Prebiotics

Prebiotics are a nutritional component that selectively stimulates the growth of beneficial intestinal bacteria using fiber.

For a comprehensive overview, see the complete guide to proper nutrition — a pillar guide from the expert team at Sport Zona.

What It Is

Prebiotics are a type of indigestible nutritional component, most commonly fiber, that pass unchanged through the upper digestive tract and reach the colon. There, they serve as a substrate for fermentation by specific strains of beneficial bacteria known as probiotics. This selective fermentation is a key characteristic that distinguishes prebiotics from regular fiber, as they purposefully nourish microorganisms that contribute to human health.

Chemically speaking, prebiotics include various types of carbohydrates, such as fructans (e.g., inulin and fructooligosaccharides - FOS) and galactooligosaccharides (GOS), but also some polyphenols and other indigestible components. These compounds possess specific molecular structures that make them resistant to enzymatic breakdown in the human stomach and small intestine, but at the same time easily metabolizable by certain groups of gut bacteria, such as Bifidobacterium and Lactobacillus.

It is important to distinguish prebiotics from probiotics. While probiotics are live microorganisms that are directly consumed to colonize the gut, prebiotics are the "food" for these microorganisms. Their function is to create a favorable environment for the growth and activity of the beneficial bacteria already present in the gut microbiome or those additionally consumed as probiotics. This synergistic action is often referred to as a "synbiotic" effect when a prebiotic and probiotic are consumed together.

How It Works

The mechanism of action of prebiotics is based on their ability to favorably alter the composition and function of the gut microbiome. After reaching the colon, they undergo fermentation by anaerobic bacteria. The result of this fermentation is the production of short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate.

These SCFAs play a crucial role in maintaining gut and overall body health. Butyrate, for example, is a primary energy source for enterocytes (intestinal lining cells) and is key to maintaining the integrity of the intestinal barrier. Propionate and acetate can influence glucose and fat metabolism, as well as have systemic effects on appetite and immune function. Furthermore, the fermentation of prebiotics leads to a decrease in pH in the colon, which inhibits the growth of pathogenic bacteria and further favors the proliferation of beneficial microorganisms.

Important effects include:

• Stimulating the growth of beneficial bacteria, such as Bifidobacterium and Lactobacillus.
• Production of short-chain fatty acids (SCFAs) that nourish intestinal cells.
• Lowering the pH in the gut, which inhibits the growth of harmful bacteria.
• Improving the absorption of certain minerals, such as calcium and magnesium.

Why It's Important for Athletes

For athletes, optimizing the gut microbiome through prebiotics offers a range of potential benefits that can directly impact performance, recovery, and overall health. The physical stress of intense training can disrupt the balance of gut microflora, leading to conditions like "leaky gut syndrome" and increased susceptibility to infections. By supporting the growth of beneficial bacteria, prebiotics can help restore the intestinal barrier, reducing inflammation and the risk of stress-related issues.

Improved nutrient absorption is another key aspect for athletes. By optimizing gut function and increasing microflora diversity, prebiotics can enhance the absorption of macro- and micronutrients, which is essential for energy metabolism, muscle function, and recovery. For instance, some studies show better absorption of calcium and magnesium in the presence of prebiotics, minerals critical for bone health and muscle contractions. Typical intake of prebiotic fiber, according to various research data, ranges between 3 to 10 grams daily to achieve beneficial effects on the microbiome. For active athletes, the upper limit of this range may be considered, but always in the context of individual tolerance and total fiber intake, which for adults is around 25-30 grams per day. The recommendations of the ISSN (International Society of Sports Nutrition) also highlight the potential of commonly consumed prebiotic fibers to support athlete health and performance, although specific dosages for prebiotics separate from total fiber intake are lacking.

Last but not least, immune modulation is an important benefit. Approximately 70% of the immune system is located in the gut. By improving the gut microbiome, prebiotics can enhance the immune response, reducing the frequency and severity of upper respiratory tract infections, which are a common problem for athletes during periods of intense training. This allows for greater consistency in the training process and reduces recovery time from illness.

Related Concepts

• Probiotics — Live microorganisms that are often consumed along with prebiotics, as they serve as "food" for probiotics.
• Microbiome and Nutrition — Prebiotics are an essential part of nutrition that directly impacts the composition and function of the gut microbiome.
• Postbiotics — End products of prebiotic metabolism by gut bacteria, which also have beneficial effects.
• Nutrition for IBS — Prebiotics can play a role in dietary strategies to manage Irritable Bowel Syndrome symptoms by modulating gut microflora.