GLOSSARY

Nutritional Supplement is a product used in addition to the usual diet for a defined nutritional or sporting purpose. Its category does not establish necessity, efficacy or safety.

A supplement can address a defined nutrient shortfall, provide a convenient sports-food format or target a specific performance mechanism. These purposes require different evidence and assessment. A product is not necessary simply because it is marketed to athletes, and normal training fatigue does not identify a nutrient deficiency. Begin with the athlete's diet, health, training and practical constraints, then define the expected benefit, suitable outcome and stopping or review point before adding a product.

A credible supplement claim needs relevant controlled evidence, an appropriate comparison and a meaningful outcome. Randomization, placebo control and blinding reduce different sources of bias but do not guarantee a useful result. Sample size, uncertainty, training status, sex, diet and protocol affect interpretation. A pooled estimate is not a promise to every individual. Mechanistic plausibility, a changed biomarker, exercise capacity and actual competition performance are distinct levels of information that should not be treated as interchangeable.