I bet all of you have heard of probiotics.
I bet that some of you have heard of pre-biotics.
But I bet that rarely any of you have heard of post-biotics (unless you are into nutrition science).
Wondering what in the world this new form of "-biotics" is? Simply put, if pre-biotics are what feeds healthy bacteria (probiotics), then postbiotics are the substances that result from the breakdown of prebiotics by probiotics.
As simply put by Dr. Will Bulsiewicz: Prebiotics + Probiotics = Postbiotics
An important part of this article then is explaining prebiotics and probiotics, which I will do before moving onto postbiotics and a diet that promotes postbiotic production.
I'll start with probiotics since they are the key factor in this equation. We couldn't use prebiotics to create postbiotics without them.
Probiotics are healthy gut bacteria living in our intestines. There are roughly 4-5 pounds of them in there. According to a massive modern scientific achievement, we have been able to map out the DNA and therefore identify the types of microbes that live in and around our bodies, and have begun to associate microbial patterns with disease outcomes.
Microbes in the intestines perform many important functions we are just beginning to understand, including vitamin production, phytochemical activation, and the release of short-chain fatty acids from otherwise undigestible pre-biotic fibers. But on the flip side, unhealthy strains of bacteria are associated with the production of cardiovascular promoting TMAO, the conversion of bile acids into secondary bile acids associated with colon cancer, the production of excess methane associated with constipation, and other GI disorders, and more.
Due to the Human Microbiome Project (HMP), we know that each person has a unique microbial profile and that these profiles may be more indicative of health or disease than even our own genes! Dysbiosis is a term used to describe a bacterial community that is associated with a diseased state.
For example, having high levels of Enterococcus bacteria was associated with higher CRP levels (a marker for inflammation) in one study. Other studies suggest that perhaps antibiotic use is responsible for some level of dysbiosis that can then predispose an individual to chronic disease.
The good news is that, unlike the genes we've been gifted by our parents, we can alter the makeup of our microbiome, and that diet obviously has a large role to play here. Abundant research is pointing out the correlation between vegan and vegetarian diets and the diversity and stability of beneficial bacterial profiles in the gut.
Prebiotics, therefore, are fuel for good gut bacteria.
In order for something to be prebiotic, it must be resistant to digestion by stomach acid and enzymes, must not be absorbed in the GI tract, must be able to be broken down by intestinal microbes, and lastly that these compounds can both benefit the microbe and improve the host's (human) health. For a more extensive definition, I recommend this article.
There are several dietary components that are considered pre-biotic. The first is Fructo-Oligosaccharides, found primarily in onions, leeks, bananas, asparagus, wheat, yacon and blue agave (and therefore yacon and blue agave syrups).
The second is Galacto-Oligosaccharides, found primarily in legumes, nuts, soy products, and root vegetables.
The third is resistant starch which is similar to fiber and found in many high fiber foods, such as starchy foods with a seed or germ, or starchy foods that aren't fully cooked or ripened like uncooked potatoes or green bananas and is also found in starchy food that has been cooked and then cooled (like potatoes or pasta in a salad).
While these are all carbohydrate derived, there is also evidence that polyphenols (a type of micronutrient found in plants) also play a role in the development of beneficial bacteria species and inhibition of pathogenic bacteria and are therefore considered prebiotic-like in their function.
Postbiotics is an umbrella term that includes a wide variety of components that result from microbial fermentation (breakdown) such as functional proteins and peptides, microbial cell components, and more. However, when I am talking about postbiotics, I am referring generally to the formation of Short-Chain Fatty-Acids (SCFA's), specifically acetate, propionate, and butyrate that result from the breakdown of prebiotics by probiotics.
Why are these important? Well, recent research has connected them primarily to gastrointestinal health. This is because they are the primary fuel source for colonocytes (gastrointestinal cells) and mediate the intestinal barrier health and immune function centered in the gut. In fact, it's estimated that approximately 10% of our daily calories come from short-chain fatty acids absorbed and used in the gastrointestinal tract.
While they are essential for preserving a strong intestinal barrier and immune response in the gut, they also are used as signaling molecules and therefore play an important role in the gut-brain axis. Some of the pathways studied that have been shown to involve SCFA's are appetite regulation, insulin sensitivity, liver function, regulation of lipid use and storage, apoptosis (cell death) of colon cancer cells, healthy gut mucous production, hormone secretion, protection against IBD and colitis, immune function, cardiovascular health markers, and more.
If that was not enough, they are also shown to be involved in regulating intestinal pH, improving the absorption of calcium, iron, magnesium, along with showing anti-inflammatory properties and protecting us from pathogenic bacteria in the intestines.
While it is not widely studied or understood yet, research is beginning to accumulate that demonstrates the neuroprotective effects of SCFA's too, possibly through strengthening the blood-brain barrier, being involved in phases of both neurodevelopment and neurodegeneration. Meaning, not only may SCFA's be important for brain development during growth, but also be protective against diseases such as dementia and Alzheimer's. Again, these compounds are used in cell and hormone signaling back and forth between the gut-brain axis, meaning they play a role in mood disorders (depression and anxiety) and their absence may be associated with even autism spectrum disorder.
Getting my point about why this new buzzword is worth the buzz? It's pretty incredible the importance that microbial by-products play in our health, which goes to show the symbiotic relationship that we've developed with these microbes and the importance of taking care of them.
If at this point you are wondering how to boost your gut's production of SCFA's, I don't blame you! SCFA's may be the reason we see so many health improvements by switching to a more plant-based diet. I encourage you to read a previous blog of mine on Explaining the Microbiome to learn more about a diet that promotes a healthy microbiome.
But know that the best thing you can do to boost SCFA production in your gut is to eat more fiber, which is something you only get from plants!
Specifically, try to incorporate sources of prebiotics and probiotics on a regular basis. Focus on whole/unprocessed fruits, vegetables, legumes, and whole grains (especially make a point to eat beans regularly). Eat both raw and cooked vegetables as this can change what is done with the remnants when they end up in the colon.
Lastly, eat less meat, dairy, and eggs, and oil/fats which have been associated with a more inflammatory microbiome profile.
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