Microbiome Dysbiosis

An astronomical number of bacteria live in our guts. The average adult human has been estimated to harbor 38 trillion (3.8 x 10¹³) bacterial cells. Ninety-seven percent of these bacteria inhabit the colon whereas much lower numbers of bacteria are present in the stomach (10⁷ bacteria) and small intestine (10¹¹ bacteria).¹

The gut microbiome is rich and diverse with more than 5000 bacterial species present.² Together these bacteria produce a wealth of molecules as part of their metabolism, e.g. vitamins, nutrients, or neurotransmitters.^{3, 4} Some metabolites are able to penetrate into the intestinal mucosa where they have local effects,^{5, 6} while others enter blood circulation and can affect organs such as the liver, or the brain.^{4, 7}

A close relationship between the diet and the composition of the microbiome determines the types of metabolites being produced in the gut.^{3, 8, 9} The homeostatic relationship between diet, microbiome and host contributes to human well-being and long-term health.^{10, 11, 12, 13}

The natural gut homeostasis may be disturbed resulting in an unbalanced, or dysbiotic microbiome¹⁴ with loss of diversity, keystone species, or pathogenic overgrowth.¹⁵ Ultimately this may have consequences for human health.^{16, 17, 18}

Although the adult microbiome is relatively stable, it is sensitive to lifestyle factors such as diet,⁹ psychological stress,¹⁹ or medication.²⁰ Use of antibiotics may cause severe dysbiosis and the effect on the microbiome may be long-lasting.²¹

Studies have shown that some probiotics may help maintain a healthy balance in the microbiome therefore, reducing the risk of antibiotic associated diarrhea. In these studies, Bifidobacterium, BB-12^® and Lactobacillus acidophilus, LA-5^® demonstrated effectiveness at reducing the duration of this condition.^{22, 23} One mechanism by which BB-12^® and LA-5^® may exert this effect is through their bactericidal action, i.e. the probiotic bacteria compete with harmful bacteria by producing substances that are toxic to the pathogens.^{24, 25} Many probiotics have been shown to produce bioactive molecules with anti-bacterial effects, including BB-12^®,²⁴ LA-5^®,²⁶ Lactobacillus rhamnosus, LGG^®,²⁷ to stimulate the body’s own antibacterial molecules, Lactobacillus paracasei, L. CASEI 431^®,²⁸ to inhibit the adhesion of pathogens to the epithelium, BB-12^®,²⁹ LGG^®,³⁰ Lactobacillus rhamnosus, GR-1^®,³¹ or to displace adhering pathogens, LGG^®.³²


BB-12^®, LA-5^®, LGG^®, L. CASEI 431^®, and GR-1^® are registered trademarks of Chr. Hansen A/S.

The article is provided for informational purposes regarding probiotics and is not meant to suggest that any substance referenced in the article is intended to diagnose, cure, mitigate, treat, or prevent any disease.