Abstract
Vigorous or prolonged exercise poses a challenge to gastrointestinal system
functioning and is associated with digestive symptoms. This narrative review
addresses 1) the potential of dietary supplements to enhance gut function and
reduce exercise-associated gastrointestinal symptoms and 2) strategies for
reducing gastrointestinal-related side effects resulting from popular sports
supplements. Several supplements, including probiotics, glutamine, and bovine
colostrum, have been shown to reduce markers of gastrointestinal damage and
permeability with exercise. Yet the clinical ramifications of these findings are
uncertain, as improvements in symptoms have not been consistently observed.
Among these supplements, probiotics modestly reduced exercise-associated
gastrointestinal symptoms in a few studies, suggesting they are the most
evidenced-based choice for athletes looking to manage such symptoms through
supplementation. Carbohydrate, caffeine, and sodium bicarbonate are
evidence-based supplements that can trigger gastrointestinal symptoms. Using
glucose-fructose mixtures is beneficial when carbohydrate ingestion is high
(>50 g/h) during exercise, and undertaking multiple gut
training sessions prior to competition may also be helpful. Approaches for
preventing caffeine-induced gastrointestinal disturbances include using
low-to-moderate doses (<500 mg) and avoiding/minimizing
exacerbating factors (stress, anxiety, other stimulants, fasting). Adverse
gastrointestinal effects of sodium bicarbonate can be avoided by using
enteric-coated formulations, low doses (0.2 g/kg), or multi-day
loading protocols.
Key words
dietary - digestion - exercise - nutrition - stomach
