• Dr. Wendy Dahl, University of Florida
Simply put, microbiota are bacteria that live in the human digestive system (gut). Another term used to describe them is intestinal microflora. These bacteria are very active little creatures! They are living organisms and have an active metabolism, and can process and change substances that enter the digestive system. For instance, certain gut bacteria make vitamin K, which your body will absorb. Gut bacteria will ferment sugar, fibre and protein from food. (Fermenting, a chemical reaction, changes an organic substance into a simpler substance.)
Probiotics (a type of microbiota) are live micro-organisms that live in the human digestive system. Bifido bacteria and lactic acid bacteria are two of these healthy micro-organisms. Probiotic bacteria create lactic acid and other acids as by-products of substances that enter the gut. Lactic acid makes the gut more acidic, protecting the body. A more acid environment in the gut hampers pathogens (substances that cause disease).
Probiotic bacteria also make other acids like acetate, propionate and butyrate. These acids are like food or fuel for the bacteria in the gut. The fuel helps probiotic bacteria to thrive and increase in number. What’s more, the acids fuel actual intestinal cells as well. Intestinal cells digest and absorb nutrients, creating a barrier so that unwanted substances are not absorbed into the system. When these cells are properly fuelled, they are stronger and healthier. They create a healthy intestinal wall and do their job better. The risk of allergies is reduced, and there is also less inflammation of the intestine.
Prebiotics are undigested food ingredients that help the host by encouraging the growth of healthy bacteria. How do prebiotics fit in with microbiota? Well, prebiotics are food that probiotic bacteria use to grow and multiply. Probiotic bacteria ferment (or process) probiotic foods to make the healthy acetate, propionate and butyrate. The strongest evidence for health benefits has been found for butyrate - sometimes called an ‘anti-cancer’ substance.
What happens in the gut if there are no prebiotic substances available? Consider a diet low in prebiotics and high in meat protein. In this case, the gut bacteria will busily ferment undigested food parts, producing substances like ammonia, amines, and phenols. These substances make the gut less acidic. Since the environment is less favourable for probiotic bacteria, other possibly less healthy types of bacteria will take over. This is linked with a less healthy intestinal wall, more inflammation, and a higher risk of disease. Not to mention there is fouler-smelling gas made!
Research suggests that prebiotics may:
Dr. Dahl’s double-blind study involving college students suggests probiotics may ease cold and flu symptoms. The experiment group was given a specific prebiotic supplement (galacto-oligosaccaride made from lactose). This group reported lower cold and flu symptom intensity, and a fewer average number of days that they really felt sick.
Research in prebiotics, probiotics and health is also being done in the area of mental health. Recent studies have considered effects related to the treatment of depression and anxiety disorders, but the jury is still out on this.
You can include foods in your diet that contain pre and probiotics.
It is interesting that human breast milk naturally contains a prebiotic called human milk oligosaccharide. This has been called the ‘original prebiotic’ and is beneficial for breastfed infants.
Certainly, many health benefits discussed here are not absolutely proven at this time. However, including many of these prebiotic foods and foods that contain probiotics in the diet can do no harm. Consume a variety of fruits and vegetables, whole grains, legumes, and fermented dairy products. These foods are packed with nutrients and fibre to support health in other ways. If the theories on the helpful effects on human health and disease prevention prove true, you will receive double health bang for your buck!