Photo courtesy of CDC on Unsplash
When you hear of the words titled above most people think yoghurt and pills. This is pretty accurate in a sense of where they come from but from my recent conversations I have noticed that there is a lack of depth in understanding. For some they’re able to reason out that prebiotics are in foods that we eat to give food to the bacteria in our gut, and that probiotics are live bacteria that is consumed. For good reason this is where most people’s knowledge stops. During my studies of microbiology I was exposed to many classes in which we were able to look at bacterial populations in rats and animal models (often not human for ethical reasons), and we were able to look at the role that having certain kinds of bacteria plays in human health. The classic example is the F/B ratio, or the firmicutes to Bacteroidetes ratio, in which these two phyla (of bacteria can often predict the health of the individual. Association is the most robust claim we can make as studying human gut microbiome’s tend to become either very invasive and unethical or weak in prescription. There is a general association with obesity and a high ratio of firmicutes which again is most likely the best strength of evidence available (still could be later disputed and shouldn’t be seen as absolute truth). Prebiotics are all fibers but not all fibers are prebiotic: fiber generally refers to carbohydrates that your body is unable to digest. Some fiber can be broken down by bacteria in which these would be prebiotics and depending on the food source these would encourage or discourage the growth of kinds of bacteria like Firmicutes or Bacteroidetes. Bacteria are able to break down the carbs that we aren’t able to if they have access to the necessary enzymes for that carbohydrate. Now little is understood exactly how certain populations of bacteria tend to impose benefits to our body though, we do know what populations do impose benefits. There is a myriad of research I don’t know all too well (and I’m sure many of it has been further clarified or improved upon), but what I am able to assert is that in order for a bacteria, hopefully a beneficial bacteria, to get into your gut it has to go through a few steps first. Most of these steps we can remember from our high school biology days when talking about anatomy and physiology. The bacteria must survive a pH of about 7.5 in the mouth to about 1.5-2 in the stomach and back to 8 again in the duodenum. This large range of pH is difficult for bacteria to survive, and as such there are a problems with simply eating good bacteria. The question is: will the good bacteria even survive? The answer is often no, but we have a few tricks available for those that are in need of some gut recolonization. The first is kind of surprising and yes the headline is accurate.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6475090/ : Fecal Microbiota Transplantation for Recurrent Clostridium difficile Infection and Other Conditions in Children: A Joint Position Paper From the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition.
That is correct, there has been studies (and current ones too, the above paper is from 2019) on the affects that a fecal transplant has on gut health, that is taking a healthy individuals fecal matter and giving it to someone who has a poor microbiota; such as the case with Chron’s disease. I still remember the day my professor started talking about the potential benefits for some people of a “poop smoothie”, gross I know but kind of fascinating and interesting too. Because most of what is left in fecal matter is indigestible the bacteria are able to cling onto the indigestible surface and survive the digestive system, making their way to the colon where they are able to recolonize the gut. The second and perhaps less obscure is simply by having Enteric Coated capsules. Enteric coatings are used for many medication that would be denatured by stomach acid and likewise we can use this same technology to encapsulate bacteria that would benefit us but would normal die to our stomach acid. Unfortunately the poop smoothie won’t be making an appearance on the pharmacist’s toolbelt.
Lets try to summarize by looking at some popular methods people try to get their prebiotics and probiotics from. Plant based food: this is a great source of prebiotics and can concur many other great benefits. Fermented foods, like suarkraut and fermented dairy: most likely these food are going to be beneficial for your health but we are just learning about this now, they’re incredibly hard to study as they span the difficult task of maintaining your study sample to eat certain foods as well as the very poor means of examining a participants gut microbiome. Let’s just say they’re not going to hurt you so why not, but we may find in a few years yet that they’re unable to establish a change in the gut microbiome.
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