GLOSSARY

Prebiotic Supplement provides a substrate selectively used by host microorganisms with an intended health benefit; tolerance and evidence depend on the actual ingredient.

Probiotic effects depend on the strain, preparation, dose and outcome rather than the word probiotic alone. Prebiotics provide substrates for selected microorganisms, and synbiotic formulations combine components with a defined rationale. Gastrointestinal comfort, immune-related measures and infection outcomes should not be conflated. More organisms or more fermentable substrate is not always better tolerated around exercise. Evaluate the actual product, athlete and symptoms, particularly in medically vulnerable people, while maintaining an adequate varied diet rather than assuming a supplement fixes every gut complaint.

Gut training means practicing the intended food and fluid strategy during suitable training sessions and progressing according to tolerance. Repeated exposure may improve comfort or handling, but symptom improvement does not directly prove increased transporter expression in an individual. Glucose and fructose transport involve different proteins and their adaptation is a specific research question. Record actual intake, conditions and symptoms. A very high intake used successfully by one athlete should not be treated as the starting requirement for everyone.

Exercise changes the distribution and activity of immune cells, but a transient laboratory change does not by itself establish increased infection risk. Sufficient energy, carbohydrate when appropriate, protein and micronutrients support normal immune function. Sleep, travel, exposure and training load also matter. More of an immune-related nutrient is not automatically better, and a supplement cannot guarantee protection from illness. Persistent symptoms require appropriate evaluation rather than being attributed solely to a supposed post-exercise immune window.