For elite athletes–who always stretch limits– heat stress can interrupt workouts, cause sickness or even be deadly. Runners cross a finish line only to vomit or collapse onto a stretcher. World-class swimmers struggle in water that proves dangerously warm.
Excess heat—caused either by outside temperatures or the metabolic fire within—stresses the body, blunting performance. Heat-stressed athletes often endure what is termed “leaky gut”, a condition where the intestinal lining becomes more permeable, allowing infections to take hold.
Leaky gut opens the door to problems:
- more chances of infections like cold and flu
- increased inflammation
- more symptoms of distress including diarrhea, nausea and vomiting
- tissue repair slows
- performance suffers
Of course, athletes of the elite type will tolerate all sorts of physical ailments to win, but when performance is part of the downside, motivation steps up to find the source of the problem and possibly treat or even better, prevent it. Many athletes are turning to probiotics to prevent leaky gut and in turn some of its ill-effects.
Is there any evidence that probiotics may be useful in leaky gut?
Some research indicates that specific probiotic strains may reduce upper respiratory tract infections in athletes. In one study, 84 highly active individuals were randomized to receive either a strain of Lactobacillus casei or placebo daily for 16 weeks. Those on placebo experienced 36% more upper respiratory infections for one or more weeks.
Another study reported in the British Journal of Sports Medicine found that probiotics given over a 4-month period to 20 healthy elite male distance runners reduced days of respiratory symptoms by half.
This one suggests a boost in gastrointestinal integrity:
A small unpublished study conducted on 12 male runners suggested that heat stress during training made the gut more permeable. It also demonstrated that a high-dose, multi-strain probiotic may reduce this intestinal “leakiness”.
And in a 2013 report from University of Otago in New Zealand, probiotic supplementation reduced the duration and incidence of infections but not severity in elite rugby players.
Sports nutrition will likely be focussing more on gut health in the future.