Probiotic supplements are used to replenish the "good bacteria" that normally reside in your intestines and help digest the food you eat. However, for all those who didn't know this before, whenever you take antibiotics, inordinate amounts of alcohol or any number of other ways, you can actually "kill off" much of the normal "good bacteria" in your intestines.
Over the years, it has been discovered that by taking the opposite of antibiotics, which are called probiotics, people can actually reduce the number and length of infections suffered by them. This has recently been proven for long-distance runners.
It's long been known that strenuous training can adversely affect the immune system and make athletes vulnerable to coughs and colds, but, recently, a study has shown that taking probiotics can cut those colds to less than half the time that runners show symptoms.
The study used 20 top-level endurance runners during an intensive winter training period. All 20 took a courses of probiotic supplement pills for the entire period -- one tablet contained the bacterium Lactobacillus fermentum (the probiotic), and the other containing no active ingredients (called a placebo).
There were a total of 72 days in which people taking the placebo pills complained of cough or cold symptoms, compared to only 30 days for those taking the probiotics. This is one study that points to the fact that probiotics can help your body get over and stay free of colds and coughs.
Sources:
BBC News February 14, 2008B
British Journal of Sports Medicine February 13, 2008