The human digestive tract is full of so many microbes that the gut has been called a “second brain” and another endocrine organ. The number of bacteria in the gut exceeds the total number of human cells that make up the human body. Also known as the gut microbiome, these bacteria play an important role in human health beyond digestive function.
The bacteria in the gut tend to fall into one of three types of bacteria: commensal, mutualistic or pathogenic bacteria.
- Commensal bacteria are also known as “normal microflora” or “indigenous microbiota.” They provide neither a benefit nor an adverse effect on the host. The normal bacteria species of the gut include Eschericia coli, streptococcus, and bacteroides.
- Mutualistic bacteria, such as Lactobacillus spp, provide benefit to receive benefit from the host. For example, mutualistic bacteria can produce short-chain fatty acids (SCFA) that further convert to butyrate. Butyrate can be stimulated by probiotics and prebiotics which influence gut and cardiovascular health and other body systems.1
- Pathogenic bacteria, such as Clostridium perfringens, cause harm to the host.2 Pathogenic bacteria and other organisms make up the larger microbiome.
- Microbiome is the whole environment that includes all microorganisms (bacteria, viruses, and others), their genomes, and the conditions of the environment.3
- Microbiota is a concept that was first described by Lederberg and McCray in 2001 as a group of microorganisms that focuses specifically on the effect on human health outcome.4 The microbiota can be influenced by introducing probiotics and/or prebiotics into the gastrointestinal system to help provide specific outcomes.
- Fiber is a non-digestible carbohydrate that is either soluble or insoluble in water. Clinicians and policy-making groups recommend intake of about 25 grams of fiber per day for women and about 35 grams per day for men.
- Probiotics consist of microorganisms that provide a health advantage to their human host when consumed. Probiotics are ingested either as a food (in yogurt or other fermented foods) or through a supplement or medical food.6
- Prebiotics are food components or supplements that cannot be digested by humans, typically a fiber. Not all fibers are prebiotics, and not all prebiotics are fibers. Prebiotics have been described as a food source for the beneficial bacteria.7 Prebiotics provide a different set of health benefits than fiber, such as:
- improving infectious or antibiotic-associated diarrhea,
- reducing inflammation associated with inflammatory bowel disease (IBD),
- protecting from colon cancer,
- improving bioavailability of minerals,
- reducing risk of cardiovascular disease, and
- supporting weight management.
- Synbiotics are a combination of probiotics and prebiotics that feed a specific bacterial strain. Providing a prebiotic food for a beneficial probiotic bacteria may result in health benefits.5