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What are you feeding your bacteria?

While probiotics get most of the press, prebiotics arguably have more potential for altering one’s microbiome. This study looks at a promising type of prebiotic supplement to see if it might impact appetite and inflammation.

Study under review: a-Galacto-oligosaccharides Dose-Dependently Reduce Appetite and Decrease Inflammation in Overweight Adults


While it is generally acknowledged that fiber is good for us, different benefits[1] come from different types of fiber. For example, viscous fibers (which have the ability to thicken or form gels when mixed with fluids) improve blood sugar control[2]. Fermentable fibers can act as prebiotics and lead to favorable changes in the gut microbiota, in turn regulating appetite[3] and food intake. But what in the world is a prebiotic?

The increasing awareness of probiotics and the importance of having healthy gut bacteria has been followed by an interest in prebiotics, which are foods for the bacteria in our gut. Specifically, a dietary prebiotic is a carbohydrate compound that resists digestion in the upper GI tract and is then fermented by the gut microflora in the colon. Prebiotics confer health benefits by causing specific changes in the composition and/or activity of the gastrointestinal microbiota.

One of the many different types of prebiotics are alpha galacto-oligosaccharides (a-GOS, pictured in Figure 1), which are made up of two to eight galactose units (galactose is a common dietary sugar and makes up half of the disaccharide lactose). They have not been studied nearly as much as other prebiotics, like inulin or fructooligosaccharides, but the prebiotic actions of a-GOS have shown benefits in animals[4] and humans[5]. The impact of oligosaccharides on the gut microbiome can be affected by a number of factors, including the dosage[6] and degree of polymerization[7] (i.e. the specific chemical configuration).

Figure 1: Structure of a-GOS

With all of that in mind, this study was designed to determine if a-GOS could reduce appetite, food intake, and inflammation in overweight but otherwise healthy participants.

Prebiotics are specific types of fiber that resist digestion in the upper GI tract and are fermented by microflora of the lower intestine, and in particular selectively feed bacteria potentially associated with health and well-being. One type of prebiotic with the potential to regulate food intake are alpha galacto-oligosaccharides (a-GOS).

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