Evidence for the benefits of maintaining adequate levels of good bacteria in the gut has been mounting. Beyond using the good bacteria to remedy digestive issues like bloating, gas and diarrhea, additional benefits of microflora are emerging. Specifically, prebiotics and probiotics may aid in weight management via several mechanisms. To achieve a proper balance of digestive flora, probiotics and prebiotics are necessary, as well as important lifestyle factors.
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Defining the "Biotics"
Probiotics are beneficial, live microorganisms that inhabit the digestive tract. Common strains of good bacteria, or probiotics, used in supplements include Bifidobacteria and Lactobacilli. Specific required species and optimal concentrations have not been determined; however, probiotic mixtures of multiple strains appear to be more efficacious than single strains, according to a review published in the "European Journal of Nutrition" in January 2011. The authors concluded that health outcomes relating to such conditions as irritable bowel syndrome, respiratory tract infections and immune function were more positive when probiotic mixtures were used rather than single strains. Probiotics can most easily be obtained through yogurt, supplements and specific functional food items.
Prebiotics are nondigestible food ingredients that stimulate growth and activity of probiotics in the gut by serving as energy sources. These include food components such as fructo-oligosaccharides and inulin, found in plants such as artichokes, bananas, chicory root, onions, wheat and barley.
Probiotics in Relation to Obesity
Since gut microbiota modulate the digestive tract and weight is largely affected by how many calories are absorbed in the digestive process, it makes intuitive sense that gut flora and weight are interrelated. A large proportion of the gut flora of those who are obese include organisms of the Firmicutes phylum, whereas lean individuals have a smaller portion of these bacteria. Firmicutes contain enzymes that enable the individual to digest and absorb otherwise indigestible dietary components, thus increasing calorie absorption. In a study published in "Nature" in December 2006, when microbiota rich in Firmicutes from obese mice were transferred to lean mice, the lean mice gained weight. The results of the study support the theory that the composition of gut flora can directly affect weight.
Soluble Fiber and Satiety
Prebiotics assist with weight management in two main ways, facilitating the proliferation of probiotics and increasing feelings of satiety after dietary consumption. Prebiotics and probiotics work synergistically, which is why they are often combined in supplements. Without prebiotics, probiotics would not flourish and harmful bacteria would predominate, ultimately impairing the immune system and vitality. Prebiotics consist of soluble fiber found in plants. They absorb water to form a gel, which results in slower transit time through the gut. This contributes to feelings of fullness, without the extra calories, making them an important asset in weight management.
Maintaining Gut Balance
Both physical and emotional stress can alter the balance of good and bad bacteria in the gut. It is important to engage in stress management therapies such as yoga, meditation and exercise to help maintain an appropriate balance. Marathon trainers and other intense athletes may inadvertently alter their microflora due to elevated levels of stress hormones produced by excessive exercise, contributing to suppression of the immune system and increasing susceptibility to illnesses. This is known as exercise-induced immune suppression and is thought to be a main cause of upper respiratory infections in those undergoing intense training, discussed in a 2007 issue of "Sports Medicine." Overuse of antibiotics has also been identified as contributing to the disruption of natural gut flora. Authors of a study published in "Gut" in January 2011 noted an alarming positive correlation between courses of antibiotics and the rate of inflammatory bowel disease among children. Inflammation is the most basic response to altered immune function and thus a commonality among problems involving microbiota imbalances.