The Difference Between Good and Bad Gut Bacteria

Bacteria is naturally present in many parts of the human body, with a significant proportion present in the gut.^1,2 Have you ever heard the phrase, “All disease begins in the gut,“ often attributed to Hippocrates? While “the gut” can refer to a series of organs in the digestive system, the large intestine is a good place to focus this discussion. It houses a complex ecosystem of microorganisms, mostly bacteria, as well as nutrients and different cells that interact with each other to maintain a healthy, balanced environment conducive for the body’s vital functions.³ Growing scientific evidence supports that these gut bacteria are supportive in nature. They are important for gut health but may also have far-reaching impact on general wellness.*

The Difference Between Good and Bad Bacteria

Bacteria usually have a bad reputation as they are often associated with infection or illness. The gut stores both “good” bacteria and “bad” bacteria. As the name suggests, good bacteria in the body are bacteria that are known to have a positive impact on health. Bad bacteria can exist in human bodies at low levels without causing much harm. However, an imbalance between the good and bad bacteria may contribute to negative consequences.⁴ This imbalance may be attributed to many factors including age, diet, medications, and presence of an infection or illness.

More About Probiotics: The Good Bacteria

The relationship between gut bacteria and health has led to increased research interest in probiotics. Probiotics are referred to as the live strains of good bacteria that when given in adequate amounts confer health benefits.*^5,6 This differs from prebiotics and postbiotics. Prebiotics are a nondigestible food ingredient, often fibers, that promote the growth of beneficial microorganisms in the intestines.* The term “postbiotic” is intended to replace previously used terms (paraprobiotics, parapsychobiotics, heat-killed probiotics, non-viable probiotics, ghost probiotics, metabiotics, bacterial lysates). To be called a postbiotic, an ingredient should be produced from a characterized, inanimate microorganism and have documented clinical evidence of a health benefit.⁷

Probiotics exert their effects and colonize usually in the gastrointestinal tract, where they may influence the intestinal microbial environment.*⁸ The mechanisms may vary widely among the different strains and probiotic supplements. Both Bifidobacteria⁹ and Lactobacilli¹⁰ are types of healthy bacteria that function in the gut and have potential health benefits.*

Specific Strains and Evidence

As each strain may act and function differently, it is important to understand the role of specific strains. Manipulation of the gut flora through probiotic intervention may be an approach to influence stress and mood.* Research suggests that probiotic strains of Lactobacilli, such as Lactobacillus paracasei Lpc-37®, may be associated with a healthy stress response.*¹¹ On the other hand, Bifidobacterium lactis HN019™, a probiotic strain from the genus Bifidobacteria, may positively influence health by supporting immune*¹² and gastrointestinal function.*¹³ Furthermore, a study suggested that Bifidobacterium lactis BL-04® strain may support respiratory health .*¹⁴

Additionally, there is growing scientific interest in understanding the long-term use of multi-strain probiotic supplements to manage regularity and gastrointestinal discomfort. One review article found 11 studies meeting internal criteria. Eight of those studies used multi-strain probiotic blends and three studies used a mono-strain probiotic. Investigators concluded there was a trend that “beneficial effects were more distinct in the trials using multi-strain supplements with an intervention of eight weeks or more.” *¹⁵ That conclusion seems to provide preliminary guidance unless patient-selection criteria and the use of a single strain of probiotic is specifically indicated.

The field of probiotics has advanced considerably in recent years, and it continues to be the focus point of on-going research. However, we are at a point where clinicians can feel comfortable with certain strains and blends for specific patient needs.

REFERENCES

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