Probiotics and immune system: how are they related? Your gut does a lot more than just digest your dinner. Your digestive tract is also home to most of your body’s immune defenses: roughly 70% of your immune system exists in and along your digestive tract. Even the gut itself is an important part of your immune function: it acts as a barrier wall to keep invaders out of your bloodstream1. So keeping the gut healthy goes a long way in ensuring a healthy immune system. Bacteria and your immune system The trillions of bacteria living in your gut are constantly interacting with your digestive and immune systems1,2. Gut microbes are an important factor in how our immune systems develop from birth; research tells us that animals without gut bacteria have a very different immune response than ones with a normal gut environment1,3. How can something so tiny have such a huge impact? It’s because in order to survive in the body, our gut microbiome has developed sophisticated ways of communicating with their world. Gut bacteria are able to protect gut health by fighting off bad bacteria, which they do by competing for space and resources, in addition to making substances like bacteriocins that kill off harmful bugs2. As part of their normal metabolism, some gut bacteria create metabolites such as short chain fatty acids that can decrease damaging inflammation, alter production of immune cells or strengthen the immune defense barrier1,2,5. If gut bacteria can do all this, can a probiotic do the same? How do probiotics work? Probiotics are beneficial bacteria, often part of the natural human gut microbiome, that have the power to influence our health2.Probiotic bacteria can be found in small amounts in probiotic beverages, probiotic tea, and other fermented probiotic foods. What are probiotic foods? These are foods with living organisms in it and when eaten, it may help support your immune system and gut. Some of these foods are: Yogurt Sauerkraut Kombucha Kefir Kimchi Tempeh Miso Some Cheeses Pickles Olives Apple Cider Vinegar You can also find higher doses (typically in the billions of live bacteria) in probiotic supplement form. The benefits can be maximized when you know when is the best time to take probiotics. Research has found that different types of probiotic strain like the Lactobacillus rhamnosus can influence the health of the human gut and immune systems, acting much like our own resident bacteria do2,3. For example, Bio-K+ probiotic capsules have been shown to effectively fight off the bacteria that contribute to antibiotic-associated diarrhea, as well as C-diff-associated diarrhea4. Research has also shown potential for probiotics to have a positive impact on the immune system function, whether by creating a stronger gut barrier, increasing beneficial immune cells, or even decreasing the risk of cold and seasonal flu2,3,5. How to choose an effective, science-based probiotic While the science of probiotics is promising, this does not mean that all probiotics will be effective. There is a big gulf between what is happening in the research and what you find on store shelves. Many products on the market do not conduct any clinical research, meaning that you can’t be sure that what you are buying is effective. What’s more, because probiotics are living organisms, each probiotic strain – or combination of strains – may have different potential effects. You can’t take the research on one probiotic and apply it to another. It can make choosing a probiotic feel a bit overwhelming – but it doesn’t have to be. Instead, tools like the Clinical Guide to Probiotics (www.usprobioticguide.com) help take the guesswork out of choosing a probiotic. The guide outlines which probiotics have evidence to support their use, and which uses they are best suited for. Our gut bacteria play an important role in our digestive and immune health. While there is much more to learn about how probiotics influence our health, there is great potential for probiotics to become an integral part of our self-care habits so always be sure to talk to your doctor, pharmacist, or dietitian about whether probiotics are right for you. Sources: Interaction between the gut microbiome and mucosal immune system - PMC (nih.gov) https://www.karger.com/Article/FullText/496426 Intestinal dysbiosis and probiotic applications in autoimmune diseases - PMC (nih.gov) https://pubmed.ncbi.nlm.nih.gov/20145608/ Probiotics for preventing acute upper respiratory tract infections - Hao, Q - 2015 | Cochrane Library
