How it works
Probiotics are live bacteria or yeasts that, in adequate amounts, may benefit the host. They interact with the gut microbiome, the lining of the intestine and the immune system, which is closely connected to the gut. Heavy training, travel and stress can affect gut and immune function. Specific strains have been studied for reducing upper respiratory tract infections, gastrointestinal symptoms during endurance events and antibiotic-associated diarrhoea. Benefits from one strain cannot be assumed for another.
What research supports
- Certain strains may reduce the number or duration of upper respiratory tract infections
- May reduce traveller's diarrhoea and antibiotic-associated diarrhoea with specific strains
- May reduce gastrointestinal symptoms in some endurance athletes
- Direct effects on performance are not established
Dosage
Doses are measured in colony-forming units (CFU), typically around 1–10 billion CFU per day or more, depending on the strain. Use the strain and dose that has been tested for the outcome you care about.
Timing
Daily intake is used in research, often for at least 2–4 weeks before a period of heavy training, travel or competition. Some products should be taken with food; follow the label.
Side effects
- Temporary gas or bloating in the first days
Cautions
- People who are immunocompromised, critically ill or have central venous catheters should not use probiotics without medical advice due to rare infection risks
- Product quality varies; viable counts may be lower than labelled by the end of shelf life
- Trial new products well before competition
- Athletes subject to anti-doping rules should only use products certified by an independent third-party testing program for banned substances; certification lowers, but does not eliminate, the risk of contamination.
Food sources
Yoghurt with live cultures, Kefir, Sauerkraut (unpasteurised), Kimchi, Miso, Tempeh.