Probiotics

Probiotics are a category of live microorganisms which, when administered in adequate amounts, confer a health benefit on the host by selective colonization of the intestinal flora.

For a more in-depth review, see the complete guide to proper nutrition — a fundamental guide from the expert team at Sport Zona.

What is it

Probiotics are defined as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. They are most commonly species of bacteria, such as Lactobacillus and Bifidobacterium, but can also include yeasts. These microorganisms naturally inhabit the human digestive tract, where they form a complex ecosystem known as the gut microbiome.

The gut microbiome plays a central role in the body's metabolic, immune, and protective functions. When the balance of these microorganisms is disrupted – a condition known as dysbiosis – it can lead to various health problems. Probiotics aim to restore and maintain this balance by introducing beneficial strains that can suppress the growth of pathogenic bacteria and support the function of the intestinal lining.

How it works

The mechanism of action of probiotics is multifaceted and depends on the specific strain. It is generally accepted that they exert their effects through several main pathways. Firstly, probiotics can colonize the gut and form a physical barrier that prevents the attachment and proliferation of harmful microorganisms. They also compete with pathogens for nutrients and receptors on intestinal cells.

Additionally, probiotics produce various metabolites, such as short-chain fatty acids (acetate, propionate, butyrate), which are important energy sources for intestinal cells and have anti-inflammatory properties. They also have an immunomodulatory effect, interacting with immune cells in the gut, which can enhance the immune response or reduce excessive inflammation. Some strains also support the production of vitamins (e.g., K and some B vitamins) and enzymes that improve digestion.

Why it's important for athletes

For athletes, especially those undergoing intense training, probiotics can offer significant benefits. Physical stress and high training intensity can lead to temporary immunosuppression and an increased risk of upper respiratory tract infections. Studies show that probiotic intake can reduce the frequency and severity of these infections by maintaining healthy immune function. For example, some data indicate a 25-50% reduction in respiratory infection symptoms in athletes taking probiotics.

In addition to immune support, probiotics can play a role in improving digestion and nutrient absorption, which is critical for recovery and performance. Athletes often have increased energy and nutrient needs, and efficient digestion is essential. By maintaining the gut barrier, probiotics also reduce "leaky gut syndrome" (intestinal permeability), which can result from intense exertion and lead to systemic inflammation and fatigue. Dosage recommendations vary, but are often based on intake of billions of colony-forming units (CFU) per day. The ISSN (International Society of Sports Nutrition) suggests that doses of 10⁹ to 10¹⁰ CFU per day, taken for a period of 4 weeks to 3 months, can be effective in improving gut health and immune function in athletes.

Related concepts

• Postbiotics — These are metabolic products produced by probiotics that provide health benefits, even when the probiotics themselves are not live.
• Prebiotics — These are indigestible dietary components that selectively stimulate the growth and activity of beneficial microorganisms, including probiotics, in the gut.
• Microbiome and Nutrition — This concept encompasses the entire community of microorganisms in the gut and how their balance and function are influenced by diet, including probiotic intake.
• Nutrition for IBS — Probiotics are often used as part of a dietary strategy to alleviate symptoms of Irritable Bowel Syndrome (IBS) due to their capacity to modulate the gut microbiome.