“Active probiotics”. This phrase can be found in large print on nearly every yogurt container at the grocery store. They are also found in fermented products, such as kimchi, pickled vegetables, kefir, sauerkraut, and kombucha. With probiotics being so widely advertised and sold, it can be assumed that probiotics are not bad for you. However, it is not always made clear what exactly “probiotics” are and why they can be good for you.
Probiotics are live microorganisms that, when consumed, can be beneficial to gut health and your gut microbiome [1]. The gut microbiome is ideally a harmonious and friendly community of bacteria that live in your gut, however it is easy to accidentally interrupt the balance by various diet and exercise habits or even by taking certain medicines. In a larger sense, the body is like one big microbiome, with specific balances that have to be maintained to function properly. A couple examples of how this microbiome can be thrown off is taking antibiotics, which kill off some of the good bacteria or consuming too much sugar, leading to an overgrowth of specific bacteria and unwanted side effects of that. Probiotics are often introduced as a natural way to attempt to restore the harmonious balance or maintain its health. While they are generally beneficial for most people, it is important to be aware there can be negative side effects and take into consideration the whole picture of health before using supplemental probiotics. Some of these side effects will be discussed later in this article.
First, an explanation of a few specific ways that probiotics work in your body. Probiotic species are living, thus are able to compete with viruses or pathogens for nutrients and space on receptors in the body. They also stimulate the immune system, leading to a more prepared defense when bad bacteria or pathogens enter the body. Probiotics have also been shown to have some success in combating viral infections, stopping their reproduction or severing the virus's attachment to your body. They have also been successful in treating a range of digestive diseases such as IBD and diarrhea and many types of general infections [4].
In an experimental study with human subjects testing intestinal transit time or the time that it takes for food to travel from mouth to excretion, it was found that while probiotics showed moderate improvement in most individuals overall, there was specific improvement in subjects with constipation [1]. Intestinal transit time was used as a measure because it can be a good indicator of good gut health. Another study found probiotics to be successful in preventing the insulin resistance caused by high-fat diets common in the US and other places throughout the world, which also leads to a lower incidence of type 2 diabetes [2].
While these are great benefits, it is not advisable to over-consume probiotics as a way to maximize these benefits. Probiotics, as with many other things, are good in moderation and can be dangerous in excess. While the bacteria that make up probiotics have been previously referred to as “good”, the same rule applies. Too much of these bacteria can lead to many unfavorable and possibly life-threatening effects, such as antibacterial resistance, diarrhea, inflammation, blood poisoning, and sepsis [3]. These symptoms have also arisen more commonly in at-risk populations, such as cancer patients or people with certain infections.Thus, it is important to keep in mind the overall picture of health and consult a doctor if needed.
Despite all those scary symptoms listed above, realistically, it is not likely that a cup of yogurt in the morning or a kombucha every once in a while will make the average person sick. The amount of probiotics that are safe beneficial may differ from person to person, so it is important to be mindful of what you are putting in your body, apply common sense, and consult a professional if you are unsure about adding something to your diet.
References
[1] E. Miller et. al. 2016. World Journal of Gastroenterology. Contemporary meta-analysis of short-term probiotic consumption on gastrointestinal transit. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4886388/.
[2] Carl. J Hulston et.al. 2015. British Journal of Nutrition. Probiotic supplementation prevents high-fat, overfeeding-induced insulin resistance in human subjects. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/probiotic-supplementation-prevents-highfat-overfeedinginduced-insulin-resistance-in-human-subjects/5D1FA04446458C03DC71C5E5FE2EB705
[3] Damini Kothari et.al. 2019. Biomedicine & Pharmacotherapy Volume 111. Probiotic supplements might not be universally-effective and safe: A review. https://www.sciencedirect.com/science/article/pii/S0753332218345657.
[4] Abdolmajid Ghasemian et. al. 2018. Medical Microbiology. Probiotics and their increasing importance in human health and infection control. https://www.researchgate.net/profile/Majid-Eslami/publication/328000395_Probiotics_and_their_increasing_importance_in_human_health_and_infection_control/links/5bbbaebca6fdcc9552d9a122/Probiotics-and-their-increasing-importance-in-human-health-and-infection-control.pdf
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