A consensus panel convened by the International Scientific Association of Probiotics and Prebiotics (ISAPP) in 2001 defined probiotics as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Probiotics comprise many different types of microbes, with the most common strains belonging to the Lactobacilli and Bifidobacteria species. It is important, therefore, to remember that they are described by their genus, species and strain designations. Using the example of one well-studied probiotic, Lactobacillus rhamnosus GG, Lactobacillus is the genus, rhamnosus is the species and GG is the strain designation. All three components are necessary to identify a probiotic.
The most common fermented foods that naturally contain probiotics or have probiotics added to them include yoghurt, kefir, kombucha, sauerkraut (fermented cabbage), pickles, miso, tempeh, kimchi, sourdough bread and some cheeses. Also, probiotics are available commercially in tablets, capsule form, as a powder (added to drinks) and probiotic-enriched chews. Probiotics supplementation helps gastrointestinal function, reduces the muscle damage in exercise and increases recovery after exercise.
A diet high in simple sugars and refined carbohydrates is known to feed potentially harmful bacteria and yeast in the gut as well as decrease the number of good bacteria, so it should be avoided where possible, or consumption kept to directly before, during or after training. To boost the number of probiotics, it is important to consume prebiotics, which are defined as substances that induce the growth or activity of microorganisms that potentially contribute to the well-being of their host.
Prebiotics can be found in bran sources, raw foods (chicory root, dandelion greens, raw garlic, leek, onion, asparagus and banana). The following are potential food sources: tomatoes, artichokes, asparagus, berries, onions, green vegetables, legumes, as well as oats, linseed, barley and wheat. Some artificially produced prebiotics are, among others, lactulose, galactooligosaccharides, fructooligosaccharides, maltooligosaccharides, cyclodextrins, and lactosaccharose. Lactulose constitutes a significant part of produced oligosaccharides (as much as 40%). Fructans, such as inulin and oligofructose, are believed to be the most used and effective in relation to many species of probiotics.
There are many ways and circumstances in which probiotics can be of benefit to athletes. They can increase the number of beneficial gut microflora, help support a healthy gut lining and boost immunity. The mechanisms of actions are through the reduction of luminal pH, competition with pathogens (disease-causing microbes) for colonisation sites and nutritional sources, production of antimicrobial substances, toxin inactivation and immune stimulation.
The health of the gut flora can impact on how athletes are able to cope with levels of stress during training and competitions. Preventing illness during heavy training and competition is a high priority for athletes, coaches and exercise scientists. Some athletes, especially elite athletes undertaking prolonged, intense exercise, may suffer from an increased incidence of upper respiratory tract illness during heavy training and competition, which is often the result of exercise-induced immunosuppression.
Clinical evidence is mounting to support the role of probiotic intervention to modulate the gut microflora in reducing anxiety and stress responses, as well as improving mood in those who suffer from irritable bowel syndrome-type symptoms, such as abdominal pains, cramping and urgent bowel movements. People doing high-intensity exercise often experience gastrointestinal discomfort, such as abdominal pain, diarrhoea, vomiting and abdominal cramps, which affect performance by forcing athletes to reduce the intensity at which they exercise, or to stop exercising altogether.
Healthy bacteria level is important for optimal immune and digestive function in athletes. Beneficial bacteria can help to break down foods, aid absorption of nutrients and supplements and reduce uncomfortable symptoms of bloating that can affect performance.
Efficient protein utilisation is necessary to ensure regular bowel movements for those athletes who need to increase their daily protein intake. Also, B vitamins are essential for energy production in every cell in the body. As water-soluble vitamins, they are only present in the body for a short time after consumption of certain foods. To ensure a constant supply of energy, a healthy gut microflora works to support B vitamin product to retain adequate levels of energy and prevent fatigue. In addition, gut microbiota plays an important role in the maintenance of proper hydration during exercise and in the prevention of inflammatory responses, especially in the case of endurance athletes who are more susceptible to dehydration because of increased fluid loss from sweating for prolonged periods of training.
Dr Sa’eed Bawa is a Senior Lecturer, Human Nutrition and Dietetics at the University of the West Indies and a Registered Dietitian and Nutritionist.
Dr Marquitta Webb is a Lecturer, Human Nutrition and Dietetics at the University of the West Indies and a Registered Dietitian and Licensed Nutritionist.
