Not all Bacteria are Bad
There are at least a 100 trillion microbes of different species that live in our gastrointestinal (GI) tract, some beneficial and some pathogenic. Probiotics, such as Bifidobacterium and Lactobacillus, are the “good” bacteria in the gut, which have beneficial effects on human health. In the early 1900s, the concept that some microorganisms can replace pathogenic microbes in the gut, and therefore improve the ecosystem in the GI tract and confer other physiological benefits, was first introduced. In recent years, there has been extensive scientific effort to “map” the microbes in the gut and understand their role in many different areas of health, wellness and the prevention of disease. It has been suggested that many degenerative diseases, GI and non-GI related, start in the gut as a result of an altered GI microflora (bacteria) where pathogenic bacteria outnumber and outperform beneficial bacteria. This has been implicated in many GI disorders such as irritable bowel syndrome (IBS), constipation and infectious diarrhea, as well as metabolic conditions including diabetes, and obesity, and also disorders of the liver, immune system and mental health. Probiotics flourish by digesting carbohydrates (prebiotics) that are indigestible by normal human enzymes, in doing so they reduce the growth of the bacteria that promotes GI disorders and disease.
Prebiotics and Your Health
Prebiotics are plant derived fibres which are indigestible by humans and are instead fermented by intestinal microflora. This promotes the growth of the microflora and changes the composition and activity of the GI ecosystem in a beneficial way. When the bacteria in the gut digest and ferment prebiotic fibres, they produce compounds called Short Chain Fatty Acids (SCFAs) such as butyrate, acetate, propionate and lactate. SCFAs play a key role in the body; their functions range from lubricating the GI tract, providing energy to intestinal cells, lowering pH levels (increasing acidity) to reduce the growth of pathogenic bacteria, reducing fat and cholesterol production in the liver, improving intestinal motility to reduce constipation and regulating immunity and inflammation. Prebiotics are a necessary source of energy that the bacteria need to produce these compounds and, without them, pathogenic bacteria have a more hospitable environment in which to grow.
Xylo-oligosaccharide or XOS (z-a:-s) is a prebiotic fibre that promotes bowel regularity and digestive health. XOS is composed of a short chain of carbohydrate units, known as “oligosaccharides,” which are indigestible by humans and, therefore, non-caloric. As a prebiotic, XOS is digested by the microflora found in the intestines where it is highly effective at increasing the growth of beneficial probiotics, especially bifidobacteria, and improving the gut ecosystem to preferentially favour the growth of “good” vs “bad” bacteria. This improvement in gut ecology is beneficial to human health for a number of reasons; it regulates bowel function to prevent and/or relieve constipation and diarrhea, improves metabolic parameters such as reducing fat production in the liver, increases the excretion of cholesterol in the feces, improves nutrient absorption and improves altered gut microflora in type II diabetics. Furthermore, XOS is considered to be a source of dietary fibre, which has benefits for cardiovascular, metabolic, digestive and cellular health amongst its role in promoting bowel regularity.
The Take Home Message
XOS is one of many different prebiotics including fruco-oligosaccharides (FOS), galacto-oligosaccharides (GOS), raffinose and inulin; however, XOS differs from these other prebiotics in a very important way. All prebiotics promote the growth of gut microflora, good and also bad, but XOS selectively promotes the growth of only beneficial microflora, namely bifidobacteria. As the number of beneficial flora increases, they can inhibit the growth of harmful bacteria by competing with them for resources and lowering the pH of the intestines to make it an inhospitable environment for them to live. XOS is considered to be one of the most beneficial prebiotics because it is highly effective at improving the GI ecosystem compared to the other prebiotics.
The Importance of Bifidobacteria
Bifidobacterium species are some of the most abundant types of bacteria in the human colon, They are also found in the vagina and the mouth. Bifidobacterium’s role in gastrointestinal health, and preventing the symptoms of GI disorders, has been well documented. Studies have shown that individuals with inflammatory bowel diseases display abnormal alterations in gut flora (dysbiosis) with reduced “good” bacteria, especially reduced Bifidobacterium. In these individuals, pathogenic bacteria may account for 40% of their gut ecology, a significant factor in inflammation and altered immunity. Reduced Bifidobacterium and increased pathogenic bacteria, such as E.coli, has also been observed in individuals with celiac disease, likely due to carbohydrate restriction, an important source of energy for gut flora. There are numerous strains of bifidobacteria; they have different roles in the body but all preferentially favour XOS over other types of prebiotics.