We are discovering more and more every day about how our gut health influences the rest of our bodies. Much like our skin, the gastrointestinal lining is the body’s first defense against the environment. However, this thin lining is fragile and can be easily disrupted by genetic, dietary, and environmental factors. Changes to gut homeostasis can lead to chronic inflammation, poor nutrient absorption, abdominal pain, and even gastrointestinal cancers. Many diseases are associated with the gastrointestinal tract, such as irritable bowel syndrome, inflammatory bowel disease, ulcerative colitis, peptic ulcers, and can all lead to lower quality of life and poor health outcomes.
And with the discovery of the gut-brain axis, in which the intestinal system has been found to be neurologically linked to the cognitive and emotional centers of the brain, researchers are realizing that the gut plays a major role in our mental and psychological health. For example, the neurotransmitter serotonin is responsible for stabilizing mood, feelings of well-being, and happiness. 95 percent of serotonin is found in the gastrointestinal tract and may be one of the mediators of the gut-brain axis.
That said, probiotics, prebiotics, and postbiotics are becoming major health trends in improving gut health.
What are the differences between them, and how do they assist in improving one’s gut health? Learn more about the how and why in this article.
What are probiotics?
If you’ve heard of any of these types of biotics before, you’ve probably heard of probiotics. Probiotics are dietary supplements and fermented food products that contain a very high concentration of live, beneficial microorganisms. Consuming probiotics encourages the growth of beneficial microorganisms in our gut. The World Health Organization (WHO) defines probiotics as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. Probiotics typically contain a well-defined microbial strain or species that has been shown to improve health in clinical settings. Common genera of probiotic bacteria and fungi include Lactobacillus, Bifidobacterium, Bacillus, Saccharyomyces, Escherichia, and Enterococcus. By consuming several billion bacteria cells in a probiotic, we increase the likelihood that these bacteria survive and benefit the gut. The key difference between the types of biotics is that probiotics are composed of living organisms, whereas prebiotics and postbiotics are not.
The first concept of probiotics was described by Élie Metchnikoff, who won the Nobel Prize in Medicine/Physiology in 1908 for his work on innate immunity. Metchnikoff noticed that Bulgarian peasants who drank yogurt lived longer. He speculated that special bacteria in the yogurt had an influence on aging and conferred health benefits through the intestinal tract. In order to confirm his findings, he drank sour milk containing the microorganisms throughout his life. And while he shared his theory on the subject in several of his writings, the concept of probiotics would not become common until the 1990s, when experimental data on the subject emerged.
Since the 1990s, probiotic popularity has only grown. Between 2022 and 2027, the probiotic market is predicted to grow at CAGR of 8.1%. The projected value of probiotics is $85.7 billion by 2027, a significant jump from the current estimated market value of $57.8 billion in 2022. The most common formats for probiotics include supplements and functional foods/beverages. On the supplement side, multiple probiotic product categories exist, including tablets, capsules, powders, liquids, soft gels, and gel caps. For functional foods and beverages, probiotics can be delivered through dairy products, non-dairy alternatives, infant formula, cereals, and shakes. An additional growing category for probiotics is their use in animal feed as an alternative to antibiotics.
What does a probiotic do?
There are several mechanisms by which probiotics affect our health when consumed. The most common way is that the specific strain of microbes used in the probiotic can outcompete pathogenic microorganisms found in the gut through a variety of strategies. Probiotics may release metabolites that have antibacterial properties against these pathogens, lower the pH of the surrounding environment to exclude the growth of other microbes, or produce natural biofilms that prevent foreign microbes from sticking to the gut.
Some probiotics might consume nutrients and resources faster than their competitors. Others work with our immune system and gastrointestinal lining to reduce inflammation, either by releasing metabolites that signal our body to inhibit inflammation in the gut or strengthening the natural mucus barrier found at the boundary of the gut lining.
Certain bacterial species that reside in the colon can serve as probiotics as well, and they are able to ferment starches and fibers into a class of compounds known as short chain fatty acids. Acetic, propionic, and butyric acid are the most common ones, which can serve as direct sources of energy for intestinal cells while simultaneously inhibiting the growth of pathogens.
What are prebiotics?
Prebiotics contain materials that stimulate the growth of beneficial gut bacteria. Prebiotics are usually not usable by pathogens because of their complex structure. For this reason, prebiotics can be used to rebalance the gut microbiota when equilibrium is lost. To do this, the gut ferments prebiotics and makes byproducts like short-chain fatty acids which themselves have benefits on the gut, such as strengthening intestinal barrier function and improving mineral absorption. Examples of prebiotics include certain fibers and carbohydrates, like inulin, beta-glucan, resistant starches, and oligosaccharides.
What are prebiotic foods?
Many prebiotics are found in nature. Sources of prebiotics include fiber-rich vegetables and fruits like Jerusalem artichoke, oats, garlic, green bananas, grains, flaxseeds, beans, corn fiber, and seaweed. They can also be engineered by modifying the chemical structure of pre-existing carbohydrates, converting them into materials that can only be fermented by certain beneficial strains. Alternatively, they can be produced by modified microorganisms that can secrete novel types of prebiotics.
In 2021, the prebiotic market was valued at $6.05 billion, with a CAGR of 14.9% estimated between 2022 to 2030. The fast growth of prebiotics is driven by demand for healthier-for-you foods as well as the technological developments in inulin, prebiotic fiber, and oligosaccharides. These products have potential benefits for helping alleviate the symptoms of chronic gastrointestinal diseases like irritable bowel syndrome, inflammatory bowel disease, and Crohn’s disease. As premium health ingredients, prebiotics have a healthy return with relatively low costs associated with production. One consumer research study found that prebiotic fiber is the #1 ingredient consumers want to add to their diets for digestion and gut health.
The prebiotic market is broken up into several categories that include inulin, chicory fructans, and a variety of oligosaccharides (fructo-oligosaccharides, mannan-oligosaccharides, galacto-oligosaccharides, human milk oligosaccharides, xylan-oligosaccharides, and many others). Each type of prebiotic supports the growth of specific bacteria that are capable of cleaving their molecular structure. Inulin dominates the market category due to its ease of processing and inclusion in many different healthy food and nutrition products, with galacto-oligosaccharides poised to gain significant growth between 2022 and 2030.
What does a prebiotic do?
Humans do not possess the right enzymes in our guts to break down prebiotics. Instead, prebiotics are able to pass through our stomach and small intestine, and reach the large gastrointestinal tract. There, beneficial gut microbes are able to degrade the prebiotics into more useful molecules. These microbes have specific enzymes that can cleave chemical groups found in prebiotics.
This allows the gut microorganisms to break down the complex carbohydrates, normally resistant to fermentation by other microorganisms, into sugars that can be more easily transported across the bacterial membrane. The sugars provide energy for the beneficial bacteria to feed and multiply rapidly, allowing them to outcompete other microorganisms in the gastrointestinal tract. Additionally, the sugars serve as raw material for the bacteria, which can convert the sugars into health-benefiting metabolites, vitamins, and short chain fatty acids.=
What’s the difference between prebiotics and probiotics?
In summary, there are a few differences between prebiotics and probiotics. First, probiotics are living microorganisms whereas prebiotics are not: they are fibers or carbohydrates. Both function to balance gut microbiota and aid gut health, but through different mechanisms.
What are postbiotics?
Postbiotics are the products formed when probiotics and beneficial bacteria break down prebiotics and other nutrients, forming metabolites beneficial to health. They can also include the fragments of dead probiotic cells that are still capable of influencing the gut ecosystem. A probiotic cell can be killed by heat treating, enzymatically destroying, adding an antimicrobial agent to, or physically rupturing a live sample of probiotics.
Like we mentioned before, some examples of metabolites that help improve the gastrointestinal lining are short chain fatty acids, which serve as an energy source for colon cells. But the most commonly used materials are inanimate or deactivated probiotic bacteria cells. During the life cycle of a probiotic, the bacteria cells naturally die and leave postbiotics in the human body. Consuming postbiotics simply increases the concentration of these natural bioactive fragments.
These are early days for postbiotics, as they are not as well understood by consumers and more technological development is necessary to design effective health and nutrition products. However, Postbiotics are expected to grow at a CAGR of 6.2% from 2022 to 2031, with a current market value of $1.6 billion. COVID-19 ushered in tremendous growth for postbiotics as a way to include more health-promoting supplements and ingredients into consumers’ diets. Right now, most postbiotics research has focused on their use in animal husbandry and farming to help improve livestock health, as they are easier to develop and do not require the same strict regulatory requirements as human-grade supplements. There is also strong growth in the cosmetic industry for postbiotic use on the skin microbiome, again, due to the lower barrier to entry from a regulatory standpoint. Examples of postbiotic ingredients include short-chain fatty acids, microbial cell fragments, extracellular polysaccharides, and cell lysates.
What does a postbiotic do?
Deactivated or dead probiotics can serve as postbiotics. When these dead cells are consumed, the body’s enzymes may shred them into pieces, and part of the cell membranes and proteins still serve as signaling molecules.
Essentially, the husk of the bacteria cell still contains molecular fragments that signal to the immune system through the gastrointestinal lining. Or the postbiotic might contain metabolites and molecules that still harbor an antimicrobial effect against pathogens in the gut microbiome. Other ways postbiotics might work is that a protein fragment might serve as a signaling molecule to gastrointestinal cells to reduce inflammation or tighten up any microscopic hole or tear in the membrane. However, the concept of postbiotics is relatively new and still actively being explored by researchers, so new insights and mechanisms are sure to come out of the research.
Despite postbiotics being relatively new, you may have inadvertently consumed them already. If a probiotic product experiences storage or processing hiccups, the probiotics may die and become postbiotics. Postbiotics can also be found in fermented foods after the foods have been heat treated to improve their shelf-life stability. Any of the microorganisms that originally fermented the food product would die during this process, leaving only their potentially active remains. Finally, postbiotics can be deliberately designed by taking bacterial cells and deactivating them through heat or chemical means. Most postbiotics on the market today are there unintentionally, but the growing evidence of their benefit suggests that intentional postbiotic products may become more common.
We’re still learning how probiotics, prebiotics, and postbiotics work together to improve gut health by modifying the gut microbiome. Prebiotics are an especially fast-growing category that will be important to watch for future ingredient trends. While much work has been done on probiotics alone, research on the combination of all three working in tandem will be an interesting topic for the future. As researchers discover more about how these ingredients work, we will have more ways on hand to improve our health for generations to come.
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