome research Huge investment has gone into research about microbial populations in the body and their genetics, exploring links with health and disease. The National Institutes of Health’s Human Microbiome ProjectTrusted Source was a large-scale initiative to assess various microbiome compositions on health and whether there are identifiably “healthy” makeups. The project helped establish links between specific microbial compositions and diseases across demographics. Due to the project, researchers can better understand the genetic composition of the gut microbiota and establish methods of classifying and analyzing their varying microbial compositions. Recent developments include further confirmation of inserting a new strain into an existing microbiota using nutrient availability without affecting the overall balance and function of the microbiome. This opens up the potential for probiotic treatments and new methodsTrusted Source of analyzing the makeup of the gut microbiota.