What are prebiotics? Types and health benefits
Prebiotics are a big topic in nutrition these days. As with probiotics, their relationship with human health has gathered a lot of interest in recent years. Prebiotics are compounds derived from non-digestible carbohydrates that confer health benefits to the host by selectively stimulating the growth of intestinal bacteria.
What are prebiotics?
Prebiotics are non-digestible food ingredients that confer health benefits to the host by selectively stimulating the growth and/or activity of a limited number of our intestinal bacteria [1].
Fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), and trans-galacto-oligosaccharides (TOS) are the most common prebiotics.
Fermentation of prebiotics by gut microbiota produces short-chain fatty acids (SCFAs), such as lactate, butyrate, and propionate. These SCFAs have multiple beneficial effects on the body and gut health, as SCFAs are small enough to enter blood circulation through gut cells.
The difference between probiotics and prebiotics is that, while probiotics are beneficial bacteria, prebiotics are the food for these bacteria. Both are important for human health, but they have different roles. Probiotics are live bacteria and prebiotics are compounds derived from non-digestible carbohydrates –mostly fibre.
Did you know you can combine prebiotics and probiotics to create synbiotic dietary supplements? Read more about that here!
What are the different types of prebiotics?
There are various types of prebiotics. These include:
• Fructans. In this category, we can find inulin and fructo-oligosaccharides (FOS). Several bacterial species can be promoted directly or indirectly by fructans.
• Galacto-oligosaccharides (GOS). GOS can greatly stimulate Bifidobacteria and Lactobacilli, as well as Enterobacteria, Bacteroidetes and Firmicutes to a lesser extent [2].
• Hemicellulose-derived oligosaccharides. These are derived from hemicellulosic macromolecules such as arabinoxylans. Arabinoxylans have demonstrated to produce a strong prebiotic activity, in particular bifidogenic.
• Starch and glucose-derived oligosaccharides. Resistant starch, a type of starch resistant to the upper gut digestion, can stimulate the production of butyrate, a short-chain fatty acid (SCFA) [3]. Polydextrose, a glucose-derived oligosaccharide, can also stimulate Bifidobacteria [4].
• Pectic oligosaccharides (POS). Some oligosaccharides come from a polysaccharide called pectin. This type of oligosaccharide is called pectic oligosaccharide (POS).
• Non-carbohydrate oligosaccharides. Although carbohydrates are more likely to meet the criteria to be considered prebiotics, there are other compounds not classified as carbohydrates, but that can be classified as prebiotics, such as some flavanols [5].
What are the health benefits of prebiotics?
Research shows that prebiotics have several health benefits. These include the following:
• Modulation of the microbiota. Prebiotics provide energy sources to gut microbiota. This way, they are able to modulate the function and composition of these microorganisms [6].
• Modulation of the immune system. SCFAs have multiple benefits in the immune system, such as increasing antibody responses toward viral vaccines, like influenza and measles [7].
• Prevention of colorectal cancer. Fermentation products of probiotics, such as butyrate, have protective effects against the risk of colorectal cancer [8, 9].
• Prevention of necrotizing enterocolitis. Prebiotics can prevent the development of this life-threatening disease in preterm infants [10].
• Decrease the risk of allergic skin diseases. Prebiotics decrease both the risk of development and the severity of atopic dermatitis [11, 12].
• Reduction of the risk of cardiovascular diseases (CVD). Prebiotics are able to lower the risk of CVD by reducing the inflammatory elements, improving lipid profile [7].
• Increase in calcium absorption. Some prebiotics can help increase calcium absorption [13].
How can I add prebiotics to my diet?
Prebiotics play an important role in human health, so it is important to consume them. They can be found in foods that are high in fibre, such as vegetables, fruits, legumes and whole-grain products. Foods that are high in prebiotic fibre include:
• Wheat
• Soybeans
• Oats
• Bananas
• Tomatoes
• Berries
• Asparagus
• Garlic
• Leeks
• Onions
• Chicory
Another option to increase prebiotic intake are supplements. They can be purchased in health food stores and online. They can be found in capsule form, in powder blends or even in bars.
Prebiotics are generally considered safe. They can have some minor side effects, such as diarrhea, bloating and flatulence. However, prebiotics’ chain length is the main parameter related to the development of these side effects.
Prebiotics with a shorter chain length have more side effects because they are fermented earlier and more rapidly, while longer chain prebiotics –such as arabinoxylans from wheat– are fermented later and slower.
