Prebiotics – fuel for the microbiome

A healthy digestion is fundamental to the health of the whole body. There are billions of bacteria in our digestive system, and more precisely in the intestines. Many of these bacteria, which are called probiotics, are necessary and highly beneficial. Probiotics are involved in the final and very important phase of digestion – they protect the body against pathogens by creating metabolic conditions that inhibit their growth, they aid in the synthesis of some vitamins B and vitamin K, and are central to the normal functioning of the immune system. Beside beneficial bacteria, the intestines also house harmful ones. In fact, it is the balance between beneficial and harmful bacteria that determines the function of the digestive system, and thus health in general.

Numerous factors can disturb this balance, such as stress, a poor and unbalanced diet, physical and mental exhaustion, chronic medical conditions and fever, and, not to be overlooked, the use of medicines, especially antibiotics. This can cause an increase in “bad” bacteria, leading in turn to a number of health issues, including diarrhoea, constipation, bloating, vitamin and mineral deficiencies due to limited intestinal absorption, and a weakened immune system. This triggers inflammatory processes, compromises the integrity of the intestinal mucosa, making it permeable to harmful substances, which in turn leads to metabolic problems. In other words, intestinal microbiota are constantly undergoing transformation and need to be replenished on a regular basis. Prebiotics, or nourishment for beneficial bacteria, can be of great help. 

Prebiotics are indigestible food components that stimulate the growth and activity of beneficial microorganisms in the gut. Prebiotics consist mainly of fibre and oligosaccharides, complex carbohydrates that the body is not able to digest. They travel through the small intestine undigested and reach the large intestine, where they are fermented by beneficial bacteria.

Prebiotics are a class of nutrients that are broken down by the gut microbiota. Their link to overall health has attracted increasing interest in recent years. They can provide food for the gut microbiota, and their breakdown products are short-chain fatty acids that are released into the bloodstream, affecting not only the digestive tract, but also other organs.

Although some endogenous factors, such as the secretion of mucin, can affect the microbial balance, diet is the main source of energy for their growth. Indigestible carbohydrates in particular can significantly alter the composition and functioning of the gut microbiota. Beneficial gut microbes ferment these indigestible substances in foods, called prebiotics, and obtain energy for their survival by breaking down the indigestible bonds of prebiotics. Prebiotics can thus affect the gut microbiota selectively. In turn, this influences intestinal functions such as metabolism.

The concept of prebiotics was introduced in 1995 by Glenn Gibson and Marcel Roberfroid. They defined a prebiotic as “a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health”. This definition has remained almost unchanged for more than 15 years. Under it, only a few carbohydrate compounds can be classified as prebiotics, such as short- and long-chain β-fructans (fructooligosaccharides and inulin), lactulose, and galactooligosaccharides.

At the 6th meeting of the International Scientific Association for Probiotics and Prebiotics (ISAPP) in 2008, the category of “dietary prebiotics” was defined as “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health”.

Mechanisms of prebiotic action

Since prebiotics provide sources of energy for the gut microbiota, they can modulate the composition and activity of these microorganisms. The breakdown products of prebiotics are mainly SCFAs (short-chain fatty acids). These molecules are small enough to diffuse through intestinal enterocytes and pass into the bloodstream. Prebiotics therefore affect not only the digestive tract, but also other organs and systems in the body.

By fermenting prebiotics, beneficial bacteria produce short-chain fatty acids (SCFAs) such as butyrate, acetate and propionate. These fatty acids have a number of health benefits:

• Improved digestion: SCFAs stimulate intestinal peristalsis, help regulate digestion, and prevent constipation.
• Improved immune system function: SCFAs strengthen the intestinal barrier and stimulate the production of immune cells.
• Reduced inflammation: SCFA have anti-inflammatory properties and may help reduce the risk of chronic diseases.
• Improved mineral absorption: SCFAs promote the absorption of calcium, magnesium, and other minerals.
• Blood sugar level regulation: SCFAs can help improve insulin sensitivity and regulate blood sugar levels.

Sources of prebiotics

Prebiotics can be found in a variety of foods, including:

• Fruits and vegetables: onions, garlic, leeks, artichokes, bananas, apples.
• Wholegrain cereals: oats, barley, rye.
• Legumes: beans, lentils, chickpeas.
• Chicory root: rich in inulin, a type of prebiotic.
• Honey

The importance of prebiotics for health

Consuming prebiotics regularly is essential for maintaining a healthy gut microflora and overall health. Prebiotics can help with:

• Preventing and treating digestive disorders (irritable bowel syndrome, inflammatory bowel disease).
• Strengthening the immune system and reducing the risk of infections.
• Reducing the risk of chronic diseases (type 2 diabetes, cardiovascular diseases, some types of cancer).
• Improving mental health (research shows a link between the gut microbiota and mental health).

Prebiotics are an important part of a balanced diet and are key to maintaining a healthy gut and overall health. By including a variety of foods rich in prebiotics in your diet, you will feed the good bacteria and improve your health.

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