Live microbes are microscopic organisms, like bacteria and yeasts, that are all around us and inside the human body. The term refers to microorganisms that are active and can provide certain effects when consumed. While some microbes can be harmful, many are beneficial to human health.
Sources of Live Microbes
Beneficial live microbes can be obtained from two primary categories: food and dietary supplements. Many food sources contain these microorganisms as a result of fermentation, a process where microbes convert sugars into compounds like acid or alcohol. Common examples include yogurt, kefir, kimchi, sauerkraut, and certain cheeses. Fermentation preserves the food and cultivates large populations of live microbes.
Unpeeled raw fruits and vegetables are also sources of live dietary microbes. However, not all fermented products contain live organisms at consumption. Processes like baking or heat-treating after fermentation, common for sourdough bread or shelf-stable pickles, will kill the active microbes. For a more direct and concentrated intake, dietary supplements are formulated to deliver high quantities of select microbes.
Role in Human Health
The community of microorganisms in the human gut, known as the gut microbiota, has a significant impact on overall health. These microbes are instrumental in digestion, helping to break down dietary components that the human body cannot digest on its own, such as certain fibers. Through this process, they produce beneficial compounds, including short-chain fatty acids (SCFAs), which serve as an energy source for cells in the colon.
Beyond digestion, the gut microbiota is deeply interconnected with the immune system. A large portion of the body’s immune cells reside in the gut, where they constantly interact with the resident microbes. This relationship helps train and mature the immune system, enabling it to distinguish between harmless bacteria and dangerous pathogens. The microbes also contribute to the structural integrity of the gut barrier.
The influence of these microbes extends to other parts of the body through the gut-brain axis. This communication network links the gastrointestinal tract with the central nervous system. The microbes can produce neurotransmitters and other signaling molecules that can influence mood and neurological function. A balanced and diverse gut microbiota is associated with positive health outcomes.
Common Strains and Their Functions
Two of the most well-researched and commonly utilized genera are Lactobacillus and Bifidobacterium. Each of these groups contains numerous different species and strains that perform distinct functions. Their roles are often location-specific, with certain types thriving in different parts of the gastrointestinal tract.
Lactobacillus species are frequently found in the small intestine and are known for their role in digesting dairy products. They produce lactic acid, which helps create an acidic environment that inhibits the growth of less desirable microorganisms. Some strains of Lactobacillus are also noted for their ability to enhance the gut’s barrier function and are commonly found in fermented foods like yogurt and kefir.
Bifidobacterium species are predominantly found in the large intestine and are among the first microbes to colonize an infant’s gut. These microbes are especially adept at breaking down complex carbohydrates and dietary fibers that are indigestible by human enzymes. This breakdown process yields beneficial short-chain fatty acids. Certain Bifidobacterium strains have been associated with producing B vitamins and helping to regulate immune responses.
Ensuring Microbial Viability
For live microbes to confer a health benefit, they must be alive and active when they are consumed. Viability is affected by manufacturing processes, storage conditions, and time. When choosing a supplement, the label provides information regarding the quantity of live organisms, measured in Colony Forming Units (CFUs). This number indicates the quantity of viable cells capable of replicating.
Proper storage is another important factor in maintaining microbial viability. Many products containing live microbes, such as certain yogurts and supplements, require refrigeration. Low temperatures slow the metabolic activity of the microbes, keeping them in a dormant but living state. Exposure to heat, moisture, and oxygen can be detrimental to their survival.
Paying attention to the expiration date on a product is a practical way to ensure you are consuming an effective number of live microbes. Reputable manufacturers add an excess of microbes during production to account for some loss over time, guaranteeing the stated CFU count remains accurate through the product’s shelf life.